Biodiversity and soil moisture drive the response of ecosystem multifunctionality to grassland salinization

Abstract

Salinization is well known to impair ecosystem functions. Many researchers have focused on the variation in individual ecosystem functions caused by salinization. However, few researchers have considered ecosystem multifunctionality (EMF) at above- and belowground biodiversity levels under salinization conditions. In particular, the relationship between multiple ecosystem functions and ground-dwelling arthropod biodiversity with grassland salinization has been rarely explored. Here, we assessed the effects of grassland salinization on soil nutrients, productivity, biodiversity and overall EMF in the Hexi Corridor Region, Gansu Province, China. Both the direct effect of grassland salinization and the indirect effects of plant richness, ground-dwelling arthropod diversity and abiotic factors on EMF were quantified. Our results showed that salinization significantly impaired the EMF of the salinized grasslands. The EMF was significantly and positively related to plant richness, ground-dwelling arthropod taxa richness and soil water content, but not to soil pH. Structural equation modeling revealed that grassland salinization indirectly affects the EMF through soil moisture, plant species and ground-dwelling arthropod taxa richness changes. Plant species richness indirectly influences EMF by controlling ground-dwelling arthropod taxa richness. Overall, biodiversitiy and soil moisture are crucial in mediating the response of EMF to grassland salinization.