Nitrogen fertilization reduces plant diversity by changing the diversity and stability of arbuscular mycorrhizal fungal community in a temperate steppe.

Nitrogen (N) deposition resulting from anthropogenic activities poses threats to ecosystem stability by reducing plant and microbial diversity. However, the role of soil microbes, particularly arbuscular mycorrhizal fungi (AMF), as mediators of N-induced shifts in plant diversity remains unclear. In this study, we conducted 6 and 11 years of N addition field experiments in a temperate steppe to investigate AMF richness and network stability and their associations with plant species richness in response to N deposition. The N fertilization, especially in the 11 years of N addition, profoundly decreased the AMF richness and plant species richness. Furthermore, N fertilization significantly decreased the AMF network complexity and stability, with these effects becoming more enhanced with the increase in N addition duration. AMF richness and network stability showed positive associations with plant diversity, and these associations were stronger after 11 than 6 years of N addition. Our findings suggest that N deposition may lead to plant diversity loss via a reduction of AMF richness and network stability, with these effects strengthened over time. This study provides a better understanding of plant-AMF interactions and their response to the prevailing global N deposition.

Zhang C ，Xiang X ，Yang T ，Liu X ，Ma Y ，Zhang K ，Liu X ，Chu H ... -  《-》

Suppression of Arbuscular Mycorrhizal Fungi Aggravates the Negative Interactive Effects of Warming and Nitrogen Addition on Soil Bacterial and Fungal Diversity and Community Composition.

Yang X ，Yuan M ，Guo J ，Shi L ，Zhang T ... -  《-》

Differential Responses of Arbuscular Mycorrhizal Fungal Communities to Long-Term Fertilization in the Wheat Rhizosphere and Root Endosphere.

Ma Y ，Zhang H ，Wang D ，Guo X ，Yang T ，Xiang X ，Walder F ，Chu H ... -  《-》

Microbial mediators of plant community response to long-term N and P fertilization: Evidence of a role of plant responsiveness to mycorrhizal fungi.

Climate changes and anthropogenic nutrient enrichment widely threaten plant diversity and ecosystem functions. Understanding the mechanisms governing plant species turnover across nutrient gradients is crucial to developing successful management and restoration strategies. We tested whether and how soil microbes, particularly arbuscular mycorrhizal fungi (AMF), could mediate plant community response to a 15 years long-term N (0, 4, 8, and 16 g N m-2  year-1 ) and P (0 and 8 g N m-2  year-1 ) enrichment in a grassland system. We found N and P enrichment resulted in plant community diversity decrease and composition change, in which perennial C4  graminoids were dramatically reduced while annuals and perennial forbs increased. Metabarcoding analysis of soil fungal community showed that N and P changed fungal diversity and composition, of which only a cluster of AMF identified by the co-occurrence networks analysis was highly sensitive to P treatments and was negatively correlated with shifts in percentage cover of perennial C4  graminoids. Moreover, by estimating the mycorrhizal responsiveness (MR) of 41 plant species in the field experiment from 264 independent tests, we found that the community weighted mean MR of the plant community was substantially reduced with nutrient enrichment and was positively correlated with C4  graminoids percentage cover. Both analyses of covariance and structural equation modeling indicated that the shift in MR rather than AMF composition change was the primary predictor of the decline in perennial C4  graminoids, suggesting that the energy cost invested by C4 plants on those sensitive AMF might drive the inferior competitive abilities compared with other groups. Our results suggest that shifts in the competitive ability of mycorrhizal responsive plants can drive plant community change to anthropogenic eutrophication, suggesting a functional benefit of mycorrhizal mutualism in ecological restoration following climatic or anthropogenic degradation of soil communities.

Wang G ，Koziol L ，Foster BL ，Bever JD ... -  《-》

Shifts in plant community composition weaken the negative effect of nitrogen addition on community-level arbuscular mycorrhizal fungi colonization.

Lu Y ，Liu X ，Chen F ，Zhou S ... -  《-》