中文摘要：

森林是具有重要服务功能的生态系统之一,在城区和郊区都普遍存在,但对于森林土壤微生物群落特征的城郊差异研究却很少。本研究在北京城市与郊区选择三种相同树种（油松Pinus tabulaeformis、侧柏Platycladus orientalis和毛白杨Populus tomentosa）的森林,主要研究比较了土壤微生物量碳、微生物群落结构和功能多样性的城郊差异。结果表明,郊区森林的土壤微生物量碳含量显著高于城区（郊区微生物量碳为367.29 mg kg-1,城区为294.23 mg kg-1）。同一树种下郊区微生物活性高于城区,差异未达到显著。微生物多样性和均匀度城郊差异不明显;但树种间存在一定的差异,城区毛白杨林下土壤微生物群落的均匀度显著低于柏树与油松,多样性指数显著低于柏树。结果表明城市化过程对城市土壤微生物量以及微生物群落的结构和功能有一定影响,且不同树种对于这种影响存在差异。随着城市化加快,城乡梯度上土壤微生物量碳的城乡差异明显,而土壤微生物群落结构、功能的差异有减小的趋势。

英文摘要：

Widely spreading forest,either in urban or suburban areas,is considered as one of the most important ecosystems that provides essential ecosystem services.However,researches on the differences of forest soil microbial community function have received insufficient attention.In this study,three forest types were selected,including Pinus tabulaeformis,Platycladus orientalis and Populus tomentosa in urban and suburban regions,to analyze and compare the differences of soil microbial community structure and function.The results showed that soil microbial biomass carbon in suburban forests was significantly larger than urban forests;whereas suburban microbial quotient was greater than that in urban forests.For the same forest type,microbial activity was higher in suburban regions with insignificant differences.There was no considerable difference of microbial diversity and homogeneity in urban and suburban areas.However,differences among varied forest types were more noticeable.Specifically,microbial community homogeneity of Populus tomentosa was significantly lower than Pinus tabulaeformis and Platycladus orientalis,and the Shannon＇s diversity index of Populus tomentosa was significantly lower than Platycladus orientalis.Derived results indicated that the process of urbanization has exerted impacts on urban soil microbial biomass as well as the structure and function of microbial community;and such differences varied in different forest types.As the process of urbanization accelerates,there are significant differences of microbial biomass carbon in urban center and suburban areas,while the differences of soil microbial community structure and function along urban-rural gradient tend to decrease.