The degradation of subalpine meadows significantly changed the soil microbiome

Grassland degradation seriously affects the health of our planet, thereby weakening the ability of grasslands to provide multiple ecosystem services. Soil microbes have been recognized as game changers in the succession of degraded lands; therefore, the determination of their responses to grassland degradation is crucial for restoring degraded grasslands. However, soil microbial responses to grassland degradation are still far from being well understood, especially for low-latitude meadows. Hence, this study was performed in one natural and two artificial degraded subalpine meadows in Southern China to identify the soil microbial responses to the degradation of low-latitude subalpine meadows. At each site, soils were collected from nondegraded, moderately degraded, and heavily degraded subalpine meadows. Soil microbial abundance and diversity were analyzed via real-time PCR and amplicon NovaSeq sequencing, respectively. We found that the degradation of subalpine meadows significantly decreased the concentrations of almost all of the soil nutrients and considerably changed soil pH and texture. We also found that soil microbes demonstrated almost consistent responses to the degradation of the natural and artificial subalpine meadows. Specifically, degradation did not affect soil microbial abundance but significantly changed microbial community profiles. The relative abundance of most plant growth-promoting microbial taxa significantly decreased with subalpine meadow degradation, whereas the microbial taxa that were adverse to plant health exhibited a reverse trend. Soil microbial richness was also significantly decreased by the heavy degradation of the subalpine meadows. Additionally, the heavy degradation of the subalpine meadows significantly decreased the complexity and stability of the microbial co-occurrence network. The aforementioned soil microbiome changes also showed the significant correlations with plant biomass. Collectively, the changes in the soil microbiome can be critical factors affecting the degradation of subalpine meadows, and the regulation of soil microbiome is a promising restoration strategy.