城市化对南亚热带常绿阔叶林土壤生物群落结构的影响

Effects of Urbanization on Soil Community Structure under Subtropical Evergreen Broad-leaved Forests

以广州市城郊梯度上存留的南亚热带常绿阔叶林为对象,量化分析城市化对南亚热带常绿阔叶林土壤微生物和土壤动物群落结构的影响,运用生态[火用]（Eco-exergy）理论方法,量化揭示土壤生物群落生物热力学结构对城市化的综合响应规律。结果显示,城市化对南亚热带常绿阔叶林土壤动物和微生物群落结构影响的方向、速率和机制各不相同,可能的影响主要有土壤含水率、铵态氮、有机质、硝态氮以及草本层生物量等。城市化会降低南亚热带常绿阔叶林土壤微生物群落生物量和生态[火用],并加剧干、湿季差异;而适度的城市化干扰可增加南亚热带常绿阔叶林土壤动物类群数和生态[火用],并减少干、湿季的差异。综合而言,广州近郊和城区残留的南亚热带常绿阔叶林土壤生物群落生态[火用]与结构[火用]值均高于远郊区的水平（2.39～2.99倍）;南亚热带常绿阔叶土壤生物群落生态[火用]主要由大型土壤动物贡献（〉64.41%）,而中小型土壤动物则是结构？的主要贡献者（〉50.00%）;不考虑生命周期,土壤微生物对于土壤生物群落生态[火用]与结构[火用]值的做贡献较小。生态[火用]理论方法可以综合度量土壤生物群落的自组织程度,但在具体计量中受到权重因子的有限性制约。

The impact of urbanization on community structure of soil microbes and soil fauna under Subtropical Evergreen Broadleaf Forest（SEBF） was measured along an urban-suburban-rural gradient in Guangzhou,China.Furthermore,the impact on the biophysical structure of the soil community was quantified using the eco-exergy method.The results showed that the impact of urbanization on soil microbes and soil fauna was different in both direction and degree,and that these differences were mainly related to soil moisture,ammonium and nitrate nitrogen,soil organic matter,and the biomass of herbs.Urbanization can decrease the biomass and eco-exergy of soil microbes under SEBF,and increase the differences between the dry and wet seasons; while a low degree of urbanization can increase the group richness as well as the eco-exergy of soil fauna,and decrease the differences between dry and wet seasons.After counting both the soil microbes and soil fauna,the eco-exergy of the whole soil community at the suburban study site was higher than that at the urban and rural study sites.Larger fauna is the main contributor to the eco-exergy of the soil community（〉64.41%）,while middle and small fauna contribute more to the specific eco-exergy（〉50.00%）.The eco-exergy method can measure the biophysical organization of the soil community,but its application is limited by the availability of weighting factors.