中文摘要：

采用凋落物分解袋法,以宁南山区典型草本植物长芒草、铁杆蒿、百里香为研究对象,分析了3种植物茎叶分解过程中土壤酶活性变化特征和分解后期微生物多样性特征,以及土壤酶活性与初始土壤化学性质的关系.结果表明：植物茎叶分解480 d后,各处理土壤酶活性均有不同程度的增加,且长芒草处理土壤蔗糖酶活性和碱性磷酸酶活性最高,分别为32.40和1.99 mg·g-1·24 h-1,百里香处理土壤脲酶活性最高（2.66 mg·g-1·24 h-1）,铁杆蒿处理土壤纤维素酶活性最高（1.42 mg·g-1·72 h-1）.分解末期土壤纤维素酶活性与土壤初始微生物生物量碳呈显著正相关;分解末期土壤纤维素酶活性与土壤初始硝态氮含量呈显著负相关.添加植物茎叶处理土壤细菌和真菌的Ace指数、Chao指数和Shannon指数均显著大于对照,Simpson指数显著小于对照.植物茎叶的分解显著提高了土壤细菌和真菌的丰度及多样性,进而提高了植物茎叶的分解速率,促进了生态系统营养物质的循环与转化.

英文摘要：

With the method of litter bags,the characteristics of soil enzyme activities,soil microbial diversity at later stage of decomposition,and the relationships between soil enzyme activity and initial soil property were investigated in the process of stem and leaf decomposition of three typical herbs,i.e.,Stipa bungeana,Artemisia sacrorum and Thymus mongolicus in the south Ningxia loess hilly region,Northwest China.The results showed that soil enzyme activity increased under different treatments after 480 d during stem and leaf decomposition.Soil sucrose activity（32.40 mg·g-1·24 h-1） and alkaline phosphatase activity（1.99 mg·g-1·24 h-1） were the highest in S.bungeana treatment.Soil urease activity（2.66 mg·g-1·24 h-1） was the highest in T.mongolicus treatment,and soil cellulase activity（1.42 mg·g-1·72 h-1） was the highest in A.sacrorum treatment.Soil cellulose activity at later stage of decomposition had significant positive correlation with initial microbial biomass carbon of soil.Soil cellulose activity at later stage of decomposition had significant negative correlation with initial nitrate nitrogen content of soil.Ace index,Chao index and Shannon index of soil bacteria and fungi in plant tissue addition treatments were higher than in the control.However,Simpson index was opposed.The stem and leaf decomposition significantly promoted the abundance and diversity of soil bacteria and fungi,accelerated the decomposition rate of stems and leaves,and promoted the cycle and transformation of soil nutrients.