Data from: Trait hierarchies are stronger than trait dissimilarities in structuring spatial co-occurrence patterns of common tree species in a subtropical forest

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.