The influence of forest structure on the abundance, biomass, and composition of lianas in tropical forest fragments

Abstract

Abstract Deforestation in the Amazon creates fragmented landscapes and increases the exposure of forest remnants to altered microclimates, leading to forest structural changes that can alter vegetation density and the forest's vertical profile. Trees are crucial to defining tropical forest structure, but lianas contribute as much as 25% of species and can intercept 10–20% of the total light in forest. While much is known about the effects of forest fragmentation on trees, much less is known about lianas. Our study aimed to understand how the liana structure and composition community respond to forest fragmentation, especially forest-structural changes and distance to forest edge, in Central Amazonia. We used data from 1,336 individuals (diameter-at-breast-height ≥ 2 cm) of 172 liana species recorded in 2 ha of forest. Then, we tested the relationship of abundance, biomass, number of species and species composition as a function of forest structural parameters obtained through Terrestrial LiDAR, a 3D-remote-sensing technique, and distance to forest edge. At sites with a lower density of canopy vegetation, liana abundance and species richness both increased. However, increases in liana biomass and changes in liana species composition occurred only near forest edges. We conclude that unanalyzed factors, such as microclimatic variation and intrinsic characteristics of lianas, may be affecting liana community composition. In the long term, the effect of reduced canopy density on liana abundance and climate change may cause further changes in liana species composition in forest fragments.