DOI: 10.5061/dryad.6v0gd
title: Data from: Using plant functional traits and phylogenies to understand patterns of plant community assembly in a seasonal tropical forest in Lao PDR

description: Plant functional traits reflect different evolutionary responses to
 environmental variation, and among extant species determine the outcomes
 of interactions between plants and their environment, including other
 plant species. Thus, combining phylogenetic and trait-based information
 can be a powerful approach for understanding community assembly processes
 across a range of spatial scales. We used this approach to investigate
 tree community composition at Phou Khao Khouay National Park
 (18°14’-18°32’N; 102°38’- 102°59’E), Laos, where several distinct forest
 types occur in close proximity. The aim of our study was to examine
 patterns of plant community assembly across the strong environmental
 gradients evident at our site. We hypothesized that differences in tree
 community composition were being driven by an underlying gradient in soil
 conditions. Thus, we predicted that environmental filtering would
 predominate at the site and that the filtering would be strongest on
 sandier soil with low pH, as these are the conditions least favorable to
 plant growth. We surveyed eleven 0.25 ha (50x50 m) plots for all trees
 above 10 cm dbh (1221 individual trees, including 47 families, 70 genera
 and 123 species) and sampled soils in each plot. For each species in the
 community, we measured 11 commonly studied plant functional traits
 covering both the leaf and wood economic spectrum traits and we
 reconstructed a phylogenetic tree for 115 of the species in the community
 using rbcL and matK sequences downloaded from Genebank (other species were
 not available). Finally we compared the distribution of trait values and
 species at two scales (among plots and 10x10m subplots) to examine trait
 and phylogenetic community structures. Although there was strong evidence
 that an underlying soil gradient was determining patterns of species
 composition at the site, our results did not support the hypothesis that
 the environmental filtering dominated community assembly processes. For
 the measured plant functional traits there was no consistent pattern of
 trait dispersion across the site, either when traits were considered
 individually or when combined in a multivariate analysis. However, there
 was a significant correlation between the degree of phylogenetic
 dispersion and the first principle component axis (PCA1) for the soil
 parameters. Moreover, the more phylogenetically clustered plots were on
 sandier soils with lower pH. Hence, we suggest that the community assembly
 processes across our site may reflect the influence of more conserved
 traits that we did not measure. Nevertheless, our results are equivocal
 and other interpretations are possible. Our study illustrates some
 difficulties in combining trait and phylogenetic approaches that may
 result from the complexities of integrating spatial and evolutionary
 processes that vary at different scales.
description: Tree species
 assemblagesData on plots of tree
 &gt; 10 cm dbhcommunity.csvPhylogenetic tree-rootedSpecies phylogeny for treesspecies functional trait matrixPlant Functional Traitstrait.csvPhylogenetic structure analysisR-script for phylogenetic analysesTrait and phylogenetic similarityR-script for trait and phylogenetic similarity analysisTrait dispersion analysisR-script for functional trait dispersion analysis