呼伦贝尔草原不同利用方式对土壤微生物群落结构的影响

The Influence of Different Utilization Methods of Hulunbuir Grassland on the Structure of Soil Microbial Clusters

土壤微生物是土壤生态环境变化的敏感因子,其群落组成及结构易受到人为干扰的影响。本研究通过比较内蒙古呼伦贝尔草地在围封、割草、连续放牧、休牧等不同利用方式下土壤微生物群落组成及结构的差异,结合土壤理化性状的变化阐明影响土壤微生物群落的主要因素,探索有利于土壤微生态环境的草地利用方式。结果显示:生长季节休牧处理的土壤微生物磷脂脂肪酸总量均高于其他利用方式,随着休牧时间的推后,土壤微生物数量呈升高趋势;连续放牧处理下土壤中的革兰氏阳性菌/革兰氏阴性菌比值最大,表明连续放牧降低土壤底物的养分供给能力,影响微生物生长;土壤理化性质与微生物的冗余分析表明,土壤pH值及电导率是影响土壤微生物群落结构的主要因子,高电导率且偏碱性土壤更有利于土壤微生物生存。因此,土壤盐碱度和pH值可作为呼伦贝尔草原土壤微生物群落结构及功能的关键预测指标。

Soil microorganisms are sensitive factors of soil ecological environment changes,and their community composition and structure are easily affected by human disturbance.This study compared the differences in soil microbial community composition and structure under different utilization methods such as enclosure,mowing,continuous grazing,and rest grazing in Hulunbuir grassland in Inner Mongolia,combined with changes in soil physical and chemical properties to clarify the main factors affecting soil microbial communities,and explored the grassland utilization method which was conducive to the soil micro-ecological environment.The results showed that:(1)The total amount of PLFA in the soil under the no-grazing treatment during the growing season was higher than that of other utilization methods.With the delay of the no-grazing time,the number of soil microorganisms showed an upward trend;(2)The ratio of gram-positive bacteria/gram-negative bacteria was the largest,indicating that continuous grazing reduced the nutrient supply capacity of soil substrates and affected the growth of microorganisms;(3)Redundant analysis of soil physical and chemical properties and microorganisms showed that soil pH and electrical conductivity were the main factors affecting the structure of soil microbial community.High conductivity and alkaline soil was more conducive to the survival of soil microbes.Therefore,soil salinity and pH could be used as key predictors for the structure and function of soil microbial community in Hulunbuir grassland.