【摘要】 以祁连山北支冷龙岭东段南麓的甘柴滩夏季牧场集体长期混合(藏系绵羊、牦牛)放牧的高寒金露梅(Potentilla fruticosa)灌丛草地为对象,采用平板涂抹分离法和氯仿熏蒸法对不同放牧压力梯度下土壤微生物(细菌、真菌和放线菌)和土壤微生物碳、微生物氮量进行研究,结果表明:不同放牧压力梯度下,金露梅灌丛和丛间草地土壤微生物以细菌占绝对优势,放线菌和真菌较少,垂直分布明显;随着放牧压力梯度的增加,金露梅灌丛和丛间草地,0～25cm土层中的细菌、放线菌、真菌及微生物碳和微生物氮数量呈降低趋势,其降低程度与放牧压力梯度呈直线正相关。与无放牧金露梅灌丛相比0～25cm土层的细菌、真菌、放线菌最大降幅分别为49.64%、37.76%和46.64%;金露梅灌丛土壤微生物碳量占土壤有机碳的比例变化为0.85%～0.43%,微生物氮占土壤全氮的0.90%～1.11%,微生物量对土壤营养库的贡献率较低;土壤微生物量和土壤有机质呈显著线形正相关;土壤细菌数量和土壤水分呈显著线形正相关。更多还原

【Abstract】 This study was carried out in collective-shared summer grassland in Ganchaitan, which is located at the south foot of east- ern Lenglongling Mountain (a branch of north Qilian Mountain), with yak and Tibetan sheep miscellaneously grazing on it. The grassland could be classified as alpine meadow, dominated by potentilla froticosa shrub (PFS). This study, under grads grazing stress, focused on soil microbial (bacteria, fungi and actinomycetes), soil microbial biomass carbon and soil microbial biomass nitrogen of PFS by using dilute plate counting and chloroform fumigation methods. Results showed that under different grads of grazing pres- sure, bacteria was predominate biology in soil microbial, fungi and actinomycetes were less and had an obviously vertical distribu- tion among PFS and amongst PFS grassland. As the grads of grazing pressure increasing, the amount of bacteria, actinomycetes, fungi, microbial biomass carbon and microbial biomass nitrogen had a trend of decline in grassland amongst PFS and PFS grass- land(in soil 0~25 cm layer), and there was a linear positive correlation between the reduced degree and the intensity of grazing pres- sure. The amount of bacteria, actinomycetes and fungi were decreased by 49.64%, 37.76% and 46.64% respectively, compared with the non-grazing in grassland amongst PFS (in soil 0~25 cm layer). The ratio of microbial biomass carbon in grassland amongst PFS soil organic carbon was changed between 0.85%～0.43%, The ratio of microbial biomass nitrogen in soil total nitrogen was 0.90%～ 1.11%, microbial biomass had a little contribution to soil nutrition base. There were a significant linear positive correlation between soil microbial biomass and soil organic matter, between the amount of soil bacteria and soil water content.更多还原