Role of soil biotic and abiotic properties in plant community composition in response to nitrogen addition

Abstract Nutrient addition can alter plant–soil‐microbe interactions. However, knowledge remains limited about how the soil biotic and abiotic properties drive changes in plant community composition and diversity after nitrogen (N) addition. In this study, four N addition rates (N0, N3, N6, and N9: 0, 3, 6, and 9 g N m −2 yr −1 ) were applied to a grassland community on the Loess Plateau (China) to evaluate the response of plant community biomass, evenness, and composition to N addition. Overall, N addition significantly increased plant shoot and root biomass by 27.75%–31.37% and 39.60%–65.42% compared with N0, but no significant difference was observed among N3, N6, and N9. N addition significantly decreased shoot/root biomass ratio by 7.17%–21.84%, and plant community evenness by 3.80%–8.80% compared with N0, particularly under N3 and N6 treatments. Furthermore, N addition enhanced the abundance of bacteria and fungi, but their composition was not altered. Responses of plant biomass and evenness to N addition were correlated to changes in NO 3 − ‐N, soil total phosphorus, and the abundance of bacteria and fungi; additionally, the composition was primarily affected by the microbial abundance. Our research indicates that N addition can significantly alter plant community composition, particularly at low addition rates, and such alteration may be more affected by the soil microbial abundance. The findings of this study have important implications for the sustainable management of grassland ecosystems.