Community composition, structure and productivity in response to nitrogen and phosphorus additions in a temperate meadow.

Global nitrogen (N) enrichment likely alters plant community composition and increases productivity, consequently affecting ecosystem stability. Meanwhile, the effects of N addition on plant community composition and productivity are often influenced by phosphorus (P) nutrition, as the effects of N and P addition and interactions between N and P on plant community structure and productivity are still not well understood. An in situ experiment with N and P addition was conducted in a temperate meadow in northeastern China from 2013 to 2016. The responses of plant community composition, structure, functional group cover, richness and productivity to N and P additions were examined. N addition significantly reduced species richness and diversity but increased aboveground net primary productivity (ANPP) during the four-study-year period. P addition exerted no significant impact on species richness, diversity or ANPP but reduced cover of grasses and increased legume cover. Under N plus P addition, P addition alleviated the negative effects of N addition on community structure by increasing species richness and covers of legume and forbs. N and P additions significantly altered plant community structure and productivity in the functional groups. N addition significantly increased the cover of gramineous and reduced the cover of legume, P addition significantly increased legume cover. Our observations revealed that soil nutrient availability regulates plant community structure and ANPP in response to nutrient enrichment caused by anthropogenic activities in the temperate meadow. Our results highlight that the negative influence of N deposition on plant community composition might be alleviated by P input in the future.