Comparison between the strengths of trait dissimilarity and
hierarchy on spatial patterns
As the absolute trait distances of individual traits used in this study
generally had negative effects on pairwise spatial associations, which
supports environmental filtering or hierarchical competition (Fig. 1d),
we compared the strengths between trait hierarchy and trait
dissimilarity on pairwise spatial associations by simultaneously
including explanatory predictors of both absolute and hierarchical trait
distances in equation (2) to distinguish these two mechanisms. For the
80 focal species in this study, we found that LA, WD, and
Hmax consistently showed stronger trait hierarchy
effects on pairwise spatial associations than trait dissimilarity
effects for more focal species across different summary statistics and
spatial scales
(Fig.
3 and Fig. S2-S6). For SLA and WDMC under situations where we observed
negative relationships between trait dissimilarity and spatial
associations, the strengths of trait hierarchy did not vary
significantly from the strengths of trait dissimilarity effects (Fig. 3
and Fig. S3, Fig. S4 and Fig. S6).
The relationship betweenthe
magnitude that trait hierarchy effect outcompetes trait dissimilarity
effect and the abundance of focal species
Overall, LA, WD and Hmax showed stronger trait hierarchy
effects than trait dissimilarity effects on their pairwise spatial
associations for the 80 focal species. For LA and WD, we observed a
positive relationship between the magnitude that trait hierarchy effects
outcompete trait dissimilarity effects (MHD) and the abundance of each
focal species, while for the trait of Hmax, the MHD
decreased with the abundance of focal species (Fig. 4).