Importance of plant community composition and aboveground biomass in shaping microbial communities following long-term nitrogen and phosphorus addition in a temperate steppe ecosystem

Abstract

Background and aims

Human activities have increased the input of nitrogen (N) and phosphorus (P) into terrestrial ecosystems since the industrial revolution. These activities are expected to increase aboveground biomass (AGB) and further affect plants and soil microbial communities. Plant–microbe interactions play a significant role in shaping microbial communities. However, how soil microbial community respond to change in plant communities after N and P addition remains unclear, particularly in temperate steppe ecosystems.

Methods

A 12-year factorial combination experiment of N and P addition was conducted in a temperate steppe ecosystem to evaluate soil microbiomes in relation to plant communities and soil characteristics.

Results

Long-term N addition shifted the dominance of plant community from multiple species to sole dominance by Leymus chinensis. N addition did not significantly affect microbial α-diversity. However, P addition led to significantly increased bacterial richness, while NP addition led to significantly decreased arbuscular mycorrhizal fungal richness. Structural equation modeling indicated that available phosphorous (AP) significantly affected bacterial richness, while AP, dissolved inorganic nitrogen (DIN), and AGB significantly influenced arbuscular mycorrhizal fungal richness. Nutrient addition also significantly altered soil microbial community structures that can largely be explained by AGB and plant community compositions. Finally, network analysis revealed strong correlations between plant functional groups and dominant microbial taxa.

Conclusions

Microbial communities can be influenced by both N and P addition-induced changes in soil properties and plant communities. The significant associations between plant functional groups and dominant microbial taxa emphasize the important roles of plant-mediated effects on microbial communities after N and P addition.