The páramo vegetation of Ramal de Guaramacal, Venezuela. 1. Zonal communities - Cuello & Cleef 2009

Page 1

Phytocoenologia, 39 (3), 295–329 Berlin – Stuttgart, October 21, 2009

The páramo vegetation of Ramal de Guaramacal, Trujillo State, Venezuela. 1. Zonal communities by Nidia L. CUELLO A., Guanare, Venezuela and Antoine M. CLEEF, Amsterdam, The Netherlands with 10 figures, 4 photographs and 7 tables Abstract. Zonal páramo vegetation communities present on top of Ramal de Guaramacal, Trujillo state, Venezuela, have been studied with the aim to provide a syntaxonomic scheme or classification, based on analysis of the physiognomy, floristic composition, ecological relations and spatial distribution of the different vegetation communities. A total of 91 vascular species, 33 species of bryophytes and 11 species of lichens have been documented from fifty 10 mline intercept transects, each surveying 10 m of altitudinal interval on zonal páramo vegetation present between 2800 and 3100 m altitude. The interpretation of the TWINSPAN clustering allowed the recognition of five vegetation communities at association level grouped into two alliances and one order. Three associations of lower subpáramo or shrubby páramo and two of upper subpáramo or bunchgrass páramo dominated by rosettes and tussock plants have been documented. The alliance Hyperico par a m i t a n u m -H e sp e ro m e l e t i o n o b t u si f o l i a e groups the shrubby páramo associations: Ruilopezio paltonioi d e s-Ne u ro l e p i d e t u m g l o m e ra t a e and D i st e ri g m o a c u m i n a tum-Arcytophylletum nitidum, present on wind protected slopes, dwarf forests edges or along streams. The alliance Hyperico cardonae–Xyridion ac u t i f o l i a e groups one widely distributed shrubby páramo association Co rtaderio hapalotrichae-Hyperice t u m j u n i p e ri n u m and two open grass páramo associations: P u y o aristeguietae-Ruilopezietum lopez-pal a c i i and R h y n c h o sp o ro g o l l m e ri -R u i l o p e z i e t u m j a b o n e n sis, present on wind exposed slopes. Asteraceae and Ericaceae are the most speciose of families, followed by Poaceae and Cyperaceae. The most diverse genera are Ruilopezia (Asteraceae), Rhynchospora (Cyperaceae) and Hypericum (Clusiaceae). Diversity of species and growth forms is greater among the shrubby communities, decreasing in the bunch grass-rosette communities. Canonical correspondence analysis (CCA) indicates that floristic composition of zonal vegetation communities is mostly related to slope angle and altitude than to other observed variables such as pH, soil depth and humus depth. The generic and species composition is that of a rain bamboo páramo. eschweizerbartxxx ingenta

Keywords: floristic composition, phytosociology, zonal bamboo páramo, Chusquea, Espeletiinae, Andes, Venezuela. Abbreviations: UFL = Upper Forest Line; SARF = Subalpine Rain Forest or high Andean forest; UMRF = Upper Montane Rain Forest or Andean forest.

Introduction Andean páramos play an essential role in the evolution and the ecology of the Andes (Vuilleumier & Monasterio 1986, Luteyn 1999, Hofstede et al. 2003, Hooghiemstra et al. 2006) and represent strategic ecosystems due to the environmental services they offer in the regional hydrological balance and agricultural production (Molinillo & Monasterio 1997, 2002; Monasterio & Molinillo 2003; Hofstede et al. 2003). Andean páramos are also, however, highly fragile ecosystems as a function of mounting demographic pressures, the expansion of agricultural and mining activities and of global warming, all of which represent major threats to the maintenance of environmental services and for the conservation of Andean biodiversity (Hofstede 2002, Van der Hammen 2002, Llambi et al. 2005). Since the publication of the ‘Flora de los Páramos de Venezuela’ by Vareschi (1970), a substantial number amount of studies in but a few Venezuelan páramos has been published. The ecological studies by M. DOI: 10.1127/0340 – 269X/2009/0039– 0295

Monasterio and (own staff/foreign) collaborators (Monasterio 1980a, Sarmiento et al. 2003) were developed primarily in the central core of dry páramos in the state of Mérida. They remain ongoing in these páramos with highest altitude and most extension of the Cordillera of Mérida. At present, a great number of studies by researchers from the ICAE-ULA-Mérida, are available (see Sarmiento 2006 CD-ROM). These studies are mostly concerned with ecophysiology and functional processes in both natural and agro-ecosystems of the páramo and as such, remain unique in that there are not similar groups of this magnitude and focus elsewhere in the tropical Andes and high mountains of Central America and Mexico. Despite a great environmental variability throughout a number of páramo areas and their associated vegetation communities along of the Cordillera de Mérida (Monasterio & Reyes 1980, Monasterio 1980, Luteyn, 1999), little is currently known about páramo vegetation communities and their flora in other sectors of the Venezuelan Andes beyond the borders of Mérida state. To date, local floristic list0340 – 269X/09/0039 – 0295 $ 15.75 © 2009 Gebrüder Borntraeger, D-14129 Berlin · D-70176 Stuttgart


Turn static files into dynamic content formats.

Create a flipbook
Issuu converts static files into: digital portfolios, online yearbooks, online catalogs, digital photo albums and more. Sign up and create your flipbook.
The páramo vegetation of Ramal de Guaramacal, Venezuela. 1. Zonal communities - Cuello & Cleef 2009 by JPZ. - Issuu