Interactions of soil water content heterogeneity and species diversity patterns in semi-arid steppes on the Loess Plateau of China

Abstract

• Coverage, biomass were significantly increased with surface soil water contents. • Plant diversity were closely correlated to soil water content of 0–10 cm soil layer. • Soil water content affect species richness and then affect belowground biomass. • Species diversity is an indicator of community responses to soil water content. Soil water is a major driving force for plant community succession in semi-arid area. Many studies have focused on the relationships of species diversity–productivity, but few studies have paid attentions to the effects of soil water content heterogeneity on the plant species diversity in the semi-arid loess regions. To determine relationship of soil water content heterogeneity and plant community structure properties a semi-arid steppe on the Loess Plateau, we conducted a gradient analysis of soil water content variation and above- and below-ground properties of plant communities. Results showed that community coverage, above- and below-ground biomass were significantly and positively related to the surface soil water contents (0–5 cm). Plant diversity (Shannon index and Richness index) were closely correlated to soil water content at the soil depth of 0–10 cm. But plant height, litter biomass and root/shoot ratio were not related to soil water content. These results showed that there is an positive interaction effects for plant diversity and soil water content in the semi-arid grassland communities. Our observations indicate that change of plant species diversity is also an important community responses to soil water content heterogeneity in the semi-arid grassland ecosystem.