Mowing mitigates the adverse effects of fertilization on plant diversity and changes soil bacterial and fungal community structure in the Inner Mongolia grassland

Abstract

Fertilization and mowing are commonly used grassland management measures. However, an understanding of how plant, soil bacterial, and soil fungal diversity responds to these two management measures are limited. We ran a fertilization and mowing experiment using a completely randomized design for 7 years (from 2014 to 2020) to explore the effects of fertilization and mowing on plant, soil bacterial, and soil fungal diversity. We used one-way and two-way Analysis of Variance (ANOVA) to compare how fertilization and fertilization + mowing impacted plant, soil bacterial and fungal diversity. We also used a structural equation model to analyze the maintenance mechanisms about fertilization and mowing affecting plant, soil bacterial, and soil fungal diversity. Our ANOVA results showed that when nitrogen addition level was beyond 8 GNM-2YR-1, fertilization significantly reduced plant taxonomic and functional diversity. However, the fertilization + mowing significantly increased plant diversity compared to fertilization. Fertilization and fertilization + mowing had no significant effect on soil bacterial and fungal diversity, but could change soil bacterial and fungal community structure by altering soil pH. Our structural equation model showed that fertilization reduced plant diversity mainly by increasing light competition in plant community and causing soil acidification. These results confirm light competition and soil acidification as maintenance mechanisms of fertilization and mowing affecting grassland plant diversity. Our findings highlight mowing can mitigate the adverse effects of fertilization on grassland plant diversity. However, the application of fertilization + mowing in grassland management needs to consider fertilization concentration.