Palaeobotanical-palaeoecological studies of tropical high Andean peatbog sections - Kuhry 1988 by JPZ.

DISSERTATIONES BOTANIC!E BAN DI1 6

Pa lae o botanical-palaeoecological stu die s of tro pic al high An de an pe atb og sec tio ns (Cordillera Or ien tal , Colombia) by PET ER KU HRY

J . CR AM ER in der Gebri ldcr Born uaege r Verla gsbuc hhan dlung

BER LIN Â· ST UT TG AR T 1988

T 11

Contents

CONTENTS PART I: GENERAL INTRODUCTION

1. Introducing the subject

2. Present climate and vegetation of the study area Introduction Present climate Present vegetation Zonal vegetation types Azonal vegetatio n types Human influence on the vegetation cover Taxonomical notes

16 16 18 18 18 28 32 33

3. Material and methods

34 34 35 35 38

Field work and preparatory work Preparation of the samples in the laboratory Microfossil and macrofossil analyses Daring of the sections PART II: RESULTS 4. Paramo de Laguna Verde: the PLV I and PL V II sections Introduction Geoecology of the area Palynological and macrobotanical analyses of the PLV I section Zonation of the regional vegetation diagram Subdivision of the local vegetation diagram Palynological analysis of the PL V II section Zonation of the regional vegetation diagram Subdivision of the local vegetation diagram Dating of the PL V I and II sections, and inferred calculations 14 C datings Regional pollen influx data and pollen density time scales Interpretation of the data of the PLV I section Regional vegetation development Local vegetation development Interpretation of the data of the PLV II section Regional vegetation development Local vegetation development Conclusions and discussion 5. Paramo de Peiia Negra: the PPN I section Introduction Geoecology of the area Some physico-chemical properties of the PPN I section Palynological and macrobotanical analyses of the PPN I section Zonation of the regional vegetation diagram Subdivision of the local vegetation diagram Dating of the PPN I section, and inferred calculations 14C darings Regional pollen influx data and pollen density time scale Sediment accumulation rate, net organic production and C/N quotient of the local vegetational phases Interpretation of the data of the PPN I section Regional vegetation development Local vegetation development

40 40 40 46 49 49 51 52 52 52 57 57 57 58 58 59 60 60 60 61 64 64 65

72 72 77

79 79 79 80 82 82

Palaeobotanical-palaeoecological studies

Sedimentation rate, primary organic production and primary decomposition Conclusions and discussion

6. Paramo de Agua Blanca: the P AB II and PAB ill sections Introduction Geoecology of the area • Palynological and macrobotanical analyses of the PAB II section Zonation of the regional vegetation diagram Subdivision of the local vegetation diagram Palynological and macrobotanical analyses of the P AB ill section Zonation of the regional vegetation diagram Subdivision of the local vegetation diagram . Dating of the PAB II and PAB ill sections, and inferred calculations 14 C datings Regional pollen influx data and pollen density time scales Interpretation of the data of the P AB II section Regional vegetation development Local vegetation development Interpretation of the data of the PAB ill section Regional vegetation development Local vegetation development Conclusions and discussion PART ill: GENERAL CONCLUSIONS

84 85 89 89 90 99 99 99 100 100 101 102 102 102 104 104 110 110 110 111 112115

7. Introduction

115

8. Synopsis of the palynological data in the study area

122

9. Conclusions and correlations Late Quaternary geoecological history of the study area The Fuquene stadia! ("' 22,500 to "' 14,000 yr BP) The 'Early' Late Glacial period("' 14,000 to"' 12,400 yr BP) The 'Late' Late Glacial and Earliest Holocene period("' 12,400 to"' 9,500 yr BP) The Holocene period("' 9,500 to 0 yr BP) Exogenous causes of vegetational changes

125 125 125 125 126 126 128

PART IV: DESCRIPTIONS AND ILLUSTRATIONS OF MICROFOSSILS AND MACROFOSSILS

144

10. Microfossil descriptions Pollen types Fungal types Algal types Fern spore types Bryophytic types Zoological types

144 144 147 149 150 150 151

11. Macrofossil descriptions Plant remains of cormophytes Plant remains of bryophytes · Plant remains of lichens Fruits and seeds Other macrobotanical remains Some zoological macrofossils

152 152 153 . 156 156 159 161

Contents

12. Microfossil plates

163

13. Macrofossil plates

181

ACKNOWLEDGEMENTS

221

REFERENCES

222

SUMMARY

227

SAMENVATTING

230

RESUMEN

234

MICROFOSSIL INDEX

238

MACROFOSSIL INDEX

240

Palaeobotanical-palaeoecological studies

3. MATERIAL AND METHODS

Material and methods

especially mention Hooghiemstra ( 1984) who gave complete descriptions of pollen and spores of almost all palynologically recognizable zonal and azonal plant taxa common m the study area.

Field work and preparatory work

Preparation of the samples in the laboratory

In 1982, the author had his base at the Instituto de Ciencias Naturales of the Universidad Nacional in Bogota, Colombia. For the present study, a good working knowledge of the Andean flora, especially of species common in the azonal paramo vegetation types, was indispensable. In absence of a Âˇcomprehensive floristic treatise for the study area, this knowledge was acquired by examination of collectio~s of the Herbario N~cional. at the Instituto de Ciencias Naturales in Bogota and in short field tnps to the paramo regiOns With staff and students of the above mentioned institute. In the field, the collection of the studied sections occurred in various ways. A first method was. to dig a hole in the boggy depressions and to clean one of the exposed faces after which the secnon was taken from the cleaned proflle by cutting out large pieces of material, ca 15cm deep x ca 15cm broad x 40-50cm long. A second method applied was the handboring with Dachnovsky samplers. With the small Dachnovsky sampler the sediment was sampled in cores of 25cm length and 2.5cm diameter; with the larger one the cores had a length of 50cm and a diameter of Scm. All the collected material was stored in plastic bags and transported to the Hugo de Vries Laboratory, Department of Palynology and Paleo/Actuo-ecology, University of Amsterdam; The Netherlands. In the areas where the sections were collected the following observations and collections were made:

At the Hugo de Vries Laboratory in Amsterdam, the lithological sequences of the studied sections were carefully examined and stratigraphical columns were drawn. . Samples for the microfossil and the m~crofossil analyses were .taken at ~onstant mtervals. In the cases that the collec;tion of the secuons was earned out wtth the atd of a Dachnovsky sampler, nearly all individual cores were compressed. F~r ~e collection of the actual samples to be analyzed every core was regarded as representing ongmally a length of 25 or 50cm and the sample distances were taken by ratio. . . For the preparation of the microfossil samp!es a known vo!~me of matenal was treated wtth a boiling 10% aqueous KOH solution (peaty sediments) or a bo1ling 10% aqueous Na4Pp7 .10~0 solution (clayey sediments) for deflocculation, followed by. acetolysis (Erdtm~n. 1952) and a gravity separation by means of a bromoform-alcohol nuxtu~e (spec. gravity 2). Tablets containing exotic pollen grains of Eucalyp,tus. were added tn ord.er to de.ten~une pollen concentrations in the sediment (see below). The restdues were mounted m glycenne Jelly. Samples for the analysis of macroscopi~al plant remains we~e taken at the same intervals as the microfossil samples.: For the preparation of the macrofossil samples a known volume of matenal was treated with a gently boiling 5% aqueous KOH solution for defloccul~t!on and subsequently cleaned of fine debris by rinsing through a 175 J..lrTl sieve. The remam s were temporarily stored in serued plastic bags. A large number of samples were collected for 14C dating. These samples we~e.dated at the 14C Laboratory of the University of Groningen. the Netherlands, under the superviSion of Prof. Dr. W.G. Mook.

a) Geology and geomorphology of the area with the assistance of Mrs. K.F. Helmens, who also made ge.omorphological maps on the basis of aerial photographs and field observations. b) Topographical and climatological aspects. Elevation was determined with a Thommen altimeter and checked on topographical maps (I : 25,000) obtained from the Instituto Geogratico "Agustin Codazzi" in Bogota. c) Records of the floristic components and the distribution of the zonal vegetation belts in the area. 1( d). Description of the local azonal vegetation types, with special attention to the hydroseral zonauon. The distribution of the azonal vegetation types was studied along a transect from the central part to the boggy margins of the depressions where the sections were collected. The cover-abundance values of all taxa present in the local vegetation zones were estimated and expressed in the scale of Braun-Blanquet (in Mueller-Dombois & Ellenberg, 1974; pp. 59-60) . .2.,H was~ed in the top moss layer and in the sediment at a depth of 25-75cm. A detailed observation of the local vegetation stand near the bonng site was also made. . e~ Copection of unkn~wn az~mal and zonal taxa reference numbers Kuhry et al., 1-423) for 1dennficanon a~ the Herbano Nac10n m ogota, ~ e~e IS matena as also been deposited. f) Collection of azonal taxa for the comptlauon of a reference collection of recent macro botanical material. No specialized literature is available concerning morphological and' anatomical characters of macr?scopical parts of azonal plant taxa common in the study area that can fossilize. For the tdenllficaoon of the macroscopical plant remains found in the analyzed sections it was essential to make a reference collection of significant pans of these plant taxa. At flfst, a list was made of co~ophytes and bryophytes that are common in aquatic, reedswamp, mire, peatbog and cushton bog communities in the high Andean areas of the Colombian Cordillera Oriental based on own field observ~tions and .liter~ture (Cleef, ~981). The n:ference ~ollection was compiled by the author at the Insntuto de C1enctas Naturales m Bogota w1th matenal of own fie ld collections and of the Herbario Nacional and completed, in 1983, with material of the Herbarium of the University of Utrecht, The Netherlands. The collection is built up of macroscopical parts which are known to be able to fossilize from similar palaeobotanical studies in NW-Europe ~e.g. Van Ge~I, 1978; Kuhry, 1985). It contains macroscopical parts of cormophytes such as flowers, fruitS, leaves, branches, seeds, megaspores and slides of leaf, stem and root epidermis and bryophytes, including mosses and liverworts. For the identification of microfossils a reference collection of recent pollen and spores was already available at the Hugo de Vries Laboratory in Amsterdam. This collection is rather ex.haustiv~ as far as subandean, Andean and paramo taxa are concerned. A large number of mtcrofosstl types have already been desoribed in earlier "Ublicarions. In this sense we m ay

Microfossil and macrofossil analyses The microfossil analysis of the slides was carried out with the aid of a Leitz microscope, magnification x400 and x lOOO. Microfossil countings were generally co~tinued until the arboreal pollen sum had reached a minimum value of at least I 00. The frequenctes of pollen, spores and other microfossils recorded during the microfossil analysis were calculated as percentages of the arboreal pollen sum. Microfossil types, with the exception of some useful indicator taxa, found in fewe r than three spectra and fewer than five times in one sectio n, were not recorded separately in the diagrams. . . . The results of the microfossil analysis of a section are expressed tn a regiOnal vegetauon diagram that includes a general diagram and a l?Cal vc:getation dia~m. . . . In the conventional general diagram used m earher palynolog1cal stud1es tn the Colomb1~n Andes, four groups of pollen taxa are distinguished ~hat reflect as clearly ~s poss1ble the mam composition of the regional vegetation in terms of alntudinal belts (see secuon 2). These groups are given in Table I. Vander Hammen & Gonzalez (1960) already remarked that peatbog sections, contrary to lake sections, yield regional diagrams strongly influenced by the presence of ~<?me taxa (e.g. Gramineae) in the successive local stands of vegetation. In order to get additiOnal data for correlating peatbog and lake sections they drew regional diagrams based only on the sum of forest elements. Most of the elements which are representative for the zonal subparamo and grass paramo vegetation belts may also be abundantly present .in the local az<?nal par.amo vegetation. types involved in the present study. Species of Gramtneae, Composnae, Encaceae, H ypencum, Aragoa and Arcyrophy//um are of frequent occurrence in paramo r;nire. and peatbog vegeta.tion types (see section 2) and are indeed found in the actual local vegetanon m the boggy depress1ons where the sections were collected (see Table V, Table VIII and Table Xli). Macroscopic remains of Gramineae, Compositae, Ericaceae and/or Hypericum were found at several levels in all analyzed sections, giving irrefutable evi~ence of the l?Ca} gro"':th of t~~se taxa in the azonal vegetation types. The presence of these remams m~stly cmnctded wtth positive fluctuations in the pollen t::urves of the taxa. Therefore, the changes tn these pollen curves seem to be partly of local instead of regional origin.

Palaeobotanical-palaeoecological studies

TABLE I. Groups of pollen taxa in a conventional general diagram.

------------------..--------------------------------------------------------------------·--------------------·----Lower tropicalsubandean elements

Subandean-Andean elements (cont.)

Subandean-Andean elements (con t.)

Acalypha Alchornea Cecropia

Abatia

Alnus Dodonaea Eucalyptus Pinus

Urticales excl. Cecropia

Croton Elaeagia-type Heliocarpus Hieronima Vismia Salix Subandean-Andean elements

Quercus Billia Podocarpus Juglans Styloceras Viburnum

Melastornataceae Solanaceae

Hedyosmum Ra.panea Clusia Brunelli a Weinmannia Bocconia Ternstroemia Clethra Gaiadendron Macrocarpea

Hesperomeles Myrica I lex Oreopanax Eugenia Vallea Xylosma

Subparamo elements

Sericotheca Polylepis -Acaena Escallonia Cornpositae tub. Ericaceae

Hypericum Aragoa Arcyt ophyllum Grass paramo elements Gramineae

-----------------------------------------------------------------------------------·-----------------------------The arboreal elements never played any role in the local vegetation types. For that reason, in order to obtain correlable information on the regional vegetation changes devoid of local inf1uences, the author preferred for the present study an arboreal pollen sum. In general dia~am 1, four groups of arboreal pollen sum taxa are distinguished that express as clearly as posstble the main composition of the forest vegetation in terms of altitudinal belts (see se~tion 2). Th~ diagn?stic value of these groups is also confirmed by the composition of the actual pollen ram m the dtfferent zonal forest belts (Grabandt, 1980; Melief, 1985). The groups are given in Table II. TABLE II. Groups of arboreal pollen sum taxa in general diagram 1.

-----------------·------ ---------------------------------------------------------- .. ------------------------------Lower tropicalsubandean elements

(Upper) Andean elements

(Upper) Andean elements (cont.).

Acalypha Alchornea Cecropia

Podocarpus Juglans Styloceras Viburnum · Abatia

Hesperomeles Solanaceae (558) I lex Oreopanax Eugenia Val lea Xylosma Alnus Dodonaea Eucalyptus Pinus

Urticales excl. Cecropia

Croton Elaeagia-type Heliocarpus Hieronima Vismia Salix

Melastomataceae Solanaceae excl. 558

Hedyosmum Rapanea Clusia Brunelli a Weinmannia

Upper subandean-lower Andean elements Quercus

Billia

Bocconia Ternstroemia Clethra Gaia dendron Macrocarpea

Subparamo elements

Myrica Sericotheca Polylepis-Acaena Es callonia

- -- -------- ------------------- .... .... ---------------------------------- --- .. ------------------------ .... ----------------

II I '

I I

I i

Material and methods

Many of the arboreal taxa mentioned in Table ll are not restricted to a single altitudinal zone. Clusia, Eugenia, Rapanea, Melastomataceae, Solanaceae, Urticales excl. Cecropia and, to a less extent, Brunellia, Hedyosmum, Myrica and Oreopanax have a broad altitudinal distribution. Nevertheless, they are more abundantly present, both in terms of quantitative composition of the plant cover and of the pollen rain, in the altitudinal zones mentioned above. For instance, Urricales excl. Cecropia, which includes representatives of the Moraceae, Ulmaceae and Urticaceae, are present from the lower tropical belt to the paramo belt. The arboreal taxa (e.g. Boehmeria, Celtis, Chlorophora, Coussapoa, Ficus, Myriocarpa, Trema, Urera ), however, are almost completely confined to the lower tropical and subandean belts, and only low herbaceous taxa (e.g. Parietaria, Pilea, Urtica) are found in !'he Andean and paramo belts. T he arboreal taxa are reasonably good pollen producers (Melief, 1985), contrary to the herbaceous taxa which seem to contribute in an insignificant way to the regional pollen rain. In the regional vegetation diagram, beside the general diagram 1 separate curves are drawn for all identified taxa, both those included and those excluded from the arboreal pollen sum, that are indicative of the regional vegetation development. This diagram includes the arboreal pollen sum taxa, non-arboreal regional pollen taxa and regional fern spore taxa. The microfossil types of the local vegetation diagram are used to reconstruct, in combination with the data of the macrofossil record, the local .vegetation development. This diagram includes non-arboreal pol:en taxa, fern spore taxa, bryophytic spore taxa, algal spore taxa, fungal taxa and zoological taxa, which are all excluded from the pollen sum and considered to be partly or exciusive1y of local origin. Descriptions and illustrations of some useful indicator taxa and of newly recogn ized microfossil types are given separately in part IV. The macroscopic plant remains were studied with the aid of a Leitz stereomicroscope, magnification x6-25. The determination of some remains, such as small seeds, epidermal remains and bryophytes, was carried out with the aid of the microscope, magnification x 100 and x250. For the macrofossil analysis of the samples, macrobotanical remains were counted (seeds, leaves, etc.) or alternatively assessed as volume percentages (epidermal remains, bryophytes, rootlets, etc.) of the sample used. Countings were recalculated on the basis of a constant sample volume. Rootlets represent the vast majority of the undeterminable remains in the samples. Their volume percentages are not given separately in the macrofossil diagram of the sectio ns. The often very low volume percentages of detenninable remains indicate that rootlets frequently form a major constituent of the plant tissue remains found in the analyzed sections. The results of the macrofossil analysis are expressed in the local vegetation diagram and are used to reconstruct, in combination with the microfoss il record, the loca l vegetation development. Descriptions and illustrations of all macrofossil types found in the analyzed sections are given separately in part IV. The microfossil and macrofossil diagrams were plotted on a HP-87 microcomputer-plotter. The computer programs for handling and ploning the data were developed by Melief & Wijmstra (1984) and De Vries & Wijmstra (1986). The regional vegetation diagram and the local vegetation diagram of the analyzed sections have been zoned independently, the zone systems being intended for local use only. The zoQation of the regional vegetation diagram· is based on major c hanges in the representation of the groups in general diagram 1. Subzones are additionally distinguished on the basis of fluctuations in the curves of the individual taxa, the pollen production rates of these taxa (Grabandt 1980; Melief 1985) being taken into account. The zones are indicated by arabic cy pher symbols and are numbered from bottom to top; subzones are indicated by letter sym bols. Evidence for regional vegetational and climatic change is deduced from fluc tuations in the representation of the altitudinal arboreal groups and the individual tree taxa which are interpreted in terms of shifting arboreal belts and changing floristic composition of forests. Especially, the representation of low pollen producing trees (e.g. Hesperomeles, Polylepis, Rapanea , Weinmannia, Solanaceae) has been used as an indication for the distance of the forest belt to the site where the sections were collected. In the description and interpretation of the (s ub)zones a somewhat simplified nomenclature of taxa and altitudinal arboreal groups has been used. The subdivision of the local vegetation diagram js primarily based on the macrofossil record. On the basis of fluctuations in the representation of the local vegetation elements, a sequence of local phases, indicated by capital letter symbols and also named from bottom to top, has been distinguished. Evidence for local endogenous processes and regional climatic changes is

Palaeobotanical-palaeoecological studies

deduced from the sequence of local phases, which is interpreted in terms of successive local plant communities. In the description and interpretation of these local phases a so~ewhat simplified nomenclature of taxa and synsystematic units has been used. In part lli of this publication, a summary of the palaeoecological data obtained in the study area and a synthesis of the vegetational development in the area, over approximately the last 24,000 years, are presented. Simplified diagrams of the most imponant palynological records are provided. In these diagrams, general diagram 2 has a conventional (sometimes) simplified group composition. It provides very useful information on regional vegetation development when the analyzed sediments have been deposited in an open water facies and local vegetational influences are negligible (see above). The conventional composition of the groups in general diagram 2 is given in Table I. The simplified conventional composition of the groups in general diagram 2 is given in Table III. The regional "zonal" arboreal vegetation development is illustrated by means of general diagram 3, which includes groups of selected arboreal taxa that are representative for the different zonal forest belts. The composition of these groups is given in Table IV. Separate curves of the arboreal taxa mentioned in Table IV and of useful regional indicator taxa of humidity (Alnus) and of aridity/erosion/human influence (Dodonaea) are also provided. TABLE III. Simplified groups of pollen taxa in general diagram 2. Lower tropicalsubandean elements

Subandean-Andean elements (cont . )

Acalypha Alchornea Cecr opia Urticales excl . Cecropia

Myri ca Alnus Dodonaea Subparamo elements

Subandean-Andean elements Quercus Podocarpus Hedyosmum Rapanea Weinmannia

Polylepis-Acaena Compositae t ub. Grass paramo elements Grarnineae

TABLE IV. Groups of selected arboreal pollen taxa in general diagram 3. Lower tropicalsubandean elements

Acalypha Alchornea Cecropia Upper subandean - lowe r Andean elements

Quercus

(Upper) Andean elements

P.odocarpus Hedyosmum Rapa.nea

Weinmannia

Subparamo elements

Myrica Poly1 epi s - Acaena

Dating of the sections The dating of the analyzed sections is primarily based on the radiocarbon age determinations. In all sections the conventional radiocarbon ages have been used. A first reason is that in this way an easier correlation with previously published palynological records is possible. A second

Material and methods

is that corrections are not possible for the older 1"C datings (Early Holocene and Late Glacial periods) obtained from the sections. Additionally, indirect time calculations were carried out by means of a method based on pollen concentrations in the sediment as recently developed by Middeldorp (1984). If cenain conditions are fulfilled, the method proved to be much more reliable than the approximate time calculations based on the simple assumption that the rate of sediment deposition between any two 14 C datings is constant. The pollen concentration numbers were obtained by adding tablets containing exotic pollen grains of Eucalyptus to the microfossil samples of known volume. The number of pollen grains of Eucalyptus per tablet is of 13,550 Âą 210. The pollen concentration calculations are based only on the elements included in the arboreal pollen sum, because the pollen supply of the local vegetation elements is too highly subjected to local vegetational changes. The number of pollen grains of elements included in the pollen sum per cm3 of material was calculated as follows: number of pollen grains of pollen sum elements per cm3 of material

number of added pollen number of grains of Eucalyptus counted pollen x ------------------------------ x -------------sum elements number of counted pollen volume of grains of Eucalyptus sample used

Pollen concentrations are given as the number of pollen grains o f elements included in the pollen sum per cml of material (P.cm-l); a pollen concentration curve of pollen sum elements is given for each section. On the basis of the pollen concentration numbers, cumulative pollen concentration curves were calculated staning from the base of the sections. In these curves, the original pollen concentration numbers have been multiplied with a factor corresponding with the sample interval of the microfossil analysis. This on the assumption that the pollen concentration calculated for each sample is representative for the whole interval it represents. Knowing the total number of pollen grains accumulated in a section and the time-span in which the sediment deposition of the corresponding section took place, the average annual pollen influx of pollen sum elements over the whole section, given in pollen grains per year per cm 2 (P.yr 1.cm- 2), can be calculated. Naturally, this calculation can also be carried out between each pair of radiocarbon dates, knowing the total of accumulated pollen grains and the corresponding time-span for that particular interval. Assuming a constant pollen influx of pollen sum elements, the changes in pollen concentration numbers are a function of the rate of sediment deposition . As a consequence, the number of years covered by each sample can be calculated. In this way a detailed "pollen density" time scale can be obtained for each section and shon time variations in the rate of sedi ment deposition could be detected within centimeters. Otherwise these changes are not registrated by the 14 C datings which lie too far apart. The condition of a constant pollen influx of pollen sum elements has to be proven for each section separately. Pollen supply of the forest vegetation is the primary factor influencing the pollen influx. Changes in the floristic composition of the arboreal vegetation, like replacement of low pollen producing trees by high pollen producing ones or vice versa, may influence the pollen influx. Likewise, increasing/decreasing distances of the forests to the sedon sites and increasing/decreasing areas occupied by forest vegetation may lead to changes in the pollen supply. Beside these regional factors there are also local factors influencing pollen infl ux data, such as sediment focusing processes (Davis et al., 1984), hiatuses in the sedimen tation, corrosion of pollen grains during/after deposition and differential pollen deposition between micro-habitats (e.g. hummock vs hollow). In each case these possible errors have to be evaluated before results are interpreted.

. 45

Para mo de Laguna Verde

II secti on is given in Fig. 9. Seve ral addit ional drillings were carried out in orde bottom of the depression. r to trace the

~~ J!jl

PLV I (3625m)

::::

:::::

100

150

200

250

300 ~ ~ ~-

6 ""'

350

__..,. 6 â&#x20AC;˘

Fig. 8. Stratigraphical column of the PL

pea 1

g y t t 1a

lig,H cr

du.ktr l tfh I t I

dlf llt t

cIa y

o:::D

peal comp onen t

E3 D

clay comp onent

It t iliff

I ~

sand comp onent

grave I comp onent

Oiatom eae comp onent

wa ter I aye r

VI section (Paramo de Lagu na Verde).

For the microfossil analysis of the PL was taken at intervals of ca 5cm. Polle V I section a known volume of material (range l -4cm l) n sum values range between 107-144. In section, lcm3 of material was collected at intervals of 5 or lOcm. Pollen sum value the PLY II By adding tablets containing exotic polle s are 76-1 38. n grains of Eucalyprus polle n conc entra sediment could be established. tions in the Samp les for the macrofossil analysis were taken on ly in the PL V I secti depths as the microfossil samples. The volume of the samples was of 4-18 cm3 on, at the same â&#x20AC;˘ The countings in the macrofossil analysis were recalculat ed on the basis of a constant sample volu me of !Ocm A total of seven samples were taken for 14C dating, five in the PLV I secti on (see Fig. J. two in the PL V II section (s~e Fig. 9). 8) and

2 Palaeobotanical-palaeoecological studies

Pliramo de Laguna Verde

Subd ivisio n of the local vegetation diagr am (Fig. 14a-c ) Local phase A (350-300cm) PlV II- section

F.!""'~

Elati ne seeds, Jsoetes megaspores and Chara ceae oospo res are found in large quantities. Tillaea and Juncus seeds are abundant. In the microfossil analysis, Isoetes is very abund ant. Algae (Botryococ cus and Pediastrum ) are also prominent.

peat and

bedrock

~ w i th soil

The very pale clay deposit at this level is very rich in Diatomeae, but contained only very few other microfossils. These data have therefore not been used for the diagr am. In the macrofossil analysis, Isoetes mega spore s are foll11d in large quantities. Local phase B (300-250cm1

PLV I - section

~lac us trine

deposit with mo ss layer

z - - l l - . . - d ___ lL--- -- - - Vegetat ion types

- - b I c -- - - - -- - - - - ' ' - a -

a) submerged lsoiu s p ~l meri- Drep•n ocladu s vegeut ion Elatin~ - Jvn cus ecu1do riensis r eeds wamp

c) Sph1gn um· Xyris acu t ifolia peatbog d) A rag o• abieti na dwarf scrub z 1 zonal Espele t il - C1fam1Jgrostis e lfus. grass paramo vegetat ion

Fig. 11. Hydroseral zonat ion of the local (Paramo de Laguna Verde). The borin g sites vegetation types in the st;nall lak~ u~der study of the PLV I and PL V II secuons are rnd1cated.

1 Jvncus ecuado ritmsis 1 Puy11 S4ntosi i 2 Eleochaos mauos tachya 8 SphtJgn um cyclo phyllum 3 £Iarine sp. 9 S. sect. Cuspid lta 4 Xyns acu tilot;.a

O.Sm

S Aragoa abunina

10 S. magella nicum

6 Perntu ya p rostrat3

11 Bteuteli a sp.

12 Campy/ opus sp. 13 Rtcntd ia

Local phase C (250-235cm) . Macroscopic remains of Sphagnum eyclophyllu m, Drep anocladus fluita ns and Campy/opus becom e more frequent. Seeds of Ti/lae a and Calli trich e, cf. Vacc inium and Puya are Elatine are very abundant. Seeds of Juncus, cf. found . Polyp odiale s spora ngia and leafle ts are prom inent. Leav es of Hypericum goyan esii and Elatine are found. The quantities of Isoete megaspores and Characeae oospores decrease. s Tillaea pollen is relatively well represented. The I soetes curve show s a tendency to decrease. Gaeumannomyces cf. caricis attains high perce ntages. Local phase D (235-193cm) In the macr ofoss il recor d, Spha gnum Campy/opus remains are very abundant. Seedscyclo phyl! um , Drep anoc ladus jluita ns and of Hypericum goyanesii and Elatine are prom of Elatine, cf. Vaccinium and Puya, and leaves inent. Seeds of Juncus, Tillaea, Gentiana sedifo /ia and Care x cf. bonplandii, leaves of VacciniumJ At the end of the phase Ranuncu/us seeds are Pernettya and calyptrae of Musci are also found. very frequent. In the micro fossil record, Tillaea and abundantly represented, as is fungal type 562.Puya attain relati vely high value s. Gram mitis is Local phase E (193-152cm) Cype racea e basal leaf sheaths are abundant. remains of Pleurozium schreberi and Breutelia In the lower part of the phase, macroscopic bonplandii is best represented. Xyris seeds are chrysea are found. Amon g the seeds, Carex cf. present. Cyperaceae pollen and Grammitis spores reach high values. Fungal types 562, 563, 564 and 565 are well represented.

sp.

Local phase F (152-22cm)

t t 1/ tl

Macroscopic remai ns of cf. Juncaceae, Drepa nocladus jluita ns, Rhacocarpus purpurascens and Sphag num mage llanic um are very abund ant. Chorisodo ntium speci osum and Campy/opu cucu l/atij olius remai ns are occas ionall y s frequent. Care x cj. bonp landi i seeds are represented. Juncus seeds are found in small well quantities. In the micro fossil recor d, the polle n curve s of Cype racea e, Gram ineae , Erica ceae, Hypericum, Areytophyllum and Valeriana attain (relatively) high percentages. Among the funga types, espec ially Antho stome l/afue giana reach l es very high values. At the end of the phase Aragoa curve shows a clear rise. the

••

to s/toltJ 12

1it 3

Local phase G (22-0cm) Fig. 12. Detail of the local stand of vegetation near the

boring site of the PLY I section.

At first, macro scopic remains of Sphag num remains of Campy/opu s (including C. cucullatifo mage llanic um are very abund ant. Later on, lius), Breutelia allionii, Kurzia verrucosa and

Palaeobotanical-palaeoecological

studies

52 - . u

Riccardia hansmeyeri beco me prom branches are found throughout the inen t Xyris seeds, Vaccinium/Pernettya leaves and Ericaceae whole zone. In the microfossils diagram, show max ima in the low er part Puya, Xyris, Aragoa, Grammitis, SphagnumÂˇ and Ericaceae of fungal, bryophytic and zoological the phas e, as does Gra min eae in the upp er part. Several types also show maxima.

Palynological a nalysis or the PL V II section Zon atio n of the regi ona l vege tatio n diag ram (Fig. 15) Zone 1 (99-83cm) The subandean-Andean group (Qu ercus) is relatively well repr esen group attains a high representatio ted. The uppe r Andean n, especially due to high percenta Alnus. ges of the azonal element Zon e 2 (83-63cm) The values of the tropical-suba (Qu ercu s) is well repr esen ted. ndean group are increasing. The subandean-Andean group Am ong the upper And ean elem Podocarpus are high, those of Hed ents , the perc enta ges of yosm are relatively low. Dodonaea appears. um and Weinmannia tend to increase and those of Alnus em

Zone 3 (63-0cm) The representation of the tropicalsubandean group shows a tendency upper Andean group, the zonal elem ents are constantly well represented. to increase. Within the Subzone 3a (63-43cm) Hedyosmum and Weinmannia are well represented. The curve of Mel increase . Alnu s attains relatively high percentages. Dodonaea and Cheno-Aastomataceae tends to Sub zone 3b (43-23cm) ms are present. The percentages of Hedyosmum, Wein man nia and Mel asto matacea Rap ane a tend to increase. The curve of Alnu s drops tow ards lowe are high, while thos e of represented. Dodonaea and Cheno-A values. Myri ca is well ms are pres ent. Subzone 3c (23-0cm) Hed yosm um, Weinmannia ,- Rap anea and Melasto mat acea e are shows low values. Myrica attains well represented. Alnu s values. Eucalyp tus and, late r on, relatively high percentages. The Dodonaea curve reaches high Pinu very high. At the end of the subzone s are present. The perc entages of Rumex acetosella are Compositae Jig. are also found. Sub divi sion of the loca l vege tatio n diag ram (Fig . 16a ,b) Local phase A (99-83cm)

Eryngium pollen and Grammitis spor es are well represen

ted.

Local phase B (83-43cm) The Cyperaceae curve reac hes Gentianaceae curv es show som e relatively high values. The Plantago, Xyris, Valeriana and maxima. Lycopodium fov. spores lsoetes and Sphagnum appear. are very well represented. Local phase C (43-23cm) The pollen curv es of Cyp erac Valeriana are significantly represeneae and Gentianaceae show high percentages. Xyr is and the phase. Fungal types 562, 564 ted.lsoiites microspores show a clear maximum at the end of and 582 also show maxima.

Fig. 15. R1

Paramo de Laguna Verde

Local phase D (23-0cm)

X yris attains high percentages in the lo wer part of the phase, as do Valer iana, Aragoa, Sphagnum and Ericaceae in the upper pan. Several fungal and zoological types show maxima.

Dating of the PL V I and PLV II sections, and inferred calculations

d~tings

A total of seven samples was selected for radiocarbon age determination. The re.s ults are presented in Table VI. TABLE VI. Radiocarbon dates of the PLY I and PLY II sections (Paramo de Laguna Verde).

PLV I section Laboratory numbe r s

Sample numbers

GrN GrN GrN GrN GrN

COL COL COL COL COL

12905 12906 12907 12908 12909

491 492 493 494 495

Depth below surface in em 104-109 145- 148 195- 198 246-249 288 - 296

P LV II

Age i n yr BP 1,870 2,2 70 3, 7 8 0 5, 0 40 5, 2 2 0

± 60 ± 70 ± 70 ± 60

± 70

PLV II section

Laborato ry numbers

Sample numbers

GrN 12904 GrN 12078

COL 490 COL 381

Depth b elo w surface in e m 63 95

Age in yr BP 1 ,8 2 0 ± 5 0 5 , 1 90 ± 80

Regional pollen influx data and pollen density time scales GrN 1290 4 1. 820± 50 75

Gr N 1207 8 ·5 . 190 ± 80

0 - em-

-y r

BP-

- x 10 5 Pic m3-

0.5

1.5

2.5

3 3.5 4 6 - x 10 P/ cm1-

poll~~g~~:~e~:.:o~c~:()Dt)•;fdp~~fgs (B) and po llen cfothncentratio n cu:ve (C) and cumulative 1

Verde).

en sum e ements, o

e PLY II secuon (Pfuuno de Laguna

In Fig. !7, the depth scale, the 1•c datings and the pollen concentration and cumulative pollen concentration curves of the elements included in the pollen sum of the PL V I section, are given. In Fig. 18, the same data are given for the PLV II section. Average annual poLlen influx numbers of pollen sum elements were calculated for the interval 5,220 to 0 yr BP in the PLY I section and for the interval 5, 190 to 0 yr BP in the PLV II section. Furthermore, both in the PLV I section and the PLV II section, pollen influx numbers were calculated for the time intervals between any two 1"C datings. Additionally, in order to cqmpare data of both sections, pollen infl ux numbers were also obtai ned for the time interval 5,220 ro 1,870 yr BP in the PLV I section. The data are summarized in Table VII. Pollen influx numbers for the d ifferent time intervals in the PL V I section are extreme ly variable, contrary to those of the PL V II section which are rather constant. The very high pollen infl ux numbers of time intervals 5,220 to 5,040 yr BP and 2,270 to 1,870 yr BP in the P LY I section must be the result of sediment focusing processes. These processes could be expected taking into account the location of the boring site of the PL V I section just in front of the outlet of a small' intermittent stream, the rather irregular bottom of the basin and the type of sediment. Gyttja is known to be easily resuspended and focused towards deeper pan s of sedimentary basins (Davis et al., 1984). Po llen influ x numbers in the time interval 1,870 to 0 yr BP are on the o ther hand anomalously low. This can be explained by the fair amount of suspended 'organic material in the water layer of the lithological sequence (see Fig. 8) that was im possible to collect. Sediment focusing of this material towards deeper pans of the depression may also have played a role. Anyhow, a hia tus seems to be present. Therefore, the pollen influx numbers in this time interval have to be considered as minimum values. In view

Palaeobotanical-palaeoecological studies

of the irregularities mentioned, a time scale based on pollen concentration data has not been applied to the PLV I section. Sediment focusing processes probably did not affect sediment- deposition in the PLV II section, because of its "quiet" location and type of sediments. Pollen concentration data seem provide a good basis for indirect pollen density time calculations. However, one must bear to in mind that in this section these data are based on only very few samples and on (sometime s) low pollen sum values. Pollen density time calculations are, therefore, statistically less reliable in this case. rABLEVI I. Pollen influx data of the PLV I and PLV II sections (Pliramo de Laguna Verde). PLV I section Time-int erval (in yr BP)

5220

-o

5220 -1870

5220 -504 0

5040 -3780

3780 - 2210

2270 -1 870

187 0

-o

Pol len influx data .<in P .cm- 2 .yr- 1 ) - Pollen sum elements

1364

1940

1113 4

746

477

6955

>36 0

5190 -0

5190 -1820

1820

638

590

730

-o

Pollen i nflux data (in P .cm- 2 . yr- 1 ) - Pollen sum elements

The upper Andean forest belt, with Weinmannia and Hedyosmu m gradually developed to replace former Quercus and Podocarpus st;mds. Pioneer elements (e.g. Dodonaea, Myrica, Chenopodiaceae-Amaranthaceae) were present In the tropical-subandean belt Acalypha seems to had become one of the important elements. In subzone 3b, human influence upon natural vegeuition became catastrophic, permitting the developme nt of large stands of secondary vegetation types with Dodonaea, Rapanea, Myrica, Melastomataceae and ChenopodiaceaeAmaranthaceae. This explains also the percentual over-representation of tropical-subandean elements in the pollen diagram. Land-use by men commenced in the Paramo de Laguna Verde itself, ruderal herbaceous taxa like Rumex acetosella and Compositae (Hypoclweris ?) becoming prominent. The registration of introduced trees (Eucalyptus and Pinus) and herbs (R. acetosella) indicates that this subzone corresponds with "hispanic" times (5: 450 yr BP). The azonal Alnus forests had upon the whole a limited extension. Local vegetation developm ent Local phase A Low pollen concentration numbers in this phase make it very probable that sediment deposition took place very rapidly. A submerged community of lsoetes with Diatomeae developed at the boring site. This vegetation type belongs to the Dirriclw-lsoi!tion. Local phase B

'PLV I I section Time-inte rva l (in yr BP)

Paramo de Laguna Verde

Interpreta tion of the data of the PLY I section Regional vegetation developm ent Zone 1 The surface occupied by Quercus forests on the slopes below the Paramo de Laguna Verde was larger than it is at present. Halfway up the period correspon ding with subzone 1b, Podocarp us stands became more abundant. Striking then, is the appearance of the pioneer element Dodmu:rea indicating some disturbance . The surface of .ill-drained areas on the high plain of Bogota and surroundings seems to have been rather large, allowing a good development of the awnal Alnus forests. Zone 2 Quercus and Podocarpu s stands were still rather abundant. Now, Hedyosmu m also became an imponant element in the Andean forests. Pioneer elements such as Dodonaea and Myrica (probably as a treelet in the Andean forests) were present. 'Prehispanic' Zea mais is recorded, which is most probably indicative of agricultural activities by prehistoric men in the study area. The area occupied by marshy Alnus forests diminished. Zone3 A gap in the registration is present in this zone.

A submerged vegetation type dominated by lsoetes with algae (Characeae, Botryococcus and Pediasrrum ), belonging to the Dirriclw-lsoerion, developed locally. As a result of sediment focusing processes, elements (e.g. Elarine, Tillaea , Juncus) of the former shore zone of the lake are also abundantly found. This shore communit y belongs to the Junco-Eieocharirion. Local phase C A transitional phase between the former deep water community (Ditriclw-l soetion) and next shallow open water community (Junco-Ei eocharirio n). Especially cf. Callitrich the e is characteristic for this successional phase. In the former shore zone of the lake a peatbog community began to develop. As a consequence of sediment focusing, a number of elements this vegetation type (Vaccinium, Hypericum goyanesii, Puya, Campy/opus, Polypodiales) of are also recorded locally. Local phase D A floating mozaic of shallow pools and peatbog patches, as found at present, expanded over the boring site. Locally, a pool community (Junco-Eleocharition) with Elatine, Sphagnum cyclophyllum Drepanocladus jluirans was present. Tillaea and Juncus were also growing at the boring site. and The pool was surrounded by peatbog vegetation in which Carex cf. bonplandii, Gentiana sedifolia, Puya, Grammitis and Campy/opus were dominant; Hypericum goyanesii and Vaccinium dwarf shrubs were also present. Local phase E Locally, stands of Carex cf. bonplandii with Xyris were dominant. At the transition from the previous pool community to this bog community, at first, Ranunculus and, later on, P/eurozium schreberi and Breutelia chrysea were characteristic. Local phase F A gap in the registration is present in this phase.

Palaeobotanical-palaeoecological studies

As a result of renewed sediment focusing processes, a mixture of elements belonging to the mozaic of pool and peatbog communities is found. In the Junco-Eleoclulrition community !uncus and Drepanocladus fluitans were prominent. Peatbog stands were dominated by Carex cf. bonplandii, Valeriana, Gramineae and several mosses such as Sphagnum magellanicum, f?.hacocarpus purpurascens, Campy/opus cucullatifolius and Chorisotfontium speciosum. Dwarf shrub taxa such as Arcytophyl/um, Hypericum, Ericaceae (probably Vaccinium) and, later on, Aragoa were present Local phase G The actual Xyris acutifolia hummock with Ericaceae (probably Vaccinium d warf shrub) developed locally. Initially, Sphagnum magel/anicum with Aragoa, Puya and Grammitis were dominant. Next, Gramineae and bryophytes such as Campy/opus (including C. cucu/latifolius), Breutelia allionii, Kurzia verrucosa and Riccardia lulnsmeyeri became more abundant in the probably somewhat degenerating hummock

Interpretation of the data of the PL V II section R egional vegetation development Zone 1 (z 5,600 to= 3,900 yr BP)

In the Andean forest belt Quercus was more abundant than it is at present.' The area occupied by azonal Alnus forests on the high plain of Bogota and surroundings was large. Zone 2 ("' 3,900 to= 1,820 yr BP)

Quercus and Podocarpus stands were abundant. Upper Andean elements, such as Hedyosmum and Weinmannia gradually became more important. The pioneer element Dodonaea was present, indicating some disturbance. TJ;e area occupied by marshy Alnus forests diminished. Zone 3 ("" 1,820 to 0 yr BP) Former Quercus and Podocarpus stands were partially replaced by Weinmannia forest with Hedyosmum. Secondary vegetation types with Dodonaea, Myrica (as a treelet in the Andean forests), Rapanea and Melastomataceae expanded considerably from subzone 3b onwards, indicating increasing destruction of Andean forests by men during the last "' 350 years. This e~plains also the percentual over-representation of tro,pical-subandean elements in the pollen dtagram. In subzone 3c (=50 yr BP to present) intensive land-use by men in the immediate vicinity of the lake under study is registered, ruderal herbaceous taxa as Rumex acetose/la and Compositae (Hypochoeris?) beco ming abundant. At the same time reforestation with Eucalyptus and, later on, Pinus started in the area surrc.unding the Pliramo de Laguna Verde. The azonal Alnus forests had generally a limited extension.

Local vegetation development Local phase A (=- 5,600 to"' 3,900 yr BP) Exclusive azonal elements are lacking. Probably, a zonal lower grass paramo vegetation on peaty ground was present locally. The abundance of Eryngium would be indicative of some local disturbances. Grammitis was important in the ground layer. Local phase B (=- 3,920 to"' 350 yr BP) At the boring site, probably a marginal azonal cushion bog community be longing to the Gentia no-Oritrophion developed. Characteristic taxa were Cyperaceae (Oreobolus

Paramo de Laguna V'erde

obtusangulus?) and Lycopodium. Accompanying taxa included Plantago (probably P. rigida), Xyris, Valeriana and Gentianaceae. Local phase C ("' 350 to"' 50 yr BP) The vegetation at the boring site resembled to a high degree the former vegetation type. The cushion bog community, dominated by Cyperaceae (Oreobolus obtusangulus?), belongs to the Gentiano-Orirrophion. Gentianaceae, Xyris, Valeriana and l soetes (surely the terrestrial species I. boyacensis or /. andina) were also locally present. Local p hase D (= 50 to 0 yr BP) The actual Xyris acutifolia hummock developed. In a later stage, Sphagnum magellanicum, Valeriana, Ericaceae (Pernettya prosrrata) and Aragoa dwarf shrubs developed on the hummock. The abundance of Gelasinospora spores, usually associated with fires (Van Gee!, 1978), is most probably caused by human influence in the direct surroundings of the depression under study. Conclusions and discussion In Fig. 19, a compilation of the data of the PLY I section is presented. The changes in floristic composition of the zonal forests, the changes in the area occupied by azonal Alnus forests on the high plain of Bogota and surroundings, the successive local vegetation ty_Q_es related to fluctuations of the water level in the lake and the local synsystematic units are summarized. In Fig. 20, the same data are given for the PL V II section. During the time-span represented by the PLV I and II sections, i.e. the last "' 5,500 years, only minor changes seem to have occurred in the zonal arboreal vegetation, which were mostly related to the changing floristic composition of the forests. As pollen influx numbers in the PL V I and II sections are insufficiently reliable, objective criteria are lacking concerning possible minor venical displacements of the forest belts. The data of both sections suggest a partial replacement of Quercus stands by upper Andean elements during the terminal phase of the Middle Holocene and the Late Holocene. At flTSt Podocarpus and later on Weinmannia and Hedyosmum became important elements. This change correlates rather well with an increasing area occupied by pioneer vegetation types with Dodonaea, Myrica, Melastomataceae and Chenopodiaceae-Amaranthaceae. At the same time, the area occupied by azonal Alnus forests on the high plain of Bogota and surroundings diminished. If these changes, both in the zonal and azonal forests, are originated by a climatic change (i.e., changing humidity) or increasing human influence is for the moment still uncertain. As far as we are dealing with the changes in the floristic composition of the zonal arboreal vegetation, the possibility cannot be ruled out that they might be the result of endogenous processes (e.g. soil maturation) in the forest ecosystems. Human impact was certainly the predominating factor during the last "' 350 years. Then, large stands of secondary vegetation type s with Dodonaea, Rapanea, Myrica, Melastomataceae and Chenopodiaceae-Arnaranthaceae developed. Correlation of these regional vegetation data with other palynological data in the study area and with the general chronostratigraphic sequence of the Cordillera Oriental will be dealt with in part III. Around "' 5,200 yr BP the lake under study was formed. At the boring site of the PLV I section a gradual, mostly endogenous, development started towards relatively drier local vegetation types resulting from the filling up of the sedimentary basin. At the boring site of the PLV II section local conditions became gradually wetter as a consequence of the formation of the ~e, originating a local development from a zonal grass paramo vegeia!ion type towards the Âˇactual azonal peatbog vegetation type. The possible causes leading to the formation of the lake, some ;, 5,200 years ago, will be discussed in part Ill.

Palaeobotanical-palaeoec ological studies

PL V I

(362 5m)

Flo ristic composi tion of zonal forests in the study a rea

,.,

.c c. .c

"' 00

Area occupied by azonal Alnus forests on the high U> "'U> plai n

.c c.

<( I

"'"

lll

"' :!

0 ,._

a:>

0 0

,.,

Q) Q)

oo" em

•.

200

(/)

r::-

b og and

Upper Andean fo r e sts began to devel op Quercus domina nt i n Ande an f o r es t s

(/),::!.

"' 0

.." .. 0.

,=!-

Eleochar ition

0 N

::>

Genriano-

narrow ing

f--

2 f----

Oritrophion ?

Is Upper Andean forests began to deve ;o p Q uercus domi nan t in Andea n fo rest s

1--- ----

I-

a:>

Quer cus domina nt i n And e an for est s

...

u-i

IDevelopme nt of Upper Andean forests

~· co_ 75

o l

bog

Quer cus zo ne 0

Local Syns ys temat ic unit s

'Sphagnum'

Gradual deve l opment of p i oneer v egetation type s

Junco -

"',._ ,.; 25 0

= ..E ""':0

(/)

f----

' Sphagnum·

0 ,._

:0::>

Mozaie of

c-i

Local vegeta ti o n types at the bo ring site

narrowing

..,._

150

<I)

"c:

Area occupi ed by azona l A lnus fo res ts o n Q) the high U> U> plain "' .c

yr BP

Quercus zone 0 ,._

D ev e lopment of upper And e an fo r ests

Flor is ti c co mposit ion of zonal forests in the study area

( 3 625m)

Gradu al d e v e lo pme nt of p io nee r vegetati on types

PL V II

Loca l Synsys . tema ti c units

100

Local vege tation types at the boring site

yr B

Paramo de Laguna Verde

~·

.,;

Q uercus dom ina nt

in Andean fore sts

'--

1/c

Grass paramo v e ge tat io n

300

.. I

"'u-i"'

6 ~

350

Di rr i c ho •

lso ti rion

Fig. 19. Changes in floristic c?mposition of zo_nal forests (A), changing areas occupied by azonal Alnus fores ts (B), successive local vegetauon types (C) and local synsystematic units (D), deduced from the data of the PLY I section (Paramo de Laguna Verde).

Fig. 20. Changes in floristic composition of zonal forests (A), changing areas occupied ~Y azonal Alnus forests (B), successive local vegetation types (C) and local synsystemau c umts (D), deduced from the data of the PLY II section (Paramo de Laguna Verde).

Palaeobotanical-palaeoecological studies

S. PARAMO DE PENA NEGRA: THE PPN I SECTION Introduction The Paramo de Peiia Negra (ca 5005' N; 74005' W) is situated at the northwestern periphery of the high plain of Bogota in the Colombian Cordillera Oriental (see Fig. 1). The 250cm long PPN I ~ection was taken in the boggy shore of the Laguna Negra, a small lake located in the area at an altitude of ca 3625m (Fig. 21).

Paramo de Peiia Negra

analysis were recalculated o n the basis of a constant sample volum~ o~ 5cm3• :me average contribution of rootlets to the volume percentages of plant nssue remams m the different local phases recognized in the PPN I section was also calculated. A total of five samples were taken for ' 4 C dating (see Fig. 22).

PPN 11 3625 m) 50

• •

I DO

l i t ~ ~~ f

•

pea t

1 II a r \u

150

li gfrl l ll

cI a y

d I f k tf

20 0

250-

1-:..- I

cIa y com pone n t

sa nd c ompo ne nt

gr avel co mponent

I"' ---1

vol can ic ash compone nt

. Fig. 21. View of the Laguna Negra (Paramo de Peiia Negra). The boring site of the section m the boggy shore of the lake is indicated by an arrow. Fig. 22. Stratigraphical colunm of the PPN I section (Paramo de Peiia Negra). Th~ upper 125c~ .of the PPN I section w.as colle~ted from a profile after peat digging operauons; the re!flammg pan. was collected with the aid of a small Dachnovsky sampler. The bottom of the ~edi!Dentary bast? was ~e~che.d at a depth of 25qcm. ~e litholo~cal sequence of the PPN I secnon IS presented m detail m F1g. 22. The volcaruc ash m the sedtment is from the vo~canoes of the Cordillera Central, as there is no young volcanism in this pan of the Cordillera Onental (Riezebos, 1978). Several additional drillings were carried out in order to trace the bottom of the depress ion. Samples for determination of some physico-chemical properties, such as bulk density, ash content and C/N quotient, were taken at a constant interval of Scm. For the microfossil analysis of the section a known volume of material (range l-5.5cm 3) was taken at.intervals of 2.~cm in the upper pan of the PPN I section and of Scm in the lower pan of the secuon. The matenal of the latter ones was taken all over the interval that they represent. Pollen sum values are 156-257. By adding tablets containing exotic pollen grains of Eucalyptus pollen concentrations in the sediment could be determined. Samples for the macrofossil analysis were taken at the same intervals as the microfossil samples. The volume of the samples varied from 3.2-6.lcm 3 . The countings in the macrofossil

5.2. Geoecology of the area T he Paramo de Peiia Negra forms the northernmost part of the eastern main water divide o.f the Subachoque valley. Lying at an elevation of ca 3500 to 3750m above present sea level, H covers an area of approximately 8km2. B~k mai~ly consists of L~te_ Cretaceous sandsto~es dipping to the W. The area has been glaciated dunng 0e la~t glac1aoon m d several &lacial features, such as cirques and moraines, can be recogmzed m the landscape. Accordmg to Helmens (in prep.) the ice disappeared from the area before 14,000 yr BP. On the flat bottoms . of the cirques small glaciallalces and/or bogs have developed (Fig. 23). No exact climatological data are available from the area Mean annual temperature IS about 6goc; mean annual precipitation is in the order of 1400mrn. The western slopes of the Par~o ~e Peiia Negra are exposed to ascending winds of the Magdalena valley often resultmg m cloudiness and drizzle in the area. On the western slopes of the Paramo de Peiia Negra the forest line is situated at an altitude of approximately 3400m. Nowadays, however, little is left of the upper Andean forests in the area.

Palaeobotanical-palaeoecological studies

fixation. TheN concentration in different plant taxa, in the same plant taxa with different microhabitat and even in different parts of the same plant may be variable. The bulk of the ~ fixing !s achieved by aerobic bacteria (Rosswall & Granhall, 1980), so that presumably more rutrogen ts added in this way to the hummock than to the hollow. This does not necessarily imply that this greater input also results in a greater sequestration of nitrogen in the sediment (Middeldorp, 1984).

P PN I section ( 3625m )

Spec i fic weig ht

g . ~ m-J

Paramo de Pena Negra

Bulk density

Ash co nt ent g.cm- 3 .10- 3

g. cm-3 .10-3

PPN I s e ct i o n ( 3625m)

N co nt ent -3 -3 g . em .10

C co nten t -J

-3

g . em .1o

C/N

100

15 0

20 0

250 ....1.....-.---,----0.8

1.2

1.6

200

400

600

800

100 0

200

400

600

800 1000

Fig. 26. Specific weight, bulk density and ash content given in g cmÂˇl of the analyzed ' Âˇ ' samples of the PPN I section (Paramo de Pena Negra).

TheN c~ntent in th~se ec.osy~tems depends on primary fixation in the living plant mass, runoff and erosion. De~Itnficat!On IS mostly negligible and most of the nitrogen in the ecosystem gets lost by becomm.g sequest~red i.n the organic component of the sediment. Within the ecosystem there are di~ferences tn N tnput between micro-habitats (e.g. hummock vS hollow) and plant taxa, due to differences in N

Fig. 27. C content and N content, given in g.l(}l.cmÂˇ3, and inferred C/N quotient o f the analyzed samples of the PPN I section (Paramo de Pena Negra). Less reliable N content and C/N quotient values are indicated by black dots.

Palaeobotanical-palaeoec

ological studies

Th e los s of car bon am oun ts of nit tog en res by pri ma ry dec om pos itio n and the mo re or ults les Ho lm, 198 4). In this wa in a ma rke d low erin g of the C/N quo tien t in thes con sta nt rem ain ing acr ote lm (M aim er & pri ma ry dec om pos itio n, y, the C/N quo tien t see ms to be a goo d ind ica tor of the deg ree of alth oug h it ma y be inf lue quo tien t of the pla nt tiss nce d in.. asi gni fica nt wa y ues. Fo r instance, Gra min I C/N quo tien t tha t, as a res eae are kno wn to hav e pla by the ori gin al C/N nt tissues with a low ult of the ir che mic al com pos itio n, see m to \ On the oth er han d, dec om pos e rath er qui ckl Eri cac y. dec om pos e ver y slo wty eae and Sph agn um hav e pla nt tissues wit h hig h C/N quo tien ts tha (se e Du cha ufo ur, 197 t Likewise, the inf lue nce of pos teri or pro ces ses (se 7, En gli sh ver sio n 198 2; pp. 44- 45, 55) . be crit ica lly reg ard ed. As con dar y dec om pos itio n, dec ay pro ces ses bec om gen era l dec ay) has to e ver y slo w in the cat ote in org ani c sed ime nts for lm, the C/N quo me d by suc ces { goo d ind ica tio n of the ori gin al pri siv e veg eta tion al pha ses in the eco sys tem mig tien ts ma ht giv e a ry dec om pos itio n in the com mu niti es. cor res pon din g for me r pla nt Th e acr ote lm in the Sph agnum-Swallenochlo Ne gra see ms to cor res pon d to the upp er 40- 50c a tessellata pea tbo g eco sys tem in the Lag una m of the seq uen ce (se e Th is dep th cor res pon ds Fig . 26 and Fig . 27) . rat her well wit h the min aut hor dur ing the dry imu m sta nd of the wa ter sea son s. Th e low er 200 -21 0cm of the seq uen ce tab le obs erv ed by the cat ote lm of the act ual pea cor res pon ds with the tbog eco sys tem . Th ere is a lac k of rec pro duc tion , dec ay, etc . ent dat a con cer nin g C/N quo tien t in tiss ues of iri the tro pic al high An dea n azo nal eco sys tem livi ng pla nts , pri ma ry stu dy. Us e has bee n ma s inv olv ed in the pre sen de. of dat a fro m res ear ch t Eur ope and Sca ndi navia. don e on mir e and pea tbo As the inf orm atio n and g arg um ent atio n are insuff eco sys tem s in NWderived fro m the phy sic o-c hem ica l dat a hav e to icient, interpretation s by future actuo- and pal be aeoecological reseazch in see n as hypothetical until they are con firm ed the are a. Pal yno log ica l and ma cro bo tan ica l ana lys es of the PP N I sec tio n Zo nat ion of the reg ion al veg eta tio n dia gra m (Fi g. 28) Zo ne 1 (~ 5 0-210cm) Th e con trib uti on of Aca lyp ha bei ng significanthe tro pic al- sub and ean gro up to the p olle n sum is ver tly rep res Sub zone Ia (250-240c m) ented. Hig h percentages of the sub par am o gro y low , onl y up. Th e Myrica cur ve attains high Sub zon e I b (240-225c m) values. Ve ry high per cen tag es of Quercus, wh ile tho se of My rica sho w a min or fall Subzon e lc (22 5-2 10c . Th e Myrica cur ve rise s m) aga in to high values . Zo ne 2 (2 10- 180cm) Th e percen tages of the wh ile tho se of the s ubp tro pic al-suba nde an gro up are slig htly hig her tha ara especially due to hig h per mo gro up are low er. Th e upp er An dea n gro n the y are in zon e I , up atta ins hig h val ues, centages of the azo nal ele me nt Alnus. Sub zone 2a (2 10- 195cm ) Quercus, Weinmannia relatively low. Dodonaea and Rapanea sho w relatively high percentages. Myrica percentages are is found. Sub zon e 2b ( 195-180cm ). Th ere is a min or rise o f the My rica cur ve. Th Rapanea decrease. e per cen tag es of Qu erc us, Weinmannia and Zo ne 3 (18 0-8 8cm) Thi s zone is ma rke d by high per cen tag es of the Andean gro up. Th e con trib utio n of the sub par am tropical-subandean gro up and the subandean (53 6) is fou nd. o gro up to the pollen sum is ver y low. Zea mais

\ I 1

I. I

Pciramo de Peiia Negra

Subzone 3a (180-135cm) All important tropical- subande an arboreal pollen taxa, especial ly Cecropia), and Quercus attain high percentages. Weinmannia is significa Urticales (including ntly represented. Alnus shows low values. Subzone 3b (135-88cm) The contribution of the tropical-subandean elements to the pollen sum still attains relatively high percentages. The curve of Alnus shows high diminished. Quercus values. Podocarpus, Hesperomeles and Rapanea show minor rises. Towards the end of the subzone the percentages of Weinmannia increase, while those of Quercus decrease. The thick ash layer, at a depth of 121-113cm, containe d only very few microfossils. The pollen countings at the 119, 117 and 115cm levels are statistica lly unreliable and have been ignored. Zone 4 (88-0cm) This zone is characterized by high percentages of the tropical-subande an group. The upper Andean group attains high percentages due to the increased values of the zonal elements. The percentages of Alnus are graduall y decreasing. The percenta ges of (Myrica) slightly increase. Aragoa and Arcytophyllum are well represen the subparamo group ted . Zea mais (536) and Cheno-Ams are found. Subzone 4a (88-74cm) Hedyosm um and Weinmannia show high values. Alnus still attains high percentages. The percentages of Quercus, Podocarpus and Hesperomeles tend to decrease . Dockmae a is present. Subzone 4b (74-56cm) Hedyosmum, Weinmannia and Melastomataceae show high values. important tropical-subandean elements show a tendency to increase , The percentages of all while those of Alnus are decreasing. DodtJnaea is found. Subzone 4c (56-0cm) Hedyosmum, Weinmannia, Rapanea and Melastomataceae attain high important lower tropical-subandean elements. Dodona ea shows high percentages, as do all percentages. Polylepi s· Acaena and Zea mais (548) are found. Eucalyptus, Pinus, Rumex acetosel la and Compos itae Jig. are well represented in the upper part of the subzone.

....... ........................... .........r:;................. ,... ~-................ ........... ......... ~ ~ .............................

.... ............... r;.. ...... ..

" ""' ""' = = =

··•ZZ%!''

""""' =

=lZZJ ~

········· ................. ...... ................... ......... ··· ···························· ..................

Subdivi sion of the local vegetati on diagram (F igs. 29a-c)

s;;;; :::. ~ . ~. . . . . . . ... ..

Local phase A (250-180crn)

In the macrofossil record, lsoiites cleefiilsteyermarkii megaspores are fo und in very large quantities. Tillaea seeds are present. In the upper part of the phase Dicotyle occur. The average contribution of rootlets to the volume percenta ges doneae remains (T64) of plant tissue remains found in this local phase is very high (> 95%). In the microfossils diagram, the curves of pollen type 554, Umbelliferae (555), Geranium, Cruciferae, Gentianaceae, Plantag o (P. rigida-ty pe), Lachem i//a and percentages, showing a tendency to decrease towards the top. The same Valeriana attain high holds for Lycopodium fov. lsoiites shows very high values. Botryoc occus is well represen Compositae tub. and bryophytic type 601 attain high percentages at ted. Tillaea, Gramineae, the next local phase. The fluctuations of the Gramineae and the Compos transition tOwards the itae tub. curves, with the exception of the uppermost part of the local phase, are most probably the result of regional vegetation changes (see below). Local phase B ( 180-165cm) Seeds of !uncus, Tillaea and £Iarine are very abundant. Drepanocladusfl found. The amounts of /soiites c/eefiilsreyerma rkii megaspo res show uitans remains are a gradual decrease . Rootlets volume percentages gradually decrease from 99% to 85%. The percentages of Gramineae and Compositae tub. pollen and lsoi!tes The Cyperaceae curve shows a minor rise in the upper part of this phase.spores are decreasi ng. lower values than in local phase A. Zygnema and Debarya are present Botryococcus shows in the lower part of the phase, as is fungal type 562 in the upper part.

Palaeobotanical-palaeoecological studies

Local phase C (165-135cm) Some charcoal is found. . . . Macroscop ic remains of Sphagnum sect. Cuspuiata are abundant. Remams of Grllllll:I?eae, Juncaceae and Carex occur. Cf. Luzu/a seeds are rather abu~dant. Carex cf. bonplandu and Gramineae seeds are present. Mean rootlets volurr;e percentage JS "' 80%. Lupinus pollen and Sphagnum spores are relanvely well represente d. In ~e ~ower part of the phase Botryococcus and fungal type 562 show high value~, as does Gramr:z.ws m the upper part. Gramineae , Cyperacea e and Composita e tub. show mwnma at the ttans1Uon towards the next local phase.

Local phase H (46-0cm)

Sphagnum mage//anicum remains are very abundant. In the lower part of the phase seeds of cf. Pernetrya and leaves of Vaccinium/Pernetrya and B/echnum are found. In the upper part Riccardia hansmeyeri remains become abundant and Polypodiales sporangia are found. Rootlets volume percentages decrease from average 50% to S: 10%. In the microfossils diagram, the Ericaceae curve shows a clear maximum in the lower part of the phase•. while the curves of Gramineae , Sphagnum and Grammitis show a rise in the upper part. Several fungal types and Assulina show maxim~.

Dating of the PPN I section, and inferred calculatio ns

Local phaseD (135-117cm)

Seeds of ]uncus and Til/aea are found in large quantities. Seeds of E/eocharis and Lachemi~la also occur. Sphagnum magel/anicum r~mains are abundant in the lower part of the phase, while Oreobo/us obtusangu lus remains are found in the upper ,Part. Rootlets volume percentage s increase from"' 60% in the lower part of the phase to 100% m the ~sh layer. . The microfossi l curves of Umbellife rae excl. 555 (Eryn~tum-type) and Ttllaea s~ow relatively high values, as do Plantago (P. rigida-type), Lachem1lla, Ranunculus, Lycopo~tu m fov., Hymenoph yllum and Zygnema in the lower part of the phase, and Botryococ cus m the upper part. .. h 1 · ed The thick ash layer (121-113c m), at ~e ttans1Uon towards t e next oc al p hase, contam only very few microfossi ls and macrofosslis. Local phase E (117-81cm)

fsoetes cleefii/steyermarkii megaspores and ]uncus seeds are found in large quantities. ~eeds of Tillaea, £/atine ar1d E/eocharis, and remains of Oreobolus o~tusangulus and El~ocharts also occur. Remains of Sphagnum magel/anic~ and S. sect. Cu~ptdata are abun~ant Ln the lower part of the phase, as are Dicotyledonea¢: remams (T65) and Enocaulac eae seeds m the upper part. Average rootlets volume percentage s 1ncrease from = 55% 1n the lower part of the phase to > 90% in the upper part. . . · . the microfossi l diagram, l soeres attams high percentage s. The curves of Tt//aea Sphagnum show minor rises. Borryococcus ~nd Zygnema are wei_! represented. Towards and the end of the phase, Composita e tub., Gram1neae and Ly copodtum fov. are more amply represented.

Local phase F (81-56cm) Very few macrofoss ils were found, probably as a result of a high degree of decomposi tion. Mean rootlets volume percentage is very high(> 90%). . . . Pollen of Graminea e, Cyperacea e, Composlta e tub . and Luptnus atta_m very high percentage s. Several fungal types show their maximum in this phase. Bryophyuc type 597 1s found. Charcoal is found at the transition towards the next local phase. Local phase G (56-46cm)

Carex (including C. cf. bonp/andii) seeds are frequent. Remains of several gramineous_ taxa, Carex and Campy/op us are found. Towards the _top of the phase Sphagnum mage/lam remains become verv abundant and leaves of Vaccmtum!Pernerrya and Blechnum appear cum for the first time. Rootlets .;olume percentages decrease from 90% to_average 30%. . Cyperacea e pollen is very frequent. The curves of Grarruneae and Compos1~ae tub. show a gradual decrease. Fungal types 562 and Anrhosrome//a fuegtana, and bryophyuc type 597 are well represented.

Pciramo de Pena Negra

IX.

C datings

Five samples were selected for radiocarbon age determination. The results are given in Table

TABLE IX. Radiocarb on date$ of the PPN I section (Paramo de Peiia Negra). Laborat o ry numbers GrN GrN GrN GrN GrN

12897 12070 12069 120 68 12898

Sample numbers COL COL COL COL COL

483 378 37'7 376 484

Depth belo w surface in em

52 82 122 163- 174 213- 224

Age in yr BP

(98 .52% ± 0. 55) 1,965 ± 35 5,210 ± 80 8, 32 0 ± 80 12,450 ± 370

The age of sample number COL 483 (GrN 12897) can be considered asS: 275 yr BP (Klein et al., 1982). As the exact age of the sample remain s uncertain, it has not been used to calculate regional pollen influx data, nor to perform pollen density time calculations.

Regional pol/en influx data and pollen density time scale In Fig. 30, the depth scale, the 14 C datings and the pollen concentration and cumulative pollen concentration curves of the elements included in the pollen sum of the PPN I section, are given. Average annual pollen influx numbers of pollen sum elements were calculated for the interval 12,450 to 0 yr BP and for the time intervals between any two 14C datings. Furthermo re, estimated maximum pollen influx numbers were obtained for the interval~ 14,000 to 12,450 yr BP, assuming that sediment deposition in the depression began at least around 14,000 yr BP but most probably earlier (see Helmens, in prep.). Pollen influx calculation s were also performed for the different altitudinal groups in the pollen sum, for the zonal arboreal elements, for the azonal arboreal t'lement Alnus and for the conventional subparamo and grass paramo elements (see Table 1). The data are summarized in Table X. The nature of the Laguna Negra, a glacially eroded basin with flat bottom and no fluvial inflow filled up with peaty and clayey sediments, makes it very unlikely that sediment focusing processes have played a significant role during sediment deposition (Davis et al., !984). Furthermore, hiatuses in the sedimentation and corrosional effects upon pollen grains seem to be absent. Therefore , changing pollen influx numbers of the regional vegetation elements are tentatively interpreted in terms o f a changing regional pollen supply to the sedimentar y basin. Pollen influx numbers of the convention al subparamo and grass paramo elemen ts show very clearly the influence of the local growth of certain of these taxa (Graminea e, Ericaceae and Compositae) in the local azonal vegetation types, especially in the interval 1,965 to 0 yr BP. By means of the 14C datings and the pollen concenttat ion d ata the age and duration of the periods correspon ding with the different (sub)zones and local phases could be estimated. Indirect time calculations between the radiocarbo n dates are based on the pollen influx data for pollen sum elements between any two 14C datings (see Table X). Time calculations in the interval 12,450 to 8,320 yr BP are less reliable because the contribution of the zonal arboreal taxa to the

Palaeobotanical-palaeoecological studies

Paramo de Peiia Negra

TABLE X. Pollen influx. data of the PPN I section (Paramo de Pefia Negra).

pollen influx of pollen sum elements seems to have been highly variable due to the influence of major regional vegetation changes during this period. Likewise, the varying extent of the areas occupied by Alnus forests on the high plain of Bogota and direct surroundings in the interval 12,450 to 0 yr BP disturb, although less significantly, the pollen density time calculations (see below).

Time- interval (in yr BP)

;::14000 -12450

12450 -0

1245 0 - 8320

8320 -5 210

52 10 - 1 965

1965 -0

S444 Pollen sum elements Lowe r tropicalS9 subandean elements Upper subandeanS96 lower Andean elements Upper Andean S235 elements zonal upper S60 Andean e l ements Azonal upper Andean S175 elements (=Alnus) Subparamo S104 elements zonal pollen sum S269 elements (=LAP -Al nus)

828

759

791

991

76 1

140

228

14 8

123

112

566

541

431

738

560

232

1 34

206

327

319

334

407

225

411

2 41··

494

3 52

566

580

52 0

Pollen influx data ( in P. cm-2. yr-1)

PPN

GrN 12070 1,965±35

10 0

GrN 12069 5.210 ± 80

150

jGrN12068 8, 320 ±80

20 0

GrN 12898 1 12,450±370

p ~

250

· em-

-yr BP-

0 1 2 3 -x10 5Ptcm -

12 10 5 1 - x10 P/cm -

Fig. 30. Depth scale (A), 1•c datings (B) and pollen concentration curve (C) and inferred cumulative pollen concentration curve (D) of pollen sum elements, of the PPN I section (Paramo de Peiia Negra).

- Conventional S280 436 422 164 34 5 10 51 subparamo elements - Conventional grass :5324 1116 820 836 1 077 2243 paramo elements ---- ---·------------------------------------ ---------------------------------- -----------------------------------The organic component in the samples was calculated on the basis of the bulk density values, obtained after drying at 1050C, multiplied by the percemualloss of weight after incineration at 650°C. These values were multiplied with a factor 5 corresponding with the sample interval of the analysis, assuming that the value calculated for each sample is representative for the whole interval it represents. MSAR and MNOP values for the different local phases are given in Table XL Mean C/N quotient (MCNQ) values in the different local phases are also given. TABLE XL Mean sediment accumulation rate (MSAR), mean net organic production (MNOP) and mean C/N quotient (MCNQ) values for the different local phases of the PPN I section (Paramo de Peiia Negra). B 9079 -7 962

796 2 -58 64

.58 64 -5089

5089 -1849

1849 -369

369 -3 04

304 -0

S0.021 0.011

0 '013

0 . 014

0 .023

0 . 011

0.0 17

0 . 15 4

0.151

10.1

1 7. 6

19 . 3

1 9' 4

13.7

22.7

112.6

93.2

31.9

15.6

22.1

21.5

24 . 0

1 7.1

21. 8

24. 1

A2 Local phase A' T ime-interval ;::14000 12450 (in y r BP) - 1 2450 - 9079 MSAR (in cm .yr- 1 )

MNOP (in g.m-2 .yr-1) MCNQ

(I>

Sediment accumulation rate, net organic production and C!N quotient of the local vegetational phases By means of 1<C datings and pollen concentration data the age and duration of the periods corresponding with the different local phases were estimated (see above). Subsequently, the mean sediment accumulation rate (MSAR) values, given in cm.yr· 1, in the different local phases could be calculated. In the same manner, mean net or$anic production (MNOP) values, given in g.m·2.yr 1 , were obtained.

In view of the closed nature of the Laguna Negra depression (see above), sediment focusing processes, hiatuses in the sedimentation, run-off and erosion seem not to have influenced sediment deposition. MSAR values have to be interpreted in terms of inorganic and net organic accumulation and degree of compaction. Compaction and general decay processes in the catotelm are of minor importance as there is no general and continuous drop in the MS AR, MNOP and MCNQ values with increasing depth. Furthermore, secondary decomposition seems to be absent

·,, Palaeobotanical-palaeoecological studies

as conditi~ns stayed r_elatively wet ~~ng all lO<:a~ vegetation~ phases. MNOP and MCNQ values ~e l!lterpreted 1':1 terms of. flonsuc composition of the vanous local vegetational phases and therr pnmary orgaruc producnon (POP), and the primary decomposition (PD).

Zone 4 (= 2,600 to 0 yr BP) During the last = 2,600 years the forest line shifted to its present altitude. . . In the surroundings of the Laguna Negra, a subparamo dwru:f shrub vegetatiOn wt~ Aragoa and Arcytophyllum developed. Weinmannia forests, now wtth Hedyosmum, continued to replace former Quercus forests. The areas occupied by these fores~ types became confined ~o their present distribution. Pioneer elements such as Dodonaea, Mynca (probably as a treelet m the Andean forests), Melastomataceae and Chenopodiaceae-Amaranthaceae were pr.esent, indicating disturbances. Although percentages ? f the tropical-s?bandean elements m the diagrams gradually increased, on the whole pollen m~ux nw;tbers did n'?t. The percentual overrepresentation in the diagram can be ascribed to th~ mc~asmg destrucnon of zonal and azonal Andean forests by men, which became catastrophic dunng the last= 350 years (subzone ~). Then, secondary vegetation types with pioneer elements sue~ as Dodonaea, Rapanea, Mynca, Melastomataceae and Chenopodiaceae-Amaran.thaceae raptdly devel_?ped. Lan~-use by men (cattle-breeding and agriculture) commenced m the Paramo de Pena Negra Itself, ruderal herbaceous taxa as Acaena, Rumex acerose/la and Compositae (Hyp ochoeris ?) becoming prominent. . . . The area occupied by azonal Alnus forests on the high plam of Bogota and surroundings diminished considerably after"' 1,700 yr BP. . . . Some 100 years ago, reforestation with introduced trees like Eucalyptus and Pmus staned m the area surrounding the Paramo de Peiia Negra.

Interpretation of the data of the PPN I section R egional vegetation aevelopment Zone 1 (2: 14,000 to"' 12,150 yr BP) . I~ ~e ~eriod represented by zone 1 the forest belt lay far below the Paramo de Peiia Negra. Thi~ Is m~cated by the low frequency of low pollen producing trees (Hesperomeles, Rapanea,

Weznmanma) and the low pollen influx numbers of the zonal arboreal taxa. Downwar?s, the area occupied by s~bparamo scrub of Myrica was very broad. During subzone 1b.thts az:ea was probably panly mvaded by Quercus forest, which would indicate that .the forest lme shtfted closer to the Paramo de Peiia Negra. The area occupied by tropicalsubandean forests lay not only far away! bu~ was probably also considerably reduced in size, only Acalypha (and proba~ly Quercus) bemg tmpo~t ~lements in the remaining stands. The very low pollen mflux numbers of Alnus md1cate that the area on which this azonal ~lem~nt cou.ld grow was very reduced. It is quite probable that Alnus was completely lacking on the htgh plrun of Bogota and direct surroundings. Zone 2 ("' 12,150 to"' 9,100 yr BP)

D~ring the perio~ corr~sponding with zone 2, the representation of low pollen producin a trees I S htgher, espectally m subzone 2a (Rapanea, Weinmannia). Likewise, the pollen influ~ numbers of the zonal arboreal elements show an increase. Altogether, this means an approaching forest belt. · The area occ~pied by subparamo scrub of Myrica decreased. Especially during subzone 2a the forest belt ~htfted clos~r to the Paramo de Peiia Negra. Striking then, is the presence of the pioneer vegetatt<?n types wtth Dodonaea that probably preceded the establishment of the Andean f?rests .. The trOpH:~-subandean forests gradually developed. Elements belonging to the Unicales (mclodmg Cecropta) became more frequent. High pollen !nflux !lumbers of Alnus reflect an upon the whole good development of this ~lement on the ~1gh plrun .o f Bogota and surroundings. Considering a probable drop of the zonal arboreal pollen. mflux dunng subzone 2b (see below), one could expect that if the area occupied by Alnus remamed constant, thts element ~ould be percentually over-represented in the pollen dia!,rra.m. As the percentages of Alnus r~main more or less constant during both subzones, it is v~~ l!kely ~hat the area occupted by thts azonal element was very large during subzone 2a but dimintshed m subzone 2b. Zone 3 (= 9, 100 to"' 2,600 yr BP) . In this period ~he forest belt invaded the slopes directly below the Paramo de Peiia Negra Itself. The pollen mflux numbers of the zonal arboreal elements are slightly higher than those ove.r the l~st "' 1,965 years and low pollen producing trees (Hesperomeles, Rapanea, Wemmanma) are well represented. The subpar~o scrub of Myrica almost disappeared. During subzone 3a ("' 9,100 to= 5850 yr BP) the tropical-subandean f~rest ~It, especially with Un icales (including Cecropia), and the Qu~rcus fo~st belt reached t~eir maxtmum development. The area occupied by upper Andean ~eznm~nma.fore.st was relal!vely small. In subzone 3b (= 5,850 to .. 2,600 yr BP) the forest bne attruned Its h1~hest l~auon. He~perome/es and Rapanea were growing not far below the Laguna N~gra. Wemmannza forest w1th Podocarpus gradually began to invade areas originally covere? ~lth Quercl.fS. forest. The tropic~-subandean forests shifted downwards and/or changed m ~onsuc comp?sltlon. Re!ll~kable IS t~e p:esenc~ of 'prehispanic' Zea mais, probably attributable to agnc~ltural acuvmes by prehlStonc men m the study area, going as far back as .. 6,600 yr BP or poss1bly even more(= 8,150 yr BP). ~he azonal f<?rests of Alnus had a litnited extension during subzone 3a, but they expanded considerably dunng subzone 3b.

Paramo de Peiia Negra

Local vegetation development

I i I

Local phase A(~ 14,000 to= 9,100 yr BP) In the period represented by this phase, a su~me~ged deep water co~unity dominat~d by lsoetes with Botryococcus, developed at the bonng site. Other accompanytng taxa wer~ T_rUaea and Umbelliferae (Hydfocotyle or Lilaeopsis?). This vegetation. t~ belongs to the Duncholsoetion. At present, Gramineae and Compositae are not present m this type of submerged deep water community. The boggy shore zone was probably very narrow. I:Iere, a Plantago rigfda cushio~ bog community (Gentiano ·Oritrophion) with accompanymg taxa as Lachemrl/a, Valenana, Geranium, Lycopodium, Gentianaceae and Cruciferae developed. . At the transition towards the next local phase TWaea became more frequent m the open water vegetation stands; shonly, a mire vegetation type (Calamagrostion Ugulatae) with Gramineae and Compositae developed on the boggy shore zone. Local phase B (= 9,100 to~ 7,950 yr BP) During this phase, shallow open water vegetation types ~e':'eloped locally ... At fi~st, an amphiphytic community of the TWaeion was present. Charactensuc taxa were lsoe~es, T tllaea, Elatine, Zygnema, Debarya and Botryococcus. Later on, a reedswa~p com.mumty (Jun.coEleo charition) developed. Then, ]uncus, Cyperaceae (Eleocharzs ?), T tllaea, Elattne, Drepanocladusjluitans, Botryococcus and fungi (type 562) were prominent. Local phase C (= 7,950 to"' 5,850 yr BP) In this phase, a mire vegetation type developed at the boring site. Sphagnum sect. Cuspi~ta was dominant. Higher plant taxa were poorly represented. ~mong them~ cf. Luzula ~d Lupmus were most prominent. Botryococcus, Grammitis and fungt ~ere occasi.onally gro':"mg locally. At the transition towards the next local phase, shortly, a mrre vegetanon type with Carex cf. bonp/andii, Gramineae and Compositae developed. Both vegetation types belong to the Calamagrostion ligulatae. Local phase D (= 5,850 to "' 5,100 yr BP) In this phase, reedswamp communities of the Junco-Eleocharition developed at t~e boring site. At first, Juncus, Eleocharis, Ranunculus, Hymenophyllum, Sphagnum magellamcum and

Palaeobotanical-palaeoecological studies

Zygnema were dominant. Later on, ]uncus, Tillaea, Eleocharis and Botryococcus were prominent. In the narrow boggy shore zone of the lake, cushion bog communities of the GentianoOritriphfon develope~. At first, Plantago rigida, Lachemi/la, Eryngium (E. humile?) and Lycopodium were dormnant. Later on, Oreobolus obtusangu/us became more prominent Local phase E ("' 5,100 to"' 1850 yr BP) The beginning of this phase corresponds with a thick volcanic ash layer. The deposition time of this layer was very short as indicated by the extremely low pollen content. L<?cally, communities of the D~tricho-lsoetion and the Junco-E/eocharition were growing in a mozatc p~ttern. The f'rrst vegetanon type, that was developing in deeper pools, is principally charactenzed by the presence of Isoetes, the second by ]uncus, Tillaea, Elatine Eleocharis ' ' Sphagnum magellanicum and S. sect. Cuspidata. In the. narrow boggy shore zone, a cushion bog community of the (Jentiano-Oritrophion charactenzed by Oreobolus obrusangulus and, later on, also by Compositae (Werneria?) and Lycopodium developed. . Towards the end of the phase a mire vegetation type (Ca/amagrostion /igulatae) with Gramineae and Eriocaulaceae (Eriocaulon.?) began to expand over the fo~r lake bottom. Local phase F (= 1,850 to"' 350 yr BP)

!n thi~ phase, a ~e conrrnunity belonging to the Calamagrosrion lfgulatae dominated at the bonng ~lie. Gram~nea.e (Ca/amagrosris ligulara?), Cyperaceae (Carex cf. bonplandii?), Composuae (Senecw mveo-aureus?), Lupinus, Campy/opus? and several fungi were prominent. Local phase G ("' 350 to = 300 yr BP) At the transition from the previous phase towards this phase charcoal has been found. Gelasinospora spores, usually associated with f'rres (Van Gee!, 1978), are also abundant. Short transitional p~ase dominated by Carex (including C. cf. bonplandii), gramineous taxa, CamP_ylopus and fungt marking the succession from the previous Calamagrostion ligulatae commumty to a Sphagnum peatbog community. Synsystematically, this mire vegetation type also belongs to the Calamagrostion ligulatae. Local phase H ("' 300 to 0 yr BP)

!=>uri~g the last 300 years, a Sphagnum magellanicum peatbog community was present at the bonn~ site. Hummock development started with cf. Pernettya and Blechnum. Later on, 9rammeae (Swallenochloa tessellata?), Grammitis and Riccardia hansmeyeri became dominan t tn the Sphagnum mage!lanicum hummock. Several fungi and the rhizopod Assulina were occasionally present locally.

Sedimentation rate, primary ·organic production and primary decomposition .~~ phases A an.d E, with subm~rged deep water communities belonging to the Dirricholsoeuon, mean sed1ment accumulation rate (MSAR) and mean net organic production (MNOP) are lo:-v. The m~an C/N quotient .<MCNQ) is gen~r~lly speaking high. Probably, both primary orgamc production (POP) and pnmary decompositiOn (PD) were low. Very low C/N quotient ~alues at the lowermost levels of phase A are most probably due to an initially high percentual tnput of strongly decomposed exogenous material to the sedimentary basin. . In phases B, C, D and F, with shallow open water and mire communities belonging to the T11laelo'!, Junco-Eleoc~itiqn and Calamagrostion ligulatae, MSAR and MNOP are higher. The MCNQ IS lo:-ver, especially m phases ~ and F: POP seems to have been much higher than in the above mennoned phases. PD was htgh dunng phases B and F, when successions towards relatively drier local. conditio~s ~ook plac~. One must keep in mind, however, that the MCNQ valu~ of phase F .rmght be stg~tficantly Influenced. by the original low C/N quotient of the grarmneous plant nssues and therr relanvely fast chermcal decomposition.

Paramo de Peiia Negra

In phases G and H (Carex mire and Sphagnum peatbog, respectively), a dramatic increase in MSAR and ~OP can be recognized. The MCNQ is high, especially in the upper lOcm. High MSAR values are due to the uncompacted structure of the sediment and to a very high POP; PD was low. The uppermost 1Ocm of the section corresponds according to the pollen density time scale to the last"" 14 years. Primary organic production in the Sphagnum magellanicum top moss layer would then be in the order of .. 385 g.m·2 .yr 1, under the assumption that decomposition in this part of the acrotelm is almost negligible. As a result of primary decomposition in the lower parts of the acrotelm, ~ 75% of the C content gets lost, again under the assumption that the loss of N content is negligible. However, as these calculations are time-dependent, one must keep in mind that pollen contributed by arboreal vegetation during the last hundreds of years is probably less than the average over the last 1,965 years, as a result of the increasingly disastrous influence of men upon forests. If this is true, it would mean that the time-span represented by the uppermost lOcm is longer than"' 14 years and, consequently, that POP in the upper acrotelm and PD in the lower acrotelm were less. Conclusions and discussion In Fig. 3la, a compilation of the regional vegetation development deduced from the data of the PPN I section is presented. The vertical movements of the zonal upper forest line, the changes in floristic composition of the zonal forests and the changes in area occupied by azonal Alnus forests on the high plain of Bogota and direct surroundings are sunrrnarized. In Fig. 3 1b, the successive local vegetation types related to fluctuations of the water level in the Laguna Negra, the local synsystematic units and relative data on the primary organic production (POP) and the primary decomposition (PD), are given. Shifting arboreal vegetation belts, changes in the floristic composition of forests and changing areas occupied by azonal Alnus forests are principally caused by major climatic changes. During the period from~ 14,000 to= 12,100 yr BP (zone 1) the forest line was toea ted at a much lower elevation than at present, due to a colder climate. Mean annual temperatures increased somewhat during subzone 1b. If we accept that Alnus was not able to grow at all on the high plain of Bogota because of the too cold climatic conditions, it would mean that the forest line shifted at least 600-700m downwards representing a temperarure fall of at least -4°C, even in the relatively warmest interval (subzone I b). The floristic composition of the forest and the lower shrub subparamo belts during this period showed a close resemblance with the actual vegetation types of the (very) dry Chicamocha valley (see section 2), although one must remember that as a result of the colder climate all vegetation belts lay at a lower elevation than nowadays. The tropical-subandean forests were almost absent, Acalypha and Quercus being important elements in the remaining stands. Most of the tropical-subandean belt was probably occupied by (sub)xerophytic vegetation types. Quercus was abundant all over the Andean forest belt. A broad subparamo belt, dominated by My rica scrub, was present. From an actualistic point of view it would imply that during this period climatic conditions were not only considerably colder but also markedly drier. Between .. 12,100 and "' 9,100 yr BP (zone 2) major vertical displacements of the forest line continued to occur. Temperatures increased considerably during subzone 2a resulting in a relatively high location of the forest line which, however, never attained an altitude comparable with that of the period"" 9,100 to 0 yr BP. Temperature dropped again during subzone 2b. Mean annual precipitation increased allowing the gradual development of tropical-subandean forests even in spite of the temperature fall in subzone 2b. The higher humidity of the climate is also reflected in the upon the whole abundant stands of azonal Alnus forests on the high plain of Bogota, which also implies that temperatures were allways high enough to permit the development of arboreal vegetation types at this altitude. The conclusion can be drawn that mean annual temperatures during this period fluctuated between -1 and -40C. The vertical movements in the forest line as described above are corroborated by the fl uctuations in the Gramineae and Compositae tub. curves in the pollen diagram, which, as explained earlier (see above), are in this period of regional origin. From the end of zone 2 and local phase A onwards, the influence of local growth of Gramineae and Compositae began to play a major role and fluctuations in the curves of these taxa have to be interpreted in te rms of local vegetational successions. Colder climatic conditions during the above mentioned periods

Palaeobotanical-palaeoecological studies

Pru-arno de Peiia Negra

are also reflected in the local vegetation types (local phase A), which at present are frequently found in the zonal superparamo belt and the upper grass paramo belt (see section 2).

PPN

PPN I

<1>

Z o na l upper fo r es t line

E E

"'.. 0"

E ~ ~

0 <D

en"

~ em

(3625m)

0 0

"' "'

+• 1/)

1/) (')

"'.n

.."' I

0 0

(')

200

,._

"' ": "'

(')

250

1'-

Ouetcus dominant in Andea n fore s t s

B r oad Myr ica scn·b subparamo

Quercus dom1nant in

I A

Andean forests Only f ew stands o t trop i ca l- subandean forests with AcJiypha and Quercus

150

"'· .n

P OP low PO low

Cala magros 110n ligu la/a~ Junco - E leo ... charition ..!._illaeion /'

POP rei. high P O rei. low

POP rei. high PO hioh

200

I+

POP high P O r ei. low P OP re i. hi g h P O hi gh

Junco- Eleo charit1on

(')

Ditricholsoecion and Junco -Eieocharition

."' 0

Tropical -subandean fo r ests we l l d eve l oped

~6ap?~~~ -~~b~~0J'e":t~n,to~! s t s

r--

+•

Andean fores t s

Myr ica zone narrowing

"' •

POP hi gh P O low

Mozaic of

Q u ercus dominant in

! 50

•

Calamagrostion /igulatstJ

tOO

U pper An dean fo r ests began to dev elo p

•

bog

1/)

<D Ol

No M yrica sc ru b subparamo zone

., "'

<1> <1>

yr BP

+•

'•

T ropica l -suba nde an tores t s r eason abl y we ll developed 1-- -- --

100

"'<1> i~ a:"'"'

Pr ima r y O rganic Product i on (POP) a nd Prim ary De c o mposi ti on (P O)

"'~ 0"'

·Sphagnum'

Quercus zone narrowing

•

C/1

Loc al Synsys t e ma ti c un i ts

Deve lopme n t o t upper Andean f or ests 1/) (')

N o M yric a scrub subparamo zone

"'0 F-

()

:!:

Gradual d evelopment o t pioneer vegetati on types

= .. 0 em

·~ ~ ~

N (") "'V. "'"'

yr BP

<1>

a. E 01 0

Loca l vege t a t io n t y p e s at the bo ring s it e

Fl or istic c o mpos iti o n Ar ea oc cupie d of zon al fores t s by azo n al Atin the study ar ea nus fo r es t s on th e high p l a in

0 0

(3625m)

D1rricho lsoecion

0 ,._

PO P low P O low

..._ "' 1/)

250

I I

Fig. 3lb. Successive local vegetation types (D), synsystematic units (E) and relative data on primary organic production -'POP'- and primary decomposition -'PD'- (F), deduced from the data of the the PPN I section (Pru-amo de Peiia Negra).

F ig. 3 Ia. Displaceme nts of the zonal upper forest line (A) , changes in the flori stic composition of zonal forests (B), and changing areas occupied by azonal Alnus forests (C), deduced from the data of the PPN I section (Pliramo de Peiia Negra).

Between "' 9,100 and = 2,600 yr BP (zone 3) the forest line shifted from a slightly lower to a slightly higher altitude than at present. In the period from = 9, 100 to = 6 150 yr BP climatic conditions were relatively dry as reflected in the diminishing surface of ill-drained areas occupied by Alnus forests on the high plain of Bogota and surrounding s and in the sudden local vegetational succession in the Laguna Negra fro m a submerged deep water community (local '-

Palaeobotanical-palaeoecological studies

phase A) towards a relatively drier mire vegetation type (local phase C). The mean annual precipitation amounts were, however, sufficient to allow a good development of the tropicalsubandean forests. As a result of the relatively low amounts of precipitation the forest line was probably located at a slightly lower elevation than one could expect considering the prevailing temperatures. The forest line attained its highest location from= 6,150 to= 2,600 yr BP. This was at least partly due to a hi~her climatic humidity, as deduced from the increased areas occupied by Alnus forest and the local vegetational succession towards wetter vegetation types. The effect of temperature and precipitation upon the location of the forest line are difficult to discriminate but temperatures were during the whole period most probably slightly lower to slightly higher (-1 to+ 1°C) than at present. Around = 4, 750 years ago Weinmannia forest began to replace former Quercus forest in the Andean belt. If this was caused by the changing climatic conditions, endogenous processes (e.g. soil maturation) , human influence, etc. is for the moment still uncertain. During the period from = 2,600 yr BP to present (zone 4) the forest line shifted to its present altitude. The mean annual temperatures became as at present. The decreasing areas occupied by azonal Alnus forests and the local successions towards drier vegetations types seem to be indicative of a less humid climate. However, regionally the destruction by men of the natural vegetation on the high plain and locally the filling up of the sedimentary basin may have been also (partly) responsable for these developments. Anyhow, human impact gradually became a more important factor in fluencing regional vegetation types. As a result of the major changes in the regional arboreal vegetation during zones 1 and 2, the given pollen influx numbers must be considered as mean values over the whole corresponding periods because they were most probably not constant. For instance, during the colder intervals (subzones Ia, l c and 2b) the pollen supply of the zonal arboreal elements must have been lower than it was during the relatively warmer intervals because of the greater distance of the forest belts to the Laguna Negra. Pollen density time calculations over these periods are therefore rather inaccu.rate, as they were based on co~stant JJ:Ollen influx numbers. Likewise, the changing areas occupted by Alnus forests on the htgh plam of Bogota and surroundings (zones 2, 3 and 4) resulted in differences in arboreal pollen supply. 14 C datings were not all ways taken at the depth on which major changes in this respect took place. As a result, pollen density time calculations are also less accurate. · Correlation of the regional vegetational and climatic data deduced from the PPN I section with data derived from other pollen diagrams in the study area and with the general chronostratigraphic sequence of the Cordillera Oriental will be dealt with in part III. The ~eneral development of the local vegetation types , from a su bmerged deep water commumty towards a relatively dry peatbog community, was determined by the filling up of the sedimentary basin, which is an endogenous process . On the contrary, the floristic composi tion of the local vegetation types and sudden successions were determined by exogenous factors, such as the climate, a climatic change and, possibly, volcanic ash rain and human influence. The influence of the climate upon the floristic composition of the local vegetation types and the local vegetational successions has been partly dealt with above. The repeated development of mire vegetation types, dominated by Gramineae (most probably Calamagrosris lig ulata ), in those periods in which major local changes did occur (transitions local phase A-B and C-D, and local phase F) is noteworthy. Especially the vegetation types of the Junco -Eleocharirion (local phases B. D and E) and of the Calamagrostion ligulatae (transition local phase A-B, local phases C and F), wh!ch are bound to the zone of the ~ater table, were very susceptible to regional changes in humtdtty. The re-appearence of lsoeres m local phase E seems to be related to the deposition of the thick volcanic ash layer. Although a definite answer cannot be given, it seems probable that the ash buried the fo rmer fl oating reedswamp vegetation creating some deeper pools in which lsoeres could develop. Human activities seem to have influenced local vegetation development d~ring the last~ 350 years. !ben, sud~en successions took place towards local vegetation types with a htgh pnmary organic production (local phases G and H). The high concentration of charcoal around '" 350 yr BP. most probably resulting from repeated burning in the area by men, is striking. Charcoal found in local phase C seems to be the product of natural fires. They occurred less frequently and had less influence upon local vegetation development.

Paramo de Agua Blanca

6. PARAMO DE AGUA BLANCA: THE PAB II AND PAB lli SECTIONS Introduction The Paramo de Agua Blanca (ca 5000' N; 7401~· W) is ~ituated at t~e northwestern periphery of the high plain of Bogota in the Colombian Cordillera Oriental (see ~Ig. 1). al . d f Three sections were taken in the central part of a peatbog, located m the area at an ntu eo ca 325Qm·(Fig. 32).

Fig. 32. View of the peatbog·in the Paramo de Agua .Blanca ~h~re the three sections were collected. The boring sites of the PAB II and PAB Ill secuons are mdicated by arrows.

The results of the palynological analysis of the PAB 1section, representing approximately the last 465 000 years have been published by Helmens & Kuhry (1986). The 99cm long PA ~ 11 section ~as cut ou; from a profile after peat digging operations. The 12lcr:t long PAB III section was collected with the aid of the larger Dachnovsky sampler. In all sections the bottom of the sedimentary basin was not reach~d. The lithol?gical sequences of the PAB II and PAB lii sections are given in Fig. 33 and Fig. 34, respecuvely. For the microfossil analysis of the PAB II section samples of known volume (range 1-Sc.m 3) were taken at constant intervals of Scm. Pollen sum values are 127-210. In the PAB III secnon, sample interval was also Scm, their volume v~mg from 0.4-30.9cm3• Pollen sum values a:e 136-183. Tablets containing exotic pollen grams of Eucalyptus were added to the samples 10 order to determine pollen concentrations in the sediment. . . Samples for the analysis of macrobotanical remains were taken m both ~ecnons ~t the. same intervals as the microfossil samples. Sample volumes are 7 .5-12.0cm . Counungs m the macrofossil analyses were recalculated on the basis of a constant sample volum~ of 10cm3: A total of five samples were taken for 1 •c dating, two from the PAB I1 secnon (see Ftg. 33) and three from the PAB III section (see Fig. 34).

[

Paramo de Agua Blanca

TABLE XII. pH records and floristic composition with cover-abun dance values of the local vegetation types in the peatbog under study (Paramo de Agua Blanca).

-----·-----------·--------------------·-------------------------------·----------------------------------·----------b) Vegetatio n types

pH moss layer (hummock) moss layer . (hollow) p eaty sediment

a ) pea tbog 4. 0- 4.5 5.0 4.5-5. 0

scrub

4.0-4.5 5.0 4.5-5.0

Taxa i n dwarf shrub layer (0 . 5-l. Sm)

Diplostep hium cf. rosmarini f olium Hyperic um laricifoli um Blechnum l oxense Hypericum goyanesii Swallenoc hloa tess ellata Espeletia grandiflo ra

+ 4

2 2 1 2

l l

Taxa in herb layer (0.1- 0 .Sm)

........-I=

carex pichi nchensis Calamagr ostis cf. planifoli a Calamagr ostis effusa Eryngium humboldt ii Puya santosi i Castillej a fissifolia Junc us ecuadorie nsis J uncus echinocep halus Rhynch ospora ma c r ochaeta

'""'

.................................. ....................... .......... ~.......................

;::

······································ · F

········

...... E ... ~

I .......!..... . ..........

CO UNTI NGS

4 l

+ +

r r

r r r

Taxa i n ground layer ( < 0 .1m)

f····

...................... ........................................................... ........

~==.I

t r

Geranium s p . Pleuro zium schreberi Polytrichu m juniperinu m Marchanti a s p . Ac aena cylindris tachya Ho l cus lanatus Lachemill a sp. Rumex acetosell a Halenia sp. Breutelia spp. Perne ttya prostrata Paepalant hus alpinus Ranunculu s nubi genus Nertera granaden sis Riccardia sp. Senec io sp. Cl adonia sp. vaccinium fl o r ibundum Oritrophi um limnophyl um Sphagnum sect . Cuspidata Sphagnum magellani cum Campyl opus spp. Hypnum sp . Rhacocarp us purpurasc ens Lophoc olea bidentata Leptodont ium sp.

+ + +

+ r r r r

3 l l

1 l

+ +

r r

r r l

2 2 2

+ + +

+ +

------4-----------------------------------------------------------------------------------------------------------

.. Palaeobotanical-palaeoecological studies

PAS 11-uction

The PAB ll section was taken in a hollow. Prominent taxa were Calamagrostis effusa and Rhynclwspora macrochaeta. Bryophytes such as Breutelia, Campy/opus and R iccardia marked the ground layer. The PAB ill section was taken in a ca 35cm high hummock with Espeletia grandijlora, Blechnum loxense, Swallenochloa tessellata and Sphagnum magellanicum.

PAB Ill-section

Paramo de Agua Blanca

Palynological and macro botanical analyses of the P AB ll section

Zonation of the regional vegetation diagram (Fig. 38) Zone 1 (99-68cm) Sm

/-~: 'j peat and lacustrine deposit with mo.ss layer

b --

Vegetation t vpes

a I Sphagnum- Esp~leti• grandlflora pea rbog bl Hyptricum lancilolium dwarf scrub

the. peatbo~ un.der study (Paramo de Agua Bl~~~/~;:z~nsi~!:~~.~~l~g~:odnPtAypBesillinsecuons are mdicated.

The tropical-subandean group is very poorly represented. The contribution of the upper Andean group to the pollen sum is high. The subparamo group reaches relatively high values. Dodonaea is found. Subzone la (99-78cm) The Hedyosmum curve attains high percentages. Alnus shows low values. M yrica and Sericocheca are well represented. Polylepis-Acaena is also found. Subzone 1b (78-68cm) The percentages of Alnus gradually increase. Among the subparamo elements, Myrica and Sericotheca are well represented. Zone 2 (68-38cm) The percentages of the tropical-subandean group are slightly higher than they are in zone 1. Very high representation of the upper Andean group, due to increasing values of the zonal element Weinmannia and high values of the azonal element Alnus. The subparamo group shows low values. Zea mais (536) is found.

1 Hypericum /ancJ/oltum

Zone 3 (38-0cm)

2 Sw;,l/~nochloa tusellar.

O.Sm

3 Cflamagrostis ellvsa

The percentages of the tropical-subandean group gradually increase. High representation of the upper Andean group, due to high percentages of the zonal elements. The values of Alnus gradually decrease. The percentages of the subparamo group (i.e. Myrica) show a slight rise. Zea mais (536 & 548) is found. Subzone 3a (38-18cm) Hedyosmum and Weinmannia are well represented. The Melastomataceae curve tends to · increase. ·subzone 3b (18-0cm) High representation of all tropical-subandean elements. Weinmannia , Rapanea and Melastomataceae show high values. Dodonaea and Cheno-Ams are found. Rumex acetosella attains high percentages. In the upper part of the subzone, Eucalyptus and Compositae Jig. are present.

4 N~rrera granadtUJs 1 s

5 Rhynchospora macrochatua 6 Petnertya prostra r a 7 Btechnum Joxenss

8 fspelet1a gNJnddlor8 9 Sphilgnum magellanicum

Subdivision of the local vegetation diagram (Fig. 39a-c) Local phase A (99-73cm)

! I to

VII 10/11 6/ 13

In the macrofossil record, lsoeces megaspores (T1 36) and Eriocaulaceae seeds are found in large q uantities. The microfossil curves of Plantago (P. rig ida-type), Valeriana and lsoeces show very high percen tages. Gentianaceae and Umbelliferae excl. Eryngium are relatively well represented. Bocryococcus and fungal type 562 are frequently found. Local phase B (73-53cm)

Fig. 37. Detail of the local stand of vegetation near the boring sites of the PAB sections.

In the lower part of the subzone, Isoetes megaspores (Tl36) and Eriocaulaceae seeds are still present. In the upper part, /soeces andinalboyacensis megaspores (Tl35) and Juncus seeds (T104) are fo und.

Palaeobotanical-palaeoecological smd

ies

100

The pollen curves of Plantago (P. rigid a-type) and Eryngium show high valu (Botryococcus, Zygnema, Debarya es. Algal types ) are also foun d. Local phase C (53-33cm) Seed s of !unc us (T10 4) andX yris are found. Isoetes andinalboyacensi s megaspores (TB5) are very frequent. • In the microfossil record, Cyperaceae and Xyris are well represented. The (P . rigida-ty pe} and Eryn gium show curves of Plantago max ima halfw ay up the phase. Tsoe fov. show a tendency to increase. tes and Lycopodi um Local phas eD (33- 18cm) Mac rosc opic rem ains of Sph agn um sect. Cus pida ta and S. s ubse abun dant . Seed s of !un cus (T10 cund um are rath er andinalboyacensis megaspores are 5) and Rhy ncho spor a mac roch aeta are found. Isoe tes of frequent occurrence. Cyperaceae and Xyris pollen are relat ively well represented. The Isoe fov. curv es reach high valu es. Fung al type 562 shows grad ually increasing tes and Lycopodium percentages. Local phase E ( 18-0cm) . Macroscopic rema ins of Sphagnum sect. Cuspidata and S. subsecundum m the lowe r part of the phase, whil are rathe r abundant . e thos e of Rhy ncho spor a macroch tomentosa are frequent in the uppermos aera and Breu telia· t part. Then , Ricc ardi a rema ins are · !unc us (TI0 4 & T 105) , Xyris and Rhynchos pora macrochaera are presalso found. Seeds of phas e, the latte r ones beco ming ent thro ugho ut the mor e abun dant in the uppe rmo st part, where also seeds of Hypericum, Oreobolus obtusangulus and Gram inea e, and sporangia and are found. Car ex seed s are pres ent at the base of the phas e. Isoe leaflets of Polypocliales meg aspo res are less frequent than res andi na!b oyac ensi s in the two previous phases. In_th ~ micr ofos sil diag rams , Cyp also stgnificantly repre sente d. /soe eraceae and Xyri s show high percentages. Hyp eric um is tes and Lycopodium fov. attain high type s show high values. percentages. All fung al Paly 'nolo gica l and mac robo tani ca l ana lyse s of the PAB III sect ion Zon atio n of the regi ona l vege tatio n diag ram (Fig . 40) Zon e 1 (121-97cm) The tropical-su bandean group is the subp_aramo group are relatively very poorly represented. The subandean-Andean group and well represented. The percentages of the upper Andean group are relau vely low. Subzone la (121 -106 cm) The Que rcus curve reac hes high Poly lepis-Acaena are well repr esen values. Alnus show s low vJ!lues. Myrica, Sericotheca and ted. Dodonaea is found. Subzone lb (106-97c m) . The Que rcus curve still attains tncreases subs tantially. Myrica is relatrelatively high perc enta ges. The representation of Alnu s ively well represented. Zea mais (536 ) is found. Zone 2 (97-67cm) The trop ical- suba ndea n group contribution of the subandean-An is slightly bett er repr esen ted than it is in zone I. The dean group to the pollen sum grad ually decreases. The uppe r Andean grou p is very well repr esen Alnus. The subparamo grou p show ted, especially due to high percentages of the azonal element s generally low values. ·

Para mo de Agua Blanca

101

Subzone 2a (97-8q<:m) . h rcentages. Sola nace ae (558) The Quercus curve snll attru.ns rela. shows a clea r max imu m at the end of the subzone. uve1~~~ pe ·a curve show s a tend ency to incr ease . The !. eznma(SS~) are found Tha D odo naea 'Zea mais (536) and li ctru m is very well Brom e lace ae . represented. · Subz one 2b (80-67cm) Hedyosm um and Wein mannia are relatively well represented . Zon e 3 (67-0cm) . to the pollen sum The contribution of the tropical-suban ually increases. The c;le~ f:"0~~cially due to high grad percentages of the zonal representation of the uppe r Anddean 1 grod up : e 1e~ is (536) is found. elem ents . The Aln.us curv e ten s to ecrea . Subz one 3a (67-54cm) Hedyosmum and Weinmannia are well represen ted. Subz one 3b (54-0cm~ . al-subandean elements . Weinmannia, High percentages of all Important anea and troptc attains hi h erce ntages in the Rap Melastomataceae are wei~ re~resente lower part of d. Hed yos;! ;:::I'onaea and ~h~no-Ams are foun the subzone, as does Myn ca m the d. The curves upper l~art h ry high values. In the uppe r part of Rum ex acet osella and Com post of the tae tg. s ow ve subz one, Euca lyptus and Pinus are found.

Sub divi sion of the loca l vege tatio n diag ram (Fig. 41 a-c) Local phase A (121 -97cm) In the mac rofossil reco rd,lsoetes meg aspo res (Tl3 6), and ]unc us (T10 4)·an d Eriocaulaceae seeds are found in large quantit_ies. U belli ~ cl Eryngium Cyp erac eae and Plan The pollen curves of Valenana , tago (P. m ~rae ex · ermo st 'art the phase . !soe ces and rigid a-ty pe) show max th~ ~tte{ on~ ~~~~ ~;~;'part. Bofryocoofccus Lycopodium fov. spores ima, and fung al type 562 reach hlg va ues 10 . are present. Local phase B (97-80cm) Seeds of Xyris an? Eri.ocaulaceEa are ~ther a~~~~a~~gh valu es. Plan tago (P. rigid In the micr ofos stls d1agram, eryng a-ty pe), cum rea Gentianaceae and Compositae tub. are relatively well represented. Local phase C (80-54cm) . Macroscopic rematns of..Rhync~os r mac rochaeca and cf. Xyri s are present. Seeds of p; a . (T\ 35) are foun d in large quan tities Xyris and megaspores of Jsoe . iWICUS tes andmal oyacens cs (Tl0 4) and ~riocaul~ceae seedXare ~so fo~n ~pre sent ed. Eryn gium still attai ns relativ~l~ high In the rrucrofos s1l record, yns IS we h w very high values. Gra mm perc enta ges. Lyc opo dium fodv· ws and ;:d Sp·7: Sg:uU :::e ~e~ds to increase. Pseu doschiza Hymenophyllum are also foun . ea circula e 1soe reac hes high values. Local phase D (54-28cm) Charcoal is found ~t the base of this phase. idata and S. mag ellanicum are abun MacroscopiC remruns of Sphagn~m dant. In the lowe r part of the p~ase Aulac_ommu se~~;;~;~emains are prese nt. At the trans ition to wards n; p d X ·s ]unc us (Tl 05) and Hypericum seeds ~e the next phase, Hyp encu m remGams rath er freq uent . Car ex and ram ~e oun .ds ya7e , also fo und. /soe tes andi nalb oyac enszs mea e see meg aspores (Tl3 5) are still rather abundant .

Palaeob otanical -palaeoe cologic al studies

102

Paramo de Agua Blanca

103

Pollen ?f Xyris and Cype:a ceae are relative!~ well represe nted. The curve of Hyperi cum gradual ly nses towards very h1gh percent ages, while the curves of /soetes and Lycopodium fov. gradual ly drop. Several fungal types and Meesia-type show maxima .

Local phase E (28-0cm )

Mac.roscopic remains . of Sphagnw:z magel~anicum and Calama Espeletza seeds, Polypod1ales sporang ia, Grarrun eae glumae and grostis effusa are frequen t. basal leaf sheaths , Hypericum seeds and branche s, and Hypericum laricijo lium and H. goyane sii leaves are found. Th~

PAB II

pol!en curves of Gramin eae and Compo sitae tub.

Hypencum m the lower part and Sphagnum in the upperm ost reach very high values, as do part of the phase. Several fungal types and Assulina show maxima .

Dating of the P AB II and P AB III section s, and inferre d calcula tions

datings

A total of five samples was dated. The results are given in Table XIII.

TABLE XIII. Radioca rbon dates of the P AB II and PAB ill sections (Param o de Agua Blanca).

GrN 12071 • 5.9 00 ±70

PAB II sectio n 75

Labora tory number s

Sample number s

GrN 12071 GrN 12900

COL 379 COL 486

Depth below surfac e in em 63 98

Age in yr BP 5,900 ± 7 0 8,290 ± 45 99

GrN 12900 "8 . 290±45 0.5

PAB III sectio n

-emLabora tory number s

Sample n umbers

GrN 12901 GrN 12902 GrN 12903

COL 487 COL 488 COL 489

Depth below surfac e in em 50-58 67-76 1 05-10 8

Age in yr BP 630 ± 50 2,210 ± 50 6,630 ± 100

The age of sample .n umber COL 487 (GrN 12901) can be conside red as 660 to 630 yr BP or 580 to 560 yr BP (StUJver, I 982). As the exact age of the sample remains uncerta in, it has not been used to calcula te regiona l pollen influx data, nor to perform pollen density time calculao ons.

Region al pollen influx data and pollen density time scales In Fig. 42, the depth scale, the ••c datings and the pollen concent ration and cumula tive pollen curves of the elements include d in the pollen sum of the PAB II section, are given. In Ftg. 43, the same data are given for the PAB III section. Average annual pollen influx numbers of pollen sum elemen ts were calculat ed for the interval 8,2~ to 0 yr BP in the P~B II section and for the interval 6,630 to 0 yr BP in the PAB III secoon. Further more, h<?th ~ the PAB II section and the PAB III section, pollen influx numbers :-vere calculat e? for the orne mtervals between any two 14C datings. In the PAB III section, pollen tnflux calculan ons were also perform ed for the differen t altitudin al groups in the pollen s um, for the zonal arboreal element s and for the azonal elemen t Alnus. The data are summar ized in Table XIV. Pollen influx number s for the differen t time interva ls in both sections are rather variable particul arly in the PAB II section. ' con~entral!on

2.5

-yr BP-

F ig. 42. Depth scale (A), t•C datings (B) and pollen concent ration curve (C) and cumula tive pollen concent ration curve (D) of pollen sum elemen ts, of the PAB II sectton (Paramo de Agua Blanca) .

Very low pollen influx number s for the time i~terv~ 8,2~0 to 5,900 yr BP in the PAB II section can be explained by a low pollen supply dunng thts penod of the azonal elem~nt Alnus, which is the major contribu tor to the pollen influx of pol)en sum element s (see pollen tnflux data of the p AB III section) , and by corrosio n of pollen grau~s. The latter one was already v1sually observed during the microfo ssil analysi s of the sectu;m . Also anoth.er fact support s thts statement. Accordi ng to Having a (1984), Quercus pollen IS more susce~uble to corros10 n t~an , for instance , fern spores. In the time interval 8,290 to 5 ,900 yr ~p 1n the PAB II secuon , percentages of Quercus are signific antly lower and percentages of reg10nal fern spores are clearly higher than they are at compar able level~ in the PA~ I section (Helm~ns ~ Kuhry, .1986) and the PAB III section suggest ing that (selecuv e) corro~10n of pollen gra1ns d1d.occ ur m th~ PA~ 12 section. The changin g pollen supply by Alnus dunng the last 5,900 years tS an?ther distur bmo factor. In view of these irregula rities, a time scale based on pollen concen tranon data has not been applied to the PAB IT section. . In the PAB III section, corrosio n of pollen grams . seems to be. abse~t. Therefo~e, changm g pollen influx number s of the regiona l vegetati on element s.are tentanv ely l~terpreted m terms of a changin g regiona l pollen supply to the sedimen tary basm. Low pollen mflux number s for the time interval 2,210 to 0 yr BP are especia lly due to a low poll~n su~ply of ~he azonal el.eme~t Alnus. As t•C datings were taken more or less at the depths m wht~h maJor changes m thiS respect took place, pollen density time calculat ions in the PAB Ill sttcnon seem to be reasona bly

.• 104

Palaeobotanical-palaeoecological studies

reliable. Time calculations in the lowermost part of the section are based on pollen influx numbers of the time interval 2,210 to 0 yr BP because in both cases pollen supply by Alnus seems to have been low. Naturally, these calculations are less reliable.

PAS

Ill

F 25

50 25

I GrN129 02 2.210 ± 50 50

10 0.

Gr N 12903 1 6.630±100

12 1 0

- em -

-yr BP-

0.5

1.5

-x 10 5 P/c m 3-

2.5

3.5

4.5

-x 10 6 P/c m2I 00

Fig. 43. Depth scale (A), t•C datings (B) and pollen concentration curve (C) and cumulative pollen concentration curve (D) of pollen sum elements, of the P AB Ill section (Paramo de Agua Blanca). <sca le : 1/10>

Interpretation of the data of the PAB II section Regional vegetation development Zone 1 A subparamo vegetation with Myrica and Sericotheca developed in the area of the Paramo de Agua Blanca. At first, Polylepis was present. Later on, Sericotheca became more abundant. The presence of Dodonaea seems to be indicative for some instability in the Andean forest belt.

Fig. 41

Paramo de Agua Blanca

105

PAB Ill (325Dm) GD1 yr BP 1 57

16 7 174

1 7

1 53 146

1 58

1 50

1 52

., ~

140

0 ~

1 51

; 36

14 5

15s

0 ·

1 36 16 7 183 144

1 57

160

10 0

1 54 1 53

1 52 1 43

16 1

121

_33

Lower tropical -subandean gr.

--;---~( )

Upper subandean- Upper lower Andean gr. Andean gr.

Subparamo group •

0510

50%

.--~---,

-0

100%

INCLUDED IN THE POLLEN S U M - - - - - - - - - - - - - - - - - - -

:LUDED IN THE POLLEN S U M - - - - - - - - - - - - - - - - - -

I 57 I 67 I 74

I 75

b I 53

3 146 I 58 I 50 I 52 140

I 5 I I 36 I 45 I 55

I 36

I67 I83 144 I 57 I 6 0

I 54 I 53 I 52 I 43

I 61

106

Palaeobotanical-palaeoecological studies

PAB Ill (3250m)

yr BP

;;: +I

."' 0

....0 +I 0

100

0 0

.."' 0

121

100%

ill section (Paramo de Fi~ 41 !1 . T-nc:~l vP.~>P.tMinn tli:~I>T:~m (noll en and fern snores). PAB

<scale: 1/10 >

PAB Ill (3250m)

yr BP

E 25

0 50

~ +O

,., "' 0

0 ~

+O 0

10 0

0 0

., ,., "' 0

12 1

0 5 10

I ' I

50%

Fig. 4lb. Local vegetation diagram (other microfossils), PAB III section (Paramo de Agua Blanca).

>ssils), PAB III section (Paramo de Agua

- ------------ ----- -- -- --

108

Palaeobotanical-palaeoecological studies

PAB Ill (3250m)

~ ..... .............. ..... .. . ....... . ......... .. .............. . ... ................... .......... . ·········· . . .

D 50

.......................

:;: +I

. 0

+I 0

100

0 0

.. 0

121

F= 5 10 0.-~~-~ so 0

100

____

PE RCENTAGES--

- - --

- - -- - -- --

- - -- -- - -- - - - --

CO UNTIN GS - - - - - --

- -- - -- - -

rrfJ5)

67'

~rA

rulll

oi n9'

)

rBD'

crs6J rllllns"ine'

rBIIIo!r>~"moex~~

rBIII

r69J cr6BJ rslll"ino

rllllloir>e

c17B)·

''''

'XcRD~~~ (16~~9 (1~pl)5~ r"lll"ir>~usP JD ~~tJicLJM ~us1Rio-'' (~9) ,osJ oD' (1g~;J (rl I~~ (fl ;!OJ r91i 1 '~' ~~~~~k~t~e~~A~~~~~i~~~~~~ Gllct.• sPHAGtJLlll ~~G~~ AV~A~tl~~~~ ~Zso9 (1 ~RiocA~~~~~A:9:d!i (fl ;utJCLl§Q:~~~x~~ G~~~1~~nR1~~t~~!nr~~~1~ .,ego9p0 ,so~~~ oir>9

gscrl" 5J

"'' f l 5 ·tJDitJA

g809

I I

.,.,.,

. . . ......... ....... . . . ......... ii: .......................................... = .

............................. .................................... ...........................................

. F= ~t==~ ~ ~ ~ L

~........ .. ...........

.....

;~J til~~"'

Ja"~u~uot1!

ot.no)

.,.

r I ...... f ........l

tr!SO'

~ ............. I ......... .........

iilg9J

.,.

p """

f=>

• ~f

io ~

.... !.. I

..a= .... .... ................. .

.................... ............... ........... ................. ....................................... ................. .................1....... .......................................................................... .

... . . . . . . . . . . . ... . .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ~. . . . . . . . ~. . .F. . ... . . . . . . . . . . . . . . . . . . . . . . . ... .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..... . . . . . . ... . . . . . .. . ...... . . . . ...... . . . . . . . . ... . . . . . . . . ... . . .. . . ... . . .

l<zz====~

0 - - - - PER CEN TAGES - - ------------

, PAB III section (Paramo de Agua

- --

---

- - - --

- - --

- -- --

rJSBJ

;Bo'~"cttl ~~ /pOi~;g~:c'~I:~c;;~tic~1fll5~~rA~r#R\J ;: t;~~19P(~~!~~~~~~k11 pD~ tP~A~l ~li~~ '~ip~R~/p£R ~)'PfR 'ri~t116o~~cAR I@{H~~ sJ5 "'eg , ••

= · .............. ;;;,;·······~············ ·· ··

(/5P"

ru 5

-- COUNTJN G S------------------~-------

Jllt.or>

9J ot1!6

Paramo de Agua Blanca

109

•

TABLEXIV. Pollen influx data of the P AB II and PAB ill sections (Paramo de Agua Blanca).

• PAB II sect ion Time-interval (in yr BP)

-0

8290 - 5900

59 00 -0

473

168

597

6630 -0

6630 - 2210

;!21 0

635

764

376

509

611

305

16 4

177

135

345

434

169

290

330

207

8290

Pollen in f lux data (in P . cm- 2.yr-l ) - Po llen sum elements PAB III section Time-i nterval (in yr BP)

·~

Pollen i nflux data (in P .cm- 2 . y r -1)

1.. .. !........... . . ... . ............... . . . ... ........ .

I I

II I J···· ···· ·· · · · · · ·· · . . . . .... . . ... .. I

- Pol len sum elements Lower tropicalsubandean elements - Upper subandeanlower Andean elements - Upper Andean elements - Zonal upper Andean elements - Azonal upper Andean elements (•Alnus) - Subparamo elements - Zonal pol l en sum elements (=LAP - Alnus)

. . ... !. ... .

I ... !...

~I ..,., I

r l~... . . . r ~+~···

~-~

. ..r.

I I

I NGS - -- - - - - -- - --

-0

[ f f f

tt '

During the period corresponding with subzone lb, azonal Alnus forests began to expand on the high plain of Bogota and surrounrlings. Zone2 Andean fores t gradually invaded the area of the Paramo de Agua Blanca, Weinmannia being the dominant tree. The presence of 'prehispan,ic' Zea mais probably indicates agricultural activities by prehistoric men in the study area, going as far back as"" 6,000 yr BP. The area occupied by azonal Alnus forests was large. Zone 3 Upper Andean Weinmannia forest with Myrica and Melastomataceae dominated in the area. In the period corresponding with subzone 3b, the destruction of Andean forests by men became catastrophic, which explains the expansion of secondary vegetation types with Rapanea, Dodonaea, Myrica, Melastomataceae and Chenopodiaceae-Amaranthaceae as well as the overrepresentation of the tropical-subandean elements in the pollen diagram. Land-use by men commenced in the Paramo de Agua Blanca itself, resulting in the development of secondary vegetation types with ruderal herbaceous taxa as Rumex acetosella and Composi tae (Hypoclweris?). The abundant presence of the introduced herb Rumex acetosella indicates that subzone 3b represents at most the last 450 years ('hispanic' times). Incidental occurrence of

Palaeobotanical-palae<>e(;ological studies

110

Rumex acetose/la and 'hispanic' Zea mais pollen grains at lower levels can be attributed to worm activity. In the period corresponding with zone 3, the area occupied by azonal Alnus forest on the high plain of Bogota and surroundings gradually decreased. Local vegetation development Local phase A An aquatic community with lsoetes and Botryococcus developed at the boring site. An umbelliferous taxon (Hydrocoryle or Lilaeopsis?) was probably also growing locally. This vegetation type belongs to theDitricho-Isoetion. In the boggy shore zone of the former lake, a cushion bog community, belonging to the Gentiano-Oritrophion, developed. Plantago r:igida, Valeriana, Eriocaulaceae and Gentianaceae were dominant. Local phase B Locally, a cushion bog community (Gentiano-Oritrophion) developed. Plantago rigida and Eryngium (E. humile? ) were dominant. Several algae were growing on the spot, indicating the presence of a wet hollow at the boring site. Local pl1ase C Transitional phase between the previous cushion bog community (Gentiano-Oritrophion) and the next Xyris-Sphagnum peatbog community. Xyris, ]uncus, Cyperaceae (Rhynchospora macrochaeta ?), Lycopodium and l soetes andinalboyacensis were growing near the boring site. These taxa are mostly found in the hollow kind of micro-habitat./. andina and/. boyacensis are terrestrial /soifres species. Local phase D The Xyris-Sphagn um peatbog community fully developed. Sphagnum sect. Cuspidata, S. subsecundum, Rhy nchospora macrochaeta, ]uncus, Lycopodium and lsoiftes andinalboyacensis were growing locally, indicating the presence of a hollow on the spot. Local phase E A Xyris -Sphagnum peatbog community was present locally . Hollow taxa, including Sphagnum sect. Cuspidata, S. subsecundum, Rhynchospora macrochaeta, Carex, ]uncus, Lycopodium and lsoetes andinalboyacensis, were growing at the boring site. In the period corresponding with the end of phase E, the actual hollow with Rhynchospora "!acrochoeta, Catc:magrostis effusa, Breutelia tomenrosa and Riccardia developed at the boring sue. Accompanymg taxa were Oreobolus obtusangulus, lsoetes andinalboyacensis and Lycopodium. Hypericum dwarf shrubs and Polypodiales (Blechnum loxense?) also became more abundant. Interpretation of the data of the PAB III section

111

Pru-amo de Agua Blanca

In the period corresponding with subzone lb (= 6,630 to= 4,900 yr BP), stands of azonal Alnus forest became very numerous on the high plain of Bogota and surroundings. Zone 2 (= 4,900 to= 1,700 yr BP) The area occupied by Quercus stands in the Andean forest belt gradually decreased, while Hedyosmlun and Weinmannia became more abundant. Upper Andean Weinmannia forest invaded the area of the Paramo de Agua Blanca. At first, a solanaceous taxon, probably a tree (Solanum?), was growing very near the boring site of the PAB m section. The presence of Thalictrum and Bromeliaceae is striking. The ftrst one is a herbaceous taxon common of clearings in the Andean forests; the second one could be eventually an epiphytic taxon growing on the Solanaceae tree. The area occupied by azonal Alnus forests was large. Zone3 (= 1,700 to 0 yr BP) Low pollen influx numbers of Quercus can be ascribed to diminished areas occupied by this tree in the Andean forest belt. Upper Andean Weinmannia forest dominated in the area of the Paramo de Agua Blanca. The extensive destruction of Andean forests by men in the period corresponding with subzone 3b allowed the development of secondary vegetation types with Rapanea, Dodonaea, Myrica, Melastomataceae and Chenopodiaceae-Amaranthaceae. It also explains the percentual over-representation of the tropical-subandean elements in the pollen diagram, in spite of the fact that pollen influx numbers did not change. Land-use by men commenced in the Paramo de Agua Blanca itself, resulting in the development of secondary vegetation types with ruderal herbaceous taxa as Rumex acetosella and Compositae (Hypochoeris ?). The beginning of reforestation practices, with Eucalyptus and Pinus, is also recorded. According to the pollen density time calculations, subzone 3b corresponds with the last"' 575 years. However, the presence of the introduced herb Rumex acetosella all over the subzone indicates that the subzone can only represent at most the last 450 years ('hispanic' times). Low pollen influx numbers of Alnus indicate an upon the whole limited extension of this azonal element on the high plain of Bogota and surrounding s.

Local vegetation development Local phase A(= 7,150? to= 4,900 yr BP) An aquatic community with lsoetes and Botryococcus developed at the boring site. I uncus, Cyperaceae (Eleocharis?) and Um~lliferae (Hydrocoryle or Lilaeopsis?) were also present. This vegetation type belongs to the Ditricho-lsoerion. In the bo ggy shore zone of the former lake, a cushion bog community belo nging to the Gentiano-Oritrophion developed. Plantago rigida and Valeriano were dominant. Eriocaulaceae and Lycopodium were also present. Local phase B (= 4,900 to= 2,850 yr BP) Locally, a cushion bog community (Gentiano-Oritrophion) developed. Dominant taxa were Plantago rigida and Eryngium (E. humile?). Accompanying taxa included Xyris, Gentianaceae, Eriocaulaceae and Compositae.

Regional vegetation development Local phase C (= 2,850 to .. 600 yr BP) Zone 1 ("' 7,150? to= 4,900 yr BP) In the Andean forest belt, Quercus was more abundant than it is at present. The area of the P~o de Agua Blanca was occupied by a subparamo vegetation type dominated by Myrica and ~er_1co~heca. At f':st, Polylep~s was also present. During that period Dodonaea is also reponed, mdicanng some disturbances m the Andean forest belt. The presence of 'prehispanic' Zea mais is probably attributable to agricultural activities by prehistoric men in the study area from .. 6, 150 ' yr BP onwards.

A Xyris-Sphagnum peatbog developed at the boring site. Accompanying taxa included Rhynchospora macrochaeta, ]uncus, Eryngium (E. humile?), l soetes andinalboyacensis, Hymenophyllum, Grammitis, Lycopodium and Eriocaulaceae. All these taxa mostly occur in hollows. I. andina and/. boyacensis are terrestrial /soiftes species.

Palaeobotanical-palaeoecological studies

112

Paramo de Agua Blanca

113

Local phaseD(= 575 to"" 25 yr BP) As explained above, this local phase commenced at most"' 450 years ago. Locally, a Xyris-Sphagnum peatbog was present. A hummock started to develop. Hollow taxa, viz., Sphagnum sect. Cusp idata, ]uncus, Carex, Isoetes andina/boyacensis and Lycopodium, were gradually replaced by hummock taxa, viz., Sphagnum mage/lanicum, Hypericum and Gramineae (Caldmagrostis effusa?). The presence of charcoal and the abundance of Gelasinospora spores, usually associated with flre (Van Gee!, 1978), at the beginning of this phase is indicative for burning practices in the direct vicinity of the boring site. ~

PAB

(3250 m )

Zona l upper fo r est line

Local phase E (~ 25 to 0 yr BP) T he actual Sphagnum magellanicum hummock with Espeletia developed. Hypericum dwarl shrubs, Calamagrostis effusa and Polypodiales (Blechnum loxense?) became more abundant. The coverage of Xyris diminished.

,..

In Fig. 44, a summary of the regional and local vegetation developments deduced from the data of the PAB II section is presented. The vertical movements of the zonal upper forest line, the changes in floristic composition of the zonal vegetation types in the area of the Paramo de Agua Blanca, the changes in the area occupied by azonal Alnus forests on the high plain of Bogota and surroundings, the successive local vegetation types related to fluctuations of the water level and the local synsystematic units, are given. In Fig. 45, the same data are given for the PAB lii section. In the Early Holocene, Quercus was an important element in the Andean forest belt on the eastern slopes of the Magdalena valley. The presence of the pioneer element Dodonaea during this period indicates a certain instability in this zonal belt. The surface occupied by azonal Alnus forests on the high plain of Bogota and surroundings was small and the upper zonal forest line was located at a slightly lower elevation than it is at present. Between ~ 6,000 and"' 4,500 yr BP, upper Andean Weinmannia forest gradually replaced the former Myrica-Sericotheca subparamo vegetation in the area of the Paramo de Agua Blanca. This was at least partly due to a rise in the effective precipitation as reflected in the increased surface of ill-drained areas occupied by azonal Alnus forest on the high plai n of Bogota and surroundings. At the same time, local conditions became drier. This apparent contradiction can be attributed to the influence upon the local water level of differences in water storage and evapotranspiration by the upper Andean forest and the (sub)paramo vegetation types, which seems to completely overrule the influence of changing humidity. The same effect has been repeatedly observed in the much longer parallel PAB I section (Helmens & Kuhry, 1986) and in the El Bosque mire, a small sedimentary basin located in the Colombian Cordillera Central (Kuhry, in press). During the Late Holocene, upper Andean Weinmannia forest with Myrica and Melastomataceae was present in the area of the P:iramo de Agua Blanca. Downwards, on the eastern slopes of the Magdalena valley, Quercus stands were partially replaced by upper Andean forest with Weinmannia and Hedyosmum. The area occupied by azonal Alnus forest on the high plain of Bogota and surroundings ·diminished . The expansion of pioneer and secondary vegetation types with Myrica, Rapanea, Dodonaea, Melastomataceae and Chenopodiaceae-Amaranthaceae can be explained by the increasing destruction of Andean forests by men. Correlation of these regional vegetation data with other palynological data in the study area and with the general chronoscratigraphic sequence of the Cordillera Oriental will be dealt with in pan III.

.c.

Conclusions and discussion

(.)

(;,

... iii

.,"'c

.c.

::>

(/)

,...:::::....

Zonal vege . Area occut ation in t he p iedbyA/area of th e nus o n the Paramo de h i gh p l a in Agua Blan ca "'

., '"

E E

"'~ (/)E ,..=.. '"

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-;;;

C')

;!:.... "'

-B .c.

u 0

,.=L

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(.)

yr BP E

Gradual de· v el opme nt of Uppe r Andean

1--

\ 1\

+' 0 0

"'-

•

I Lowe r

subparamo

Gen tiano Oritrophion

..."'

L-

l s o etion

..__

..__ A

Ditricho-

w i t h Myr.c~.~ Sericotheca

1b vegetatio n

"'.

1--

bog (hollow)

f--

,._

'Sphagnum

f orest

We inman nlfJ

.c.

L oc a l S yn sys . tematic un it s

0 .0

Loca lve getat io n typ es at t he boring s i te

Fig 44 D isplacements of the zonal upper forest line (A), changes in floristic c?mposition of the zo~al ~egetation in the Paramo de Agua Blanca (B), changing areas occupt~ by _azonal Alnus forests (C), successive local vegetation types (D) and local synsystemauc umts (E), deduced from the data of the PAB II section (Paramo de Agua Blanca).

Palaeobotanical-palaeoecological studies

114

115

Introduction

PAB

Ill

(3250m) Zonal upper lor"est line

,..

<"' I

.c 0.

"' 00 em

:! yr

"' "' Ui

"" ~

~ :I

Zonalvege- Area occu. tation inthe pied by Atar-ea of the nus on the Paramo de high pl ain Agua Blanca

"'"' "'"' v. "

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en --'

"'"'c. "' IJ

--'

Local vegetation types at the boring site

Local Syns ys. tematic units

PART III GENERAL CONCLUS IONS

~ 路-g 路-~

u:::1 <C"

C/1

7. INTRODUCTIO N

"' :::1

' Sphagnum'

bog (hummock)

An attempt is made to reconstruct the development in space and time of the zonal and azonal vegetation types in the study area over the past 24,000 years. Exogenous factors (e.g. climate) and endogenous processes involved will be discussed. A number of disciplines provided data for this historical reconstruction, i.e. palynology/palaeo botany, glacial geomorphology and archaeology. Palynology/palaeobotany

Over the last 30 years an impressive amount of palaeoecological data has been obtained in the study area. Use will be made of the following palynological/pal aeobotanical records (for geographical location see Fig. 46):

Gradua l de velopment of Upper Andean

Laguna de Fuquene II section, upper part (LFQ II; Van Gee! & Van der Hammen, 1973)

Wein man nia

forest

' Sphagnum路

bog (hollow)

.."' 0

Paramo de Laguna Verde I and Il sections (PLY I & II; present study) Paramo de Pena Negra I and II sections (PPN T & IT; present study)

'-:"!

"' 100

Laguna de Palacio section, lower part (LPA; Van Gee1 & Vander Hammen, 1973)

Gent iano 路 Oritrophion

"'"'

Ottri cho-

l sottion

12 I

Laguna de Ia America section (LAM; Vander Hammen & Gonzalez, 1960) PT I and II sections (PT I & II; Van der Hammen & Gonzalez, 1960)

Low er subparamo vege tati on with My rica. Ser icotheca

Paramo de Guasca section (PG; Kuhry, unpublished)

Paramo de Agua Blanca II and III sections (PAB II & III; present study) El Abra IV-107N ,upper part, and II-B3 sections (EA N-107N & EA II-B3; SchreveBrinkman, 1978) Ciudad Universitaria X section, upper part (CUX; Vander Hammen & Gonzalez, 1963)

Fig. 45. Displacements of the zonal upper forest line (A), changes in floristic composition of the zonal vegetation in the Paramo d e Agua Blanca (B), changing areas occupied by azonal Alnus forests (C), successive local vegetation types (D) and local synsystematic units (E), deduced from the data of the PAB III section (Paramo de Agua Blanca).

Laguna de Ia Herrera section (LH; Vander Hammen & Gonzalez, 1965a and Vander Hammen, 1986) Laguna de Pedro Palo III and V sections (LPP III & V; Vander Hammen, 1974 and partly unpublished) In section 8, these sections will be briefly discussed. Use will also be made of palynological data obtained in o ther areas of the Colombian Cordillera Oriental, viz., the Paramo de Sumapaz, the Paramo de Guantiva and the Sierra Nevada del Cocuy (for geographical location see Fig. 46). The reader will be referred to the following sections:

Palaeobotanical-palaeoecological studies

Plira.mo de Sumapaz

116

Alsacia section (Melief, 1985) La Guitarra section (Melief, 1985) Andabobos section (Melief, 1985)

Plira.mo de Guantiva â&#x20AC;˘

Laguna de los Bobos section (Vander Hammen, 1962) Cienaga del Visitador section (Vander Hammen & Gonzalez, 1965b)

Sierra Nevada del Cocuy

La Ciega I and III sections (Vander Hammen et al., 1980/81)

ot-l'~~pl

,-~"'

el~ ~~

~~~

0 em

Glacial geomorphology

Recently, Helmens (in prep.) finished a study dealing with the Late Pleistocene glacial sequence in the study area on the basis of geomorphological evidence (e.g. moraine complexes) and 14 C datings. Former glacier extensions in the Paramo de Pefia Negra and the Paramo de Palacio were mapped and dated (for geographical location see Fig. 1 and Fig. 46). Archaeology The study area is very rich in archaeological sites. Vander Hammen & Correal (1978) gave an overview of the human presence and activities in the area of the high plain of Bogotli and surroundings. These data and the information obtained from the present study will be used to establish the influence of human settlements upon the natural vegetational development in the study area.

Âˇ)

' i

I.....................

Fig.' Van Gee

0 :X:

Synopsis of palynological data

117

liDen, 1962)

wen&

Lag. de Fuquene II (258Dml GO 2'

1en et al., 0 em

GD3

yr BP

stocene glacial ine complexes) the Paramo de

eal (1978) gave Bogota and 路 will be used to elopment in the

1 of

~ +' 0

., N

o路

600 .. ..... .

:;:

[

....

+I ~ ~

Lowertro- Uppe; sub group

IU~per) Sub~a r amo - 0 510

paramo路

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group

andean gr.

Andean gr

group

o%-- - - - - - - - - - - -

I NCLUDED IN THE POLLEN SUM

(

Synopsis of palynological data

117

80m) 2'

GD3

········ ···· ·················_:·

ubparamo Grass paramo roup group

(U~perl Subparamo -0 510 Lower'tro- Uppe; subpica/· subandean-lower Andean group andean gr

Andean gr .

group

una de Fuquene II section, '\Jpper part (adapted from

50%

INCLUDED IN THE POLLEN SUM

Palaeobotanical-palaeoecological studies

118

/ Par. de Laguna Verde I (3625ml

GD2

GD3

yr BP

"' 0 .,

~ +I

~ " ,.;

_, 0

~ +I

., 0

.... ;

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~I .., 0

on"

300

lower \ropica!- subandean gr.

Subandean Subparamo Grass paramo gro up -Andean group group

' ' Subparamo lower lro ~ Upp er sub- (U pper) pi cal· subandean· lower Andean group group andean gr. Andea n gr.

-o s 10 0

so% 50

100%

iNCL UD ED IN

THE

POLLEN

SUM

., 118

recological studies

_aguna Verde I (3625ml

GD3

GD2

:z: >-

Lower tro-

Subandean Subparamo Grass

pi cal-subandean gr.

-Andean group

group

paramo group

Lower tro- Upper sub- (Upped Subparamo pica!- subandean-lower Andean group andean gr. Andean gr . group

:cl ili~l>'rnm of the Paramo de Laruna Verde I section (present studv).

so%-------or:-..:..=.-.---~ 510 % 100 0

INCLUDED IN THE POLLEN SUM

I' 'I

•

Pi1r. de Laguna Verde II (3625ml GD2

GD 3

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0 ~

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• Subandean Subparamo Grass -Andean group paramo

Lower tro- Uppe; sub-

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andean gr

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andean gr

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IU~per I Sub~ararno

- 0,_5_1_0 _ -,-_ _5-,0% - - - - INCLUDED IN THE POLLEN SUM

pical·sub· andean-lo wer Andean group Andean gr

group

Fig. 49. Simplified diagram of the Paramo de Laguna Verde II section (present study).

100

j Par. de Pef\a

Negra I (3625ml

GD3

GD2 0 em

+I ~

"'"' -·

• ...... 0

::t:

., 0

+I 0 N

•

~·

., 0

+I 0 N

.,· 200 0 ~

lo we r lropi cal-su b and ean gr.

Subandean Subp aramo Gr 'ass para mo -A ndean gr oup I

rou p

group

-0 51 0 ' Lon-er "tro · Upper' su b IU~per) Subparamo pic a!· sub - an dea n·Jowe r An dean grouP 0 andtan gr. And ean gr. QfOUp

Fig. 50. Simplified diagram of the Paramo de Pefia Negra I section (present study).

I o 5 0 /o

1 0 0~

I NC L UDE D IN TH E

GD3

::t:

lower ....tro- Uppe; sub (U~perl Sub~aramo pita!Â· subandean-lower Andean group andean gr. Andean gr . group

100~

Fig. 46. Location section (present study).

121

Fig. 46. Location of the most important palynological sections in the study area.

Introduction

Palaeobotanical-palaeoecological studies

123

122

8. SYNOPSIS OF THE PALYNOLOGICAL DATA IN THE STUDY AREA An overview is presented of the palaeoecological data obtained in the study area. Special attention is paid to the topographical location and the local conditions which are of primary importance for the interpretation of the palynological records. Simplified diagrams are provided of the most important sections from the study area published since 1960, and of all sections analyzed in the present study. "The same zone systems are used in all diagrams. It was tried to make the boundaries between zones as synchronous as possible. Zone codes are abbreviations of the chronostratigraphic units of the Colombian Cordillera Oriental. As far as the Holocene period is concerned, the subdivision only applies to the study area (see section 9). The following abbrevations have been used: · Late Pleniglacial

FUQ = Fuquene stadia!

E =Early M=Middle L =Late

Late Glacial

ELG = 'Early' Late Glacial

S = Susaca interstadial LC = La Ciega stadia!

LLG = 'Late' Late Glacial and Earliest Holocene

G = Guantiva interstadial EA = El Abra stadia!:

HOL = Holocene

X y

Holocene

The diagrams generally include a conventional, sometimes simplified, general diagram (GD2 or GD2'), a zonal arboreal general diagram (GD3) and individual curves of the most important arboreal taxa. In the sections located on the high plain of Bogota itself (El Abra II-B3 and Ciudad Universitaria X), only a simplified conventional general diagram (GD2') and, in the case of the Ciudad Universitaria X section, individual curves are given. For the group composition of the conventional general diagram (GD2), the simplified conventional general diagram (GD2') and the zonal arboreal general diagram (GD3) the reader is referred to Table I, Table III and Table IV, respectively. Laguna de Fuquene II section, upper part (Fig. 47) The Laguna de Fuquene is a lake located N of Ubate, on a relatively small inter-Andean high plain, at an elevation of ca 2580m. At the boring site, generally open water conditions prevailed during se~iment deposition. Only twice l?Cal conditions bec~me drier (Fuquene stadial-'Early' Late Glacial and El Abra stadia!). Also m these cases, the mfluence of local Gramineae and Compositae growth seems to have been of minor importance. The upper part of the section, presented here, registers the development of the regional stands of vegetation in the inter-Andean high plain and adjacent inner slopes during the last= 22,000 years. Laguna de Palacio section, lower part The Laguna de Palacio is located S of Ubate, on the same relatively small inter-Andean high plain as the Laguna de Fuquene, at an elevation of ca 2580m. The palynological record of the lower_part of the Laguna de Palacio section is highly influenced by (extra)local stands of Alnus, Gra~neae and Compositae. Between"' 12,000 and 10,550 ± 60 yr BP open water conditions prevruled locally. Alnus occupied the shores of the lake. Later on, local conditions became drier allowing the development of hydrosere vegetation types at the boring site, dominated by Gramineae. Pcirarno de Laguna Verde I and II sections (Fig. 48 and Fig. 49) The Paramo de Laguna Verde is locat~ between the inter-Andean high plains of Ubate and Bogota and the eastern Magdalena slopes. The Paramo de Laguna Verde I and 11 sections were

Synopsis of palynological data

taken in a small lake located in the area at an elevation of ca 3625m The palynological records are to some extent irifluenced by the local vegetational developments. They particularly register the changing floristic composition of the zonal forests in the study area and the changing areas occupied by azonal Alnus forests on the inter-Andean high plains and surroundings during the last= 5,500 years. Paramo de Peiia Negra I and n sections (Fig. 50) The Paramo de Peiia Negra is located between the high plain of Bogota and the eastern slopes of the Magdalena valley. The Paramo de Peiia Negra I section was taken in the Laguna Negra, a small lake located in the area at an elevation of ca 3625m An adequate interpretation of the conventional general diagram of the Paramo de Peiia Negra I section is impeded by the local development of mire and peatbog vegetation types with Gramineae, Compositae and Ericaceae stands (El Abra stadia! and Holocene). The Paramo de Peiia Negra I section registers the shifts of the upper zonal forest line, the changes in floristic composition of the zonal forests in the study are.a and the changes in _the area occupied by azonal Alnus forest on the high plain and surroundmgs over the past = 15,000-14,000 years. The Paramo de Peiia Negra II section consists of lacustrine sediments deposited behind an older moraine complex located at an elevation of ca 3400m (Helmens, in prep.). Two samples for 14C dating were taken. The age of these samples are 19,190 ± 120 yr BP (GrN 14507) and 18,130 ± 170 yr BP (GrN 14506). A first preliminar observation of the microfossil samples indicates the abundant presence of Isoetes spores. We may conclude that a lacustrine environment developed behind the moraine complex after glaciers had retreated, between"' 19,500 and,. 18,000 yr BP. Paramo de Guasca section A peat section taken in the P:irarno de Guasca, at an elevation of ca 3250rn. The Paramo de Guasca section directly overlies the rocky subsoil. One sample was taken from the basis of the section for 14 C dating. The age of the sample is 6,870 ± 70 yr BP (GrN 12077), indicating that local peat development started around "' 6,900 yr BP. Laguna de !a America section (Fig. 51) The Laguna de Ia America is a lake located in the Paramo de Palacio, at an altitude of ca 3550m. The Paramo de Palacio is situated between the high pl(\in of Bogota and the eastern slo~es of the C?rdillera Oriental. At the boring s i~e open water conditions prevailed during sediment deposltlon. The mfluence of local Grammeae and Compositae growth is upon the whole negligible. The section registers shifting vegetation belts on the inner and outer eastern slopes of the high plain of Bogota and changing areas occupied by azonal Alnus forests on the high plain itself and surroundings during the last = 13,000-12,500 years. Correlation of this reco:d with the ?ther palynological sections mentioned in this chapter is especially based on the relauve flu~tuauons. of the Alnus cur:'e, because the zonal vegetation types of the eastern slopes of the Cordillera Onental are qutte different from those of the western Magdalena facing slopes. However, one must remember that Alnus is also present in the very wet zonal Andean forests on the eastern slopes of the Cordillera Oriental. Paramo de Palacio, PT I and II sections Two peat sections taken in the P:irarno de Palacio, at an elevation of ca 3550m. Both sections (almost) directly overlie the rocky subsoil. Samples for 14C datings were taken from the basis of the sections. The sample of the PT I section was dated 4,730 ± 160 yr BP. The sample of the PT II section was dated 7,200 ± 220 yr BP. These datings indicate approximately the age at which local peat developments started. Paramo de Agua Blanca II and m sections (Fig. 52 and Fig. 53) The Paramo de Agua Blanca is located between the high plain of Bogota and the eastern slopes of the Magdalena valley. The Paramo de Agua Blanca II and III sections were taken in a peatbog, located in the area at a,n elevation of ca 3250m. The palynological records show

Palaeobotanical-palaeoecological studies

124

particularly the vertical movements of the upper zonal forest line in the Paramo de Agua Blanca itself and the changes in the surface of ill-drained areas on the high plain and surroundings occupied by Alnus stands during the last ... 8,300 years. Local influence of Gramineae, Compositae and Hypericum growth is negligible, with the exception of the last = 450 years. El Abra N-107N, upl!er part, and II-B3 sections (Fig. 54) The El Abra corridor is located in the northern part of the high plain of Bogota itself, at an elevation of ca 2570m. The palynological record of the sections is highly influenced by (extra)local stands of Alnus, Grarnineae and Compositae. Alnus is by far the most important element in the subandean-Andean group. The zonal arboreal elements only attain a relatively high percentual contribution to the arboreal pollen sum in those parts of the sections where the total representation of the arboreal elements is very low (El A bra stadial and Holocene X interval). The sections give an impression of the successive (extra)local vegetation types during the last = 24,000 years. According to the El Abra IV-1 07N section, (extra)local Alnus stands were replaced by open vegetation types with Gramineae at "' 24,000-21,000 yr BP. Ciudad Universitaria X section, upper part (Fig. 55) The section was taken in Bogota located in the southern corner of the high plain, at an elevation of ca 2560m. As in the Laguna de Palacio, El Abra IV-!07N and El Abra II-B 3 sections, the record of the Ciudad Universitaria X section is highly influenced by (extra)local vegetation stands. It registers successive (extra)local vegetation types alternately dominated by Alnus, Myrica, Compositae and Grarnineae during the last = 24,000 years. Laguna de Ia Herrera section The Laguna de Ia Herrera is a lake located in the southwestern comer of the high plain of Bogota, at an elevation of ca 2550m. The base of the lacustrine sequence, mainly consisting of diatomaceous clays, was dated 5,020 ± 80 yr BP. Peaty intercalations, indicating lower lake leve ls, were radiocarbon dated = 5,050 to= 4,650 yr BP, = 2,700 to = 2,050 yr BP and= 750 to= 550 yr BP. Laguna de Pedro Palo III and V sections (Fig. 56) The Laguna de Pedro Palo is a lake located on the eastern slopes of the Magdalena valley, at an elevation of ca 2000m. A t the boring site, open water conditions seem to have prevailed during sediment deposition. Gramineae and Compositae probably did not play a significant role in the successive local vegetation types. The sections register shifting vegetation belts and changing floristic composition of the zonal vegetation types in the area during the last = 12,500 years. Two 14C datings are available in the LPP III section, both of Guantiva interstadial age (11,880 ± 100 yr BP, GrN 6759 and 11,380 ± 130 yr BP, GrN 6758). The impressive rise of the tropical-subandean elements at the end of the 'Late' Late Glacial in the Laguna de Pedro Palo Ill section has been dated in the parallel Laguna de Pedro Palo V section (Vander Hammen, unpublished). It occurred between 10,380 ± 90 yr BP (GrN 6734) and 10,280 ± 90 yr BP (GrN 6733). The Laguna de Pedro Palo V section shows also very clearly a change in the floristic composition of the subandean forests during the Holocene, former Cecropia stands being (partly) replaced by Alchornea and Acalypha.

125

Conclusions and correlations

9. CONCLUSIONS AND CORRELATIONS Late Quaternary geoecological history of the study area T he vegetation cover and the glacier extent in the study area during the different chronostratigraphic units discussed below are tentatively illustrated by means of two transects (transects A and B of Fig. 5; for location see Fig. 3) in Fig. 58a-j. The legend of Fig. 58 is given in Fig. 57. One must bear in mind that these two transects are located, especially as far as the eastern Magdalena slopes are concerned, in areas of relatively high amounts of precipitation. The Magdalena slopes SW of the high pl'ain of Bogota, in the area of the Laguna de Pedro Palo (see Fig. 1), are considerably drier as a result of their topographical location (see Eidt, 1952).

The Fuquene stadial (= 22,500 to .. 14,000 yr BP) In the study area, the Fuquene stadial is (partly) recorded in the Laguna de Fuquene II, El Abra N-107N, Paramo de Pefia Negra I·and II, and Ciudad Universitaria X sections. According to the radiocarbon dates of the Laguna de Fuquene II (20,575 ± 190 yr BP), El Abra N -I 07N (23,870 ± 185 - 21,050 ± 210 yr BP) and Ciudad Universitaria X (23,850 ± 600 yr BP) sections,· this stadia! commenced"" 24,000-21,000 yr BP. 14C datings of the Alsacia section (14,770 ± 340 yr BP), the Andabobos section (14,360 ± 120 yr BP) and the La Ciega I section (14,140 ± 120 yr BP) suggest an age of= 15,000-14,000 yr BP for the terminal phase of this stadia! (Van der Hammen et al., 1980/81; Melief, 1985). During the Early Fuquene stadia! (Fig. 58a), that probably lasted from"' 22,500 to= 19,500 yr BP, the highest parts in the study area (e.g. Paramo de Pefia Negra, Paramo de Palacio, Paramo de Laguna Verde) were covered with ice. Grass paramo vegetation types developed on the inter-Andean high plains. In the Fuquene area some stands of Polylepis dwarf forest were present at protected sites. The zonal upper forest line was located below the level of the interAndean high plains. Exact data concerning the altitudinal location of the arboreal belts and the floristic composition of the forests on the eastern slopes of the Magdalena valley are lacking. As in the Late Fuquene stadia! (see below), most probably a broad Myrica scrub subparamo zone was present; Quercus was dominant in the Andean forest belt; the tropical-subandean forests had a limited e:ttension. In the Middle Fuquene interval (Fig. 58b) the glaciers retreated. In the Fuquene area, possibly some small patches of Quercus forest were present. Tropical-subandean forest stands were scarce on the eastern slopeS of the Magdalena valley. Only very few t•C datings are available from this period. The radiocarbon dates of the Paramo de Pefia Negra II section suggest that the interval lasted from"' 19,500 to= 18,000 yr BP. During the Late Fuquene stadia! (Fig. 58c), probably lasting from "' 18,000 to 14,000 yr BP, glaciers re-advanced but they did not reach the same extension as during the Early Fuquene stadia!. Around 15,000 yr BP they began to retreat. Grass paramo vegetation types dominated in the i!lter-Andean high plains. Some stands of Poly/epis dwarf forest were present in the Fuquene area. On the eastern slopes of the Magdalena valley, a broad Myrica scrub subparamo zone was present; in the Andean forests, Quercus was dominant; the tropical-subandean forests had a limited extension, Acalypha and Quercus being imponant elements in the remaining stands.

The 'Early' Late Glacial period (= 14,000 to "' 12,400 yr BP) In the study area, this period has been (partly) recorded in the Laguna de Fuquene II, Laguna de Ia America, Paramo de Peiia Negra I, Ciudad Universitaria X and Laguna de Pedro Palo III sections. No direct datings are available of the Susaca interstadial (Fig. 58d). During th is interval, that lasted from= 14,000 to= 13,000 yr BP, glaciers seem to have completely disappeared in the study area Possibly, some small cirque glaciers were still present in the Paramo de Palacio.

Palaeobotanical-palaeoecological studies

126

Lacustrine environments developed in the formerly glaciated areas. In the Fuquene area, Polylepis dwarf forest stands became more abundant. Grass paramo vegetation types dominated on the high plain of Bogota. On the eastern slopes of the Magdalena valley, the Andean Que;cus forests shifted upwards replacing former Myrica shrub stands; only scattered stands of tropiCalsubandean forest were present Sediments deposited in the Paramo de Peiia Negra I section during the La Ciega stadia! (Fig. 58e) were dated 12,450 ± 370 yr BP. Radiocarbon dates of the same interval in the La Guitarra section (12,880 ± 180 yr BP), the Cienaga del Visitador section (12,770 ± 130 yr BP) and the La Ciega ill section (12,830 ± 80 yr BP) give similar ages (Vander Hammen & Gonzalez, 1965; Vander Hammen et al., 1980/81; Melief, 1985). The stadia! lasted from= 13,000 to ~ 12,400 yr BP. In the study area, glaciers only reappeared/re-advanced in the Paramo de Palacio, their extension being significantly less than during the former cold periods. Grass paramo vegetation types prevailed in the inter-Andean areas. Some stands of Polylepis dwarf forest were present in the Fuquene area. On the eastern slopes of the Magdalena valley, zonal vegetation belts shifted downwards. The floristic composition of the forests still resembled very much that of the earlier mentioned periods. In the area of the Laguna de Pedro Palo, only very isolated patches of Andean Quercus forest with Hedyosmwn and Weinmannia and, downslope, a few stands of tropical-subandean forest with Acalypha, Alchornea and Quercus were present, the tropical-subandean and Andean belts being clearly dominated by open (sub)xerophytic vegetation types.

The · 'Late' Late Glacial and Earliest Holocene period ("' 12,400 to = 9,500 yr BP) In the study area, this period has been recorded in the Laguna de Fuquene II, Laguna de Palacio, Laguna de Ia America, El Abra II-B3, Paramo de Peiia Negra I, Ciudad Universitaria X and Laguna de Pedro Palo ill and V sections. The terminal phase of the Guantiva interstadial (Fig. 58 f) has been dated in the El Abra ll-B3 (11 ,2 10 ± 90 yr BP) and Laguna de Fuquene II (10,820 ± 60 yr BP) sections. During this interval, lasting from = 12,400 to = 10,800 yr BP, glaciers definitely disappeared in the study area. Lacustrine environments developed in the formerly glaciated areas. The upper zonal forest line shifted upwards. Zonal and azonal Andean forests occupied the lower parts of the inter-Andean areas. In the Fuquene area, pioneer vegetation types with Dodonaea and Rapanea followed by Andean Quercus forests developed. The high plain of Bogota was almost completely invaded by azonal Alnus forests. On the eastern slopes of the Magdalena valley a broad subparamo zone with Myrica scrub was present; Quercus was dominant in the Andean forests, but some stands of Alnus seem also to have been present; tropical-subandean forests with Cecropia began to develop. Palaeoindian hunters were present in the study area. The initial phase of the El A bra stadia! (Fig. 58 g) has been dated in the Laguna de Palacio ( 10,550 ± 60 yr BP) and Andabobos (10,530 ± 90 yr BP) sections (Melief, 1985). During this stadia!, that lasted from~ 10,800 to- 9,500 yr BP (Fig. 58g), the upper fore st line shifted downwards. In the lowermost parts of the Fuquene area Quercus forests were still present. On the high plain of Bogota Alnus forests became gradually less abundant, being finally (almost) completely replaced by Myrica and Compositae scrub and open vegetation types with Gramineae. On the adjacent inner slopes of these inter-Andean areas pararno vegetation types developed. On the eastern slopes of the Magdalena valley, Myrica and Quercus were both abundant in their respective altitudinal belt; tropical-subandean forests with Cecropia expanded considerably. Palaeoindian hunters were present in the study area.

The Holocene period (= 9,500 to 0 yr BP) This period is (partly) represented in the diagrams of all sections mentioned in section 8, except in the LPA and EA IV-107N sections. The subdivision of the Holocene presented here, applies only to the study area (see below).

127

Conclusions and correlations

Sediments deposited during the Holocene X interval (Fig. 58h) have been dated in the P:iramo de Peiia Negra I (8,320 ± 80 yr BP), Laguna de 1a America (8,130 ± 120 yr BP), Paramo de Agua Blanca II (8,290 ± 45) and Ciudad Universitaria X (8 ,960 ± 400 yr BP and 8,020 ± 120 yr BP) sections. During this interval, lasting from= 9,500 to= 7,000 yr BP, the forest line shifted upwards to an altitude only slightly lower than at present. In the Fuquene area, Quercus forest was dominant. On the high plain of Bogota, the surface occupied by Alnus forest was very reduced. Shrub (Myrica and Compositae) and/or grassland (Gramineae) vegetation types prevailed. On the eastern slopes of the Magdalena valley, the subpararno Myrica shrub vegetation disappeared; the Andean forests were still characterized by the abundal')t presence of Quercus; the tropicalsubandean Cecropia forests were very well developed but they did not invade the inter-Andean areas. Some stands of the pioneer element Dodonaea seem to have developed on the western outer and inner slopes of the high plains and on the high plains itself. A single record of 'prehispanic' Zea mais has been reported at= 8,1 50 yr BP (Paramo de Peiia Negra I section), which antedate the former first record of Zea mais in the Colombian Cordillera Oriental (Laguna de los Bobos section; Vander Hammen, 1962) in more than 5,000 years. The palaeoindians on the high plain of Bogota seem to have changed from a relatively specialized hunting culture to a somewhat more varied, partly hunting and partly gathering~ way of life. The Holocene Y interval (Fig. 58i) has been dated in the Paramo de Laguna Verde I (range 5,220 ± 70 to 1,870 ± 60 yr BP), Paramo de Laguna Veri:le II (5,190 ± 80 yr BP and 1,820 ± 50 yr BP), P:iramo de Peiia Negra I (5,210 ± 80 yr BP and 1,965 ± 35 yr BP), Paramo de Guasca (6,870 ± 70 yr BP), PT I (4,730 ± 160 yr BP), PT II (7 ,200 ± 220 yr BP), Paramo de Agua Blanca II (5,900 ± 70 yr BP) and Paramo de Agua Blanca III (6,630 ± 100 yr BP) sections. During this interval, that lasted from= 7,000 to = 1,800 yr BP, the forest line attained its highest location. In the Fuquene area, tropical-subandean elements appeared. A mixed CecropiaQuercus forest developed here. At the end of the Holocene Y interval Acalypha also became an important element in this forest type. The area of the high plain of Bogota itself was upon ihe whole almost completely occupied by Alnus stands. At the end of the Holocene Y interval the surface occupied by this azonal element began to diminish. On the eastern slopes of the Magdalena valley, at first Quercus was dominant in the Andean forest belt; later on upper Andean Weinmannia forest gradually began to develop. In the first instance, Podocarpus was abundant in these upper Andean forests. After that, at the end of the Holocene Y interval, Hedyosmum became more important. In the area of the Laguna de Pedro Palo, Cecropia probably became more dominant in the mixed Cecropia -Quercus fore sts. Especially in the paramo regions of the study area, lacustrine and peaty environments developed locally from = 7,000 and from = 5,200 yr BP onwards. Numerous records of 'prehispan ic' Zea mais have been reported from = 6,600 yr BP .o nwards (P:iramo de Peiia Negra I, Paramo de Agua Blanca II and III, and P:iramo de Laguna Verde I sections), most probably attributable to agricultural activities by prehistoric men on the eastern slopes of the Magdalena valley. At the end of the Holocene Y interval first evidences of agricultural activities in the area of the high plain of Bogota itself are found. The Holocene Z interval (Fig. 58j) covers approximately the last= 1,800 years. The zonal upper forest line was located at its present altitude. In the Fuquene area, a mixed Acalypha· Quercus forest developed; Cecropia was not present any longer. On the high plain of Bogota, the area occupied by Alnus stands diminished considerably, being partly replaced by shrub (Myrica) and/or grassland (Gramineae) vegetation types. The upper Andean Weinma nnia forests with Hedyosmum became fully developed. The Quercus forests became confined to their present distribution. Myrica, Dodonaea, Melastomataceae and Chenopodiaceae-Amaranthaceae became more abundant, probably in interfered forests. In the tropical-subandean belt on the eastern slopes of the Magdalena valley, Cecropia stands were partly replaced by Acalypha and Alchornea. Evidences of wide-spread agricultural activities, also in the area of the high plain of Bogota, have been reported. Maize was the principal crop. In the centuries foll owi ng the Spanish conquest (since ca 1,550 yr AD), large landownership, cattle raising, 'hispanic' Zea mais (probably coming from Mexico), some trees (e.g. Eucalyptus, Pinus) and some ruderal herbs (e.g. Rumex acetosella) were introduced into the study area. At the same time, it has been

r Palaeobotanical-palaeoecological studies

128

recorded that natural Andean vegetation types were partly replaced by secondary shrub (Dodonaea, Rapanea, Myrica and Melastomatac eae) and/or grassland (Gramineae and Chenopodiaceae-Amaranthaceae) vegetation types. Exogenous causes of vegetational change The shifts of the vege(ation belts, the changes in the floristic composition of the zonal forests, the changes in the area occupied by azonal Alnus forest and the formation of lacustrine and peaty environments are principally related to climatic change. However, the influence of endogenous processes and of human activities upon the vegetational development has to be critically considered. As explained in section 2, the altitudinal location of the upper forest line is determined by the mean annual temperature and, to a less extent, by the average yearly precipitation. Generally speaking, it lies somewhat lower on the drier slopes. The floristic composition of the zonal forests seems to be highly influenced by the average annual precipitation. A broad subpararno zone, an Andean forest dominated all over by Quercus and a poorly developed tropicalsubandean forest belt with Acalypha and Quercus, but without Cecropia, seem to be indicative of dry climatic conditions. On the contrary, a well developed tropical-subandean forest belt with Cecropia, a less dominance of Quercus in the Andean forests and a relatively narrow subpararno zone are indicative of wetter conditions. A high degree of humidity also favoured the expansion of Alnus forests on the inter-Andean high plains, if termic conditions allowed the development of arboreal vegetation types at this altitude. High mean annual precipitation resulted in large illdrained areas on which this azonal element could develop. One must remember, however, that in those places where lacustrine environments had developed (e.g. Laguna de Palacio), the opposite could have been the case. Here, relatively drier climatic conditions resulted in a lowering of the lake level permitting the development of Alnus forests or other azonal vegetation types on the former lake bottom. However, the area occupied by lacustrine environments in the inter-Andean areas during the last 24,000 years was insignificant when comparing with the terrestrial environments. Higher mean annual precipitation amounts could also have caused , locally, the development of lacustrine and peaty environments. A summary of the vegetational data as discussed earlier in this section is given in Fig. 59a. The vertical displacements of the zonal upper forest line (A), the changes in floristic composition of"the zonal forests (B), the changes in surface occupied by azonal Alnus forests on the interAndean high plains and surroundings (C), the periods in which numerous lacustrine and peaty environments seem to have synchronously developed (D) and the record of maize (E), are all summarized. On the basis of the vegetational history and the glacial sequence during the last 24,000 years, a reconstruction of the mean annual temperature and precipitation variations over this period is presented. Temperature fluctuations are deduced from the vertical disp lacements of the zonal upper forest line, taken into account the effect of humidity changes on its altitudinal position. Calculations are based on a temperature decrease of 0.660C per I OOm lowering of the forest line. Humidity variations are deduced from changes in the floristic composition of the zonal forests and the changes in the area occupied by azonal Alnus forests on the inter-Andean high plains and surroundings. Fluctuations in lake levels may also provide consistent information (e.g. Laguna Negra, see section 5; Laguna de Fuquene and Laguna de Ia Herrera, see section 8). The effect of rainfall variations upon lake levels, however, can in some cases be completely overru led by other factors, such as differences in water storage and evapotranspiration by various types of regional vegetation types in the neighbourhood of these lakes (see PAB sections, section 6). It was tried, by means of the palynological record of Zea mais, the secondary vegetation types and weeds, and of archaeological data, to evaluate the human influence upon the natural vegetational development. In Fig. 59b, a reconstruction of the temperature changes (F), of the humidity variations (G) and of the degree of influence of human activities upon the natural vegetation in the study area (H), are given.

Fig. 51. Simp! Hammen & Gonza

129

Synopsis of palynological data

Lag . de Ia America (3550m) GD 2'

GD3

0 yr BP

~~~

~==

I~ _, >-

0 :I:

I \~ =

--=

•

0 N

+I 0

I~=.

_, u.J

Lower ~ropi cal-subandean gr,

Subandean Subparamo Grass -Andean group paramo group group

------~ Lowertro- Uppe; subIU;per) Sub;aramo

pical·sub· andean·lower Andean group andean gr. Andean gr. group

. 51. Simplified diagram of the Laguna de Ia America section (adapted from Vander en & Gonzalez, 1960).

0 510 50%---------r---r---l..,OO%o 0 50

INCLUDED

THE POLLEN SUM

J Par. de Agua

Bla n ca II (3250ml

GD3

GD2

~c~~ iP~:cfttfJ>;~£Reus P~c~(lPI!' H60ro~u~

R~p~~6~ ;61~~~~NI~

.c~6N~ i'lyR I C~

pJS'''

pO~~CNIJS

oooo~~6~

0 em! yrBP

""'

:r:::

:r::: 0

g. "' .,;

" +I ~

"' .;

T I

Lower t'ropi cal-sub-

Subandean Subp2_ramo Grass para me -An dean group

andean gr.

group

I ' l ower tro- Upper sub- (U~perl Sub~ararno pica/- subandean· lower Andean group group andean gr. Andean gr .

Fig. 52_ Simplified diagram of the Paramo de Agua Blanca II section (present study).

50%

0 5 10 0

100%

131

Synopsis of palynological data

/ P<k de Agua Blanca Ill (3250m) GD2 0 em

GD3

yr BP

0 :t:

I I >-

100

:; +I 0 M

lower tropical-sub-

andean gr.

Subandean Subparamo Grass -Andean group

group

p aramo group

Lower'tro- Uppe; subIU~perl Sub;aramo pical- sub- an dean-lo wer Andean group andean gr. Andean gr . group

Fig. 53. Simplified diagram of the Paramo de Agua Blanca III section (present study).

0.,--::.5...:.10::_~_ 0

___:5:.:;0% - - - - - - INCLUDED IN THE POLLEN SUM 100

/ Unive rsitari a X (256Dm ) GO 2'

Ciudad

0 em

Abra 11-83 (257 0 m) GD2'

yrBP

yr BP

..... 0 :X:

. ......... 1

... .....

0 :I:

..... ~ +I 0

. . N

0 0

+I 0

"' ,.; 300 0

....... ............. ...... ...

+ I

..;

200 lo wer fropi cal-s ub andean gr.

S ub a~ dea n Su bparamo -An dean grou p

group

lro-

paramo group

(adapted from . Fig. 54. Simplified conventional general diagram of the El Abra rr~B3 section Âˇ 1978). n, Brinkma Schreve-

Lowe r pi ca l-su b an dea n gr.

Suba nd ea n Subpara mo para me gro up -A ndean gro up group

o s1o

so%

-INC LUDED IN THE PO LLEN SUM - - - - -

(adapted from Fig. 55. Simplified diagram of the Ciudad Universitaria X section, upper part 1963). , Gonzalez & Hammen Vander

eEl Abra ll-B3 section (adapted from

/ Universita ria X (2560m) GD 2'

Ciudad 0 em

yr B P

N N

0 0 M

:I: 0 N

. 0 0

"' 300 0

....... ~····· · · ·· · ··· · ········

~·~p=

.,"' ,.;

lower ~,·opi ca l-sub-

Subandean Subpa ramo Grass paramo group -A ndean

andean gr .

group

i· j

os1o

I' I

so%

-INCLUDED IN THE PO LLEN S U M - - - - - - - --

group

Fig. 55. Simplified diagram of the Ciudad Universitaria X section, upper part (adapted from Van der Hammen & Gonzalez, 1963 ).

- - - --

-------

I('

( '

' 133

Lag . de Pedro Palo Ill

Synopsis of palynological data

(zooom) GD3

GO 2' 0 em

0 M

+I 0 M M

-"I

I 0 0

~ ~

, ~~ I l o we r tro prr. al-s ub andean gr

Su ba'ndea n Su bpa' ramo Gra ss para mo g roup - An d ean gr ou p

gro up

(U ~ per ) S ubp ;u a mo Lowe r t ro - Up per subprcal - s ub Â· a nrlean - lower Andean group group anrlean gr Andean g r

Fig. 56. Simplified diagram of the Laguna de Pedro Palo III section (Van der Hammen, 1974 and partly unpublished) .

O.r-5_l .0:_-,-_ _5'-,0.% - - - - --

oo%

---

Palaeobotanical-p~aeoecological studies

135 134

3000

Conclusions and correlations

Ear ly Fuquene stadial ( - 22.500 - -19,500 yr BP}

2500 3500

2000

3000 2500 2000

LEGEND :

Trop ical- subandean (sub} xer ophyt ic veget ation ty pes

lower suband ean Cec ropia - Acal yp ha for est Upper subande an Cecrop i a -Quercus forest

Subandean Acal yp ha-Ouercus lores ts

f ?

l ower Andea n Oueteus fore st

Fig. 58a. Tentative illustration of the glacier extent and the vegetation cover during the Early Fuquene stadia!(= 22,500 to = 19,500 yr BP).

Andean Que rcus forest 7 (Upper} Ande an Querc us fores ts

Upper Andean Weinmannia forest

? Y

1500 m

Azonal Alnus forest 10 . High plain Âˇ forests

'I' 11

Myrica

scrub 3000

12 Polylepis dwarf lorest 13 Compos i1ae scrub

Midd le Fu quene interv al ( -1 9.500- -18.000 yr BP}

2500

14 (Otherl s ubparamo vegetation types 15 Grass paramo or seco nda ry grassland vegeta t ion ty pes n

ffi ""'

16 Superpara mo vegetation

3500 ~

11 Glaci ers 18 Area of human rn fluence

2000

types

Fig. 57. Legend of the illustrations of Fig. 58a-j.

25 Vtt11UI

exaggeration .c 10

3000 2500 2000 t 500 m

Fig. 58b. -Tentative illustratio n of the glacier extent and the vegetation cover during the Middle Fuquene interval(= 19,500 to .. 18,000 yr BP).

Palaeobotanical-palaeoecological studies

137

136

Late Ftiquene st adial

3000

I ~ts.ooo- -14.000yrBPl

3000

Conclusions and correlations

La Ciega stadia!

I -13 ,000 --12, 400y r BP)

2500 2500 3500 3500

2000

2000 3000

3000 2500 2500

2000 2000 1500 m

1500

Fig. 58c. Tentative illustration of the glacier extent and the vegetation cover during the Late Fuquene stadia!(= 18,000 to"' 14,000 yr BP).

. Fig. 58.e. Tentative illustration of the glacier. extent an~ the vegetation cover during the La Ctega stadtal (= 13,~ to "' 12,400 yr BP). In this case a third transect located in the area of the Laguna d~ Pedr? Palo 1~ also given, in order to illustrate the absence of a well developed forest belt on this relanvely drier part of the eastern Magdalena slopes.

Susaca in terstadial I~14.0 0 0-- 13 .000y r BP I

3000

2500 3500 3500

2000 3000

3000 2500 - - - 1 1

2500

2000 2000 1500

t500 m

Fig. 58d. Tentative illustration of the glacier extent and the vegetation cover during the Susaca interstadial("' 14,000 to 13,000 yr BP). D

Fig. 58f. Tentative illustration of the vegetation cover during the Guanriva interstadial(= 12,400 to"' 10,800 yr BP).

Palaeobotanical-palaeoecological studies

139

138

Conclusions and correlations

3500 3500 3000 3000 2500 2500 2000 2000 1500

1 sao

Fig. 58i. Tentative illustration of the vegetation cover during the Holocene Y interval (= 7,000 to= 1,800 yr BP). .

Fig. 8 g. Tentative illustration of the vegetation cover during the El Abra stadial (- 10,800 to 5 = 9,500 yr BP).

'Âˇ t#

3500

3000

2500

2000

I 500 m

I i

JSOO

3000

2500

2000

1500

I I

Fig. 58h. Tentative illustration of the vegetation cover during the Holocene X interval (= 9 ,500 to = 7 ,000 yr BP).

Fig. 58j. Tentative illustration of the vegetation cover during the Holocene 1,800 yr BP to present).

z interval (=

Conclusions and correlations

141

140

Palaeobotanical-palaeoecological studies

J Age in yr BP

Chronostratigraphic units of the Colombian Cordillera Or ienta l

Ve r tical displacements of the zonal upper forest line 0 0

0 oil

0 0 0 0., 0

Floristic composition of the zo nal forests

A r ea occu pied by AInus on the high plains

Lo ca I development of peaty and lacustrine environments

~o~"$(t't~~Qe

~~~:::.~~~

Age in

Record of Ze11

Mais

·i'~c.'

Chronostratigraphic units of t he Ce lombian Cordillera Oriental

\S~ a.C\1

.~f e~l'l\s9

Re lati ve temperatu re f luctuations

f'll'''

5,000

Holocene period

I I

Adapted to (reLl

wetter

condi-

tions

I I

10 .00 0

5, 000

Holocene per iod ··

10.000

~ 'jl

i llii[ :I

I S 000

1r1

15. 000

10 ,dry '

condt -

t•ons

Ear l y

I I

IiI A ·

I I

) - - /I

I \

I I

I II I

II i

lll

I I I I

I I I I I

l~:J)

20.00 0

( v

v Adap!ed

Ear l y

Fig. S9a. Vertical displacements of the zonal upper forest line (A), changes in floristic composition of zonal forests (B), changes in area occupied by azonal Alnus fores.ts (C),.local development of lacustrine and peaty environments (D) and the record of Zea ma1s (E), m the study area during the last = 24,000 years.

lJI '

I II

20,00 0

r----

I I

l iJ

J_) I '

-' iu man mfi uen ee in :he sl udy area

\; ;~o\e , r.t ' 'f\·~ c. o,\•''~ .. o't•" stlo9 r'of' \~'~·" \~9 c,,a

l!' ..,

l!'

"'I

Humidity var iat ions

I I I

.... .... I

Fig. 59b. Tentative temperature changes (F), humidity variations (G) and human infl uence on the natural vegetation (H), in the study area during the last"' 24,000 yr BP.

Palaeobotanical-palaeoecological studies

143

142

(= 22,500 to= 12,400 yr BP) During the Fuque ne stadia! and the 'Early' Late Glacial period ons the ronal upper forest conditi drier the of result a the climate was (relatively) cold and dry. As than one could expect, by taking the line was probably located at a slightly lower elevation tion types were adapted to the drier prevailing temperatures into account. The zonal vegeta was very narrow or almost absent, slopes lena Magda eastern the on conditions. The forest belt completely absent in the study been have to seems ia Quercus being the domin ant tree. Cecrop , (sub)xerophytic vegetation treeless almost was area. The area of the Laguna de Pedro Palo Megafauna! evidence in the study types. tion vegeta pararno with contact in directly being types the end of the Early Fuquene stadia!, area suppon s this statement (Vand er Hammen, 198 1). Atretreated/disappeared in the study area, s glacier stadia! Ciega La the and the Late Fuquene stadia! in the formerly glaciated cirques allowing the development of lacustrine and peaty environ ments and troughs . the climate was relatively warm In the Guantiva interstadial (= 12,400 to= 10,800 yr BP) formed on the inter-A ndean were lakes of r numbe a ons conditi wetter and wet. As a result of the formerly occupied by areas d invade forests n Andea ). high plains (e.g. Lagun a de Palacio were preceded by forests us Querc zonal the paramo vegetation types. In the Fuquene area, high plains S of Ubate and of Bogota The a. Rapane and aea Dodon with types ion vegetat pioneer The tropical-subandean forests on the were almost completely invaded by azonal Alnus forests . d to the relatively wetter conditions adapte became only valley lena eastern slopes of the Magda probab ly to immigrate from more after = 2,000 years, at = 10,350 yr BP. Cecr opia hadarboreal taxa, especially Quercus, had other , arrived northernly located habitats. When it finally the El Abra stadia!, possibly as a already occupied most of its ecological niche. Only during expand considerably. could ia Cecrop , change c climati by caused lity instabi result of climate became colder and drier. During the El Abra stadia!(= 10,800 to = 9,500 yr BP) theboth lower temperature and lower of result a As ards. The zonal upper forest line shifted downw high plains gradually became less humidity, stands of azonal Alnus forests on the inter-Andean and Compositae scrub and open Myrica by d replace tely comple ) (almost fmally being nt, abunda ion types became more abundant grassla nd. At the beginning of the Holocene the shrubby vegetat · types. nd at t~e cost of the open grassla the climate became warmer. The In the Holocene X interval (= 9,500 to .. 7,000 yr BP) ly dry impeding the development relative ed remain ions Condit s. upward shifted line forest upper the Holocene Y interval (= 7,000 to of azonal Alnus forests on the inter-Andean high plains. In considerably wetter. In the paramo and r warme slightly still became e climat = 1,800 yr BP) the azonal Alnus forests invaded large regions, peaty and lacustrine environments developed. The ped in the Fuquene area. The zonal develo forest rcus inter-Andean areas. A mixed Cecropia-Que Zea mais has been repeatedly recorded upper forest line gradually shifted upwards. Although table to agricultural activities by from = 6,600 yr BP onwards, which is most probably attribu the vegetational development upon ce influen human the first at area, study the in prehistoric men ne Y interval (.. 5,000 to= Holoce the of half second the In ficant. insigni seems to have been p, replacing the former develo to began forests annia Weinm 1,800 yr BP), upper Andean slow adaptation of the and l gradua the of pan fonned still Quercus stands. Possibly this process possibility cannot be the er, Howev ons. Andean arboreal vegetation to the wetter climatic conditi may have been involved. At the end tion) matura soil (e.g. es process nous endoge that ruled out climate probab ly comme nced to of the Holocene Y interval, around = 2,750 yr BP, the upper Andean Weinm annia forests The drier. and colder slightly ng deteriorate, gradually becomi an import ant element in the mixed with Hedyo smum fully developed. Acalyp ha becamethe gradual deterioration of the climate Cecropia-Quercus forests of the Fuquene area. Although have had its greatest impact upon the commenced at= 2,750 yr BP, in the study area it seems to yr BP. In the Holocene Z interval (= zonal and azonal vegetational development at = 1,800 forests on the inter-Andean high Alnus azonal by ed occupi area 1,800 yr BP to presen t) the in the mixed Quercu s forests longer any t presen not plains drastically diminished. Cecrop ia was changes at the end of the Holocene Y of the Fuquene area. However, the observed vegetational only related to climatic change but interval and in the Holocene Z interval were probably not influence that became catastrophic were conceivably panly originated by the increasing human during the last = 450 years.

Conclusions and correlations

':ari~tions in the study area during the ~!~~o~~~f~=stif~ ':.~~i~!darg toa the relative rainfall ? tmpon ance of low levels of ~elauv the of C Y curve dal inundation in the lower published e. basm, whtch has. been recentlyColom by Vande r Hammen (19861. ~~a.;,a:uca~S~/o~g bian ~e p~ly conung from the asm s. m ers · 1m l Orienta era Cordill 1 ~a_Ji~ conditions is fou~d ~rom= (~ ~5\ 2,700 to ~ 2,300 (:2,0~~t:;~~~~c~/~r (f~~&J with the dates ;t which 'veg~t~o~~ ~e begtnfm~ of ~hese p~nodhs C<;f!espond rather well yr BP and"' 1,800 ;~~).reate to ecreasmg unuditycommenced in the study area (=- 2,750

te;

d The influence of changi ng exogenous facto and of . enalo~enou$ proces ses upon small azonal paramo ecosystems is illustrated by the loc~ vegetau evelopment at the sites where on the sections of the present study were taken. 1 Verde II section, started the Paramo de tion. The general o-lsoe punch the of p!~~s num Sph~g actual development towards the determined by the was types non vegeta ~g an is which filli ng up of the sedimentary basins . . proces~ s o~enou en ' At the site of the Param succession ode Lagun a Verde I secuon, the followmg vegetational took place:

witt ~~c:;~~~e~~~~ro~~a~~c~ft~o~~· ~~~~~~in

~a~una

..rnozaic of Junco-Eieocharition and SP_.hagnum peatbog ntary probably the result of the gradual fill ing up of the sedime

Ditricho-Isoition » » »

~~;fn~evelopment was

most

' · a1 d 1 The most interesting local vegetatio N n eve opment ts recorded at the site of the Paramo de Peiia Negra I section in th L located at prese~ t in the lower grass pararno belt at an elevatione of ~~u~~25~~a tmall lak~ was f~rme~ m a glacially eroded ~e~~ basin after ice had definitely retreated fr~m t~e ~~~n~ Negra at the end of o . e thamboo. .e Pe.na the Late Fuquene stadia!. The local vegetational successt on at e nng slte was as follows: £1 ha · · Ditricho-lsoetion ,, » >> Til/aeion >>,, Jun/J~coeo ion ligularae Ecl ntzhaon. ." >> » dCa!GJ?Uigrost » » » Junco-Eleocharition , , , mozaic 0 · eoc rwon an Dunclw-!soi!tion »,, . . C l a amagrostlon ilgulatae >> >> » Sphagnum peatbog · ed d The general development from a subme r&e ~mmu~l!y towards ~relatively dry fil~f! water/ peatbo g community, was 'determined by 0 an th fl . . g up ..t e sedimentary basm, which isand endogenous process. On the contr ion types ve~etat local the of smon compo eonsuc ; m~d deter were sudden successions a climatic X xogenous factors, sue~ as .the chmate, during change and, possibly human . fl the ons conditi hmauc c col~~r the of ~ end of the Late Fuqu~ne stadi~n a::~~~~ -La~eaafsu_l ped _lo_cally (D_itrichofttelo f~es ~ommu oafc;h; zone shore boggy narrow the lso~tio n and, in 1 the a_t higher _El Ab~a stadial and at the beginning and at the end of the Hoiocene ~ i~:C~~~se~:~~~ tn the ns 0 _the local water level, causing ucruano m an acceleration or an interruption of the normal enou~ su~~es~wn. Espe_cta!ly the vegetation types of the Junco-Eieoch arition and of the c:Fdog . amagrostlon lgu a~ae, which are bound to the zone of the water table were ve _changes 10 humidity. Sudden local successions during the l~t "' 350 ry suscep nble to ~ese llgulata e >> >> >> Sphagnum peatbog) wn agro~t (C~Iam thyears f nin . be the with ed coincid de Peiia Neg~a itself. At the sites of th~ar~~ dee;u~;:::;uence m the P~s, the followmg vegetational secuon III and ll ca g succession took place:

:p~~~ ::a~~;~~ar;~(~~~ f~und

Ditriclw-lsoetion

>> >> >>

el_e~ati;n~f~ e~on:f~~a::~~~~oc~t :db~hgj

· -orirroplu·on G enuano

>> >> >>

Sphagn um peatbog

· · · · · v toward s bo This succession, from open water on types, was pnmanly ongtnated by the filling up of the sedimentary basin Hoggy eg~tau to have been accelerated by a loweri ng of the local water table which wever, It seemt t~e result of change s in ably pr? almost re;~s the 'by storage water and evapotranspiration m the ~a of the Paramo types non _ve~eta n the at nt laceme there by de Agua Blanca, caused ne Y mterval of former Holoce the s~~ ~~;~ paramo vegetation types by uppefAndean Wei~

145

144

Palaeobotanical-palaeoecological studies

Descriptions of microfossils

In the present study, this type of Zea mais grains has been found in sediments of 'prehispanic' and 'hispanic' age (= 8,150 yr BP to present). Type 537: Alternanthera-type (Amaranthaceae). Plate I. Grains apolar, spheroidal to polyhedral; periporate (11-21 pori), microechinate. Pori recessed in lacunae of coarse-ridged reticulum; muri microechinate; exine 1-l.5J.l.m thick. Diameter (n=4): 16-18 J.l.m (Heusser, 1971; Hooghiemstra, 1984: type 94).

PART IV DESCRIPTIO NS AND ILLUSTRATIONS Âˇ. OF MICROFOSSILS AND MACROFOSSILS

Type 538: Iresine-type (Amaranthaceae). Plate I. Grains apolar, spheroidal; periporate (14-18 pori), coarsely scabrate to baculate. Exine ca 2.5 J.l.ffi thick. Diameter (n=5): 15-21 JJ.m. Type 539: Antidaphne-type (Loranthaceae). Plate I. Grains isopolar, radially .symmetrical, subspheroidal, amb circular to subtriangular; tricolporate, echinate. Colpi rather indistinct; pori circular; echinae ca 1.5 J.1ffi long; exine 1-1.5 ~m thick. Size (n=4): 19-22 x 19-24 J.l.m (Salomons, 1986: type 444).

10. MICROFOSSIL DESCRIPTIONS The enumeration of the microfossil types is continuous with that of Hooghiemstra (1984) and Salomons (1986). The suffix 'type' is added to the microfo~sil types when the taxon .u ~~er discussion morphologically resembles to a high degree the f?s~il type found, but the poss1b1hty cannot be ruled out that other taxa may also be more or less surular.

Type 540: Elaeagia-type (Rubiaceae). Plate II. Grains isopolar, radially symmetrical, subspheroidal, amb circular to subtriangular; tricolporate, microreticulate. Colpi with fa int costae, equatorially with a co1pus transversalis; exine ca l~m thick. Size (n=3): 18-20 x 16-18 ~m.

Pollen types Only newly recognized, identified and unide~tified, pollen types for the. Colomb~an Andes are described here and illustrated in the microfossil plates. A few types descnbed and Illustrated . . . earlier were included when providing additional i~ormatio~. The identification of pollen grains was earned out with the rud of publications o? recent pollen types of South-America (Heusser, 1971; Vander Ham~en & Cleef, 1978; Sr:na, 1978; Markgraf & D'Antoni , 1978; Hooghiemstra, 1983) and on_foss1l types of the Colomb1an Andes (especially: Vander Hammen & Gonzalez, 1960; Hoogh1emstra, 1984; Salomons, 1986), and by comparison with the reference collection of recent trop1cal An~ean pollen types _of th~ Hugo de Vries Laboratory, University of Amsterdam. Pollen types wh1ch could not be 1denufied as belonging to any natural taxon were designated by their aperture-formula followed by the sculpture type (e.g. C3 P3 scabr = tricolporate scabrate). Measurements are generally based on 5 pollen grains. The exact number (n) is indicated for . . . . . each pollen type. The terminology used for the pollen descnpuons 1s_mamly after Iversen & Troels-Smuh (1950, English version 1981), Erdtman (1 952) and Faegn & Iverse n (1975).

Type 541: Colignonia-type (Nyctaginaceae). Plate II. Grains apolar, subspheroidal; periporate (6-9 pori), m icroechinate. Pori with faint costae pori, diameter ca 2.5JJ.m; exine ca 2JJ.m thick. Diameter (n=5): 24-28 J.l.m (Salomons, 1986: type 435). Type 542: C3 P3 fov/foss. Plate II. Grains isopolar, radially symmetrical, subspheroidal; tricolporate, irregularly foveolate to fossulate. Colpi with costae, equatorially constricted; exine ca 2 ~m thick. Size (n=5): 35-37 x 31-34 !liD. Type 543: C3 P6 microechin. Plate II. Grains isopolar, radially symmetrical, subspheroidal to prolate; ex traporate (C 3 P6 ), microechinate. Colpi with pronounced costae; porus diameter: 9-12 JJ.m; exine 2-3 ~m thick. Size (n=3): 38-42 x 29-33 J.l.m. Type 544: Potamogeton (Haloragaceae). Plate II. Grains apolar, ellipsoidal; inaperturate, (micro)reticulate. Exine $ 1 ~m thick. Diameter (n=4): 38-45 x 21 -40 ~ m (Heusser, 1971 ).

. Type 533: Eucalyptus (Myrtaceae). P l ~te I. Grains isopolar, radially symmetrical, oblate, amb t nan ~u l ar convex to con~a:--e; syncolporate, more or less psilate. Colpi fused acros_s the polar area m such a way as_to dehmu a triangular boundary; exine ca I ~m thick, slightly th1ckened (ca 1.5 ~m) near the pon. Equatonal diameter (n=5): 26-34J.l.m (Heusser, 1971). . . . . Type 534: Pinus (Pinaceae). Plate I. Grains heteropolar, bilaterally symmetncal, vesiculate, b1saccate. Ex1ne scabrate, _3-4 ~m thick; sacci reticulate. Size pollen grain, including sacci (n=5): 98- 132 x 74-87 ~m; sacc1: 53-77 x 37-6 1 ~m (Heusser, 1971).

r t

. Type 535: Rumex acetosella L. (Polygonaceae). Pla~e I. Grains isopolar, radially symmetrical, subspher01dal, amb c1rcular or sut>guadra_ngular ; tricolporate, stephanocolporate, sometir:nes peri~o~porate (3 _or 4 aperture_s), ~croreuc~l ate, perreticulate. Colpi as long and narrow hnes; pon c1rcular; exme ca l~m th1ck. S1ze (n=5). 2426 x 24-26 J.l.m (Markgraf & D'Antoni, 1978).

. . Type 536: Zea mais L. (Gramineae). Plate I. Grains heteropolar, radially symmetrical, subsp~er01dal, amb _c1rcul~; monoporate, fi nely scabrate. Porus with annulus, diameter 13-16 J.l.m; eXIne ca 1 J.l.m th1ck. D1ameter (n=5): 69-95 x ' 69-90 ~m (Herrera de T urbay, 1985; Monsalve, 1985).

Type 545: Bartsia-type (Scrophulariaceae). Plate II. Grains isopol ar, radially symmetrical, subspheroidal, amb circular; tricolporate, psilate. Colpi thin, with ragged edges; exine 1-1.5 J.1ffi thick, slightly thickened (ca 2~m) in the polar areas; dense carpet of fine distinct columellae rendering a very regular scabrate appearance. Size (n=5): 30-40 x 24-33 ~m. Type 546: Xyris (Xyridaceae). Plate II. Grains heteropolar, bilaterally symmetrical, biconvex; monosulcate (? ), finely microreticulate. Exine ca 1.5 J.l.m thick. Size (n=5): 49-59 x 32-4 1 J.l.m. Type 547: Arcytophyllum (Rubiaceae). Plate III. Grains isopolar, radially symmetrical, subspheroidal, amb circular to subtriangular; tricolporate, reticulate. Colpi long and narrow, equatorially with a colpus transversalis; diameter lumina decreasing towards the border of the colpi; exine ca 2.5 JJ.m thick. Size (n=5): 33-43 x 29-38 ~m (Hooghiemstra, 1984: type 120).

Palaeobotanical-palaeoecological studies

147

146

Descriptions of microfossils

Type 559: c;P3 psil (fov). Plate IV. Grains isopolar, radially symmetrical, prolate; tricolporate, psilate, sometimes foveolate. Colpi rat!ter ~ong and n~w. constrict~d at ~e equator, with pronounced costae; pori circular, ca 5 j..lm 1n diameter; exme ca 1.5 IJ.m th1ck. S1ze (n=4): 30-39 x 18-28 IJ.m.

Type 548: Zea mais L. (Gramineae). Plate m. Grains heteropolar, radially symmetrical, subspheroid al, amb circular; monoporate , finely scabrate. Porus with annulus, diameter ca 18 ).Ull; exine ca 1 jlm thick. Diameter (n=3): 121-145 X 100-127 jlm. In the present study, this type of Zea mais grains has only been found in sediments of 'hispanic' age (~ 450 yr BP).

Fungal types

Type 549: Macrocarpea (Gentianaceae). Plate ill. Grains isopolar, radially symmetrical, subspheroid al, amb circular; tricolporate, coarsely reticulate. Lumina 1.5-5 J.l.m in diameter, irregularly shaped; exine ca 2,5 J.1m thick. Equatorial diameter (n=1): 43 jlm.

All fungal types recorded in the analyzed sections are described here and illustrated in the microfossil plates. A number of these types have been described and illustrated in earlier publications to which will be referred. The terminology used for the descriptions is mainly taken fro m Ellis (1971 1976) and ' Dennis (1978).

Type 550: c;P3 scabr. Plate lli. Grains isopolar, radially symmetrical, prolate; tricolporate, coarsely scabrate. Colpi long and narrow, with costae; exine ca 1.5 J.1m thick, slightly thickened (ca 2 j..lm) in the polar areas. Size (n=3): 36-38 x 23-27 jlm.

Type 560: Gqeumannomyces cf. caricis J. Walker (Diaporthaceae, Ascomycetes). Plate IV. HyphoJ>?<Iia irregular in outl~e, brown, allways with blunt lobes and a prominent clear spot of ca 2 j..lm m the central area. D1arneter: 1&-27 j..lm (Pals et al., 1980; Hooghiemstra• 1984: type 369).

Type 551: Habenaria"type (Orchidaceae). Plate ill. Tetrads, tetrahedral or ellipsoidal. Grains inaperturate , reticulate. Exine ca 1.5 j..lm thick. Diameter tetrads (n=4): 62-67 x 37-59 j..lm.

Type 561: Plate IV. . Spor<?s globose to ovoid, one-celled, dark brown. One protruding apical pore of ca 1 j..lm w1dth, w1th an annulus. Surface smooth. Size: 25-31 x 23-271-J.m (Helmens & Kuhry, 1986).

Type 552: Sericotheca (Rosaceae). Plate III. Grains isopolar, radially symmetrical, prolate, arnb circular; tricolporate, microreticul ate, with a striate appearance. Colpi with faint costae; exine ca 1.5 J.1m. Size (n=4): 1&-19 x 13-14 J.!m (Hooghiemstra, 1984: types 122, 146).

Type 562: Plate IV. Ascospores elliptical in outline, one-septate, brown, with apical pores. Surface generally hairy (hairs ca 1 j..lm long). Size: 29-31 x 14-15 j..lm (Helmens & Kuhry, 1986).

Type 553: C4.7 microret. Plate lli. Grains apolar, circular to subquadrangular: pericolpate or, sometimes, stephanocolpate (4-7 col pi), microreticulate. Exine ca 1 J.U11 thick. Diameter (n=5): 38-46 x 36-43 j..lm.

Type 563: Plate IV. Spores globose to ovoid, one-celled, brown. One pore with an annulus, diameter ca 2.5 J.1m. Inner surface covered with numerous granules. Size: 18-22 x 15-18 jlm (Bakker & Van Smeerdijk, 19&2; Helmens & Kuhry, 1986).

Type 554: c;P3 (C4P.) scabr. Plate III. Grains isopolar, radially symmetrical, prolate to subspheroid al; tricolporate, sometimes stephanocolporate, scabrate. Colpi very long and narrow, with faint costae; pori indistinct; exine ca IJ.1 thick. Size (n=7): 23-29 x 16-24 J.lm.

Type 564: Plate IV. Asc?spor~s slightly curved, three-s_ept~te, constricted at the middle septum, brown. Heavy undulatrng ep1spore, 1-4 J.1m broad, wh1ch IS attached to the spore wall at regular intervals. Size (excluding the epispore): 33-40 x 12-13 IJ.m (Helmens & Kuhry, 1986).

Type 555: Umbelliferae. Plate IV. Grains isopolar, radially symmetrical , prolate, amb circular to subtriangula r convex; tricolporate, coarsely scabrate. Colpi long and narrow; col pi transversales with costae; exine ca 1 j..lm thick, clearly thickened (ca 3 j..lm) at the poles. Size (n=4): 29-31 x 18-21 j..lm (Heusser, 1971; Hooghiemstra, 1984: type 226). This type most probably includes grains which belong to the genus Hydrocoty/e.

Type 565: Plate V. C~midia ellipsoi?al, three-septate, not constricted at the septa. Apical cells dark-brown; basal cell hght-brown, wlth a truncate end and a ~ 1 j..lm wide pore. Surface smooth. Size: 3&-41 x 19-21 j..lm.

Type 556: Nercera (Rubiaceae). Plate IV. Grains isopolar, radially symmetrical, subspheroid al, amb circular; tricolporate, coarsely scabrate. Colpi short, equatorially with a broad colpus transversalis; exine ca 1.5 j..lm thick. Size (n=4): 30 x 37-41 j..lm (Heusser, 1971). Type 557: Brome liaceae. Plate IV. Grains heteropolar, bilaterally symmetrical, biconvex; monosulcate , reticulate. Greatest diameter lumina ca 2J.U11, decreasing in size towards the extremities of the grain and the border of the sulcus; exine 1- 1.5 j..lm thick. Size (n=3): 52-77 x 33-37 j..lm. Type 558: Solanaceae. Plate IV. Grains isopolar, radially symmetrical , subspheroid al, amb circular; tricolporate, finely scabrate. Colpi long, constricted at the equator, with faint costae; colpi transversales with faint costae; exine ca 1 j..lm thick. Size (n=5): 23-28 x 23-26 j..lm.

! t

Type 566: Plate V. Conidia gl~bose•. two-septate, slightly constricted at the septa. Apical cells (dark-)brown; basal cell, hyalme, wnh a truncate end and a ca 2 j..lm wide pore. Surface smooth. Size: 46-50 x 27-32jlm. Type 567: Anthostome/lajU£giana Speg. (Ascomycetes). Plate V. into Ascos~res, inequilateral (one side almost straight), one-celled, brown, tapering apically a sharp pomt; basal end truncate. Surface smooth. Size: ca 25 x 7 j..lm (Van Gee!, 1978; Helmens & Kuhry, 1986). Type 56&: Helicoon pluriseptatum Van Beverwijk (Hyphomycetes). Plate V. Conidia ~elically C?iled forming a biconical spore body, hyaline to brown. Filaments smooth, muloseptate. Diameter: 2&-36 J.lm (Van Gee!, 1978; Hooghiemstra, 1984: type 373). Type 569: Plate V. Spore~ glo~ose, one-celled, dark:brown, with a ca .2 J.lll? wide po re emphasized by an annular th1ckemng. Surface covered w1th ca 2 j..lm long hms. D1arneter (e xcluding the hairs): ca 10 jlm (Hooghiemstra, 1984: type 370; Salomons, 1986: type 491).

149 Palaeobotanical-palaeoecological studies

Type 570: Lasiosphaeria-type (Ascomycetes). Plate V. end geniculate, light-brown. Ascospores three-septate, not constric ted at the septa, at one 1978). Geel, (Van Surface smooth. Size: ca 78 x 8 1J.m Type 571: Plate V. ted at the septa or hardly so, . Heterogenous group of ascospores, three-septate, not constric . 8-lliJ.m x 34-37 Size: . hght-brown. Surface smooth

Descriptions of microfossils

148

Type 572: Plate V. rough. Size: 28-30 x 11- 13 Spores three-septate, not constricted at the septa, brown. Surface IJ.m . Type 573: Gelasinospora (Sordariaceae, Ascomycetes). Plate V. d in this type. Ascosp ores, . At ~east two types o f Ge/asin ospora ascospores are include wide hyaline pits, sometimes elhpso1dal, one-celled, dark brown, orname nted with 1-4 IJ.mHooghiemstra, 1984: types 354 forming a reticulu m. Size: 35-39 x 22-261J.m (Van Gee!, 1978; • 359). Type 574: Plate V. at the septa, brown. Surface : Ascospores elliptic al in outline, three-septate, not constricted 1986). generally rough. Size: 32-43 x 12-191..lm (Helmens & Kuhry, Type 575: Plate V. brown (basal cell hyaline). Conidia multise ptate, not constricted at the septa or hardly so, Surface rough. Size: 99-108 x 15-19 IJ.m. Type 576: Plate VI. Two furrows in both cells Ascospores one-septate, constricted at the septum, dark brown.almost the septum. Surface g reachin and zone apical the another one crossing perpendicular smooth. Size: 28-32 x 9-151-!m. Type 577: Plate VI. own. Trunca te end, provided . Spores two-sep tate, slightly constric ted at the septa, light-br J.Lm. 11-12 x 22 Size: . smooth Surface wllh a pore. Type 578: Plate VI. ing apical pores, brown. Spores, ellipsoidal, one-celled, with two ca 1.5 IJ.m wide protrud Surface smooth. Size: 26-29 x 14-21 J.Lm (Van Gee!, 1978). Type 579: Plate VI. own. One furrow on each Ascospore one-septate, slightly constricted at the septum, dark-br .m. 23-261J x cell. Surface smooth. S ize: 60-71 VI. Type 580: Pleospora-type (Pleosporaceae, Ascomycetes):· Plate rse and longitudinal septa, . Heterog enous group of spo~es, oblong , with several transve 1978; Hooghiemstra, 1984: (hght-)brown. Surface smooth. SIZe: 56-67 x 23-261J.m (Van Gee!, type 368). Type 581: Plate VI.

generally slightly constricted at the septa, ~eterogenou s ~up of ascosp~res, three-septate, smooth or finely granulate. Size: 48-62 x Surface own. light-br septum, rruddle the m part1cularly 12- I81J.m. Type 582: Plate VI. septa or hardly so, lightAscospores slightly cw;'ed, one-septate, ~ot constrict~ at the another the apical zone one icular perpend g .crossm cells both m furrows shon Two brown. · Surface smooth. Size: 28-38 x 9- 10 !lrn.

Type 583: Plate VI. ing apical pores, brown. Spores ellipsoi dal, one-celled, with two ca 2 J.Lm wide protrud Surface smooth . Size: 38-46 x 23-30 IJ.m. Type :S84: Plate VI. black, middle pan brown. Spores ellipsoi dal to ovoid, one-celled: apical zones almost m. 10-l31J. x Surface granulate. Size: 22-26 Type 585: Plate VI. um width of cells: ca 22 Conidia coiled, multiseptate, dark brown. Surface rough. Maxim J.Lm. Type 586: Plate VI. al pore, dark-brown. Surface Spores ellipsoidal, one-celled, with one apical and one subapic smooth. Size: 42-46 x 23-24 IJ.m. Alga l types here and illustrated in the All algal types recorde d in the analyzed sections are describ eded in earlier publications to microfossil plates. These types have all been described and illustrat which will be referred. Czurda (Zygne matace ae, Type 587: Spiro gy ra cf. scrobi culata (S tockma yer) Chlorophyceae). Plate VI. thick, with pits ca 21J.m wide Spores ellipsoidal to spheroidal, yellowish brown. Wall 2-3 J.Lm 1980/8 1; Helmen s & Kuhry, and ca 4 IJ.m apan. Size: 65-121 x 56-99 IJ.m (Van Gee! e t al., 1986). Type 588: Zygnema (Zygnemataceae, Chlorophyceae). Plate VI. . Surface covered with Heterogenous group of spores, ellipsoidal to rectangular, hyaline & Van der Hamme n, 1978; numerous 3-7 J.Lm wide pits. Size: 48-94 x 35-55 J.Lm (Van Gee! Hooghiemstra, 1984: types 401, 402). This type may include some spores of Oedogoniaceae. Type 589: Debarya (Zygnemataceae, Chlorophyceae) . Plate V!l. polar and an equatorial zone a Zygospores spheroidal to ellipsoidal, hyaline. Spore divided in & Vande r Hammen, 1978; by a low circum polar ridge. Size: 38-68 x 38-44 !liD ( Van Gee! Hooghiemstra, 1984: type 393). . . Plate VII. Type 590: Spirogy ra!Ciosterium (Zygnemataceae, Chlorophyceae)ium idiosporum. Although Heterogenous group including spores of Spirogyra and of Closter spores recorded belong to of the these two taxa have not been recorded separately, the majority longitudinal suture encircling the Closterium idiosporum. Spirogyra: spores ellipsoidal, with a Closterium idiospo rum Wes t et spore, rounded ends; wal ls with a faint longitudinal striatio n. , rounde d or indente d ends; furrow dinal longitu a with idal, ellipso ores West: zygosp distributed over the hyaline protuberances of ca 0.3 IJ.m in diameter and ca 1 IJ.m apan, evenly ; Hooghiemstra, 1984: 1980/81 al., et Geel Van 1978; n, surface (Van Gee! & Vande r Hamme type 406). Type 591: Mougeotia (Zygnemataceae, Chlorophyceae). Plate Vll. with depressions in the Zygospores quadrangular, sides straight to concave, retuse angles r: ca 381J.m (Van Gee! & Van center, hyaline. Surface densely covered with small pits. Diamete 397). type der Hammen, 1978; Hooghiemstra, 1984: pher. Plate VII. Type 592: 'form species' Psetuioschizaea circula (Wolff) Christo rint like striations. Diameter: finger-p coarse with Surface hyaline. ose, (?),glob ores Zygosp 41-541-!m (Christopher, 1976).

Palaeobotanical-palaeoecological studies

150

151

Type 593: Botryococcus (Botryococcaceae, Chlorophyceae). Plate VII. Colonies irregular of size, brown. Size depending on the rate of fragmentation of the colony (Hooghiemstra, 1984: type 420). Type 594: Pediastrum (Hydrodictyaceae, Chlorophyceae). Plate Vll. Colonies disk-shaped to stellate, hyaline, with polygonal cells arranged in a single layer one cell thick. Size variable (Duenas, 1979; Hooghiemstra, 1984: types 416, 417).

Descriptions of microfossils

Zoological types Type 602: Assulina (Rhizopoda). Plate VIII. Shells brown, densely and regularly ornamented with imbricate plates. Size: 53-63 x 48-55 J..Lm (Van Gee!, 1978; Hooghiemstra, 1984: type 412). Type 603: Callidina (Rotifera). Plate VIII. Loricaebrown. Mouth 24-29J..Lm in diameter. Size: 140-148 x 90-106 jlrn (Van Gee!, 1978).

Fern spore types The identification of fern spores was carried out with the aid of publications on recent fern spore types of South-America (Heusser, 1971; Murillo & Bless, 1974; Murillo & Bless, 1978; Markgraf & D'Antoni, 1978) and on fossil types of the Colombian Andes (especially: Vander Hammen & Gonzalez, 1960; Hooghiemstra, 1984), and by comparison with the reference collection of recent tropical Andean fern spore types of the Hugo de Vries Laboratory, University of Amsterdam. Only one fern spore type is described here and illustrated in the microfossil plates. __ Type 595: PilulariaÂˇtype (Marsileaceae). Plate Vll. Spores heteropolar, radially symmetrical, amb circular; trilete, densely rugulate. Sclerine ca 2,5 IJ.m thick; rugulae ca 6 IJ.m high. Equatorial diameter (excluding the rugulae): 54-60 11m (Hooghiemstra, 1984: type 281). Bryophytic types All bryophytic types recorded in the analyzed sections are described here and illustrated in the microfossil plates. A number of these types have been described and illustrated in earlier publications to which will be referred. The terminology used for the description of the bryophytic types is mainly after Boros & Jarai-Komlodi (1975). Type 596: Plate VIII. Spores more or less spheroidal, ornamented with 2-3 jlm wide densely spaced smooth verrucae of irregular shape. Diameter: ca 19 11m (Hooghiemstra, 1984: type 382). This type probably includes spores of Breutelia (Bartramiaceae). Type 597: Plate VIII. Spores more or less spheroidal, ornamented with ca 4 Jlm wide densely spaced smooth verrucae of irregular shape. Diameter: 16-18 IJ.m. Type 598: Plate VIII. Bryophytic (?) spores, spheroidal, ornamented with 1.5-2 jlm long densely spaced hairs. Diameter (excluding the hairs): ca l6jlm. Type 599: Plate VIII. Spores ellipsoidal, ornamented by a dense pattern of ca 0.5 shaped aperture. Size: 27-29 x 23jlm.

jlffi

long processes. Distinct slit-

Type 600: Meesia-type (Meesiaceae). Plate Vill. Spores more or less spheroidal, ornamented with a dense pattern of ca I 11m long processes. _ Diameter: ca 27-29jlm (Hooghiemstra, 1984: type 352). Type 60 I: Plate VIII. Bryophytic (?) spores, more or less spheroidal, ornamented with 5- 10 J..Lm wide densely spaced scabrate verrucae of irregular shape. Wall ca 5 jlm thick. Diameter: 87-I 03 jlffi.

Type 604: Amphitrema (Rhizopoda). Plate VIII. . Shells more or less cylindrical, hyaline. A pseudostoma at each end, opposlte one another. Size: 50-55 x 26-37 J..Lm (Van Gee!, 1978; Hooghiemstra, 1984: type 411).

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11. MACROFOSSIL DESCRIPTIONS All identified and unidentified macrofossil types recorded in the analyzed sections are described here and illustrated in the macrofossil plates. A number of these types have also been . . described and illustrated in Kuhry (in press). The identification of the macrpfossil types was carried out by comp~son WI~ the rc:ference collection of recent macrobotanical material assembled by the author. This co~ecnon, availabl~ at the Hugo de Vries Laboratory of the University of Amsterdam, contams flowers, fruits, branches, leaves, seeds, megaspores and slides of epidermis of. cormophytes, and bryophy~es, including mosses and liverwons, that are of frequent ~currence m the azonal ~aramo veg~tan~m types in the study area. A duplicate o~ the collection wa~ left at ~e ll_lStltuto de Clenct~s Naturales of the Universidad Nacional m Bogota, Colombta. Idennficanons are less cenam . . . . . when the prefix 'cf.' is added. The enumeration of the macrofossil types IS connnuous wtth that of Kuhry (m press). Plant remains of cormophytes The descriptions are exclusively based on the fossil materi~ found in the .an~yz~ sections. The terminology used for the anatomical descriptions of the eptdermal remams IS mrunly taken from the series 'Anatomy of the dicotyledons' (Metcalfe & _Chalk, 1950) and 'Anatomy of the monocotyledons' (C.R. Metcalfe, editor). The nomenclature IS based on Cleef (1981). Type TS3: Gramineae. Plate IX. Epidermal remains. Intercostal and costal _z ones. Long cells and shon cells, the latter ones . . quite numerous and often in pairs. C~ll walls st~uous. This heterogenous type probably mcludes eptdermal remams of several grarruneous taxa. Type T54: Ca/amagrostis /igulatd (HBK) Hitchc. (Gramineae~. P~at~ IX. Stem epidermal remains. Intercostal and costal zones rather mdi~nnct. Very extend~d long cells; shon cells not very frequent, fo~ng h_ooks or ve~ small pnckels. Cell walls sm_u<;>Us. Stomata, in the intercostal zones, paracyuc, wtth parallel-stded to low dome-shaped subs1d1ary cells. . . Type TSS: Agrostis haenkeana Hitchc. (Gramineae). Plate IX. Leaf epidermal remains. Intercostal and costal ronc:s. Long cells and ~hon c.ells; pnckels very numerous, especially in the costal zones. Cell walls st~~ous. Stomata, m the mtercostal zones, paracytic, with parallel-sided to low dome-shaped substdiary cells. Type TS6: Calamagrostis effusa (HBK) Steudel (Gramineae). Plate IX. Leaf epidermal remains. Int~rcos_tal and cost~ zones. Long ~ells and shon cells, the latter ones quite numerous and often m parrs; small harr~ and_large pncke~s are frequent. Cell walls sinuous. Stomata, in the intercostal zones, paracyuc, wl!h parallel-stded to low dome-shaped subsidiary cells. . . Type TS7: Carex (Cyperaceae). Plate X. Epidermal remains . Intercostal and costal zones .. ~ell walls smuou~. Stomata, m the intercostal zones, paracytic, with low dome-shaped substdtary cells (Kuhry, m press: type T4). Type TS8: Oreobolus obrusangulus Gaud.ich. (Cyperaceae). Plate_X. Leaf epidermal remains. Intercostal and costal zones. Cell walls smu~us. Numerous_sromata, in the intercostal zones, paracytic, with irregularly dome-shaped, sometimes almost tnangular, subsidiary cells. . . . Type T59: Eleocharis (Cyperaceae). Plate X. Epidermal remains. Intercostal and costal zones. Stomata, m the mtercostal zon~s: onentated in rows, typically elongated, paracytic, with parallel to very low dome-shaped subs1d1ary cells.

Descriptions of macrofossils

Type T60: Rhynchospora macrochaeta Steudel (Cyperaceae). Plate XI. Adaxial and abaxial leaf epidermal remains. Adaxial epidermis of subrounded cells with thick walls; no prickels and only very few stomata Abaxial epidermis of elongated cells with sinuous walls; numerous stomata, paracytic, with low dome-shaped subsidiary cells. Type T61: cf. Juncaceae. Plate XI. Leaf epidermal remains; cylindrical. Top leaf cells rounded; towards the middle part of the leaf cells more rectangular and in longitudinal rows. Thick walls. Stomata, paracytic, with , parallel-sided to low dome-shaped subsidiary cells. This type of epidermal remains are possibly coming from leaf tips of I uncus ecuadoriensis Balslev. Type T62: Juncaceae. Plate XI. Epidermal remains. No distinct costal and intercostal zones. Cr::lls rectangular, arranged in longitudinal rows. Cell walls wavy. Stomata mostly confined to longitudinal bands, paracytic, Âˇ with low dome-shaped subsidiary cells. Type T63: cf. Xyris (Xyridaceae). Plate XI. Leaf epidermal remains. No distinct costal and intercostal zones. Cells rectangular, longitudinally extended, with protuberant end walls. Stomata parncytic, with shallow subsidiary cells. Type T64: Dicotyledoneae. Plate XII. Leaf epidermal remains. Stomata anomocytic (?), equally dispersed over leaf surface, excluding some elongated areas possibly coinciding with the location of the veins. In some remains multicellulair hairs have been observed This heterogenous type pro bably includes epidermal remains of several dicotyledoneous taxa. Type T6S: Dicotyledoneae. Plate XII. Epidermal remains of linear leaf type, ca 0.6Âˇ0.9 mm broad. Cells sometimes papillose. Stomata anomocytic (?), equally dispersed over leaf surface, excluding some elongated areas possibly coinciding with the location of the veins. Trichomes present. Especially on the basis of leaf morphological characters and size, it can be suggested that this type of epidermal remains is coming from leaves of Werneria (Compositae). Type T66: Hypericum (Hypericaceae). Plate XII. Leaf epidermal remains of type Tl43 (leaves of H. goyanesii), with puzzle-piece like cells. Stomata anomocytic. Type T67: cf. lsoeres (Isoetaceae). Plate XII. Leaf(?) epidermal remains. Cells in longitudinal rows, rectangular, with straight walls. No stomata observed. Plant remains of bryophytes The descriptions are exclusively based on the fossil material found in the analyzed sections. The identification of the fossil mosses is generally based on leaf characters, because of the lack of intact plants. Determinations have been checked with collections from the Herbarium of the University of Utrecht (The Netherlands). In the descriptions, use has been made of the following publications: Wamstorf (1911), Bartram (1949), Robinson (1967), Smith (1 978), Crum & Anderson (1981), Griffin (1981), Watson (1981), Griffin & Morales (1983), Meenks (1987) and Van Reenen (in prep.). The terminology is mainly taken from Watson (1981), but the term "costa' is used instead of 'nerve'. The nomenclature is principally based on Florschiitz-de Waard & Florschiitz (1979) and Gradstein & Hekking (1979).

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leaf; many rows at the basal leaf margin only. D etermination following the key of Robinson (1967).

Type T68: Sphagnwn mage/lanicum Brid. (Sphagnaceae). Plate XIII. Plants branching in fascicles. Cortical cells of stems and branches fibrillose. Branch leaves broadly ovate, deeply concave, hood-shaped, ecostate. Leaves with a regular pattern of alternating green and hyaline cells reinforced with spiral fibers. Green cells completely enclosed on both leaf surfaces (Kuhry, in press: type T18).

Type T78: Aulacomnium palustre (Hedw.) Schwaegr. (Aulacomniaceae). Plate XV. Leaves lanceolate, acuminate, unicostate, upper leaf margin denticulate. Upper leaf cells Âˇ collenchymatous, papillose.

Type T69: Sphagnum sect. Cuspidata (Sphagnaceae). Plate XIII. Plants branching in fascicles. Branch leaves ovate-lanceolate, sometimes slightly falcate, slightly concave, ecostate. Leaves with a regular pattern of alternating green and hyaline cells reinforced with spiral fibers. Green cells broadly exposed on the dorsal surface. Pores small, less than 12 ~m (Kuhry, in press: type TIO). Type T70: Sphagnum cyclophyllum Sui!. & Lesq. (Sphagnaceae). Plate XIII. Branch leaves very large, ca 2,5 x 2.0mm, broadly ovate, deeply concave, eco state . Leaves with a regular pattern of alternating green and hyaline cells reinforced with spiral fibers. Green cells equally exposed on both surfaces. Pores very numerous. Type Til: Sphagnum subsecundum Nees (Sphagnaceae). Plate XIII. Branches with leaves. Branch leaves ovate-lanceolate, slightly concave, ecostate. Leaves with a regular pattern of alternating green and hyaline cells reinforced with spiral fibers. Green cells equally exposed on both surfaces, or slightly more so on the dorsal surface. Pores small, very numerous on the dorsal surface , usually arranged in a regular row along the length of the hyaline cells. Type 172: Pleurozium schreberi (Brid.) Mitt (Entodontaceae). Branches with leaves. Leaves ovate, concave, costa bifurcate and confined to lower half of leaf, leaf apex notched. Leaf cells smooth, linear. Distinct group of alar cells. Especially the notched apex is a differential character which separates P. schreberi from other similar mosses, such as Cal/iergon cuspidatum (Hedw.) Kindb. (Crum & Anderson, 1981). No good material was available for illustrations (see Kuhry, in press: type Tl6). Type 173: Rhacocarpus purpurascens (Brid.) Par. (Hedwigiaceae). Plate XrY. Leaves broadly obovate, round ed above, abruptly long-apiculate. Surface of lamina verrucose; border of smooth cells all around. Type 174: Bartramia (Bartramiaceae). Plate XIV. Leaves linear-subulate, wider at shoulders than below, unicostate. Upper leaf cells papillose, obscure; basal leaf cells smooth. Type 175: Breute/ia allionU Broth. (Bartramiaceae). Plate XIV. Leaves S Smm long, ovate-lanceolate, acuminate, plicate at the base, unicostate, the costa end.ing. near the apex , leaf margin serrulate. Leaf cells narrow ly rectangular, with papillae proJecung from the postenor t:nd of leaf cell wall. Upper leaf cells mostly ten times as long as wtde. Leaf base with many rows of enlarged cells extended along leaf margin, sometimes up to the widest part of the leaf. Determination following the key of Robinson (1967). Type 176: Breutelia chrysea (C. Muell.) Jaeg. (Bartramiaceae). Plate XIV. Leaves ovate-lanceolate, acuminate, plicate at the base, unicostate, the costa ending near the apex, leaf margin serrulate, leaf base not closely vaginate. Leaf cells narrowly rectangular, with papillae projecting from the posterior end of leaf cell wall. Upper leaf cells about five times as long as wide. Leaf base with many rows of enlarged cells extended along leaf margin, sometimes up to the widest part of the leaf. Determination following the key of Robin son (1967). See also Kuhry (in press): type T19. Type 177: Breutelia tomentosa (Brid.) Jaeg. (Bartrarniaceae). Plate XV. Leaves ovate-lanceolate, acuminate, plicate at the base, unicostate, the costa ending near the apex, leaf margin serrulate, leaf base not c losely vaginate. Leaf cells narrowly rectangular, with papillae projecting from the posterior end .of leaf cell wall. Upper leaf cells about five times as long as wide! Leaf base with only one row of distinctly enlarged cells up to the widest part of the

Descriptions of macrofossils

Type 'f79: Polytrichumjuniperinum Willd. ex Hedw. (Polytrichaceae). Plate XV. Leaves larnellate, narrowly lanceolate, drawn out in sharp tip, unicostate; leaf margin entire, broadly inflexed above shoulders, extending nearly to median line of blade. Cells ..non papillose. Type T80: Campy/opus cucu/latifolius Herz. (Dicranaceae). Plate XV. Branches with leaves. Leaves ovate-lanceolate, acuminate, concave, u nicostate; costa percurrent, broad, about 1/3 width of leaf base; apex slightly notched. Leaf cells smooth; acumen cells oval to rhomboidal; distinct group of coloured alar cells.

I I

I t

Type T81: CampylopiLS (Dicranaceae). Plate XVI. Branches with leaves. Leaves ovate-lanceolate, acute to narrowly acuminate, unicostate; costa excurrent or percurrent, broad, more than 1/3 width of leaf base. Leaf cells smooth; acumen cells short rectangular to rhomboidal; distinct group of alar cells (Kuhry, in press: type : T9). This heterogenous type probably includes plant remains of several Campy/opus species. Type T82: Chorisodontium speciosum (Hook. f. & Wils.) Broth. (Dicranac~ae). Plate XVI. . Leaves ovate-lanceolate, acuminate with long tips, unicostate; costa excurrent, less than 1/3 wtdth of leaf base; upper ~e~ margin entire (not serrate). Leaf cells 2: 140J.1I11, well pitted, lumina broader than cell walls; dtstmct group of coloured alar cells. Determination following the key of Van Reenen (in prep.). Type T83: Ditrichum submersum Card. & Herz. (Ditrichaceae). Plate XVI. Branch~s with leaves. Leaves narrowly Janceolate-subulate, unicostate; costa excurrent, less than 1/3 wtdth of leaf base; no apical teeth. No distinct group of alar cells. See also Robinson ( 1967). Type T 84: Bryum (Bryaceae). Branc~es with leaves. Leaves ovate-lanceolate, acute, unicostate; costa ending near the apex; leaf marg1n en lire. Leaf cells smooth, elongated hexagonal or rhomboidal; d istinct border of narrower cells. No good material was available for illustrations (see Kuhry, in press: type Tl 1). Type T 85: Drepanodadusfluitans (Hedw.) Warnst. (Amblystegiaceae). Plate XVI. ~ ! ants branched ..Leaves ovate- l~ceo l ate, falcate(-secund), acuminate, unicostate; costa e~d~ n g well above mtd-leaf; .leaf margm serrulate; leaf base straight. Leaf cells smooth, linear; dtsnnct group of alar cells, wtth slightly thickened walls. According to Cru~ & Anderson ( 1981 i' the serrulate leaf margin will separate D. fluitans from the related spectes D. aduncus (Hedw.) Wamst. The straigh t base and the slightly thtckened walls of the alar cells are differential characters that separate D . fluitans from D. exannulatus (B.S.G.) Warnst. Type T 86: Cyc/odictyon rubrisetum (Mitt.) 0 . Kuntze (Hookeriaceae). Plate XVII. . I:eaves oblong to obovate, abruptly slenderly acuminate, bicostate; generally smooth apex. Dtsnnct border of mostly 2 rows of enlarged cells. According to the literature the description follows that of C. erubescens Bartr. but Van Reenen (in prep.) finds the discriminatory characters between C. erubescens and C. r~brisetum of minor importance and therefore the former is considered conspecific with C. rubrisetum.

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Descriptions of macrofossils

Type T87: Kurzia verrucosa (Steph.) Grolle (Lepidoziaceae). Plate XVII. Plant branched, foliose. Leaves transverse, deeply divided into 3-4 segments to more than 1/2 of their length; 2-3 rows of cells in lamina; 2-3 cells wide in lower part of leaf segments. Leaf cells 12-16(20)J.I.m large, papillose.

Type T98: Gramineae. Plate XVIIi. Caryopses elliptical in l.s. Size: 1.5-1.7 x 0.6-0.8 mm. Fruit scars narrowly elliptical, 0.46-0.49 rom in length, longer than 1/ 5 of seed length, located well above the base.

Type T88: cf. Lepidozia (Lepidoziaceae). Plate XVII. Plants foliose. Leaves incubous, divided into 3(-4) segments to about 1/3 of their length; many rows of cells in lamina. Leaf cells 18-23J.1.m large, non papillose.

Type T99: Carex cf. bonplaruiii Kunth (Cyperaceae). Plate XVIII. Achenes elliptical, sometimes ovate, in l.s., flattened biconvex, elliptical in c.s. Size: 1.2-1. 8 X 0.7-1.0 X 0 .4-0.5 mm. SurfaceÂˇstriate (LM), with an overlying areolate pattern (SEM). Perigynia not found (Kuhry, in press: type T27).

Type T89: Odontoschisma (Adelanthaceae). Plate XVII. Plants foliose. Leaves, succubous, nearly orbicular, slightly concave, margin entire. Underleaves no t seen. Cells rounded, thickened in the comers. Type T90: Hepaticae. Plate XVIll. Plants foliose. Leaves concave, divided into 2 segments to about 1/3 of their length. Underleaves notseen. Leaf cells more or less rounded, wall thickenings not observed. Type T91: Hepaticae. Plate XVIII. Plants foliose. Gemmae observed. Type T92: Riccardia hansmeyeri (Steph.) Meenks & DeJong (Aneuraceae). Plate XVill. Plants branched, thallose, without well-defined mid-rib. Branches less than 2mm broad. Thallus surface without pores. Branching pattern irregularly bipinnate or, more rarely, nip innate. Main axis not winged; ultimate branches with a distinct wing. Surface cells with wall thickenings. Determination by Mr. J.L.D. Meenks (University of Utrecht, The Netherlands). Type T93: Riccardia (Aneuraceae). Plants branched, thallose, without well-defined mid-rib. Branches less than 2mm broad. Thallus surface without pores. No good material was available for illustrations. Plant remains of lichens Type T94: Cladia (Ciadoniaceae). Plate XVID. Plants thallose, branching. Thallus with cavities (Sipman & Aguirre, 1982). Fruits and seeds The descriptions are based on morphological characters of the fossil material found in the analyzed sections. The terminology is mainly taken from K5rber-Grohne (1964), Berggren (1969, 1981) and Montgomery (1977). The nomenclature is based on Cleef (1981). Abbreviations: l.s. = longitudinal section; c.s. =cross section; SEM =Scanning Electron MkToscope; LM = Light Microscope. Type T95: Gramineae. Plate XVIII. Caryopses elliptical in l.s., broadly elliptical in c.s. Size: 1.2- 1.4 x 0.6 x 0 .5 mm. Fruit scars circular, 0.14 mm in diameter, shorter than 1/5 of seed length, located well above the base. Type T96: Gramineae. Plate XVIII. Caryopses elliptical in l.s. Size: ca 1.7 x 0.6 mm. Fruit scars narrowly elliptical, ca 0.23 mm in length, shorter than 1/5 of seed length, located well above the base. Type T97: Grarnineae. Plate XVIII. Caryopses elliptical in l.s. Size: ca 1.8 x 0.7 mm. Fruit scars narrowly elliptical, ca 0.34 mm in length, about 1/5 of seed length, located well above the base.

Type T lOO: Carex (Cypera,ceae). Plate XIX. Achenes ovate to elliptical in I.s., triangular, with straight to slightly convex sides in c.s. Size: 1.5-1.9 x 0.7-1.0 x 0.6-1.0 mm. Surface sniate (LM), with an overlying areolate pattern (SEM). Perigynia not found. Carex pichinchensis HBK, C. acutata Boott and C. jamesonii Boott are Colom bian Carex species with niangular achenes (Kuhry, in press: type T24). Type Tl01: Eleocharis (Cyperaceae). Plate XIX. Endocarps obovate in l.s. Size: 0.7-0.9 x 0.5-0.6 mm. Endocarp cells transversely extended, rather indistinct on one hemisphere, becoming v ery distinct on the other one. Type T102: Rhynchospora macrochaeta Steudel (Cyperaceae). Plate XIX. Achenes obovate in l.s., flattened biconvex, elliptical in c.s. Size: 1.4-1.5 x 0 .8-0.9 x 0.40.5 mm. Surface areolate (SEM). Achenes with persistent style and bristles; persistent style up to 2mm long; bristles longer than achenes. Type T103: Oreobolus obtusangulus Gaudich. (Cyperaceae). Plate XIX. Achenes circular in I.s., with niangular tip, circular in c.s. Size: ca 1.5 x 1.0 x 1.0 mm. Surface granulate (SEM). Type T104: Juncus (Juncaceae). Plate XX. Seeds narrowly elliptical in l.s., broadly elliptical to circular in c.s. Size: 0.4-0.6 x 0.2 x 0.2 mm. Surface with longitudinal striations (LM), without thickenings (SEM). Type Tl05: }uncus (Juncaceae). Plate XX. Seeds narrowly elliptical in I.s., broadly elliptical to circular in c.s. Size: 0.8-0.9 x 0.3-0 .4 x 0.3-0.4 mm. Surface with longitudinal striations (LM), with pointy thickenings (SEM). Type Tl06: cf. Luzula (Juncaceae). Plate XX. Seeds elliptical in l.s. Size: 1.2- 1.4 x 0.8 mm. Surface areolate. Caruncle prominent, sometimes found. Type Tl07: cf. Luzula (Juncaceae). Seeds elliptical in l.s. Size: 0.9-1.0 x 0.6 mm. Surface areolate. No good material was available for illustrations. Type T108: Xyris (Xyridaceae). Plate XX. Seeds narrowly elliptical, sometimes almost oblong, in l. s. Size: 0.8-1. 1 x 0 .3-0 .4 mm. Surface with wavy longitudinal sniations. A SEM photograph of a recent X. acutifolia (Heimerl) Malme seed is also p rovided. Type Tl09: Eriocaulaceae. Seeds (broadly) elliptical in l.s., circular in c.s. Size: ca 0.7 x 0.5 x 0.5 mm.

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Surface reticulate. No good material was available for illustrations. Type TllO: Eriocaulaceae. Plate XX. Seeds (broadly) elliptical in l.s., circular in c.s. Size: 0.6-0.8 x 0.4-0.6 x 0.5 mm. Surface reticulate. Type Till: Eriocaulaceae. Plate XX. Seeds (broadly) elliptical in l.s., circular in c.s. Size: 0.7-0.9 x 0.5-0.6 x 0.5 mm. ~ Surface reticulate. Type Tl12: Puya (Bromeliaceae). Plate XXI. Seeds ovate in l.s., flattened slightly biconvex, elliptical in c.s; one end apiculate. Size: 1.52.2 x 0.8-1.3 x 0.4-0.7 mm. Surface areolate. Net-like seed coat sometimes found.

Descriptions of macrofossils

Type T122: Bartsia (Scrophulariaceae). Plate XXII. Seeds elliptical in l.s., broadly elliptical to circular in c.s. Size: ca 0.8 x 0.3 x 0.3 mm. Surface with prominent longitudinal ribs and transverse striations. No good fossil material was available for illustrations. Instead a SEM photograph of a recent Bartsia santolinnifolia (HBK) Benth. seed is provided. Type T123: Lachemilla (Rosaceae). Plate XXII. Achenes (?)obliquely ovate in l.s., elliptical in c.s. Size: 0.9-1.0 x 0.5-0.8 x 0.4 mm. Surface striate (Kuhry, in press: type T29). Type Tl24: cf. Callitriche (Callitrichaceae). Plate XXlll. Fruits splitting into 4 one-seeded nutlets. Nutlets semi-elliptical in l.s., flattened, (narrowly) elliptical in c.s. Size: 1.0-1.4 x 0.7-0.9 x 0.3 mm. Surface striate (LM), with an overlying areolate pattern (SEM). See also Kuhry (in press): type T30.

Type Tll3: Hypericum (Hypericaceae). Plate XXI. Seeds oblong, slightly curved in l.s., circular in c.s. Size: 1.0-1.1 x 0.3 x 0.3 mm. Surface indistinctly areolate. Stellate cells.

Type T125: Elarine (Elatinaceae). Plate XXIII. Seeds oblong, slightly curved in l.s., circular in c.s. Size: 0.8-0.9 x 0.3-0.4 x 0.3-0.4 mm. Surface reticulate.

T ype T114: Hypericum (1-iypericaceae). Plate XXI. Seeds oblong in l.s., circular in c.s. Size: 0.7 x 0.3 x 0.3 mm. Surface indistinctly areolate. Stellate cells (Kuhry, in press: type T28).

Type Tl26: Tillaea (Crassulaceae). Plate XXIll. Seeds elliptical in l. s., circular in c.s. Size: 0.6-0.7 x 0.3 x 0.3 mm. Surface with wavy longitudinal striations. Puzzle-piece like cells.

Type Tl15: cf. Vaccinium (Ericaceae). Plate XXI. Seeds obliquely obovate to irregularly shaped in l.s., flattened, elliptical in c.s. Size: 0.7-0.9 x 0.5-0.6 x 0.4 mm. Surface reticulate, with thick walls. A SEM photograph of a recent Vacciniumjloribundum HBK seed is also provided. Type Tll6: cf. Perneuya (Ericaceae). Plate XXI. See<;ls obliquely obovate to irregularly shaped in l.s., flattened, elliptical in c.s. Size: 0.8-1.0 x 0.5-0.7 x 0.3 mm. Surface reticulate, with faint walls. A SEM photograph of a recent Pernetrya prostrara (Cav.) DC seed is also provided. Type Tll7: Compositae. Plate XXII. Achenes narrowly oblong in l.s.; one end apiculate; I prominent longitudinal rib. Size: ca 3.3 x 0.6 mm. Surface granulate. Circular pappus rim. Type Tll8: Diplostephium (Compositae). Plate XXIl. Achenes (narrowly) obovate in l.s.; 4-5 longitudinal ribs. Size: ca 1.3 x 0.5 mm. Circular pappus rim. Type Tll9: Bidens (Compositae). Plate XXII. Achenes oblong in l.s., flattened in c.s. Size: ca 1.3 x 0.7 mm. Pappus of 2 awns (Kuhry, in press: type T23). Type T120: Espe/etia (Compositae). Plate XXII. Achenes obovate to oblong in l.s., elliptical to circular in c.s.; one end apiculate; l very prominent longitudinal rib. Size: 2.6-3.0 x 1.3-1.6 x 1.1 -1.3 mm. Surface granulate. Pappus not observed. Type Tl21: Gentiana sedifolia HBK (Gentianaceae). Plate XXII. Seeds obovate to elliptical in l.s., circular in c.s. Size: 0.8-1.1 x 0.4-0.5 x 0.4-0.5 mm. Surface faintly reticulate. Longitudinally extended cells, with many small pits.

Type T127: Ranunculus (Ranunculaceae). Plate XX:Ill. Achenes elliptical in l.s., flattened, elliptical in c.s. Size: 1.2- 1.4 x 0.8-0.9 x 0.4-0.5 mm. Surface striate (LM), with Âˇan overlying areolate pattern (SEM). Persistent style rather indistinct. Type Tl28: Potamogeron (Haloragaceae). Plate XXIII. Achenes obliquely obovate in l.s., flattened, narrowly elliptical in c.s. Size: 3.2-3.8 x 2.62.8 x 0.8-1.0 mm. Surface rather smooth. Persistent style rather indistinct. Type Tl29: Plate XXIV. Seeds (?) narrowly elliptica l in l.s., flattened, elliptical in c.s. Size 0.6 x 0 .2 x 0.1 mm. Surface areolate. Type Tl30: Plate XXIV. Endocarps (?) ovate o r obovate in l.s. Size: 0.7 x 0.5 mm. Surface faintly areolate. TypeT131: Plate XXIV. Fruits (?) (broadly) ovate in l.s., flattened , elliptical in c.s. Size: 1.0-l.l x 0.7-0.9 x 0.4 mm. Surface of seed coat(?) areolate. Type Tl32: Plate XXIV. Fruits (?)oblong to broadly oblong in l.s. Size: ca 1.2 x 0.9 mm. Other macrobotanical remains The descriptions are exclusively based on the fossil material found in the analyzed.sections. T he terminology used in the Isoetes megaspore descriptions follows Hickey ( 1985); the one used in the anatomical descriptions of glumes and basal leaf sheath s is taken from Metcalfe (1960, 1971); the one used in the morphological descriptions of flowers, branches, leaves and glumes is after Heywood (1978); finally, the one used in the Characeae oospore descriptions is taken from Wood & lmahori (1964, 1965). The nomenclature is principally based on Cleef (1981).

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Type T133: Isoeres (Isoetaceae), megaspores. Plate XXIV. Megaspores circular to subtriangular convex in outline. Diameter: 0.3-0.4 mm. Endospore surface smooth. Type Tl34: Isoeres cleejiilsteyermarkii (Isoetaceae), megaspores. Plate XXIV. Megaspores circular to subtri3.!1gular convex in outline. Diameter: 0.3-0.4 mm. Endospore surface smooth. Determination by Mr. H.P. Fuchs (Trin"Vitg, Switserland). lsoeres cleefii H.P. Fuchs and lsoetes sreyermarkii H.P. Fuchs (ined.) are both aquatic Isoeres species. Type T135: l soeres andinalboyacensis (lsoetaceae), megaspores. Plate XXV. Megaspores circular to subtriangular convex in outline. Diameter: 0.6-0.7 mm. Endospore surface of lsoetes andina Hook. ex Spruce cristate·echinate; endospore surface of lsoeres boyacensis H.P. Fuchs (ined.) reticulate. Determination by Mr. H.P. Fuchs (Trin-Vitg, Switserland) and the author. These two lsoetes megaspore types, that have been found in the PAB II and III sections, have not been recorded separately. / . andina is more frequent in the upper part of these sections, while/. boyacensis is more freque nt in the middle part. lsoetes andina and/. boyacensis are both terresoiallsoetes species: Type T136: lsoeres (Isoetaceae), megaspores. Plate XXV. Megaspores circular to subtriangular convex in outline. Diameter: 0.5-0.6 mm. Endospore surface smooth. Type T137: Gramineae, glumae. Plate XXV. Glumes ovate-lanceolate, apiculate; apex denticulate. One vein. Size: 2.1-2.2 x 0.5-0.8 mm. Epidermis with long cells and short cells; short prickels present in intercostal zones, long prickels sometimes present in the costal zone. Cell walls sinuous. Few stomata, present along the vein, paracytic, with parallel-sided subsidiary cells. Type T1 38: Gramineae, basal leaf sheaths. Plate XXV. Basal leaf sheaths with parallel venation. Costal and intercostal zones. Epidermis with long cells and short cells; short prickels in intercostal zones, longer prickels in costal zones. Cell walls sinuous. Few stomata, present in intercostal zones, paracytic, with parallel-sided subsidiary cells. Type Tl 39: Cyperaceae, basal leaf sheaths. Plate XXV. Basal leaf sheaths with parallel venation. Costal and intercostal zones. Costal cells smaller. Cell walls sinuous. No stomata observed. Type T140: flowers. Plate XXVI. Calyces of 4/5 sepals, which are fused at the base; apex of sepals acute. Anthers observed. Type T141: Hypericum (Hypericaceae), branches. Plate XXVI. Branches with decussate leaf arrangement. Hypericum leaves have been found attached. Type Tl42: Hypericum laricifolium Juss. (Hypericaceae), leaves. Plate XXVI. Leaves simple, acicular to lanceolate, apex acuminate, margin entire. Venation pinnate. Petiole short and broad. Size:~ 2.5 x 0.5 mm. Type Tl43: Hypericum goyanesii Cuatr. (Hypericaceae), leaves. Plate XXVI. Leaves simple, cordate, apex acute, margin entire. Venation pinnate. Petiole short and broad. Size: 1.5-2.0 x 1.0-1.3 mm. Type Tl44: cf. Vaccinium (Ericaceae), fruits. Fruits with immature cf. Vaccinium seeds (T115). Persistent calyx of 4 sepals, fused at the base. Ovary inferior. No good material was available for illustrations.

161

Descriptions of macrofossils

Type Tl4~: Ericaceae, flowers. Plate XXVI. Flowers With anthers carrying Ericaceae pollen. Type Tl46:.Ericaceae, branches. Plate XXVI. Branches With alternate leaf arrangement Stipules present

T1 ~7: Vaccin.i~Pernetrya (Ericaceae), leaves. Plate XXVI [ype · · · eaves. Simple, elhpucal to lanceolate ape

Petiole short. Size: 0.9-1.0 x 0.4-0.5 mm. •

x acurrunate, margm serrate. Venation pinnate.

1 · Type T148: Diplostephium phylicoides (HBK) Wedd · (Compositae), eaves bl Leaves simple r • inear to o ong, revolute, apex rounded, margin entire. Size: ;:: 5.0 x 1.5 mm. No good material was available for illustrations. Type Tl~9: Elatine (Elatinaceae), leaves. Plate XXVI . · · Leaves Simple obovate apex ro ded un 'margm enure. Venation pinnate. Petiole absent. Size: ' 2.0-2.5 x 0.5-1.0 'mm. Type T1.50: ~olypodiales, sporangia. Plate XXVI. ed s· Sporangta With annular thickening· stomium mo tl ¥h-~gia sometimes found with ~onolete psilat~ s~~fe~~nsld;ze: 0.5-0.6 x 0.3-0.4 mm. IS eterogenous type probably includes sporangia of several t~a of the Polypodiales. Type Tl51: Blechnum (Biechnaceae),leaves. . . · Compound leaves. Leaflets linear, revolute mar · No good material was available for illustrations. gtn entrre, apex rounded. Venation pmnate. Type Tl52:. Polypodiales, leaflets. Plate XXVI . . · Leaflets vanable in size Ianceolate acumi nate, margin entrre, base cordate. Leaflets one cell ' layer thick; cells thin-walled This heterogenous type p.roba bl Y·me1udes 1eaflets of several taxa of the Polypodiales. Type Tl53: .PoiYJ?odiales, leaflets. Plate XXVI. . . Leaflets vanable m size lanceolate acumi t layer thick; cells thin-walled. Size: ca 4.o x l .;~%~argm entrre, base cordate. Leaflets one cell Type TI54: .M.usci, calyptrae. Plate XXVII. Calyptrae nutnforrn, campanulate. Size: ca 2 mm long. Type TlS5: Sphagnum (Sphagnaceae), opercula. Opercula conv~x. ca I mm in diameter. No good matenal was available for illustrations (see Kuhry, in press: type T47). Type Tl 56: Characeae, oospores. Plate XXVII . . ·· t ·d Oospores globose with 6-7 promi nen n ges 10 a spiral fash ion. Membrane granulate. Size: 0.50-0.55 x 0.44-0.46 mm. Some zoological macrofossils Type T157: Cladocera, ephippia. Plate XXVII. Type T1 58: Acaridae, exoskeletons. Plate XXVII · See also Kuhry (in press): type T 5o. Type T I59: Coleoptera, elytra. Plate XXVII. Type Tl60: Collembola, exoskeletons. Plate XXV,U.

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162

Type T161: cf. Hymenoptera, puparia. Plate XXVll. See also Kuhry (in press): type T52. Type Tl62: cf. Psocoptera, exoskeletons. Plate XXVll. Type Tl63: cf. Hemiptera, expskeletons. Plate XXVll. Type T164: Insectae, head capsules. Plate XXVII. Type Tl65: cf. Oligochaeta, cocoons. Plate XXVll. See also Kuhry (in press): type T51.

12. MICROFOSSIL PLATES Abbreviations: PLY I= Paramo de Laguna Verde I section (present study) PLY II= Paramo de Laguna Verde II section (present study) PPN I= Paramo de Pefia Negra I section (present study) PAB I= Paramo de Agua Blanca I section (Helmens & Kuhry, 1986) PAB II= Paramo de Agua Blanca II section (present study) PAB III= Paramo de Agua Blanca III section (present study) PG =Paramo de Guasca section (Kuhry, unpublished)

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Microfossil plates

PLATE I

PLATE I Type 533: Eucalyptus (Myrtaceae) (a= pollen grain, xl OOO. PPN I Scm) (b,c =pollen grain, x l OOO. PPN I 12cm) • 534

Type 534: Pinus (Pinaceae) (pollen grain, x400. PLY II lcm)

Type 535: Rumex acetosella (Polygonaceae) (a-c =polle n grain, xl OOO. PLY I 7cm) (d =pollen grain, xlOOO. PLY II lcm) Type 536: Zea mais (Gramineae) . (pollen grain, x400. PPN I 143cm) Type 537: Alcernanthera-rype (Amacanthaceae) (a,b =polle n grain, x !000. PLY I 281cm) (c,d =pollen grain, xlOOO. PLY I 23cm) Type 538: !resine-type (Amaranthaceae) · (a,b = pollen grain, x 1000. PLY I I 06cm) . Type 539: Anridaplrne-type (Loranthaceae) (a,b = pollen grain, x 1000. PLY I 159cm)

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166

Microfossil plates

PLATE ll

PLATE II Type 540: Elaeagia-type (Rubiaceae) (a,b =pollen grain, xlOOO. PLV I 232cm) Type 541: Colignonia-type (Nyctaginaceae) (a,b = pollen grain, xlOOO. PPN I 22cm) Type 542: C 3P 3 fov/foss (a,b =pollen grain, xlOOO. PPN I 29cm) Type543:~P6 rrri~hln

(a,b =pollen grain, xlOOO. PLV I 130cm)

T ype 544: Potamogeton (Haloragaceae) (pollen grain, xlOOO. PLV I 275cm) Type 545: Bansia-type (Scrophulariaceae) (a,b =pollen grain, x!OOO. PAB III 60cm) Type 546: Xyris (Xyridaceae) (pollen grain, x!OOO. PAB Ill 90cm)

... ' 546

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168 PLATE III

PLATE III Type 547: Arcytophyllum (Rubiaceae) (a,b =pollen grain, xlOOO. PPN I 15cm) Type 548: Zea mais (Gramineae) (pollen grain, x400. PPN I 35cm) Type 549: Macrocarpea (Gentianaceae) (a,b =pollen grain, xlOOO. PPN I 15cm) Type 550: C3P3 scabr (a,b =pollen grain, x1000. PPN I 203cm) Type 551: Habenaria-type (Orchidaceae) (pollen grain, x1000. PLY II 73cm) Type 552: Sericotheca (Rosaceae) (a,b = pollen grain, x 1000. PAB III 118cm) Type 553: C:4 •7 microret · (a,b =pollen grain, x1000. PPN I 107cm) Type 554:

~P 3 (C4 P4 ) scabr (a,b = pollen grain, x 1000. PPN I 203cm)

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170

PLATE IV

PLATE IV Type 555: Umbelliferae (a,b =pollen grain, x1000. PPN I 228cm) Type 556: Nertera (Rubiaceae) (a,b =pollen grain, x1000. PAB III 13cm) Type 557: Bromeliaceae (pollen grain, x1000. PAB_.III 85cm) Type 558: Solanaceae (a-c =pollen grains, x1000. PAB ill 82cm) Type 559:

~P3 psi! (fov) (a,b =pollen grain, x1000. PAB III 38cm)

Type 560: Gaeumannomyces cf. caricis (Diaporthaceae, Ascomycetes) (hyphopodium, x1000. PLY I 232cm) Type 561: unidentified fungal type (spore, x 1000. PLY I 154cm) Type 562: unidentified fungal type (a,b =spores, xlOOO. PPN I 163cm) Type 563: unidentified fungal type (a,b = spore, x 1000. PLY I 11 em) Type 564: unidentified fungal type (spore, x 1000. PLY I 165cm) 560

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Microfossil plates

173

PLATE V

PLATE V Type S6S: unidentified fungal type (a= conidium, xl OOO. PLVI 16Scm) (b =conidium, xlOOO. PLY I 1S4cm) Type S66: unidentified fungal type (a,b =conidia, x!OOO. PLV I 134cm)

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Type S67: Anthostome/lajuegiana (Ascomycetes) (ascospore, xlOOO. PPN I !Scm) Type S68: Heiicoon pluriseptatwn (Hyphomycetes) (conidium, xlOOO. PPN I Scm) Type S69: unidentified fungal type (a,b = cluster of spores, x 1000. PAB II 16cm) Type S70: Lasiosphaeria-type (Ascomycetes) (ascospore, x1000. PPN I 3Scm) Type. S71: unidentified fungal type (a,b = ascospores, x1000. PLVI 3cm)

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Type S72: unidentified fungal type (a,b = spore, x 1000. PLV I 11 em) Type S73: Ce/asinospora (Sordariaceae, Ascomycetes) (A,B = ascospores, x 1000. PPN I S7cm)

572a

Type S74: unidentified fungal type (spore, x 1000. PG 39cm) Type S7S: unidentified fungal type (conidia, x400. PPN I Scm)

571a

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571b

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572 b

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174

Microfossil plates

PLATE VI

~ PLATE VI Type 576: unidentified fungal type (a,b =ascospore, xlOOO. PPN I 168cm)

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577a 576a

577b

576 b

Type 577: unidentified fungal type (a,b = spores, xlOOO. PPN l Scm) Type 578: unidentified fungal type (spore, x 1000. PLV l247cm) Type 579: unidentified fungal type (ascospore, x400. PLV l 3cm)

1,'/ '

Type 580: P/eospora-type (Pleosporaceae, Ascomycetes) (spore, x 1000. PLV I 15cm)

Type 581: unidentifie d fungal type (ascospore, xI 000. PLV I 3cm) Type 582: unidentified fu ngal type (a,b = ascospores, xlOOO. PPN I 37cm) · Type 583: unidentified fungal type (spore, x 1000. PL V II lcm)

584a

584b

Type 584: unidentified fungal type (a,b =spore, xlOOO. PLY ll lcm) Type 585: unidentified fungal type (conidium, x400. PG 9cm) Type 586: unidentified fungal type (spore, x l 000. PAB III 48cm) Type 587: Spirogyra cf. scrobicu/aca (Zygnemataceae, Chlorophyceae) (spore, x400. PLV I 159cm) Type 588: Zygnema (Zygnemataceae, Chlorophyceae) (a = spore, x400. P AB II 36cm) (b = spore, x400. P AB II 7qcm) (c = spore, x400. PPN l 85cm) (d =spore, x400. PPN I I33cm)

I i( 586

•

582b

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176

PLATE Vll

PLATE Vll Type 589: Debarya (Zygnemataceae, Chlorophyceae) (zygospore, xlOOO. PAB III 82cm) Type 590: Spirogyra!Closrerium (Zygnemataceae, Chlorophyceae) (Aa = Closrerium idiosporum zygospore, xlOOO. PLY I 281cm) (Ab = Closterium idiosporum zygospore, x400. PAB II 66cm) (B =Spiro gyra spore, x400. PLV I 202cm) Type 591: Mougeotia (Zygnemataceae, Chlorophyceae) (zygospore, x1000. PAB I 12cm) Type 592: 'form species' Pseudoschizaea circula (a = zygospore(?), xlOOO. PAB Ill 65cm) (b =zygospore(?), xlOOO. PAB II 56cm) Type 593: Botryococcus (Botryococcaceae, Chlorophyceae) (a,b =colonies, x400. PLV I 297cm) Type 594: Pediastrum (Hydrodictyaceae, Chlorophyceae) (a= colony, x400. PLV I 269cm) (b =colony, x400. PLY I242cm) Type 595: Pilularia-rype (Marsileaceae) (a,b = spore, x400. PPN I 203cm)

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179

PLATE VIII

PLATE VIII Type 596: unidentified bryophytic type (a,b = spore, x 1000. PLV I 15cm) Type 597: unidentified bryophytic type (a,b =cluster of spores, xlOOO. PPN I 57em) Type 598: unidentified bryophytic (?)type (a,b = spore, xlOOO. PPN I 85cm) Type 599: unidentified bryophytic type (a,b =spore, xlOOO. PLY I 7cm) Type 600: Meesia-type (Meesiaceae) (a,b =spore, xlOOO. PAB Ill 31cm) Type 601: unidentified bryophytic (?)type (a,b = spore, x400. PPN I 188cm) Type 602: Assulina (Rhizopoda) . (a= shell, x400. PLV I 25cm) (b =shell, x400. PLY I 15cm) Type 603: Callidina (Rotifera) (lorica, x400. PLY I 15cm) Type 604: Amphitrema (Rhizopoda) (shell, x400. PLY I 15cm)

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181

13. MACROFOSSIL PLATES Abbreviations: PLV I = Paramo de Laguna Verde I section PPN I= Paramo de Pefia Negra I section PAB n = Paramo de Agua Blanca II section PAB ill= Paramo de Agua Blanca Ill section SEM =Scanning Electron Microscope

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182

PLATE IX

PLATE IX Type T53: Gramineae (a= epidermal remains, xl OO. PPN I 153cm) (b =epidermal remains, x400. PPN I 153cm) Type T54: Calamagrostis ligulata (Gramineae) (a= stem epidermal remains, xlOO. PPN I 153cm) (b =stem epidermal remains, x400. PPN I 153cm) Type T55: Agrostis haenkeana (Gramineae) (a= leaf epidermal remains, xlOO. PPN I 148cm) (b,c = leaf epidermal remains, x400: PPN I 148cm) Type T56: Calamagrostis effusa (Gramineae) (a= leaf epidermal remains, xlOO. PAB Ill 19cm) (b =leaf epidermal remains, x400. PAB II119cm)

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184

PLATE X

PLATE X Type TS7: Carex (Cyperaceae) (a= epidermal remains, x100. PPN I 52cm) (c =epidermal remains, x 100. PPN I 153cm) (b = epidermal remains, x400. PPN I 52cm) (d =epidermal remains, x400. PPN I 153cm) Type TS8: Oreobolus obtusangulus (Cyperaceae) (a = leaf epidermal remains, xlOO. PPN I 122cm) (b =leaf epidermal remains, xlOO. PPN I 107cm) (c =leaf epidermal remains, x400. PPN I 107cm) Type T59: Eleocharis (Cyperaceae) (a = epidermal remains, xlOO. PPN I 97cm) (b =epidermal remains, x400. PPN I 97cm)

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186

PLATE XI

PLATE XI Type T60: Rhynclwspora macrodu~eta (Cyperaceae) (A= abaxial leaf epidermal remains, xlOO. PAB ill 65cm) (Ba =adaxial leaf epidermal remains, xlOO. PAB II 3lcm) (Bb =adaxial leaf epidermal remains, x400. PAB II 3lcm) Type T61: cf. Juncaceae (a= top leaf epidermal remains, xlOO. PLV I 149cm) (b =mid leaf epidermal remains, x 100. PLV I 106cm) (c =leaf epidermal remains, x400. PLV I 106cm) Type T62: Juncaceae (a= epidermal remains, xlOO. PPN 1148cm) (b =epidermal remains, x400. PPN I 148cm) Type T63: cf. Xyris (Xyridaceae) (leaf epidermal remains, xlOO. PAB III 69cm)

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162b

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188

Macrofossil plates

PLATE XII

PLATE XII Type T64: Dicotyledoneae (A= leaf epidennal remains, xlOO. PPN I 213cm) (B =leaf epidennal remains, xlOO. PPN I 198cm) Type T65: Dicotyledoneae (a,b =leaves, x25. PPN I 85cm) (c =leaf epidennal remains, xlOO. PPN I 85cm) (d = leaf epidennal remains, x400. PPN I 85cm) Type T66: Hypericum (Hypericaceae) (a= leaf epidennal remains, x 100. PAB II lcm) (b =leaf epidennal remains, x400. PAB II lcm) Type T67: cf. Isoeres (Isoetaceae) (leaf epidennal remains, xlOO. PAB IIIÂ· ll8cm)

65b

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190 PLATE Xill

PLATE XIII Type T68: Sphagnum magellanicwn (Sphagnaceae) (a= branch, xlO. PPN I 29cm) (b =branch leaves, xlO. PPN I 32cm) (c = leaf cells, x250. PPN I 32cm) (d = cortical cells of branch, x250. P AB lli 31em) T ype T69: Sphagnum sect. Cuspidata (Sphagnaceae) (a = branches, x 10. PLY I 3cm) (b = branch leaves, xI 0. PAB II 26cm) (c =leaf cells, x250. PAB II 26cm) Type 170: Sphagnum cyclophyllum (Sphagnaceae) (a= branch leaf, xl O. PLY I 175cm) (b =leaf cells, x250. PLY I 175cm) Type 171: Sphagnum subsecundwn (Sphagnacea e) (a= branch, x 10. PAB II 6cm) (b =branch leaf, x40. PAB II 26cm) (c =leaf cells, x250. PAB 1126cm)

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192

PLATE XIV

PLATE XIV Type 173: Rhacocarpus purpurascens (Hedwigiaceae) (a= leaf, x 10. PLY I 149cm) (b =leaf, xlO. PLY I llOcm) (c =leaf margin, x250. PLY I llOcm) (d = leaf cells, x400. PLY I llOcm) Type 174: Bartramia (Bartramiaceae) (leaf, x25. PPN I 153cm) Type 175: Breutelia allionii (Bartramiaceae) (a= leaf, xlO. PLY I 3cm) (b =leaf, xlO. PLY I 7cm) (c = leaf margin, x250. PLY I 7cm) (d =leaf cells, x400. PLY I ?em) (e = leaf acumen cells, x400. PLY I ?em) Type 176: Breutelia chrysea (Bartramiaceae) (a-c = leaves, xI 0. PLY I 186cm) (d = leaf margin, x250. PLY I 186cm) (e = leaf cells, x400. PLV I 186cm) (f = leaf acumen cells, x400. PLY I 186cm)

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194 PLATE XV

PLATE XV Type T77: Breutelia tomentosa (Bartramiaceae) (a= leaves, xlO. PAB II lcm) (b =leaf margin, x250. PAB II !em) (c =alar cells, x250. PAB II l cm) (d =leaf cells, x400. PAB II lcm) (e = leaf acumen cells, x4~: PAB II !em) Type T78: Aulacomnium palustre (Aulacomniaceae) (a= leaf, xlO. PAB III 48cm) (b =leaf cells, x400. PAB III 48cm) Type T79: Polytrichumjuniperinum (Polytrichaceae) (a= leaf, xlO. PAB II !!em) (b = leaf margin, xlOO. PAB II llcm) (c =leaf cells, x250. PAB II llcm) Type T80: Campy/opus cucullatifolius (Dicranaceae) (a = plant, x 10. PLV I 3cm) (b =leaf, xlO. PLV I 3cm) (c =leaf, x25. PLV I 115cm) (d = alar cells, x 100. PLV I 3cm) (e = leaf cells, x250. PLV I 3cm) Â·

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196

PLATE XVI ·

81 a

81 b

·I PLATE XVI Type T81: Campy/opus (Dicranaceae) (a= leaves, xlO. PLY I 222cm) (b =leaf, xlO. PLV I 303cm) (c =leaf cells, x250. PLVI 303cm) Type T82: Chorisodi>ntium speciosum (Dicranaceae) (a= leaves, xlO. PLY I 3cm) (b = leaf cells, x250. PLV I 3cm) Type T83: Ditrichum suhmersum (Ditrichaceae) (a= plant, xlO. PLV I 237cm) (b = leaf, x40. PLV I 237cm) (c =leaf cells, x250. PLV I 237cm) Type T85: DrepanoclaLiusfluitans (Amblystegiaceae) (a= plant, xlO. PLV I 227cm) (b = leaves, x!O. PLV I 196cm) (c = leaf, x 10. PLV I 269cm) (d = leaf margin, x250. PLV I 269cm) (e =alar cells, x250. PLV I269cm) (f = leaf cells, x250. PLV I 269cm)

85b

85c

Macrofossil plates

Palaeobotanical-palaeoecological studies

199

198

PLATE XVII

PLATE XVII Type T86: Cyclodictyon rubrisetum (Hookeriaceae) (a= leaves, xlO. PLY I 217cm) (b =leaf, x40. PLY I 2 12cm) (c = leaf, x40. PLY I 222cm) (d =leaf margin, x250. PLY I 212cm) (e =leaf cells, x250. PLY I 212cm) Type T87: Kurzia verrucosa (Lepidoziaceae) (a= plant, xlO. PLY I 3cm) (b = plant, x40. PLY I 3cm) (c =leaf, xlOO. PLY I 3cm) (d = leaf cells, x400. PLY I 3cm) Type T88: cf. Lepidozia (Lepidoziaceae) (a =plant, x40. PPN I 49cm) (b = leaf, x 100. PPN I 49cm) Type T89: Odontoschisma (Adelanthaceae) (a= plant, xlO. PLY I llcm) (b = plant, x40. PLY I 11 em) (c = leaf, x40. PLY I 3cm) (d =leaf cells, x250. PLY I 3cm)

Macrofossil plates

201 Palaeobotanica).-palaeoecological studies

· Macrofossil plates

200

PLATE XVIII 91

PLATE XVIII Type T90: Hepaticae (plant, xlOO. PLV I llcm) Type T91: Hepaticae (plant, xlOO. PPN I 133cm) Type T92: Riccardia hansmeyeri (Aneuraceae) (plant, x!O. PPN I 45cm) Type T94: Cladia (Cladoniaceae) (plant, x 10. PLV I 3cm)

Type T95: Gramineae (caryopsis, x40. PLV I 222cm) Type T96: Gramineae (caryopsis, x25. PPN I 148cm) T.ype T97: Gramineae (a = caryopsis, x25. PLV I 191 em) (b = cell soucture, x250. PLV I 191 em) Type T98: Gramineae (caryopsis, x25. PL V I 207cm) Type T99: Carex cf. bonplandii (Cyperaceae) (a= achene, x25. PLV I 207cm) (b = achene, x50; SEM. PPN I 49cm) (c = surface, x500; SEM. PPN I 49cm)

--·

Palaeobotanical-palaeoecological studies

203

202 PLATE XIX

PLATE XIX Type TlOO: Carex (Cyperaceae) (achene, x50; SEM. PPN I 52cm) Type TlOl: Eleocharis (Cyperaceae) (a = endocarp, x40. PPN I 109cm) (b =cell structure, x250. PPN I 109cm) Type Tl02: Rhynchospora macrochaeta (Cyperaceae) (achene, x50; SEM. PAB ll lcm) Type T103: Oreobolus obmsangulus (Cyperaceae) (achene, x50; SEM. PAB ll lcm)

Macrofossil plates

Palaeobotanical-palaeoecological studies

204

205

PLATE XX

PLATE XX Type Tl04: ]uncus (Juncaceae) (a = seed, x40. PLV I 264cm) (b =seed, xl25; SEM. PPN I 168cm) (c = surface, x500; SEM. PPN I 168cm) Type Tl05: ]uncus (Juncaceae) . (a= seed, x40. PAB III 43cm) (b = seed, x50; SEM. PAB II/III) (c = surface, x500; SEM. PAB II/lll) Type Tl06: cf. Luzula (Juncaceae) (seed, x40. PLV I 207cm) Type T108: Xyris (Xyridaceae) (A = recent seed of X. acutifolia, x50; SEM) (Ba =fossil seed, x40. PAB III 69cm) (B b =surface, x250. PAB III 69cm) Type Tl lO: Eriocaulaceae (a = seed, x50; SEM. PPN I) (b = s urface, x500; SEM. PPN I) Type Ti ll: Eriocaulaceae (a= seed , x50; SEM. PAB II llcm) (b =surface, x500; SEM. PAB II llcm)

Macrofossil plates

Palaeobotanical-palaeoecological studies

207

206

PLATE XXI

PLATE XXI Type Tll2: Puya (Bromeliace<\e) (a,b = seeds, x25; SE:r..:t. PLV I) Type T113: Hypericum (Hypericaceae) (seed, x40. PLY I llcm) Type T114: Hypericum (Hypericaceae) (a= seed, x40. PAB III 19cm) (b = seed, x55; SEM. P AB II/lii) (c =cell strUcture, x250. PAB III 19cm) Type Tll5: cf. Vacciniwn (Ericaceae) (A= recent seed of V.jloribundum, x50; SEM) (Ba = fossil seed, x40. PLV I 212cm) (Bb =surface, x250. PLY I 212cm) Type T116: cf. Pernettya (Ericaceae) (A = recent seed of P. prosrrata, x50; SEM) (Ba = fossil seed, x40. PPN I 39cm) (Bb = surface, x500; SEM. PPN I)

I ;

114a

Macrofossil plates

Palaeobotanical-palaeoecological studies

209

208 PLATE XXII

PLATE XXII Type Tl17: Compositae (achene, x25; SEM. PLVI 180cm) Type Tl18: Diplostephium (Compositae) (achene, x40. PLVI 247cm) Type T\19: Bidens (Compositae) (achene, x40. PLVI 242cm) Type Tl20: Espeletia (Compositae) (achene, x25; SEM. PAB III 19cm) Type Tl21: Gentiana sedifolia (Gentianaceae) (a = seed, x40. PLV I 207cm) (b =seed, x50; SEM. PLV I 222cm) (c =surface, xSOO; SEM. PLV I 222cm) Type Tl22: Bartsia (Scrophulariaceae) (a= recent seed of B. santolinnifo/ia, x50; SEM) (b = surface, xSOO; SEM) Type Tl23: Lachemilla (Rosaceae) (achene?, x40. PPN I 133cm)

Macrofossil plates

Palaeo'ootanical-palaeoecological studies

211

210 PLATE XXIII

PLATE XXIII Type Tl24: cf. Ca/litriche (Calliuichaceae) (a = nutlet, x40. PLV I 207 em) (b = nutlet, x50; SEM. PLV I) (c =surface, x250. PLV I 207cm) Type Tl25: Elarine (Elatinaceae) (a= seed, x40. PLVI 28lcm) (b = seed, x50; SEM. PLV I) Type T126: Tillaea (Crassulaceae) (a = seed, x40. PLV I 253cm) (b = seed, x125; SEM. PLVI) (c =cell strUcture, x 250. PLV I 253cm) Type Tl27: Ranunculus (Ranunculaceae) (a= achene, x50; SEM. PLV I 196cm) (b =surface, x500; SEM. PLV I 196cm) Type Tl28: Poramogeron (Haloragaceae) (achene, x12.5; SEM. PLV I 212cm)

Macrofossil plates

213 Palaeobotanical-palaeoecological studies

212 PLATE XXIV

PLATE XXIV Type T129: unidentified seed? (a= seed?, x 40. PLV 1 llOcm) (b =seed?, x 100; SEM. PAB ill 38cm) (c = cell strUcture, x250. PLV I llOcm) (d =surface, xSOO; SEM. PAB ill 38cm) Type Tl30: unidentified endocarp? (a= endocarp?, x40. PLV I202cm) (b = cell structure, x250. PLV I 202cm) Type Tl31: unidentified fruit? (fruit?, x40. PLVI 207cm) Type Tl32: unidentified fruit? (fruit?, xSS; SEM. PLV I292cm) Type T\33: Isoeces (Isoetaceae) (a= megaspore, x l OO. PLV I 28lcm) (b =megaspore, xlOO; SEM. PLY I) Type T134: Isoeres cleefiilsteyermarkii (Isoetaceae) (a =megaspores, xSO; SEM. PPN I) (b =megaspore. :d25; SEM. PPN I)

~ 131

\ l'

! i ' ·f;. i

1 l

l I !

,J ~·

Macrofossil plates

215 Palaeobotanical-palaeoecological studies

214 PLATE XXV

PLATE XXV Type Tl35: Jsoetes andinalboyacensis (lsoetaceae) · (A= I. andina megaspore, x50; SEM. PAB IIJIII) (B =I. boyacensis megaspore, xlOO; SEM. PAB ll/Ill) Type Tl36: lsoetes (lsoetaceae) (megaspore, x50; SEM. PAB ll/lll) Type Tl37: Gramineae · (a= gluma, x.40. PAB Ill Scm) (b =cell structure, x400. PAB Ill Scm) Type Tl38: Gramineae (a= basal leaf sheath. x.lO. PAB U119cm) (b = epidermal cell structure, x400. P AB Ill 19cm) Type Tl39: Cyperaceae (a= basal leaf sheath. x 10. PLV I 165cm) (b = epidermal cell structure, x400. PLV I 165cm)

Macrofossil plates

----217 Palaeobotanical-palaeoecological studies

Macrofossil plates

216

PLATE XXVI

PLATE XXVI Type Tl40: unidentified flower (flower, xlOo PAB ill Scm) T ype Tl41: Hypericum (Hypericaceae) (branch, x25; SEMO P AB Ill 19crn) Ty pe Tl42: Hypericum Iaricifolium (Hypericaceae) (leaf, x2S oPAB Ill) Type Tl 43: Hypericum goyanesii (Hypericaceae) (a = leaves, x 100 PLY 1) (b = leaf, x250 PLY l)

145

Type T1 45: Ericaceae (anther, xlOo PLY l 227cm) Type Tl46: Ericaceae (branch, x 10; SEMO PLY l) T ype T\47: VacciniumJPerne trya (Ericaceae) (leaf, xl O; SEM oPLY l) T ype T\49: Elatine (Elatinaceae) (leaf. x25 0PLY I) Type T l 50: Polypodiales (A= sporangium, xlOOoPLY 1 l96cm) (B == sporangium, x 1000 PLY I ?em)

I I â&#x20AC;¢' j

\I I

Type T152: Polypodiales _ (A= leaflet, x!Oo PLY I237cm) (B ==leaflet, x250 PLY I 227cm) Type TI53: Polypodiales 0 (leaflet, xlOo PAB lllcm) '

I \

Macrofossil plates

219 Palaeobotanical-palaeoecological studies

218 PLATE XXVII

PLATE XXVII Type T154: Musci (calyptra, x25. PLV I 217cm) Type T156: Characeae (a= oospore, xlOO; SEM. PLVI) (b =oospore, xlOO. PLV I 28lcm) Type T157: Cladocera (ephippium, x40. PLVI 242cm) Type Tl58: Acaridae (A = exoskeleton, x25. PLV I 120cm) (B =exoskeleton, x25. PLV I 165cm) (C =exoskeleton, x25. PAB III3lcm) 158A

1588

158C

Type Tl59: Coleoptera (elytrom, x i O. PLY I 159cm) Type Tl60: Collembola (exoskeleton , x25. PPN I 208cm) Type Tl6l: cf. Hymenoptera (puparium, x25. PPN I l68cm) Type T 162: cf. Psocoptera (exoskeleton, x25 . PPN I 143cm) Type Tl63: cf. Hemiptera (exoskeleton, x25. PPN I 32cm) Type Tl64: Jnsectae (A= head capsule, x25. PLVI 175cm) (B =head capsule, x25. PLV I 19lcm) Type T165: cf. Oligochaeta (cocoon, x25. PLV I 165cm)

164B

165

221

Acknowledgements

ACKNOWLEDGEMENTS At the completion of my thesis I would like to express my gratitude to all persons who, directly or indirectly, contributed to this study. The Netherlands Foundation for the Advancement of Tropical Research (WOTRO) supported this study financially (grant W 75-229). · I wish to thank Prof. Dr. T. van der Hammen, who introduced me to the study of Quaternary palynology, for his suggestions and critical revision of the manuscript. I am indebted to Prof. Dr. W.G. Mook who provided many radiocarbon ,datings, and to Prof. Dr. A. D.J. Meeuse who revised the English text. · I wish to express my thanks to the staff and students of the Institute de Ciencias Naturales in Bogota, especially to Mr. 0 . Rangel, Mr. J. Aguirre, Mr. R. Jaramillo, Mrs. M.T. Murillo, Mr. G. Lozano and·Mr. P. Pinto, for their co-operation and interest. I am indebted .to Dr. A.M. Cleef for our discussions of phytosociological and ecological matters, to Mr. G. van Reenen who aided in a considerable way in the identification and description of the fossil bryophytes, to Dr. B. van Gee! for his critical revision of the descriptions of fungal, algal, bryophytic and zoological microfossil types, to Dr. F. Bouman for his critical revision of the descriptions of fossil fruits and seeds, to Mr. J.H.D. Wolf who provided computer vegetation tables of the Colombian Cordillera Oriental, and to Mrs. E. Beglinger for her patient help in taking SEM photographs of macrofossil types. I also want to thank Dr. J.B. Salomons and Dr. A.B.M. Melief for their companionship, their assistance and the many valuable discussions we had. Finally, I wish to thank my wife Karin, for drawing all figures and preparing the fi nal diagrams, for her continuous stimulating interest, and, last but not least, for pushing me to climb high mountains from which I had a fresher, broader and more up to date view of the world.

I J

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Refere nces

224

dates: K. Ralph , 1982. Calibr ation of radioc arbon Klein, J ., J. C. Lerma n, P . E . Damo n and E. scale. time arbon radioc the ating calibr on hop tables based on the consensus data of the works Radio carbon , 24(2): 103-1 50. und sschli issel fiir subfo ssile Juncu s-sam en Korbe r-Gro hne, U., 1964. Bestim mung hen Nords eegeb iet. siidlic im ng hu nforsc ktiste der eme Probl Gram ineen -friich te. In: Wurte nforsc h., 7: 1-47. Schrif tenr. Niede rslich s. Lande~st. Marsc hen ed bog across a cover sand ridge origin ally cover Kuhry , P. , 1985. Trans gressi on of a raised l ationa veget l loca ene Holoc le Midd a of with an oak-li me forest . Palaeo ecolog ical study Palaeo bot. Palyn ol., 44: 303-3 53. Rev. any). Germ west (north ven Amts the in succes sion ologic al study of Holoc ene peat from the El Kuhry , P., in press. A paleo botan ical and palyn the Cordi llera Centra l of Colom bia. Rev. of area nic volca a Bosqu e mire, locate d in Palaeo bot. Palynol. cus fitoso ciol6g ico de un bosqu e de robles (Quer Lozan o, G. and J. H. Torre s, 1965. Estud io rsidad Unive bl.), (unpu Grado de Tesis ca. humbo ldtii H . & B.) de Ia 'Merc ed', Cundi namar Nacio nal de Colom bia, Bogot a. tos gener ales de Ia distrib uci6n , s istem atica, Lozan o, G . a nd J . H . Torre s, 1974. Aspec bia. los bosqu es de robles (Quer cus) en Colom de ica ecol6g fitoso ciologfa y clasif icaci6n Ecolo gfa Tropic al, 1(2): 45-79 . bia ecol6g icos en el Param o de Cruz Verde , Colom Lozan o, G. and R. Schne tter, 1976. Estud ios . 53-68 : (54) 11 sia, Calda les. vegeta idades II. Las comun to in the C/N q uotien t of peat in relatio n Maim er, N. and E . Holm , 1984. Varia tion 10Pb. Oikos , 43: 171 -182. 2 with ation temin agede d deco'm positio n rate an flora of Argen tina; Modern spore and p ollen Markg raf, V. and H. L. D'Ant oni, 1978. Pollen sperm ae. Univ. of Arizo na Press, T ucson , Angio types of Pterid o phyta , Gymn osperm ae and 208pp . al bian crypto gams XXV Ill. A gu ide to the tropic Meen ks, J. L. D., 1987 . Studie s on Colom 62: 161- 182. Lab., Bot. ri Hatto . Journ ticae). (Hepa ia iccard Andea n specie s of R los ecolo gy of the Parqu e Nacio nal Natur al de Melie f, A. B. M., 1985. La te Quate rnary paleo bia. T hesis Colom areas, tal) Orien illera (Cord paz Nevad os (Cord illera Centra l), and Suma as 'The Quate rnary of Colom bia', vol. 12, Univ. Amste rdam, 162pp . Also publis hed ). editor en, Hamm er d van (T. Amste rdam ing 1984. A micro -comp uter progr am for handl Melie f, ·A. B. M. and T . A. Wijm stra, 86. 577-5 ): 26(3-4 s, Spore palyno logica l data. Pollen cotyle dons I. Gram ineae. C larend on Press, Metca lfe, C. R., 1960. Anato my of the mono Oxfor d, 731 pp. cotyle dons V. Cyper aceae . Clare ndon Press, Metca lfe, C. R ., 1971. Anato my of the mono pp. Oxfor d, 597 d, of the dicoty le dons 1. Claren don Press, Oxfor Metca lfe, C. R. and L. Chalk , 1950. Anato my 724 pp. d, of the dicoty ledon s II. Claren don Press, Oxfor Metca lfe, C. R. and L. Chalk , 1950. Anato my 776 pp. of ecolog y of raised bogs. An analys is by means Midde ld orp, A. A., I 984. Funct ional palaeo al forest histor y. Thesi s Univ. region the with ction conne in g, datin pollen densi ty Amste rdam, 124pp . 4: 40the Hac ienda Lusita nia. Pro Calim a, Basel , Monsa lve, J. G., 1985. A pollen core from 44. plants of easter n Canad a and northe astern United Montg omery , F. H., 1977. Seeds and fruits of Buffa lo, 232pp . and to Toron Press, to Toron of States . Univ. and metho ds of vegeta tion ecolog y. W iley Aims 1974. erg, Ellenb H. nd a Muell er-Do mbois, D. · . 547pp to, Toron y, Sydne n, & Sons, New York, Londo a I. Trilete ophyt Pterid bian Colom t recen on s Spore Muril lo, M. T . and M. J. M. Bless, 1974. rnary of Quate 'The as hed publis Also 69. spore s. Rev. Palae obot. Palyn ol., 18: 223-2 ). editor en, Colom bia', vol. 3, Amst erdam (T. van der Hamm a II. Spore s on r ecent Colom bian Pterid ophyt Muril lo, M. T. and M. J. M. Bless, 1978. hed as 'The Quate rnary publis Also 65. 319-3 25: ol., Palyn bot. Mono lete spores . Rev. Palaeo Hamm en, editor). of Colom bia', vol. 5, Amste rdam (T. van der bog Paleo ecolo gical studie s in the Klokk eweel Pals, J. P., B. Van Gee! and A. Delfos , 1980. 18. 371-4 v30: l. Palyno bot. Palaeo Rev. near Hoogk arspel (prov . of Noord -Holla nd).

I I

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gida y es acuati cas altoan dinas I. Veget aci6n sumer Rangel,_ 0. and J. Aguir re, 1983. Comu nidad sia, 13(65 ): 719-7 42. Calda bia. Colom 3., Boyac Tota, de Lago el de nbera en icos en Ia Cordi llera Orien tal Colom biana ill. Range l, 0. an~ J. Aguir re, 1986. Estud ios ecol6g ca). Calda sia, 15(71 -75): 261- 312. (Boya Tota de ~go . La vegetaCJ6n de Ia cuenc a del nce of Quate rnary volcanic ashes from seque a f o ts Rieze bos, P. A., 19?8. Petrog raphic aspec raphic signif icance. Quat. Res ., 10·. stratig their the Lagun a de Fuque ne area, Colom bia, and 401 -424. bryop hytes of Colom bia. The Bryologist, 70: Ro~i~1)_n, ~-· 1967 . Prelim inary studie s on the M. cyclin g in a subarc tic ombro trophi c mire. In: Ross wall, T. and. U. Granh all, 1980. Nitrog en 34. 209-2 30: Bull., Ecol. mire. Sones son (edito r). Ecolo gy of a subarc tic ic soils in the Colom bian Centr al Cord illera Salom ons, J. B. , 1986. Paleo ecolo gy of volcan Thesi s Univ. Amst erdam , 212pp . Also os). Nevad los de ai N~tur (Par9 ue Naci~nal J. Crame r, Vaduz , and as 'The Quate rnary 95, and B icae, Botan publis hed ~sp1ssenanones en, editor ). Hamm der van (T. rdam of Co!omb1a , vol. 13, Amste the al srudy of the Upper Quate rnary seque nce in Schre ve-Br inkma n, E. J., 1978. A palynologic 25: 1ecol., Palaeo clim. Palaeo . geogr Palaeo El Abra corrido~ and roc~ shelte rs (Colom bia). Colom bia', vol. 6, Amst erdam (T. van der 109. Also p~bhshed as T he Quate rnary of Hamm en, editor). n s on Colom bian crypto gams XIX. Contr ibuci6 S ipman , H.!·~- and J. Aguir re, 1982. Studie los lfquen es folios os y para ica gener Clave I. bia Colom de es al c?nocu ruento de los liquen sia, 13(64 ): 604-6 34. _fruucosos de los param os colom bianos . Calda ensis Cuatr ecasas , Acaena cylindristachya boyac pis Polyle of ology morph Pollen 1978. Smlt, ~-· and its a pplica tion to fossil mater ial. Rev. ceae) (Rosa L. ta elonga a Acaen and Rmz et Pavon as 'The Quate rnary of Colom bia', vol. 5, hed publis Also 98. 393-3 25: Palaeo bot. Palyn ol., ). editor en, Hamm der van Amste rdam (T. Britai n and I re land. Camb ridge Univ Press ' Smith , A. J. E., 1978. The moss flora of 706pp . · urne, _Cambridge, Londo~, New York, Melbo carbon Radio scale time arbon radioc AD of the . Stmve r, M., 1982. A high-p recisio n calibr ation 24(1): 1-26. inar de los param os a ndino s; una visi6n prelim Sturm , H . and _0. Range l_, 1985. Ec.olo gfa292pp . 9: ui), (Bogo Tnana mtegr ada. Btbl. J. J. (C cotyle dons III. Comm elinal es-Zin gibera les · Tomh nson, P. B., 1969. Anato my of the mono 446pp. xford, O R. Metca lfe, editor ). Claren don Press, and of Holocene peat bog sectio ns in Germ any V an Gee!, B., 1978. A palaeoecologica_l study and macro - and micro scopic remai ns spores , pollen of 1s analys the on based the Net~erlands, Palaeo bot. Pa ly nol., 25: 1-120. o f fungi, algae, cormo phytes and anima ls. Rev. , r Quate rnary veget ationa l and clima tic Uppe 1973. en, · Van Gee!, B. and T. van der Hamm Colom bia). Palaeo geogr . Palaeo cl im. llera, Cordi seque nce of the Fuque ne area (Easte rn of Colom bia', vol. I, Amste rdam rnary Quate Pa laeoec ol., 14: 9-92. Also pu blishe d as 'The (T. van der Hamm en, editor). Zygne matac eae in Quate rnary Colom bian Van G_eel, B. and T. van der Hamm en, 1978. 92. Also publis hed as 'T he Quate rnary of 377-3 25: ol., Palyn sed1men_t~. Rev. Palaeo bot. en, editor ). Hamm der van (T. Colom bia, vol. 5, Amste rdam 1980/ 81. A palaeo ecolog ical study of an Upper Dee, H. and ke Bohnc .P. J S. B._, Gee!, Van Borch ert', The Nethe rlands. Rev. Palaeo bot. Late Glacial and Holoc ene seque nce from 'De 48. 367-4 1: 3 ol., Palyn de su Ia regi6n de 'Lagu na de los Bobos '. Histo ria Van ~er Hammen~ T. , 196~. Palino logia de Col. Cienc . Ex. Acad. Rev. anos. 5,000 s ulrimo los te duran ci_Ima , vegeta c16n y agncu ltura F1s. Nat., 11(44 ): 359-3 61. in tropic al South P leistoc ene chang es of vegeta tion and clima te ::!<- Vand er f:iarnmen! T., 1974. The Amen ca. J. B10geogr., 4: 3-26. tion of chang es in the North ern Andes and the extinc Vand er Hamm en, T., 1981. Enviro nment al 369-3 72. 60: ouw, M.ijnb en Mastodon. Geolo gie a nicas del nivel de inund acione s en Ia cuenc Vand er ~ammen, T., 1986. Fluctu acione s holoce . Geolo gia Norandina, 10: 11-18. del BaJo Magd alena- Cauca -San Jorge (Colo mbia) tion Holoc ene and Late Glacia l clima te and vegeta Vand er Hamm en, T. and_E. Gonza lez, 19~. Amer ica). Geolo gie en South ia, olomb C illera, Cord rn (Easte 1o of..Param o de Palac M!Jnb ouw, 39( 12): 737-7 46.

lez 1963 Historia de clima y vegetaci6n del Pleistocene Van der H ammen, T · andE· Gonza ' · G 1 11(1 3)· 189 266 Superior y del HTolocedn~ d~la Sa~~alg~~o~t:~~~~- di=~~ fro~ ;Lag~na de Ia Herrera' Vander Hammen, .,an . · onza ' · . _ 91 83 1 2 v csr~a de Bog~a~~~s~~~~~~et~s~ A\ate Giacial and Holocene pollen diagram anfro~ C~eX:U~ndel Visitad~r (Dept. B~yaca, Colombia). Leidse Geol. Meded., 32: 193-201. H g T d G Correal 1978 Prehistoric man on the Sabana de Bogota: data for Van~~col=~npreh~~ory."Palaeog~ogr. Palaeoclim. Palaeoecol., 25H: 179-190ed.~lso)published • Q f <'.:: 1 mbia' vol 6 Amsterdam (T. van der amrnen, 1tor . as Th~ uatemf o do~. M Cteef 'r978. Pollenmorphology of Lysipomia H~K ~d Va~~?:oc:~~;un~ w!~d. (Ca~panula~eae) and the revision of the pollen dete~manon • · p h ll • Killi Rev Palaeobot. Palynol., 25: 367-376. Also pubhshed as Va/enana stenop y a p. A rd (T an der Hammen editor) ~~he ~uaternaryTof C~l:;~i:\i' 0J~ ion~:~~ :..rnA. devVeer, 1980/81. Glacial s~quence and a~n~~o:=~~·hi~~ocy in the Sie~a Nevada del Cocuy (Colombia). Palaeogeogr. ~~aeochm. Palaeoecol., 32: 247-340. Also published as 'The Quaternary of Colombia, vol. 8,

va::e~~~~~~.~-. ~ fne~~~~~:~~~i:d· altitudinal zonation of bryophytes in the Andes of Colombia Thesis Univ. Utrecht (The Netherlands). , . ., d 0 · d s Zulu.aga 1980. Contribuci6n al estudio fitoecologt~o de Ia regwn e ar~~~se~a~~. Te~is de Grado (unpubl.), Universidad Nacional de C~ombla, ~o;o~aft 51 W Warnstorf, c., 191 1. Sphagnales-Sphagnaceae. In: A. Engler. Das p anzenre1c , e . · Enae!mann, Leipzig, 546pp. C b 'd u · Press, Cambridge, Watso~, E. V., 1981. British mosses and liverworts. am n ge mv. London, New York, Melbourne, 519pp. C3:d. ed.). Wood, R. D. and K. lmahori, 1964. A. rev!Slon of the Characeae II. Iconograph of the Characeae. J. Cramer, Weinheim, 3941cones.. Wood, R. D. and K. Imahori, 1965. A rev1s1on of the Characeae I. Monograph of the Characeae. J. Cramer, Weinheim, 904pp.

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Summary

SUMMARY Palaeobotanical-palaeoecological studies of tropical high Andean peatbog sections (Cordillera Oriental, Colombia) The present study deals with the palynological and macro botanical analyses of high Andean peatbog sections collected in the Paramo de Laguna Verde, the Paramo de Pefia Negra and the Paramo de· Agua Blanca, located near Bogota in the Colombian Cordillera Oriental. A reference collection of recent macrobotanical material was compiled by the author for the identification of the fos sil macroscopic remains found in the analyzed sections. This collection, available at the Hugo de Vries Laboratory of the University of Amsterdam, contains flo wers, fruits, branches, leaves, seeds, megaspores and slides of epidermis of cormophytes, and bryophytes, including mosses and liverworts, that are of frequent occurrence in the azo nal paramo vegetation types in the study area. A duplicate of the collection was left at the Institute de Ciencias Naturales of the Universidad Nacional in Bogota, Colombia. Local vegetational developments are deduced from the macrofossils and the locally produced microfossils. An approach at the level of syntaxa related to major local changes was chosen, because the state of knowledge of the autecology of several important azonal plant taxa involved (e.g. Calamagrostis, Carex, lsoi!tes, ]uncus, Xyris) is still insufficient. The macrofossil analysis provided very valuable information with regard to the local vegetational developments. The combined palynological and macrobotanical analyses have also resulted in a better record of the regional vegetation changes, as influences of local growth of certain plant taxa also present in the regional vegetation types could be objectively marked by the presence of macroscopic plant remains of these taxa in the peat and lake sediments. Regionally produced pollen and spores provided the information on the regional vegetational developments. A large number of 14 C datings and the indirect time calculations based on pollen concentration data in the sediment provided a reliable chronological basis for a good correlation of the vegetational changes in the study area. Absolute pollen infl ux data proved to be a powerful tool to support the palaeoecological interpretation of the classical 'relative' pollen diagrams. Two sections were collected in a Spha~num -Xyris peatbog in the Paramo de Laguna Verde. They give an impression of the regional and local vegetational developments over a period covering the last= 5,500 years. The section collected in the Sphagnum-Swallenochloa peatbog of the Laguna Negra (P:iramo de Pefia Negra) illustrates the regional and local vegetational developments duri ng the last= 15,000-14,000 years. Additional information on the local vegetational development was obtained by the analysis of some physico-chemical properties of the sediment. Carbon (C) and nitrogen (N) content show a relation with the primary organ ic production of the successive local vegetation types, whereas the C/N quotients give an impression of the primary decomposition in these successive azonal ecosystems. Especially in this section, the influence of changing exogenous factors and of endogenous processes upon the development of small azonal paramo ecosystems is nicely illustrated by the local vegetational succession. The sections taken in the Sphagnum-Espeleria peatbog in the Paramo de Agua Blanca give an impression of the regional and local vegetational developments over a period covering the last = 8,300 years. Descriptions and illustrations of 72 microfossil types and of all 113 macrofossil types found in the above mentioned sections are provided. On the basis of the palaeoecological data of the present study, other palaeoecological data obtained in the study area during the last 30 years, glacial geomorphological evidc;nce and archaeological data, a reconstruction of the geoecological history of the study area, during the last 24,000 years, is presented. The dynamics of the zonal and azonal Andean ecosystems in relation to changing exogenous factors (e.g. climate, human influence) and of endogenous processes is discussed. The tentative temperature differences as compared to the present-day temperature , humidity variations and shifts of the zonal upper forest line in the study area are summarized below:

Palaeobotanical-palaeoecological studies

Late Pleniglacial

Late Glacial and Earliest Holocene

Early Fuquene stadial

Period: = 22,500 to= 19,500 yr BP Climate: cold (-7-80C) and dry Upper forest line: = 2000m

Middle Fuquene interval

Period:= 19,500 to= 18,000 yr BP Climate: rel. cold (- 3-40C) and dry Upper forest line: = 2600m

Late Fuquene stadia!

Period: = 18,000 to = 14,000 yr BP Climate: cold(- 6-70C) and dry Upper forest line:= 2100m

Susaca interstadial

La Ciega stadia!

Guantiva interstadial

El Abra stadial

Holocene

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228

Holocene X interval

Period:= 14,000 to= 13,000 yr BP Climate: rei. cold(- 40C) and dry Upper forest line: = 2500m Period:= 13,000 to= 12,400 yr BP Climate: cold (-j)0C) and dry Upper forest line:= 2200m Period: = 12,400 to= 10,800 yr BP Climate: rel. warm (- 20C) and wet Upper forest line: = 3100m Period: .. 10,800 to= 9,500 yr BP Climate: rei. cold(- 3-4°C) and rei. dry Upper forest line:= 2700m Period: = 9,500 to= 7,000 yr BP Climate: warm(- 1-00C) and rei. dry Upper forest line:= 3100m

Holocene Y interval

Period:= 7,000 to= 1,800 yr BP Climate: warm(+ 1-00C) and wet Upper forest line:= 3500m

Holocene Z interval

Period:= 1,800 yr BP to present Climate: warm (± OOC) and rei. wet Upper forest line:= 3300m

Summary

During the El Abra stadia!(= 10,800 to= 9,500 yr BP) the climate became colder and drier. As a result of both lower temperature and lower humidity, stands of azonal A lnus forests on the inter-Andean high plains gradually became less abundant, being finally (almost) completely replaced by Myrica and Compositae scrub and open grassland. In the Holocene X interval (= 9,500 to = 7,000 yr BP) the climate became warmer. The upper forest line shifted upwards. Conditions remained relatively dry impeding the development of azonal Alnus forests on the inter-Andean high plains. In the Holocene Y interval(= 7 ,000 to = 1,800 yr BP) the climate became still slightly warmer and considerably wetter. In the paramo regions, peaty and lacustrine environments developed. The azonal Alnus forests invaded large inter-Andean areas. A mixed Cecropia-Quercus forest developed in the Fuquene area. The zonal upper forest line gradually shifted upwards. Although Zea mais was repeatedly recorded from= 6,600 yr BP onwards, which is most probably attributable to agriculrural activ ities by prehistoric men in the study area, at first the human influence on the vegetational development seems to have been insignificant. In the second half of the Holocene Y in terval("" 5,000 to= 1,800 yr BP), upper Andean Weinmannia forests began to develop, replacing the former Quercus stands. Possibly this process still formed part of the gradual and slow adaptation of the Andean arboreal vegetation to the wetter climatic conditions. However, the possibility cannot be ruled out that endogenous processes (e.g. soil maturation) may have been involved. At the end of the Holocene Y interval, around "' 2,750 yr BP, the climate probably commenced to deteriorate, gradually becoming slightly colder and drier. The upper Andean Weinmannia forests with Hedyosmum fully developed. Acalypha became an important element in the mixed CecropiaQuercus forests of the Fuquene area. Although the gradual deterioration of the climate commenced at= 2,750 yr BP, in the study area it seems to have had its greatest impact upo n the zonal and azonal vegetational development at = 1,800 yr BP. In the Holocene Z interval ("' l.800 yr BP to present) the area occupied by azonal Alnus fo rests on the inter-Andean high plains drastically diminished. Cecropia was not present any longer in the mixed Quercus forests of the Fuquene area. However, the observed vegetational changes at the end of the Holocene Y interval and in the Holocene Z interval were probably not only related to climatic change but were conceivably partly originated by the increasing human influence that became catastrophic during the last= 450 years. The influence of changing exogenous factors and of endogenous processes upon small azonal paramo ecosystems is illustrated by the local vegetational developmen t at the sites where the sections of the present study were taken. At the site of the Paramo de Laguna Verde I section, the foll o wing vegetational succession took place:

Ditricho-lsoetion

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mozaic of Junco-Eieocharition and Sphagnum peatbog

· h 'E 1 • L t Glacial period(= 22,500 to= 12,400 yr BP) During the Fuque~e stadtal and t e ar y f~r~st belt on the eastern Magdalena slopes was the climate was (relatively) cold and drybeT:e the dominant tree. Cecropia seems to have been very narrow or almost absent, Quercus :of the La una dt' Pedro Palo was almost treeless; completely absent In the study area. The are . ctl in Jlontact with paramo vegetation types. At here, (sub)xerophyoc -:egetauon Y,p~s :era~err;uq~ene stadia! and the La Ciega stadia! glaciers the end of the Early Fu9uene sta dta • t e ll ing the development of lacustrine and peaty retreated/disappeared tn the stu. y area, a ow environments in the formerly glactated crrques and troughs.

This development, from a submerged deep water community towards shallow open water and peatbog communities, was most probably the result of the gradual filling up of the sedimentary basin. The most interesting local vegetational development is recorded at the site of the Paramo de Pefia Negra I section in the Laguna Negra, a small lake located at present in the lower grass paramo belt at an elevation of ca 3625m. The Laguna Negra was formed in a glacially eroded basin after ice had definitely retreated from the area of the Paramo de Peiia Negra at the end of the Late Fuquene stadia!. The local vegetational succession at the boring site was as follows:

· · · 2 400 - 10 800 yr BP) the climate was relatively warm In the Guanttva mterstadtal (= 1 eli . to- ber of lakes were formed on the inter-Andean and wet. As a result of the wetter co~ uons a nu~orests invaded areas formerly occupied by high plains (e.g. Laguna de Palac!o). Andean the zonal Quercus forests were preceded by paramo vegeta~on types ..In the Fuquene d~ea, anea. The high plains s of Ubate and of Bogota pioneervegetaoon types_wnhDodonaea an l ap forests The tropical-subandean forests on the were almost completely mvaded byal~onal ( ~arne ad~pted to the relatively wetter conditions 0 eastern slopes of the Magdal:na v ey ~, be~ause Cecropia had probably to immigrate from after =2 000 years, at about - 10 •350 yr • more no;memly located habitats.

Ditricho-lsoetion >> >> >> Tillaeion >> >> >> Junco-Eleocharition >> >> » Calamagrostion ligulatae » >> » Junco-Eleocharition >> >> >> mozaic of Junco-Eleocharition and D"itricho-lsoerion » » >> Calamagrostion ligulatae >> >> » Sphagnum peatbog The general development, from a submerged deep water community towards a rela tively dry peatbog community, was determined by the filling up of the sedimentary basin, whic h is an endogenous process. On the contrary, the floristic composition of the local vegetation types and sudden s uccessions were determined by exogenous factors, such as the climate, a climatic change and, possibly, human influence. As a result of the colder climatic conditions during the end of the Late Fuquene stadia! and the Late Glacial, communities developed locally (Ditricho-

Palaeobotanical-palaeoecological studies

231

230

Jsoetion and in the narrow boggy shore zone of the former lake, Plantago rigida cushion bog) which at pre~ent are frequently found at higher elevations, in the zonal s~perparamo belt ll?d ~e upper grass paramo belt Changing regional humi~ty in the ?I A bra stadia! and at the begtnn~ng and at the end of the Holocene Y interval resulted m fluctuations of ~e local v:ater level, caus~g an acceleration or an interruption of the normal endogenous. suc~ess10n. Espe.ctally the vegetation types of the Junco-Eieocharitioft and of the Calamagrostwn ltgula~ae, wh:c~ are bound to the zone of the water table, were very susceptible to t~ese _changes m hunudity. Sudden local successions during the last,. 350 years (C~/amagros_twn llgulatae » » ~ Sphag'}um peatbog) coincided with the beginning of the human mfluence m the P~o de Pena Neg:a ttself. . At the sites of the Paramo de Agua Blanca II and Ill secnons, the followmg vegetanonal succession took place: Ditricho-lsoetion

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Gentiano-Oritrophion

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Sphagnum peatbog

This succession, from open water towards boggy vegetation types, was primarily ori_ginated by the filling up of the sedimentary basin, which is an endogenou~ process. However, It seems to have been accelerated by a lowering of the local water table, ~htch was m_ost proba~ly the result of changes in evapotranspiration and water storage by the regiOnal vegetation types m the area of the Paramo de Agua Blanca, caused by the replacement at th~ begin~ing of the Ho!ocene Y interval of former paramo vegetation types by upper Andean Wemmanma forest. SAMENVATTING Palaeobotanische-palaeoecologi sche studies van tropisch hoog-andiene veen secties (Cordillera Oriental, Colombia) In deze studie worden de resultaten gepresenteerd van palynologische en macrobotanische analyses van hoog-andiene veen secties verzameld in de Paramo de Laguna Verde, de Paramo de Peiia Negra en de Paramo de Agua Blanca. Deze gebieden ~ijn gelegen in de omgevmg van de hoogvlakte van Bogota in de Cordillera Oriental van Col<;>mbta. . Een referentie collectie van recent macrobotantsch matenaal werd door de auteur samengesteld voor de identificatie van de fossiele macroscopische r~sten aangetroffen in de geanalyseerde secties. Deze collectie, beschikbaar op het ~ugo de ~nes Laboratonum van de Universiteit van Amsterdam, omvat bloemen, vruchten, takjes, blaadjeS, zaden, me~asporen en preparaten van epidermis van cormophyten, en bryophyt~n , ?lad- en l ~vermossen mbegrepen, die veelvuldig voorkomen in de azonale paramo vegetau~s ~~ het gebted van onderz.oek. _Een duplicaat collectie werd gedeponeerd in het Institute de Ctenctas Naturales van de Umverstdad Nacional in Bogota. . De locale vegetatie ontwikkelingen werden vastgesteld aan de hand van de macrofo~stelen en de locaal geproduceerde microfossielen. Er werd gekozen v<;><>r een aanpak op het mve~u van plantengemeenschappen in relatie tot grotere locale veran~enngen, omdat de_autoec?logt~ van een aantal belangrij ke awnale elementen die een ~ol spel~n m de locale vegetane ontwikkehng~n (b.v. Ca/amagrostis, Carex,lsoetes, Juncus , Xym) op di~ moment nog_onvold~nde bekend 1~. De macroresten analyses leverden belangrijke info~atie op met betrek.ki~g tot de locale veg_etaue o ntwikkelingen. De gecombineerde palynologtsch~ en ~acrobot~ntsche analys_es letdden eveneens tot een betere registratie van de verandenngen _m de reg10nale ve~etatte, d<;>Ordat invloeden van de locale groei van bepaalde elementen dte 66k _voorkomen m de regH;male vegetaties objectief konden worden aangegeven do<;>r de aanweZJ_ghetd v~n macrobota~I!Sche resten van deze elementen in de geanalyseerde vemge en lacustrtene sedtmenten. Reg~onale vegetarie ontwikkelingen werden vastgesteld aan ~e ~and vm. pollen en sporen van regwnale herkomst. Een groot aantal I 4C dateringen en mduecte Ujdsch~len geb~seerd op pollen concentraties in het sediment leverden een betrouwbare chronologtsche bas1s voor een goede correlatie van de vegetatie veranderingen in het gebied van ond_erzoek. Absolute pollen i~flux gegevens vonnden een belangrijk hulpmiddel ter ondersteunmg van de palaeoecologtsche interpretatie van de klassieke 'relatieve' pollen diagrammen.

Summary

Twee secties. werden ~erzame~d in een Sp~agnum-Xyris veen in de Paramo de Laguna Verde. Deze sectles geven mformatte over de reg10nale en locale vegetatie ontwikkelingen in de laatste .. 5,500 jaar. _De sectie verza~eld in ~et Sphagnum:Swal/enochioa veen van de Laguna Negra (Paramo de Pena N:egra) geeft mfon:naue over de regu;male en _locale vegetatie veranderingen gedurende de laatste = 15,000-14,000 Jaar. Aanvullende mformatle over de locale vegetatie ontwikkeling werd verkregen door d~ analyse van een aantal fysisch-chemische eigenschappen van het sediment. De koolstof (q en stikstof (N) inhoud toont een relatie met de primaire organische productie van de opeenvo l&~ n~e locale vege!aties, terwijl de C/N relatie een indruk geeft van de primaire decomposltle m deze success1eve azonale ecosystemen. Met name in deze sectie komt de invloed van veranderende exogene factoren en van endogene processen op de ontwikkeling van lcleine azonale par~o ecosystem~n duidelijk tot uiting in de locale vegetatie successie. . Twe~ sectles genome~ m een Sphagnum-Espeletia veen in de Paramo de Agua Blanca geven mform_ane omtrent de reg10nale en locale vegetatie ontwikkelingen in een periode die de laatste .. 8,300 Jaar omvat. De be~chrijvingen en illustraties van 72 types microfossielen en van aile 113 types macrofosstelen, aangetroffen m bovengenoemde secties, zijn opgenomen in dit werk. .· Op g:ond van de p~aeoecolo~sche gegevens van deze studie, andere palaeoecologische 1_nformaue v~rkregen m het gebted van onderzoek gedurende de laatste 30 jaar, glaciaal geomorfologtsch7 gegevens _en ar~haeologische gegevens, wordt een reconstructie voorgesteld van de _geoecologtsche gesch1edems van het studie-gebied gedurende de laatste "' 24,000 jaar. De . dynamtek van de zonate en azonale andiene ecosystemen in relatie tot veranderende exogene factoren (b.v. lcli~aa_t~ menselijke invloed) en endogene processen wordt besproken. De ~aarschtJnhJke temperatuur verschillen, vergeleken met de huidige, neers lag verandenngen en verplaatsmgen van de bovenste zonate bosgrens in het gebied van onderzoek worden hieronder weergegeven: Laat Pleniglaciaal

Laat Glaciaal en Vroegste Holoceen

Holoceen

Yroeg fuquene stadiaal

Periode: = 22,500 tot= 19,500 yr BP Klimaat: koud (- 7-8°C) en droog Bovenste bosgrens: = 2000m

Midden Fuquene interval

Periode: ~ 19,500 tot= 18,000 yr BP Klimaat: rei. koud (- 3-4°C) en droog Bovenste bosgrens: = 2600m

Laat Fuquene stadiaal

Periode: = 18,000 tot .. 14,000 yr BP Klimaat: koud (- 6-7°C) en droog Bovenste bosgrens: = 21 00m

Susad interstadiaal

Periode: .. 14,000 tot .. 13,000 yr BP Klimaat: rei. koud(- 4°C) en droog Bovenste bosgrens: = 2500m

La Ciega stadiaal

Periode: .. 13,000 tot= 12,400 yr BP Klimaat: koud (- 60C) en droog Bovenste bosgrens: .. 2200m

Guantiva interstadiaal

Periode: = 12,400 tot"' 10,800 yr BP KJimaat: rei. warm (- 2°C) en nat Bovenste bosgrens: .. 31 OOm

El A bra stadiaal

Periode:,. 10,800 tot= 9,500 yr BP Klimaat: rel. koud (- 3-40C) en rel. droog Bovenste bosgrens: = 2700m

Holoceen X interval

Periode: ,. 9,500 tot= 7,000 yr BP Klimaat: warm(- 1-00C) en rei. droog Bovenste bosgrens: .. 3100m

Palaeobotanical-palaeoecological srudies

233

232

Holoceen Y interval

Periode: = 7,000 tot .. 1,800 yr BP Klimaat: warm (+ 1-00C) en nat Bovenste bosgrens: = 3500m

Holoceen Z interVal

Periode: = 1,800 yr BP tot heden Klimaat: warm (± OOC) en rel. nat Bovenste bosgrens: .. 3300m

Gedurende het Fuquene stadiaal en het 'Vroeg' L aat Glaciaal (.. 22,5~ tot= ~2,400 yr BP) was het k.limaat (relatief) koud en droog. De bo~ gordel op de oostelljke _hellmgen van het Magdalena dal was erg smal of nagegoeg afw~Zlg. Que:cus was de dorrunante b?Omsoort. Cecropia schijnt volledig afwezig te zijn geweest m het geb1ed van onde17oek. Het geb_Jed van ~e Laguna de Pedro Palo was nagenoeg boom loos; hier la~en (sub)xe,rofyns,ch~ vegetane ~ypes m direkt kontakt met de paramo vegetatie types. Aan het emd van _het '(roeg Fuque.~e stadJaal, het 'Laat' Fuquene stadiaal en het La Ciega stadiaal trokken de gletsJers z1ch gedeelteh~k en/of geheel terug, met als gevolg het ontstaan van meren en venen in de voorheen vergletsJerde karen en trogdalen. In het Guantiva interstadiaal ("' 12,400 tot"' 10,800 yr BP) was het klimaat rela~ief wa~ en nat. De nattere condities leidden tot de formatie van e~n aan~al ~eren op d_e mterand1ene hoogvlakten (b.v. Laguna de Palacio). Andi~ne bossen ~re1dden z1ch u1t over geb1eden voorheen begroeid met paramo vegetaties. ln het Fuquene geb1ed werden de zonate Quercu~ bossen voorafgegaan door pionier vegetaties met Dodonaea en Rapanea. De hoogvlakten ten zu1de~ van Ubate en van Bogota werden nagenoeg geheel bezet door azonale Alnus bossen. De tropi~ch subandiene bossen op de oostelijke hellingen van ~et Magdalena dal raakten pas na = 2 ,000 Jaar geadapteerd aan de relatief nattere omstandtgh7den, rond "': 10,350 yr BP, naar a~le waarschijnlijkheid als gevolg van het felt dat Cecropia moest tmm:greren van meer noordehJk gelegen habitats. Gedurende het El A bra stadiaal (= 10,800 tot= 9,500 yr BP) werd het kl~ma~t kouder en droger. A Is gevolg van zowel de lagere temperat~ren als _de afgenomen vochn~het~ n~m~n ~e standp!a::usen van de azonale Alnus bossen op de mterandtene hoogvl~kten &eletdehJk m aantal af, om tenslotte (bijna) in het geheel te worden ver.:angen door strUJkachnge vegetanes, met Myrica e n Compositae, en door open grasland vegetanes. In het Holoceen X interval (= 9,500 tot "' 7,000 yr B~). werd het klimaat warmer. De bovenste bosgrens verplaatste zich hellingopwaans. De co~dmes bleven relauef droog hetgeen de ontwikkeling van azonale Alnus bossen op de mterandtene hoogvlakt:n tegenhteld. In het Holoceen y interval (= 7,000 tot= 1,800 yr BP) werd het kltmaat nog tets warmer en vee! vochtiger. In de paramo gebieden..onts.tQQQen v<;!!.\<.r:L.C:.~_!!leren. De azonale Alnus ~os~en bedekten grote interandiene oppervlakten. Een gemengd Cecropw-Quer_cus 60s ont~~elde-z1ch in het Fuquene gebied. De bovenste zonale ~>?sgrens verplaatste z1ch geletdehJk omhoog. Alhoewel Zea mais herhaaldelijk werd geregtstree~d v~af = 6,600 yr !3P, hetgeen toe te schrijven valt aan landbouw activiteiten van prehtsto~sche s_tamn:ten ~n het ge~1ed v~n onderzoek, lijkt de menselijke invloed op de vegetane ontwt~ehng tn eerste mstanue onbelangrijk te zijn geweest. In de tweede helft van het Holoc_een Y mter.:al (= 5,000 tot= 1,800 yr BP) begonnen de hoog-andiene Weinmannia bosse~ z1ch te on twJ_kke_l~n ten koste van Quercus bossen . Misschien maakte ?it proces dee! unvan de ~eletdehJk~. en langzame aanpassing van de andiene bosvegetaue aan de nattere khmatologtsche cond1~~s_. Echter de mogelijkheid kan niet worden uitgesloten dat endoge~e processen (b.v. bodem-nJpmg) een rol hebben gespeeld. Aan het eind van het Holoceen Y_ mterval, rond = 2,750 yr BP, begon_ het klimaat waarschijnlijk te verslechteren. Het werd 1ets kouder en droger. De hoog-and1e_~e Weinmannia bossen met Hedyosmum ontwikkelden zich yolledig. ~calypha w~rd een belangnJk element in de gemengde Cecropia-Quercus bo~sen 1n het Fuq~ene ~eb1ed. ~lhoewel _ de geleidelijke verslechtering van het k.ltmaat = 2,750 Jaar geleden aanvt~g, hjkt_deze_ m het gebted van onderzoek zijn grootste invloed op de zonale en azonale vegetaue o ntwikkelmg te hebben gehad rond- 1,800 yr BP. In het Holoceen Z interval (= I ,800 yr BP tot heden) nam. het area_al van de azonale Alnus bossen op de interandiene h?Ogvlakt;n drasusc~ af. C~cropw was met meer aanwezig in de gemengde Quercus bossen m het Fuquene geb1ed. N1etterrun moet er

Summary

rekening worden gehouden met het feit dat de waargenomen vegetatie veranderingen aan het eind van het Holoceen Y interval en in het Holoceen Z interval mogelijkerwijs niet aileen gerelateerd kunnen worden aan klimaatsverandering maar ook gedeeltelijk veroorzaakt werden door de toenemende menselijke invloed, die catastrofaal werd in de laatste = 450 jaar. De invloed van veranderende exogene factoren e n endogene processen op kleine azonale ecosystemen wordt gei1lustreerd door de locale vegetatie ontwikkeling op de bonngplaatsen waar de secties van deze studie zijn verzarneld. Op ~e boringplaats van de Paramo de Laguna Verde I sectie, vopd de volgende vegetatie success1e plaats: par~mo

Ditricho-lsoetion

>> >> » mozai'ek van

Junco -Eleocharition en Sphagnwn veen

De ontwikkeling van open water naar venige vegetatie types was naar alle waarschijnlijkheid het gevolg van de geleidelijke opvulling van het sedimentaire bekken. De meest interessante locale vegetatie successie werd geregistreerd op de boringplaats van de Paramo de Peiia Negra I sectie in de Laguna Negra, een klein meer tegenwoordig gelegen in de ond~rste grasparamo zone op een hoogte van ca. 3625m. De Laguna Negra was ontstaan in een glac1aal geerodeerd bekken nadat het ijs zich defmitief had teruggetro19cen uit het gebied van de Par_amo de Peiia Negra aan het eind van het Laat Fuquene stadiaal. Op de plek van de · bonngplaats vond de volgende locale vegetatie successie plaats:

Ditricho-lsoetion » >> >~ • Tillaeion >> >> >> Junco-Eleocharition >> >> ,~ Calamagrostion ligulatae >> >> >> Junco-Eleochannon » » >> moz.alek van Junco-Eleocharition en Ditricho-lsoetion >> >> >> Calamagrostion ligulatae >> >> >> Sphagnwn veen De algemene ontwikkeling van aquatische vegetatie types naar relatief droge venige vegetatie types ~as het geyo~g van de opvulling van het sedimentaire bekken, hetgeen een endogeen proces IS. De flonsnsche samenstelling van de locale vegetatie types en plotselinge successies werde~ echt~.r bepaald_ ~~r exogene factoren, zoals het klimaat, een klimaatsverandering en, mogehjkerw!JS, mensehjke mvloed. A Is gevolg van het koudere klimaat aan het eind van het Laat Fugu~n e stad~_aal en in_ het Laat Glaciaal, ontwikkelden zich locaal plantengemeenschappen (Dtmcho_ -lsoetton, en m de smalle oever zone, Plantago rigida kussen veen) die hedendaags vee)vuld1g voorkomen op grotere hoogten, in de zonale superparamo zone en de bovenste grasparam o zone. ~eranderingen in de regionale vochtigheid in het El Abra stadiaal en in het beg1n en aan het emd van het Holoceen Y interval veroorzaakten fluctuaties in de locale grondwater-spiegd, die leidden tot een versnelling of een onderbreking van de nonnale endogene successte. Met name de vegetatie types behorende tot het Junco -Eleocharition en het Calam~grostion ligulatae,_ die gebonden zijn aan de zone rond de grondwater-spiegel, waren zeer gevoehg voo_r ve_randenngen in de regionale vochtigheid. Plotselinge locale successies ~Ca!amagrosnon ltgl!-_fat~e >> >> >~ Sphagnt:= veen) in de laatste = 350 jaar vielen samen met het begm van de n:ensehJke mvloed m h~t geb1ed van de Paramo de Peiia Negra zelf. Op _de bonn&plaatsen van de, Paramo de Agua Blanca II en lii secties, vond de volgende · vegetane success1e plaats:

Ditricho-Isoetion

>> >> >>

Gentiano-Oritrophion

>> >> >>

Sphagnwn veen

De successie :van open water_ naar v~nige vegetatie types kan in hoofdzaak worden toegeschreven aan de opv_':lllmg van het sedimentaire ~kken, hetgeen een endogeen proces is. De successie lijkt echter te ZIJn :versneld door een v~rlagmg van de locale grondwater-spiegel in het begin van het Holoceen Y mterval. De verlagmg was waarschijnlijk het gevolg van veranderingen in de evapotransp!Tatle en de wateropslag door de regionale vegetatie types in het gebied van de P:iramo de ~gua Blanca. Deze. veranderingen werden veroorzaakt door de vervanging van de oorspronkehjke paramo vegetaue types door hoog-andien Weinmannia bos.

Palaeobotanical-palaeoecological studies

235

234

RESUMEN Estudios paleobotanic os- p aleoecologico s de secciones de turberas tropicales altoandinas (Cordillera Oriental, Colombia) En este trabajo se presentan los resultados de los anli.lisis palinologicos y macrobotanicos de secciones de turberas altoandinas coleccionadas en el Paramo de Laguna Verde, en el Paramo de Peiia Negra y en el Paramo de Agua Blanca, localizados en los alrededores de Ia Sabana de Bogota en !a Cordillera Oriental de Colombia. Con el fin de poder identificar los macrof6siles encontrados en las secciones analizadas, el au tor compil6 una colecci6n de referenda de material macrobotanico reciente. Esta colecci6n, di sponible en el Laboratorio Hugo de Vries de !a Universidad de Amsterdam, contiene flores, fru tos, ramas, bojas, semillas, macroesporas y preparados de epidermis de cormofitas, y briofitas, incluyendo musgos y hepaticas, que son de frecuente ocurrencia en las vegetaciones azonales paramunas en el area de estudio. En el Instituto de Ciencias Naturales de Ia Universidad Nacional de Bogota, Colombia, se deposito un duplicado de esta colecci6n. El desarrollo de las vegetaciones locales se dedujo a partir de los macrof6siles y de los microf6siles de origen local. Se utiliz6 un enfoque a nivel de comunidades vegetales relacionadas con cambios locales mayores, puesto que el conocimiento de la autoecologia de varios elementos azonales importances involucrados (p.e. Calamagrostis, Carex,lsoetes, ]uncus, Xyris) es por el momento insuficiente. El analisis de macrof6siles contribuy6 de manera importante al conocimiento del desarrollo de las vegetaciones locales. Los analisis palinol6gicos y macrobotanicos combinadas tambien contribuyeron a mejorar el registro de los cambios en las vegetaciones regionales, dado que pudieron detectarse objetivamente influencias causadas por la presenc ia local de ciertos elementos tambien presences en las vegetaciones regionales, por Ia presencia de restos macrobotanicos de estos elementos en los sedimentos turbosos y lacustres analizados. El desarrollo de las vegetaciones regionales se dedujo a partir del polen y de las esporas de origen regipnal. Una gran cantidad de fechas de radiocarbono y un metodo de dataci6n indirecta basado en las concentraciones de polen en el sedimento, crearon una s6lida base cronol6gica para Ia correlaci6n de los cam bios en Ia vegetaci6n en el area de estudio. Los datos ~bsolutos sobre el aporte de polen resultaron ser muy utiles para contribuir en !a interpretacion paleoecol6gica de los diagramas palinologicos 'relatives' clasicos. Se coleccionaron dos secciones en una turbera de Sphagnum-Xyris en el Paramo de Laguna Verde. Estas secciones reflejan los cambios en Ia vegetaci6n regional y local durante los ultimos = 5,500 aiios. La secci6n coleccionada en !a turbera de Sphagnum-Sw allenochloa en Ia Laguna Negra (Paramo de Peiia Negra) muestra el desarrollo de !a vegetacion regional y local durante los ultimos ~ 15,000-14,000 ai'ios. Informaci6n complementaria para Ia interpretaci6n del desarrollo de !a vegetaci6n.local fue obtenida por medic del anli.lisis de ciertas caracteristicas fisico-qufmicas del sedimento. El conten ido de carbone (C) y ni trogeno (N) m uestra una relaci6n con Ia producci6n organica primaria de las vegetaciones locales sucesivas, mientras que Ia relaci6n C/N da una impresion de Ia descomposici6n primaria en los ecosistemas azonales correspondientes. Especialmente en esta secci6n, !a influencia de cambios ex6genos y de procesos end6genos sobre el desarrollo de pequeiios ecosistemas azonales paramunos se refleja clararnente en Ia sucesi6n vegetal local. Las secciones colecc ionadas en !a turbera de Sphagnum-Espeletia en el Paramo de Agua Blanca reflejan los cam bios en !a vegetaci6n regional y local durante los ultimos = 8,300 aiios. Se dan las descripciones e ilustraciones de 72 tipos de rnicrof6siles y de todos los 113 tipos de macrof6sil es enconrrados en las secciones analizadas. Con base e n los datos paleoecologic os obtenidos en es te trabajo, en otros datos paleoecol6gico s obtenidos en el area de estudio durante los ultimos 30 aiios, en evidencias geomorfol6gicas de glaciaciones yen datos arqueol6gicos, se presenta una reconstrucci6n de Ia historia geoecol6gica en esta area durante los ultimos 24,000 afios. Se discute Ia dinarnica de los ecosistemas andinos zonales y azonales en relaci6n con cambios en los factores ex6genos (p.e. clima, influencia humana) y procesos end6genos.

Summary ,

Las diferencias tentativas en temperatura, comparadas con la del presente, asi como en la precipitaci6n, y las fluctuaciones del limite superior del bosque en el area de estudio se presentan. ~~

Pleniglacial Tardio

Tardig1acial y Holocene mas Temprano

Holocene

Estadial Fuquene Temprano

Periodo: .. 22,500 basta = 19,500 aiios AP Clima: frfo (- 7-8°C) y seco Limite superior del bosque: "' 2000m

Intervale Fuquene Medic

Periodo: = 19,500 basta= 18,000 aiios AP Clima: rei. frfo (- 3-4°C) y seco Limite superior del bosque: "' 2600m

Estadial Fuquene Tardio

Periodo:"' 18,000 hasta .. 14,000 aiios AP Clima: frio (- 6-7°C) y seco Limite superior del bosque: "' 21 OOm

Interestadial Susaca

Periodo: "'14,000 basta= 13,000 aiios AP Clima: rei. frfo (- 4°C) y seco Limite ~uperior del bosque: "' 2500m

Estadial La Ciega

Periodo:"' 13,000 basta = 12,400 aiios·AP Clima: frio(- 6°C) y seco Limite superior del bosque: "' 2200m.

Interestadial Guantiva

Periodo: = 12,400 hasta"' 10,800 aiios AP Clima: rei. calido (- 20C) y hUmedo Limite superior del bosque:"' 3100m

Estadial El Abra

Periodo: = 10,800 hasta = 9,500 aiios AP Clima: rei. frfo (- 3-4°C) y rei. seco Limite superior del bosque: "' 2700m

Intervale Holocene X

Periodo: "'9,500 hasta "' 7,000 aiios AP Clima: ca.Iido (- 1-QOC) y rei. seco Limite superior del bosque:= 3100m

Intervale Holocene Y

Periodo: = 7,000 basta = 1,800 aiios AP Clima: ca!ido (+ 1-QOC) y htilnedo Limite superior del bosque: = 3500m

Intervale Holocene Z

Periodo: = 1,800 aiios AP hasta el presente Clima: ca!ido (± OOC) y rei. humedo Limite superior del bosque:= 3300m

Durante el estadi~l de Fuquene y el Tardiglacial Temprano(= 22,500 hasta"' 12,400 afios AP) ~! cltma fue relauvarnente frio o frio "t seco. En la pendiente oriental del valle del Magdalena !a faJa de bosque era muy estrecha o cas1 ausente. Quercus era el elemento arb6reo dominante. Cecropia parece haber estado completarnente ausente en el area de estudio. En Ia regi6n de Ia Laguna de ~edro Palo Ia vegetaci6n arb6rea faltaba casi por complete; aqu{ tipos de vegetacion (sub~xerofiuca se en~ontraban en contacto directo con Ia vegetacion paramuna. En Ia fase t~rmmal de los estad!a!es de Fuquene. Temprano, Fuquene Tardio y La Ciega los glaciares d1smmuyeron en extens16n o desaparec1ero n en el area de estudio, permitiendo el desarrollo de lagos y turberas en los circos y valles previamente cubiertos por el bielo. En el interestadial de Guantiva ("' 12,400 basta= 10,800 aiios AP) el clima fue relativamente cli.lido y h~med~. Como ~onsecuencia del clima rna~ humedo se formaron una serie de Iagunas en l~s reg10nes mterandinas (p.e. Laguna de Palac10). Los bosques andinos invadieron areas prevtamente ocupadas por vegetaci6n paramuna. En Ia regi6n de Fuquene, los bosques zonales de Quercus fueron precedidos por tipos de vegetaci6n pionera con Dodonaea y Rapanea. Los

Palaeobotanical-palaeoecological studies

altiplanos al sur de Ubate y de Bogotli fueron invadidos casi por completo por los bosques azonales de Alnus. En Ia pendiente oriental del valle del Magdalena, los bosques tropicalessubandinos empezaron a desarrollarse lentamente, adaptlindose por completo a las condiciones mas hfunedas s6Io 2,000 ailos despues, alrededor de= 10,350 aiios AP. Esta lenta adaptaci6n se debe probablemente a! hecho de que Cecropia tuvo que inmigrar desde loca!idades situadas mas al norte en el valle del Magdalena. Durante e1 estadial de El Abra (= 10,800 hasta = 9,500 anos AP) el clirna se volvi6 mas frio y seco. Como resultado del descenso tanto en !a temperatura como en Ia precipitaci6n, los bosques azonales de Alnu.s'-en los altiplanos interandinos disminuyeron en extension, siendo al final casi o completamente reemplazados por vegetaci6n arbustiva de Myrica y Compositae y vegetaci6n abierta de Gramineae. En el intervalo Holoceno X(= 9,500 hasta .. 7,000 aiios AP) el clima se volvi6 mas clilido. El lfmite superior del bosque se desplaz6 hacia arriba. Las condiciones permanecieron relativamente secas impidiendo el desarrollo de los bosques azonales de Alnus en los altiplanos interandinos. En el intervalo Holoceno Y (= 7,000 hasta .. 1,800 aiios AP) el clima se volvi6 aun mas cli!ido y mucho. mlis hUmedo. En las regiones paramunas se formaron numerosas Iagunas y turberas. En el lirea de Fuquene se desarroll6 un bosque mixto de Cecropia-Quercus. El limite superior del bosque zonal se desplaz6 gradualmente mas hacia arriba. Aunque se registr6 repetidamente Zea mais a partir de = 6,600 aiios AP, to cual se puede atribuir a actividades agricolas de tribus prehist6ricas en el area de estudio, at principio Ia influencia humana sobre el desarrollo de Ia vegetaci6n parece haber sido insignificante. En Ia segunda pane del intervalo Holoceno Y (= 5,000 hasta = 1,800 anos AP) los bosques altoandinos de Weinmannia empezaron a desarrollarse, reemplazando bosques de Quercus. Posiblemente este proceso formaba pane de Ia lenta y gradual adaptaci6n de Ia vegetaci6n arb6rea andina a las condiciones climaticas mas humedas. Sin embargo, no se puede ignorar Ia posibilidad de que procesos end6genos (p.e. maduraci6n de los suelos) estuvieran involucrados. AI final del imervalo Holoceno Y, en aproximadamente = 2,750 aiios AP, el clima probablemente comenz6 a deteriorarse, volviendose paulatinamente un poco mas frio y seco. Los bosques altoandinos de Weinmannia con Hedyosmum se desarrollaron por completo. En el area de Fuquene, Acalypha apareci6 como elemento importance en el bosque mixto de Cecropia-Quercus. Aunque el deterioro del clima empez6 en= 2,750 aiios AP, en el area de estudio este parece haber tenido su maximo impacto sobre el desarrollo de Ia vegetaci6n azonal y zonal en= 1,800 aiios AP. En el intervalo Holoceno Z (= 1,800 aiios AP hasta el presence). Ia superficie ocupada por los bosques azonales de Alnus en los altiplanos interandinos disminuy6 de manera drastic a. Cecropia ya no estaba presente en los bosques mixtos de Quercus en el area de Fuquene. No obstante, hay que considerar que los cambios en Ia vegetaci6n observados al fmal del intervalo Holoceno Y y en el interv alo Holoceno Z no estan unicamente relacionados con cambios climaticos sino probablemente tam bien con el aumento de Ia influencia humana, Ia cual se volvi6 catastr6fica en los ultimos = 450 aiios. El desarrollo de las vegetaciones locales en los lugares donde se realizaron los sondeos del presente trabajo, muestra Ia influenc ia de cambios en los factores ex6genos y de procesos end6genos sobre pequenos ecosistemas azonales pararnunos. En el lugar de sondeo de Ia secci6n Paramo de Laguna Verde I, se present6 Ia siguiente sucesi6n vegetal:

Dirricho-lsoerion

>> » >>

237

236

mosaico de Junco-Eieocharicion y de turbera de Sphagnum

Este desarrollo, de tipos de vegetaci6n acuatica a tipos de vegetaci6n de turbera. seguramente se debi6 al relleno gradual de Ia depresi6n con sedimentos. La sucesi6n vegetal local mas interesante se present6 en el Iugar de sondeo de Ia secci6n Paramo de Pena Negra I en Ia Laguna Negra, una pequena laguna que se encuentra hoy en dfa en Ia zona del paramo propiamente dicho bajo a una altura de unos 3625m. La laguna se form6 en una depresi6n glaciar despues de que esta fuera abandonada definitivamente por los glaciares a! fmal del estadial Fuquene Tardio. En ellugar de sondeo se present6 Ia siguiente sucesi6n local:

Summary

Ditricho-Isoetion >> >> » Tillaeion >> >> >> Junco-Eieocharition >> » » Calamagrosticn /igulatae » » >> Junco-Eieocharition » >> » mosaico de Junco-Eleocharition y D!tricho-lsoerion >> >> >> Calamagrostion ligulatae » >> » turbera de Sphagnum El desarrollo general de tipos de vegetaci6n acuatica a tipos de vegetaci6n de turbera relativarnente secos, se debi6 al relleno de Ia depresi6n, lo cual es un proceso end6geno. Sin embargo, Ia composici6n floristica de los tipos de vegetaci6n local y sucesiones repentinas fueron determinados por factores ex6genos, tales como el clima, un cambio climatico y, posiblemente, influencia humana. Como consecuencia del clima mas frio al final del estadial Fuquene Tardfo y en el Tardiglacial, se desarrollaron localmente comunidades vegetales (Dirricho-lsoerion y, en Ia estrecha zona de ribera, turbera de cojines de Plantago rigida) que hoy en dia ocurren frecuentemente en alturas mas altas, en Ia zona del superpliramo y del paramo propiamente dicho alto. Cambios en !a humedad regional durante el estadial de El Abra y al principio y al fin del intervalo Holoceno Y causaron fluctuaciones en el nivellocal de agua, originando una aceleraci6n o una interrupci6n de Ia sucesi6n end6gena normal. Especialmente los tipos de vegetaci6n del Junco-Eieocharition y del Ca/amagroscion ligulacae, los cuales estlin asociados a Ia zona del nivel de agua, fueron muy susceptibles a estos carnbios en Ia humedad regional. Sucesiones repentinas (Calamagroscion ligulatae >> » >> turbera de Sphagnum) en los ultimos = 350 aiios coincidieron con el comienzo de Ia influencia humana en el Paramo de Pena Negra mismo. En los lugares donde se realizaron los sondeos de las secciones Paramo de Agua Blanca II y III. se present6 Ia siguiente sucesi6n vegetal:

Dirricho-lsoecion

>> >> >>

Gentiano-Orirrophion

>> >> »

rurbera de Sphagnum

Esta sucesi6n, de un tipo de vegetaci6n de agua abierta a tipos de vegetaci6n de turbera, se debi6 en primer instante a! relleno de Ia pequena depresi6n con sedimentos, to cual es un proceso end6geno. No obstante, Ia sucesi6n parece haber sido acelerada por una baja en el nivel del agua local al principio del intervalo Holoceno Y. Esta baja en el nivel del agua se debi6 probablemente a cambios en Ia evapotranspiraci6n y en Ia rerenci6n del agua por los tipos de vegetaci6n regional en el area del Paramo de Agua Blanca, causados por el reemplazo de la vegeraci6n paramuna original por un bosque altoandino de Weinmannia.

Palaeobotanical-palaeoecological studies

239

238

An alphabetical list of the microfossil types that have been described and illustrated in the present publication is given below. The reader will be referred to the page and plate numbers of the corresponding descriptions and illustrations. Pollen and fern spore types are placed both under their generic and their family names. Fungal, algal, bryophytic and zoological types are only inserted under their generic n·ame. Microfossils Algal types

Altemanthera-type Amaranthaceae

A/ternanthera-type lresine-type Amphirrema Anthostomel/afuegiana Antidaphne-type Arcytophyllum Assulina Bartsia-type Botryococcus Bromeliaceae Bryophytic types

Callidina Closterium idiosporwn Colignonia·type Debarya

E/aeagia- type Eucalyptus Fern spore types Fung.al types

Gaeumannomyces cf. caricis Gelasinospora Gentianaceae Macrocarpea Gramineae

Zeamais Habenaria-type Haloragaceae

Potarnogeton Helicoon pluriseptatwn lresine-type Lasiosphaeria-type Loranthaceae

Antidaphne·type Macrocarpea Marsileaceae

Piluiaria-type Meesia-type Mougeotia Myrtaceae

Eucalypms Nenera Nyctaginaceae

Colignonia-typ<" Orchidaceae

Habenaria-type Pediasrrum

Descriptions

Microfossils

MICROFOSSIL INDEX

Descriptions

149-150 145 145 145 145 151 147 145 145 151 145 150 146 150 151 149 145 149 145 144 150 147-149 147 148 146 146 144,146 144,146 146 145 145 147 145 148 145 145 146 150 150 150 149 144 144 146 145 145 146 146 150

lllustrations

VI-VII I I I I

vm v

I III VIII II VII IV VIII VIII VII II

II I VII IV-VI IV

III I1I !,III ! ,III Ill II II

v v

I I III

Vll VIII VII I I IV II II III

III VII

Pilularia- type Pinaceae

Pinus Pleospora-type Pollen types Polygonaceae

Rumex acetosella Potamogeton Pseudoschizaea circula Rosaceae

Sericotheca Rubiaceae

Arcytophyllum E/aeagia-type Nertera Rumex acetosella Scrophulariaceae

Bansia-type Sericotheca Solanaceae Spirogyra cf. scrobicu/ata

Spirogyra Umbelliferae Xyridaceae

Xyris Zeamais Zoological types

Zygnema

Microfossil index

(

150 144 144 148 144-147 144 144 145 149 146 146 145,146 145 145 146 144 145 145 146 146 149 149 146 145 145 144,146 151 149

lllustrations

VII I I VI

I-N I I II VII Ill III II,III,IV Ill II IV I II II Ill IV VI VII IV II II I, III VIII VI

j Palaeobotanical-palaeoecological studies

240

241 Macrofossils

MACROFOSSIL INDEX

Hypericum /aricifolium leaves Hypericum branches Hypericum epidermal remains Âˇ Hypericum seeds

An alphabetical list of the macrofossil types that have been described and illustrated in the present publication is given below. The reader will be referred to the page and plate numbers of the corresponding descriptions and illustrations. Illustrations Descriptions Macrofossils Acaridae exoskeletons Agrostis haenkeana epidermal remains Aulacomnium palustre remains Barrramia remains Bartsia seeds Bidens fruits Blechnum leaves Breutelia allionii remains Breurelia chrysea remains Breutelia tomentosa remains Bryum remains Calamagrostis effusa epidermal remains Calamagrostis ligulata epidermal remains cf. Callitriche fruits Campy/opus cucullatifo lius remains Campy/opus remains Carex cf. bonplaruiii fruits Carex epidermal remai..s Carex fruits Characeae oospores Chorisodontium speciosum remains Cladia remains Cladocera ephippia Col.eoptera el ytra Collembola exoskeletons Compositae fruits Cyclodictyon rubrisetum remains Cyperaceae basal leaf sheaths Dicotyledoneae epidermal remains Diplostephium phylicoides leaves Diplostephium fruits Ditrichum submersum remains Drepanocladus fluitans remains ÂŁ/atine leaves Elatine seeds Eleocharis epidermal remains Eleocharis fruits Ericaceae branches Ericaceae flowers Eriocaulaceae seeds Espeletia fruits Fruits and seeds Gentiana sedifolia seeds Grarnineae basal leaf sheaths Gramineae epidermal remains Gramineae fruits Gramineae glumae cf. Hemiptera exoskeletons Hepaticae remains cf. Hymenoptera puparia Hypericum goyanesii leaves

161 152 155 154 159 158 161 154 154 154 155 152 152 159 155 155 157 152 157 161 !55 !56 161 161 160 158 !55 160 153 161 158 155 !55 161 159 152 157 161 161 157,158 158 156-159 158 160 152 156,157 160 162 156 162 160

XXVII IX

XV XIV XXII XXII XIV XIV XV IX IX

XXIII XV XVI XVIII X

XIX XXVII XVI

xvm

XXVII XXVII XXVII XXII

XVII XXV XII XXII

XVI XVI XXVI

I !

XX Ill X

XIX XXVI XXVI XX

XXII XVIII-XXIV XXII XXV IX

XVIII XXV XXVII XVIII XXVII XXVI

I I

Insectae head capsules Iso~tes andina megaspores lso~tes boya~ensis megaspores lsoetes__cleefiz_lsteyermarkii megaspores cf. Jsoetes epidermal remains lsoetes megaspores Juncaceae epidermal remains cf. Juncaceae epidermal remains ]uncus seeds Kurzia verrucosa remains Lachemil/a fruits(?) cf. Lepidozia remains cf. Luzu/a seeds Musci calyptrae Odontoschisma remains cf. Oligochaeta cocoons Oreobolus obtusangulus epidermal remains Oreobo/us obtusangulus fruits Other macrobotanical remains cf. Pernettya seeds Plant remains of bryophytes Plant remains of connophytes Plant remains of lichens P/eurozium schreberi remains Polypodiales leaflets Polypodiales sporangia Polytrichum juniperinum remains Potamogeton fruits cf. Psocoptera exoskeletons Puya seeds Ranunculus fruits Rhacocarpus purpurascens remains Rhynchospora macrochaeta epidermal remains Rhynchospora macrochaeta fruits Riccardia hansmeyeri remains Riccardia remains Sphagnum sect. Cuspidata remains Sphagnum cyc/ophyl/um remains Sphagnum mage/lanicum remains Sphagnum subsecundum remains Sphagnum opercula Ti/laea seeds cf. Vaccinium fruits Vacciniwn/Pernettya leaves cf. Va ccinium seeds cf. Xyris epidermal re'm ains Xyris seeds Zoological macrofossils

Macrofossil inc)ex

De~criptiQns

160 160 153 158 162 160 160 160 153 160 153 153 157 156 159 156 157 161 156 162 152 157 159-161 158 153-156 152-153 156 154 161 161 155 159 162 158 159 154 153 157 156 156 154 154 154 154 161 159 160 161 158 153 157 161- 162

ntustrations

XXVI XXVI XII

XXI XXVII XXV XXV XXIV XII XXIV XI XI XX XVII XXII XVII XX XXVII

xvn

XXVII X XIX XXIV-XXVII XXI XIII-XVIII IX-XII XVIII XXVI XXVI XV XXIII XXVII XXI XXIII XIV XI XIX XVIII XIII XIII XITI XIII XXIII XXVI XXI XI XX XXVII