放牧强度对典型草原土壤微生物特征的影响

Effects of Grazing Intensity on Soil Microbial Characteristics of Typical Grassland

在内蒙古典型草原,以32年围封样地为对照,选取4个放牧强度样地(3.0羊单位/hm2、4.5羊单位/hm2、6.0羊单位/hm2和7.5羊单位/hm2),分层测定0～10cm、10～20cm和20～30cm土壤细菌、放线菌和霉菌的数量及微生物生物量碳和氮,分析不同放牧强度对典型草原土壤微生物主要特征的影响,结果表明:(1)三种微生物数量在各土层及0～30cm区域内均呈显著性差异,且霉菌<放线菌<细菌;(2)土壤微生物数量及生物量碳和氮均随着土层深度的增加而减少,不同深度土层之间呈极显著差异(P<0.01);(3)围封或轻度放牧利用下土壤微生物数量和生物量碳和氮高于其他放牧强度;(4)不同微生物种类对放牧强度响应的敏感程度不同,微生物数量变异规律为霉菌<细菌<放线菌,土壤微生物量碳、氮表现相对稳定。

In typical grassland of Inner Mongolia, four different grazing intensity （3.0, 4.5, 6.0 and 7.5 sheep/ hm2） were chosen, compared to control which enclosed 32 years, the number of soil bacteria, actinomyces,mold, soil microbial biomass carbon and nitrogen in soil of 0-10cm, 10-20 cm and 20-30 cm were determined. The influence of different grazing intensity on the main characteristics of soil microor- ganisms in the typical grassland was analyzed, the results showed that： （1） the quantity of three kinds of microbes in every soil layer and in 0 to 30 cm in depth were significantly different, and the order was mold actinomycetes% bacteria; （2） soil microbial number and biomass carbon and nitrogen were increased with the increase of soil depth, there were extremely significant differences between different soil depth （P 0.01） ; （3） the soil microbial number, hiomass carbon and nitrogen under enclosed and light grazing ar- ea were higher than other grazing intensity; （4） the different microbial species had different response sen- sitive degree to the grazing intensity, microbial quantity variation rule were mold 〈 bacteria 〈 actinomy- ces, and the soil microbial biomass carbon and nitrogen was relatively stable.