Phytocoenologia, 39 (1), 79–107 Berlin – Stuttgart, April 21, 2009
A phytosociological study of the páramo along two altitudinal transects in El Carchi province, northern Ecuador by Marcela C. MOSCOL OLIVERA and Antoine M. CLEEF, Amsterdam, The Netherlands with 9 figures and 7 tables Abstract. We here present a plant composition study of páramo grasslands in the East Andean Cordillera of northern Ecuador that discerns altitudinal distribution patterns. This study took place at two locations: the relatively undisturbed Guandera Biological Reserve site and the highly disturbed El Angel Ecological Reserve site. The analysis included a field survey following the relevé method of Braun-Blanquet. The study focussed on altitudinal distributions of specific plant communities discernable by our analysis, as well as for traces of human influence in these communities. We examined 100 plots of zonal and azonal páramo vegetation located between 3400 and 4000 m altitude. The phytosociological classification by means of TWINSPAN revealed seven páramo communities at the association level (three for zonal páramo proper and three for azonal bogs), which clustered each into two alliances and one zonal order on the basis of both floristic composition and percentage of cover. The newly described phytosociological order Espeletio pycnophyllae-C a l a m a g ro st i e t a l i a e f f u sa e unifies all the zonal bunchgrass páramos of the Guandera-El Angel study area. There was no structural subpáramo community detectable in our study area. This can probably be explained by the frequent fires that affect the páramo-forest ecotone and which result into a sharp discontinuity in the vegetation at the upper forest line location in Guandera. For Guandera we described two distinct zonal páramo communities: a bamboo patch and páramo islands in high Andean Forest. In El Angel, the floristic composition of subassociation paspaletosum bonplandiani (bunchgrass páramo at 3430–3550 m) of the G y n o xy o Calam agrostietum suggests that the vegetation of this syntaxon was probably located on former forested land, as evidenced by the disappearance of high Andean forest and the upper part of Andean forest, combined with the presence of many native and exotic weedy species. The presence of distinct taxa in the subassociation of Paspalum bonplandianum undeniably was a response to habitat alteration induced by human activities. For the azonal páramo, we describe three communities at the association level; two of them belonging to the newly established alliance Paep alantho muscosi-Oreobolion c l e e f i i , marking a separate northern Ecuadorian alliance and including the first report of a Xyris cushion bog in Ecuador. eschweizerbartxxx ingenta
Keywords: Páramo, Andes, Ecuador, Upper Forest Line, Andean Rain Forest, grassland, cushion bogs, phytosociology Abbreviations: UFL = Upper Forest Line, SARF = Subalpine Rain Forest/high Andean Rain Forest, UMRF = Upper Montane Rain Forest/Andean Rain Forest
Introduction The páramo is a tropical high altitudinal grassland ecosystem that naturally occurs in Venezuela, Colombia, Ecuador and northern Peru between 3000–3500 m and 4800–5000 m (the permanent snow line), but can also be found in Panamá and Costa Rica (Troll 1973, Cuatrecasas 1968, Cleef 1978) and Bolivia (Beck 1995, García & Beck 2006). The vegetation consists of characteristic tussock grass communities with a high level of plant endemism (Luteyn et al. 1992; Luteyn 1999; Jørgensen & Ulloa Ulloa 1994). Because of their outstanding biodiversity value, the high grade of endemism, and the attractiveness of the landscape, some páramo areas are included in Andean countries’ Protected Area systems. Scientific evidence already proved the important role of páramo as a regulator of water availability due to the high retention capacity of its soils (Guhl 1968; Luteyn et al. 1992). In addition to this, Grabherr et al. (2003) suggested the páramo could be a promisDOI: 10.1127/0340 – 269X/2009/0039 – 0079
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ing indicator of global change if subject to permanent long-term ecological monitoring. Páramos in Ecuador cover approximately 12,600 km2 (Medina & Mena-Vásconez 2001), which is about 5 % of the country’s surface, and form an important agricultural and livestock area for indigenous farming communities (Medina et al. 1997). Unfortunately, inappropriate land use such as burning, agriculture and livestock grazing have resulted in high pressure on the natural and hydrological conditions of this fragile ecosystem, creating threats to their conservation and sustainable development (Buytaert et al. 2006, Lægaard 1992, Luteyn et al. 1992, Hofstede 2001). Some researchers believe that the grass páramo below 4100–4300 m represents, at least partially, secondary vegetation in formerly forested areas (Cuatrecasas 1958, Ellenberg 1979, Lægaard 1992) that has been created and maintained by man using fire (Lægaard1992), but this hypothesis is still debated. Analyses of the floristic composition of the forestpáramo ecotone may offer insights into this topic. 0340 – 269X/09/0039 – 0079 $ 13.05 © 2009 Gebrüder Borntraeger, D-14129 Berlin · D-70176 Stuttgart
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