Strategies of tree occupation at a local scale in terra firme forests in the Colombian Amazon
The goal of this study was to define differences in species richness and tree and liana species assemblages of three adjacent terra firme forests in the middle Rio Caqueta, Colombia. A vegetation survey of trees and lianas equal to or more than 10 cm diameter at breast height (DBH) was carried out along a single longitudinal transect (10 x 2160 in) passing through a low plain terrace, a high dissected terrace, and a high plain terrace. Species were classified as either locally abundant or locally rare. Abundant species were defined as "generalists" (in all environments), "intermediate" (in two environments), and "specialists" (in only one environment) using a 2 x 3 contingency table. There were 146 (39%) species classified as locally abundant and 231 (61%) as locally rare. Among the abundant species, 70 percent were generalists, 25 percent were specialists, and 5 percent were intermediate. Although there was a significant number of rare species, for those species with sufficient numbers to statistically test spatial distribution, the results suggest that many species are generalists and that beta diversity at the local scale (2.16 ha) is low. Larger data sets over larger geographical areas should be analyzed to determine the degree of species turnover in Amazonian forests.