Livestock grazing increases soil bacterial alpha-diversity and reduces microbial network complexity in a typical steppe

Abstract

The preservation of biodiversity and the proper functioning of grassland ecosystems depend on our ability to understanding the effects of livestock grazing on soil characteristics and microbial communities. However, how soil microbial communities— including their diversity, composition, and network complexity—respond undergo change in response to increasing grazing intensity in typical grasslands remains unclear. To address this, a meticulously designed, ten-year controlled experiment was conducted in a typical grassland in Inner Mongolia to investigate changes in the soil microbial community under increasing grazing intensity. The results showed that grazing significantly affected the structure and composition of soil microorganisms, leading to a significant decrease in bacterial β-diversity with increasing grazing intensity. In contrast, bacterial α-diversity significantly increased, while fungal α-diversity remained largely unchanged. However, higher grazing intensities reduced soil multifunctionality and network complexity, with stronger effects on bacteria. These findings enhance our understanding of how grazing intensity influences microbial communities and provide a theoretical basis for assessing grazing’s impact on grassland soil ecosystems, thereby addressing a critical knowledge gap regarding its effects on subsurface ecosystems.