中文摘要：

研究了克氏针茅（Stipa krylovii）草原未退化、中度退化和重度退化草地的植被和土壤微生物的季节动态。结果表明, 随退化程度增加, 克氏针茅的重要值降低, 冷蒿（Artemisia frigida）的重要值增加, 重度退化草地群落多样性最低。重度退化草地土壤全氮含量最高而有效磷含量最低。未退化草地土壤微生物碳、氮含量高于退化草地, 草地退化对菌根真菌（AMF）孢子密度、细菌、真菌和放线菌数量的影响随季节变化而不同。5―8月未退化草地真菌数量大于重度退化草地, 9月两者差异不显著。7―9月未退化草地细菌数量大于重度退化草地, 6月两者差异不显著。各指标均在7月或8月达到最高值。土壤真菌、细菌、放线菌与土壤全氮、微生物氮均有显著相关性。土壤真菌、细菌与土壤微生物碳有显著相关性。

英文摘要：

服务 Plant community and soil microbial characteristics in undegraded, moderate and heavy degraded grasslands were studied. The important value （IM） of Stipa krylovii decreased with grassland degradation, but IM of Artemisia frigida increased. Plant diversity of undegraded and moderate grassland were higher than that of heavy degraded grassland. Total soil nitrogen concentration of heavy degraded grassland was higher than that of undegraded and moderate grasslands, but soil available phosphorus of heavy degraded grassland was the lowest. Soil carbon and nitrogen microbial biomass of undegraded grasslands were higher than degraded grassland. The effects of degradation on arbuscular mycorrhizal fungal spore density and number of bacteria, actinomyces and fungi depended on seasonal dynamics. Number of fungi in undegraded grassland was higher than heavy degraded grassland from May to August, but there was no significant difference between these two types of grassland in September. Number of bacteria in undegraded grassland was higher than heavy degraded grassland from July to September, but there was no significant difference between these two types of grassland in June. Total soil nitrogen concentration, soil available phosphorus, and number of microorganism were highest in July or August. There was significant linear correlation between number of bacteria, actinomyces or fungi and total soil nitrogen or microbial biomass nitrogen. There was significant linear correlation between Number of bacteria and actinomyces and microbial biomass carbon.