The páramo vegetation of Ramal de Guaramacal, Trujillo State, Venezuela 1. Zonal communities
Cuello A., Nidia L.; Cleef, Antoine M.
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 m-line 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 paramitanum-Hesperomeletion obtusifoliae groups the shrubby páramo associations: Ruilopezio paltonioides-Neurolepidetum glomeratae and Disterigmo acuminatum-Arcytophylletum nitidum, present on wind protected slopes, dwarf forests edges or along streams. The alliance Hyperico cardonae–Xyridion acutifoliae groups one widely distributed shrubby páramo association Cortaderio hapalotrichae-Hypericetum juniperinum and two open grass páramo associations: Puyo aristeguietae-Ruilopezietum lopez-palacii and Rhynchosporo gollmeri-Ruilopezietum jabonensis, 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.