1. In tropical rainforest, most vascular plants have some capacity to resprout, and lianas are often effective resprouters after canopy fall. However, the diversity of resprouting responses of liana species and the consequence for plant persistence are poorly understood. We hypothesized that variation in regeneration among | 1313

Soil hydrology, nutrient availability and forest disturbance determine the variation of tropical tree species composition locally. However, most habitat ltering is explained by tree species' hydraulic traits along the hydrological gradient. We asked whether these patterns apply to lianas. At the community level, we investigated: (i) whether the hydrological gradient, soil fertility and forest disturbance explain liana species composition; and (ii) whether differences in leaf and stem wood functional traits were linked to species composition along ecological gradients. We sampled liana species composition in 18 1-ha plots across a 64 km² landscape in Central Amazonia and measured ten leaves and stem wood traits across 115 liana species in 2,000 individuals. We correlated liana species composition summarized with PCoA with the functional composition summarized by PCA, considering the species mean values of traits at the plot level. We tested the relationship between ordination axes and the environmental gradients. Liana species composition was highly correlated with functional composition. Taxonomic (PCoA) and functional (PCA) composition were strongly associated with the hydrological gradient, with a slight impact of forest disturbance on functional composition. Species at valley areas had higher stomata size and higher proportions of self-supporting xylem than plateau. Differently, lianas on plateaus invest more in fast-growing leaves (higher SLA), although with a higher wood density. Our study reveals that lianas use different functional solutions in dealing with each end of the hydrological gradient and that the relationships between habitat preferences and traits explain lianas species distributions not straightforwardly as previously found for trees.

Soil hydrology, nutrient availability and forest disturbance determine the variation of tropical tree species composition locally. However, most habitat filtering is explained by tree species' hydraulic traits along the hydrological gradient. We asked whether these patterns apply to lianas. At the community level, we investigated: (i) whether the hydrological gradient, soil fertility and forest disturbance explain liana species composition; and (ii) whether differences in leaf and stem wood functional traits were linked to species composition along ecological gradients. We sampled liana species composition in 18 1-ha plots across a 64 km² landscape in Central Amazonia and measured ten leaves and stem wood traits across 115 liana species in 2,000 individuals. We correlated liana species composition summarized with PCoA with the functional composition summarized by PCA, considering the species mean values of traits at the plot level. We tested the relationship between ordination axes and the environmental gradients. Liana species composition was highly correlated with functional composition. Taxonomic (PCoA) and functional (PCA) composition were strongly associated with the hydrological gradient, with a slight impact of forest disturbance on functional composition. Species at valley areas had higher stomata size and higher proportions of self-supporting xylem than plateau. Differently, lianas on plateaus invest more in fast-growing leaves (higher SLA), although with a higher wood density. Our study reveals that lianas use different functional solutions in dealing with each end of the hydrological gradient and that the relationships between habitat preferences and traits explain lianas species distributions not straightforwardly as previously found for trees.

Plant distribution patterns may indicate habitat specialization either by closely related species with conserved traits or by phylogenetically distant species with converging traits. Lianas represent a large proportion of the overall tropical species diversity and abundance. Despite their importance, little is known about the relationship between habitat specialization and the phylogenetic structure of lianas, especially at the landscape scale where forest disturbances and hydro-edaphic gradients are crucial. To explore this knowledge gap, we used one of the most diverse lineages of Neotropical lianas to test whether (i) landscape environmental gradients explain liana species diversity and composition, (ii) habitat specialization is phylogenetically conserved along ecological gradients, and (iii) closely related liana species have more similar distribution patterns. We hypothesized that hydro-edaphic and forest disturbance gradients determine the compartmentalization of a subset of closely related species in different portions of the ecological gradients. To test our hypothesis, we examined the distribution of the tribe Bignonieae on 34 1-ha permanent plots systematically distributed over a 42 km2 forested landscape area in Central Amazon. We used proxies for the hydro-edaphic, forest disturbance, and soil nutrient gradients. Liana diversity increased along the hydro-edaphic gradient (i.e., toward dry plateaus), but slightly decreased along the forest disturbance gradient. Further, we found evidence of habitat specialization along the hydro-edaphic gradient on plateaus with deeper water tables, where liana assemblages are subsets of closely related species, exhibiting phylogenetic clustering. The opposite pattern was found on valleys, where liana assemblages were phylogenetically overdispersed. Our results support the role of phylogenetic niche conservatism on plateaus and a stronger environmental filter within the hydrologically dynamic valleys, associated with a functional convergence of more distantly related species. The selection of more distantly related species on hydrologically dynamic areas is a general pattern among trees, palms and now lianas. We conclude that ecological filters and phylogenetic history have played fundamental roles in structuring liana assemblages unevenly at the landscape scale. Fine-scale hydrology determines several aspects of plant community organization, whose mechanisms need to be experimentally investigated in the Amazon basin.