Effect of human intervention on soil microbial community in desertification grassland of the Yellow River Source Region

Soil microorganisms are an important part of grassland ecosystems. The soil microbial community structure is an effective indicator for reflecting the changes in soil quality. The desertified grassland of the Yellow River source region was the focus of this study, for which Illumina MiSeq sequencing was used to investigate the effects of different human intervention measures unmanaged plots (CK), planting plots of 4 years (P₁), rocky checkerboard sand barriers and planting plots of 4 years (P₂), and rocky checkerboard sand barriers and planting plots of 12 years (P₃) on the bacterial and fungal community structures. Our results showed that: 1) for bacteria, the CK and P₁ groups were placed into one group, with P₂ and P₃ in another; for fungi, CK and P₁ were grouped first, then clustered with P₂, whilst P₃ was significantly different from the other three samples; 2) the content of the soil organic carbon and nitrate nitrogen in P₃ was significantly higher than that in CK and P₂ (P < 0.05), whereas the content of the total soil ammonium nitrogen showed no significant differences in any of the plots (P > 0.05); 3) the plant coverage in P₃ was significantly higher than that in CK and P₂ (P < 0.05), whilst the above-ground biomass of forbs in P₃ was significantly higher than that in CK (P < 0.05). Our research suggests that the rocky checkerboard sand barriers and growing plants are effective measurements for combating desertification in alpine-cold areas. Additionally, the mixed human intervention measure is conducive to the change of the soil microbial community structure, accumulation of soil organic matter, and growth of grass seedlings in the early period of restoration of desertified grassland.