Resumo

CORREA-GOMEZ, Diego F  e  STEVENSON, Pablo R. Structure and diversity of riparian forests in a seasonal savanna of the Llanos Orientales Colombianos (Tomo Grande Reserva, Vichada. Orinoquia [online]. 2010, vol.14, suppl.1, pp.31-48. ISSN 0121-3709.

Gallery forests of the Colombian Eastern Plains are important reservoirs of global biodiversity as a result of the small area occupied and its high structural and functional heterogeneity. However, to date there are no one-hectare permanent plots reported in the gallery forests of the seasonal savannas of the Colombian Eastern Plains. This study provides information about the diversity and vegetation structure of three hectares of mature gallery forests associated to three waterways that flow into the Tomo River (Tomo Grande Reserve, munici pality of Santa Rosalia, department of Vichada), through the analysis of diversity (Fisher's alpha) and physiognomy (vertical structure, the importance value index IVI, timber volume by diameter class) and also the relation between the diameter at breast height (DBH) and total height for the individuals measured except palms. We included trees, vines and hemiepiphytes with DBH greater than or equal to 10 cm. A total of 120 species were found, and a low diversity compared with Amazon plots (α-Fisher mean=27.0), which is related to a reduced area occupied by gallery forests in relation to large Amazon blocks. However, the most abundant families (Arecaceae, Annonaceae, Rubiaceae, Bignoniaceae, Moraceae, Burseraceae, Fabaceae, Chrysobalanaceae, Euphorbiaceae and Lauraceae) match the most abundant families of Amazon plots, except for Bignoniaceae, fact that shows the similarity between the Llanos and the Amazonian flora. Most species showed local dominance (high IVI), compared with plots placed on other gallery forests and in the Amazon, which indicates that despite the closeness, there may be biogeographic, climatic, geologic and biotic differences that may affect the successful recruitment of species in each area.

Palavras-chave : Orinoco; Permanent plots; Diversity; IVI; Composition.

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