The epiphyte communities of a montane rain forest in the Andes of Venezuela: patterns in the distribution of the flora

Abstract

The dependent flora was surveyed on 20 trees at a 1.5-ha site in montane rain forest at 2600 m altitude in western Venezuela. Vascular species were recorded over the whole site and totalled 120 epiphytes, 21 climbers, 3 hemiepiphytes, 5 nomadic vines and 6 mistletoes. Non-vascular species were recorded within 95 sample plots and totalled 22 mosses, 66 liverworts and 46 macrolichens. The angiosperm species were restricted in geographical range to the Neotropics; 22.1% were endemic to Venezuela. Pteridophyte and bryophyte species were largely restricted to the Neotropics but few were endemic. Macrolichen species were mostly pantropical or cosmopolitan; only 9.6% were restricted to the Neotropics and none was endemic. Canonical Correspondence Analysis found the environmental variables most closely correlated with variation in community composition to be height above ground and a horizontal gradient reflecting differences in forest structure. The epiphytic vegetation was classified using Two-way Indicator Species Analysis into a Syrrhopodon gaudichaudii–Elaphoglossum hoffmannii group of lower trunks, an Omphalanthus filiformis–Maxillaria miniata group of intermediate levels and an Usnea–Parmotrema group of upper crowns. Diversity increased with height above ground; non-vascular diversity was greatest in upper crowns whereas vascular diversity was greatest at intermediate levels. Similarity levels were low among sample plots of the same community, whereas between-tree and between-stand similarities were relatively high.