Data for taxon-dependent effects of dispersal limitation versus environmental filters on bryophyte assemblages―Multiple perspective studies in land-bridge islands

Aim: To explore the taxon-dependent contribution of dispersal limitation
vs. environmental filters to bryophyte assemblages. Location: The Thousand
Island Lake, China Taxon: Bryophytes Methods: We compared the observed
beta diversity with the expected values based on six null models (EE, EF,
FE, FF, PE, PF) and detected the partial correlation of beta diversity
with geographical distances. We quantified the contributions of spatial
vs. environmental variables, and island isolation per se to species
composition (SC) by using variance partitioning. We modeled the
species-area relationships (SARs) for bryophytes and other eight biotas.
To explore the taxon-dependent effects of spatial vs. environmental
filters on bryophytes, sixteen taxa including five categories (total
bryophytes, total mosses, liverworts, acrocarpous and pleurocarpous
mosses) and eleven species-richest families were included in the analyses.
Results: The observed beta diversity values were significantly different
from the predicted values based on the six null models for all 16 taxa.
For all five categories, the observed partial correlations between beta
diversity and geographical distance after controlling environmental
effects were not only positive but also significantly different from the
predicted values based on the null models. Spatial eigenvectors are more
important in shaping SC than environmental variables for all 16 taxa
except Brachytheciaceae and Anomodontaceae. Spatial eigenvectors
contributed more to SC variation in liverworts than in mosses, and in
pleurocarpous mosses than in acrocarpous mosses. The effects of island
isolation on SC were significant for all five categories and varied highly
at the family level. The z-values of the SARs for the five bryophyte
categories were all larger than those of the other eight biotas. Main
conclusions: In subtropical fragmented forests, dispersal limitation
exerted significant, taxon-dependent effects on bryophyte assemblages. It
was dispersal limitation rather than environmental filtering that
predominantly regulated SC patterns of bryophytes.