Usman Muhammad, Li Lan, Wang Mengyuan, Wang Zhen, Hu An, Shi Liyuan, Hou Fujiang
State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Engineering Technology Research Center for Ecological Restoration and Utilization of Degraded Grassland in Northwest China, National Forestry and Grassland Administration, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China.
State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, Engineering Technology Research Center for Ecological Restoration and Utilization of Degraded Grassland in Northwest China, National Forestry and Grassland Administration, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China.
Environ Res. 2024 Apr 1;246:118126. doi: 10.1016/j.envres.2024.118126. Epub 2024 Jan 8.
Livestock grazing is an influencing factor playing a key role in shaping the plant community, microbial community, and soil properties in grassland ecosystems. Northern China's Loess Plateau has been used for livestock grazing for centuries and is a vulnerable ecosystem. In this study, the fates of bacterial and fungal communities of the typical steppe of the Loess Plateau were investigated under increasing grazing intensities practiced in summer and winter seasons. The results revealed changes in soil physiochemical properties, plant community properties, and microbial diversity in response to alterations in the grazing intensity. The alpha diversity of microbial communities (including bacteria and fungi) exhibited an uneven trend during summer grazing due to an increase in grazing intensity, but it decreased during winter grazing; however, the observed changes were not significant. The beta diversity of the bacterial community was highly influenced by grazing intensity, the summer community clustered near nongrazing, and the winter community presented significantly different results. The beta diversity of the fungal community was not influenced by grazing intensity or season. Grazing induced the growth of fast-growing bacteria (such as Actinobacteria and Firmicutes) and saprophytic fungi and a reduction in overall pathogenic traits. Co-occurrence network analysis and a structural equation model revealed changes in soil and plant properties (such as soil nitrogen level, soil organic carbon level, aboveground biomass, and litter biomass), with an increase in grazing intensity contributing to alterations in bacterial and fungal diversities. This finding demonstrates that grazing intensity can directly affect soil microbes and play an indirect role by modifying soil nutrients and reducing plant biomass, which eventually contributes to changes in microbial communities. Overall, implementing low grazing intensity is suggested for maintaining the microbial community structure the same as that of the native microbiome (ungrazed) in the steppe ecosystems.
牲畜放牧是影响草原生态系统中植物群落、微生物群落和土壤性质的关键因素。中国北方的黄土高原几个世纪以来一直用于牲畜放牧，是一个脆弱的生态系统。在本研究中，调查了黄土高原典型草原在夏季和冬季放牧强度增加的情况下细菌和真菌群落的命运。结果表明，土壤理化性质、植物群落性质和微生物多样性随放牧强度的变化而改变。微生物群落（包括细菌和真菌）的α多样性在夏季放牧期间由于放牧强度增加呈现出不均匀的趋势，但在冬季放牧期间有所下降；然而，观察到的变化并不显著。细菌群落的β多样性受放牧强度的影响很大，夏季群落聚集在接近未放牧的区域，而冬季群落呈现出显著不同的结果。真菌群落的β多样性不受放牧强度或季节的影响。放牧诱导了快速生长细菌（如放线菌和厚壁菌）和腐生真菌的生长，并降低了总体致病特征。共现网络分析和结构方程模型揭示了土壤和植物性质（如土壤氮水平、土壤有机碳水平、地上生物量和凋落物生物量）的变化，放牧强度的增加导致细菌和真菌多样性的改变。这一发现表明，放牧强度可以直接影响土壤微生物，并通过改变土壤养分和减少植物生物量发挥间接作用，最终导致微生物群落的变化。总体而言，建议实施低放牧强度，以维持草原生态系统中与原生微生物群落（未放牧）相同结构的微生物群落。
