The páramo vegetation of Ramal de Guaramacal, Trujillo State, Venezuela 1. Zonal communities

Abstract

Zonal paramo 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 oil 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 in of altitudinal interval oil zonal paramo vegetation present between 2800 and 3100m 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 subparamo or shrubby paramo and two of upper subparamo or bunchgrass paramo dominated by rosettes and tussock plants have been documented. The alliance Hyperico paramitanum-Hesperomeletion obtusifoliae groups the shrubby paramo 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 parama, association Cortaderio hapalotrichae-Hypericetum juniperium and two open grass paramo 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 paramo.