Short-term nitrogen and phosphorus additions rather than mycorrhizal suppression determine plant community composition and productivity in desert steppe

Abstract

Anthropogenic enrichment of soil nitrogen (N) and phosphorous (P) has dramatically altered ecosystem structures and functions. However, our understanding of the interactions between soil nutrient enrichment and arbuscular mycorrhizal (AM) fungi with plant community performance remains elusive. We examined the impacts of soil N and P enrichment and mycorrhizal suppression on plant community composition and productivity in desert steppe. Our results showed that short-term addition of P alone and combined N and P had stronger influence on plant community composition and productivity, but the addition of N alone had a minimal effect. Individual and combined addition of N and P mainly altered plant community productivity by increasing the biomass of annual forbs, but decreasing that of perennial forbs and C3 grasses, regardless of AM fungi. AM fungal suppression did not alter plant community composition and productivity. Addition of P alone and combined N and P slightly increased plant species richness and diversity. Our findings highlight that the short-term N and P enrichments, rather than the presence of AM fungi, change plant community dynamics in desert steppe.