Beta diversity of epiphyllous bryophyte communities increases with microclimate fluctuation

Background/Question/Methods

Beta diversity is a major component of regional diversity. However, we have little understanding of factors that regulate beta diversity. The current study uses leaf-dwelling (epiphyllous) bryophyte communities as a model system to investigate the effects of microclimate on beta diversity. Over 800 epiphyllous bryophytes communities from 36 sites on the island of Mo'orea, French Polynesia were collected and identified. At each site, temperature and relative humidity were measured and converted to vapor pressure deficit (VPD). The multivariate dispersion among communities within each site was calculated as a measure for beta diversity, 

Results/Conclusions

The analysis showed that beta diversity increased significantly with the increasing range of VPD at a given site. The results suggest that epiphyllous communities tend to be more varied (higher beta diversity) in a habitat experiencing a greater amount of change in amount of water vapor available. The finding is consistent with previous anecdotal observations, as well as theoretical predictions from community assembly of epiphyllous communities.