DOI: 10.5061/dryad.9kd51c5ft
title: Data from: Trait hierarchies are stronger than trait dissimilarities in structuring spatial co-occurrence patterns of common tree species in a subtropical forest

description: 1. The dissimilarity and hierarchy of trait values that characterize niche
 and fitness differences, respectively, have been increasingly applied to
 infer mechanisms driving community assembly and to explain species
 co-occurrence patterns. Here, we predict that limiting similarity should
 result in the spatial segregation of functionally similar species, while
 functionally similar species will be more likely to co-occur either due to
 environmental filtering or competitive exclusion of inferior competitors
 (hereafter hierarchical competition). 2. We used a fully mapped 50-ha
 subtropical forest plot in southern China to explore how pairwise spatial
 associations between saplings and between adult trees were influenced by
 trait dissimilarity and hierarchy in order to gain insight into assembly
 mechanisms. We assessed pairwise spatial associations using two summary
 statistics of spatial point patterns at different spatial scales and
 compared the effects of trait dissimilarity and trait hierarchy of
 different functional traits on the interspecific spatial associations.
 These comparisons allow us to disentangle the effects of limiting
 similarity, environmental filtering and hierarchical competition on
 species co-occurrence. 3. We found that trait dissimilarity was generally
 negatively related with interspecific spatial associations for both
 saplings and adult trees across spatial scales, meaning that species with
 similar trait values were more likely to co-occur and thus supporting
 environmental filtering or hierarchical competition. We further found that
 trait hierarchy outweighed trait dissimilarity in structuring pairwise
 spatial associations, suggesting that hierarchical competition played a
 more important role in structuring our forest community than environmental
 filtering across life stages. 4. This study employed a novel method, by
 offering the integration of pairwise spatial association and trait
 dissimilarity as well as trait hierarchy, to disentangle the relative
 importance of multiple assembly mechanisms in structuring co-occurrence
 patterns, especially the mechanisms of environmental filtering and
 hierarchical competition, which lead to indistinguishable co-occurrence
 patterns. This study also reinforced the importance of trait hierarchy
 rather than trait dissimilarity in driving neighborhood competition.
description: Adult (DBH &gt; 10 cm) and saplings (1 cm &lt; DBH &lt;3 cm)
 were measured, identified and mapped in a 50 ha plot established in 2013.
 Data on these traits (leaf area (LA; cm2), specific leaf area (SLA; cm2
 g-1, calculated as leaf area/dry mass), leaf dry matter content (LDMC; g
 g-1, calculated as leaf dry mass/fresh mass), wood density (WD; g cm-3,
 calculated as trunk wood dry mass/fresh volume), wood dry matter content
 (WDMC; g g-1, calculated as dry wood mass/fresh wood mass) and tree
 maximum height (Hmax; m) ) on species-level were collected and measured
 from the HSD plot, in which Hmax was estimated by averaging the top 1%
 tallest trees for each species in the plot.