Data from: β-diversity of herbaceous versus woody plant communities across a tropical rainfall gradient

Aim: Most of our current knowledge of tropical forest plant communities is
based on trees, despite the substantial contribution of other life forms
to plant diversity in these systems. In particular, studies of understory
herbaceous plants are limited. With their lower dispersal abilities,
higher rates of evolution, and lower drought tolerance than trees, herbs
are expected to exhibit different patterns of species composition across
space. The aim of the study is to compare the patterns and drivers of
variation in species composition (i.e., β-diversity) of trees and
understory herbaceous plants.Location: Mudumalai, Western Ghats,
India.Time period: 2018 - 2019.Major taxa studied: Angiosperms.Methods: We
surveyed tree and understory herb communities in 13 one-ha plots along a
strong rainfall gradient in a seasonally dry forest landscape in the
Western Ghats, India. In both groups, we estimated among-plot β-diversity,
which we decomposed into two components: turnover and nestedness. Then we
partitioned the relative influences of spatial and environmental
predictors, including rainfall, temperature, soil, and fire frequency, on
β-diversity.Results: Contrary to our expectations, β-diversity was
remarkably similar for herbs and trees, and both groups exhibited high
turnover along the gradient. Rainfall and temperature explained the most
variation in composition within both groups, while fire and soil explained
less variation, and their effects differed between groups.Main
Conclusions: While trees and herbs show contrasting patterns of
α-diversity across this rainfall gradient, our study suggests that both
life forms are impacted strongly by environmental filtering, predominantly
rainfall and temperature, resulting in similar patterns of β-diversity.
The high turnover observed in tree and herb communities, and the influence
of rainfall and temperature in structuring these communities, should be
considered when designing conservation and restoration strategies in the
face of ongoing global changes and other anthropogenic pressures on
tropical forests.