两种林龄中山杉(Taxodium hybrid 'Zhongshanshan')林地土壤质量评价

Evaluation of Soil Quality in Two Different Ages of Taxodium Hybrid'Zhongshanshan' Forest plantations

以江苏省靖江市牧城公园和东湖公园两种种植年限分别为5a和9a的中山杉（z缸。击umhybrid’Zhongshanshan’）人工林土壤和无林地为研究对象，对0—15cm、15—30cm和30一45cm深度土层土壤理化性质、养分含量和微生物生物量进行了分析。典型相关分析表明，土壤微生物生物量的变化是一个复杂的过程，是土壤各因子共同作用的结果，3种土壤U、V值均表现出层次性，随着土壤深度的增加逐渐降低；不同取样点相同深度土层U、V值为9a林〉5a林〉对照；单相关分析表明，土壤微生物生物量与速效磷、速效钾、有机质和全氮呈极显著正相关（P〈0．01），因此土壤微生物可以作为评价中山杉人工林在促进林地土壤质量改善过程中的重要生物指标；主成分分析表明，综合得分最高的9a林为2．993，其次是5a林为0．748，作为对照的无林地则为一3．742，说明9a林地土壤质量最高。可见，中山杉对林下土壤质量有显著提高作用。

This studyexamined soil physicochemical properties and microbiological indicators of 5 and 9 year-old Taxodium hybrid ＇Zhongshanshan＇ plantations in Mucheng Park and Eastlake Park in Jiangsu Province, China. An adjacent bare land was also investigated to serve as a control. Canonical correlation analysis showed that change in soil microbial biomass was complex and attributed to several factors in soil. With increase in soil depth, U and V values decreased in 5 a and 9 a forest plantations and control, respectively. At the same soil layer, U and V values exhibited as 9 a 〉 5 a 〉 control. Correlation analysis indicated that soil microbial biomass waspositively correlated （P 〈 0.01） with the content of available phosphorus, available potassium, soil organic matter and total nitrogen. Meanwhile, principal component analysis （PCA） exhibited that the 9 a plantation scored the highest of 2.993, indicating the highest soil quality, followed by 5 a plantation and bare land, which were scored 0.748 and -3.742, respectively. In a word, T. hybrid ＇Zhongshanshan＇ plantations increased not only soil physicochemical properties but also soil microbial biomass, showing significant effects of T. hybrid ＇Zhongshanshan＇ plantations on the improvement of soil quality.