Effects of grassland utilization on microbial community structure in Hulunbuir grassland

Grassland soil microorganisms are key elements in maintaining the nutrient cycle function of ecosystems, and are sensitive indicators of changes in grassland ecosystems. Based on the study of soil microbial community composition and soil physicochemical properties under four utilization modes, namely enclosure, mowing, grazing, and reclamation in the Hulunbuir grassland, the effects of grassland utilization mode on grassland microbial communities were expounded. The results showed that: 1) After grassland reclamation, the soil total carbon (TC) and nitrogen (TN) content decreased by 41.45% and 45.08%, respectively, whereas the electrical conductivity (EC) and available phosphorus (AP) content increased by 371.93% and 139.93%, respectively, and the phospholipid fatty acid (PLFA) content of the farmland microbial community was limited by carbon and nitrogen. 2) Compared with enclosed grassland, grazing grassland, and farmland, mowing significantly increased the PLFA of soil bacteria, fungi, actinomycetes, gram-positive bacteria (G⁺), gram-negative bacteria (G⁻), and microbial communities. 3) According to the comprehensive analysis of the four grassland utilization modes, TC and TN were positively correlated with PLFA content of soil bacteria, fungi, actinomycetes, G⁺, G⁻, and other microbial communities, while AP, pH, and EC were negatively correlated. Therefore, grassland reclamation resulted in soil carbon and nitrogen nutrient loss for farmland and further reduced the amount of PLFA in the microbial community. Considering the reduction in soil nutrients and PLFA in microbial communities, it is not recommended that Hulunbuir grasslands be reclaimed as farmland.