Regional and local patterns of soil arthropod diversity are explained by different processes in southwest China

Abstract

Understanding the distribution patterns and underlying mechanisms of community assembly at different spatial scales is crucial for the ecology and conservation of organisms, yet little is known about soil arthropods. In this study, we tested the relative importance of the two hypotheses that could explain soil arthropod distribution patterns at local and regional scales: (1) the habitat heterogeneity hypothesis (spatial complexity and variability of a habitat allow the coexistence of many species), and (2) the more-individuals hypothesis (the amount of resources per se, regardless of its spatial heterogeneity, increases overall soil arthropod abundance and richness). We extensively collected soil arthropods (identified to families or subfamilies) and measured soil physicochemical properties in four forests distributed across latitudes in Yunnan Province, China. We found that soil arthropod abundance and taxon richness increased with increasing latitudes, contrasting with the generally known pattern for plants and aboveground animals. Litter biomass (resources) explained the taxon richness and abundance at the regional scale, which aligned with the more-individuals hypothesis. Other soil physicochemical properties (e.g., Ca, TP, Mg, Mn, and pH) were more important at the local scale, underpinning the habitat heterogeneity hypothesis. However, the relative importance of individual soil properties was highly location-specific, suggesting that the environmental factors operating in one location do not necessarily reflect those operating in others at different latitudes. These findings improve our understanding of the community assembly and ecological processes of soil arthropods at different spatial scales, which is vital for predicting the future of soil biodiversity.