Divergent roles of environmental and spatial factors in shaping plant β-diversity of different growth forms in drylands

Abstract

The biogeographic patterns and its drivers of plant diversity across drylands have been well documented, while the associated difference in the determinants of plant β-diversity between different growth forms remain unclear. Here, we selected 68 plots from a typical dryland region of Northwest China to explore how and to what extent different environmental and spatial factors influence plant β-diversity of different growth forms. The results showed that environmental and spatial factors were significantly correlated with whole community, shrub and herb β-diversity (P < 0.001), and the combinations of soil, climate, topography, and spatial factors explained approximately 24, 10, and 20% of the variation in whole community, shrub and herb β-diversity, indicating that niche and neutral processes work together to regulate plant β-diversity in drylands of Northwest China. However, the relative contribution of environmental filtering and spatial processes varid between shrub and herb layers, where shrub β-diversity was predominantly determined by spatial processes, but herb β-diversity was largely determined by environmental filtering. Taken together, these findings provide an important empirical evidence that niche processes may not always be dominant processes of community assembly, even in harsh environments of drylands. Future research that focuses on the comparisons among different plant growth forms would likely shed new insights into mechanisms of community assembly under climate change.