Lianas and trees in a liana forest in Amazonian Bolivia

The distribution of lianas (woody climbing plants) on trees in a lowland “liana forest” of northeastern Bolivia was clumped and varied with characteristics of individual trees and tree neighbors. In twenty-four 900-m2 square plots established to estimate tree (≥10 cm DBH [diameter at breast height]) and liana (≥2 cm DBH) densities and to count the number of lianas a tree carried, we estimated a mean of 65 tree species and 51 liana species per hectare. Mean tree density at the study site (564 trees/ha, SE = 23.7) was similar to other tropical sites, but mean liana density was much higher (2471 lianas/ha, SE = 104.3). Basal area of trees ≥10 cm DBH was low in Oquiriquia (19.2 m2/ha) in comparison to other tropical forests. Liana diversity, as expressed by the ratio of liana/tree species, was higher in this forest than in any other so far reported. Of trees ≥10 cm DBH, 86 percent carried lianas. Four tree species (Astrocaryum aculeatum, Euterpe precatoria, Xylopia sericea, and Astronium fraxinifolium) had a lower proportion of liana-infested individuals than expected based on the mean percent of liana infestation in this forest. Forest plots with similar tree species composition did not have similar liana composition or liana loads per tree, which suggests that lianas and trees have no specific associations with each other. Lianas showed an aggregated distribution on trees, suggesting a facilitation process in which new lianas use already established ones to climb trees. Lianas of four different climbing mechanisms climbed a similar number of trees. Plots in the forest with high palm density also had high liana density, suggesting that palms and lianas respond positively to common forest conditions in the study site (perhaps related to successional forest status). Larger-diameter trees carried more lianas than slender trees, but this relationship was affected by the density of trees 10–30 cm DBH surrounding each tree, which suggests again that the successional stage of the forest in which a tree grows affects the number of lianas a tree carries. We found little evidence to support the idea that lianas were more likely to climb some tree species than others. Instead, larger trees and trees growing in the vicinity of trees 10–30 cm DBH, tended to have more lianas, perhaps as result of longer exposure to liana infestation