Lianas and trees in a liana forest of Amazonian Bolivia

The distribution of lianas (woody climbing plants) on trees in a lowland "l iana forest" of northeastern Bolivia was clumped and varied with characteri stics of individual trees and tree neighbors. In twenty-four 900-m(2) squar e plots established to estimate tree (greater than or equal to 10 cm DBH [d iameter at breast height]) and liana (greater than or equal to2 cm DBH) den sities and to count the number of lianas a tree carried, we estimated a mea n 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 sit es, bur mean liana density was much higher (2471 lianas/ha, SE = 104.3). Ba sal area of trees greater than or equal to 10 cm DBH was low in Oquiriquia (19.2 m(2)/ha) in comparison to other tropical forests. Liana diversity, as expressed by the ratio of liana/tree species, was higher in this forest th an in any other so far reported. Of trees greater than or equal to 10 cm DB H, 86 percent carried lianas. Four tree species (Astrocaryum aculeatum, Eut erpe precatoria, Xylopia sericea, and Astrocaryum fraxinifolium) had a lowe r 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 chat lianas and trees have no specific association s with each other. Lianas showed an aggregated distribution on trees, sugge sting a facilitation process in which new lianas use already established on es to climb trees. Lianas of four different climbing mechanisms climbed a s imilar 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 sire (perhaps related to successiona l forest status). Larger-diameter trees carried more lianas than slender tr ees, bur this relationship was affected by the density of trees 10-30 cm DB H surrounding each tree, which suggests again that the successional stage o f the forest in which a tree grows affects the number of lianas a tree carr ies. We found little evidence to support the idea that lianas were more lik ely 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.