尾矿砂堆积地五节芒自然定居对土壤微生物生物量、呼吸速率及酶活性的影响

为了认识重金属耐性植物五节芒（Miscanthus floridulus）对尾矿砂土壤的改良作用，在尾矿砂堆积地上选择1个裸露的尾矿砂样点（对照）和4个五节芒定居的尾矿砂样点（RI、RII、RIII和RIV）为样地，研究了土壤微生物生物量、呼吸速率和酶活性随五节芒定居梯度的变化规律以及这些微生物参数与土壤理化特性和重金属含量的关系。结果发现，随着五节芒在尾矿砂上的定居，除土壤pH以外，土壤有机碳、总氮、总磷、NH4+-N、NO3--N和速效磷的含量以及团聚体稳定性和最大持水量均显著提高（P 0.05），而土壤重金属总量与DTPA可提取量均显著下降（P 0.05）。土壤生物生物量碳、氮、磷、基础呼吸速率、基质诱导呼吸速率、10种土壤酶活性均显著提高（P 0.05），但土壤呼吸熵和多酚氧化酶活性显著下降（P 0.05）。主分量分析（PCA）结果表明，土壤微生物参数、土壤理化特性和土壤重金属数据均可显著区分出5个研究样地；典范相关分析（CCA）结果看出，土壤微生物参数总体变化与土壤理化特性呈显著正相关（pH除外），与土壤重金属呈显著负相关。

Effects of natural inhabitation of Miscanthus floridulus on soil microbial biomass,respiration rate and enzyme activity in a mine tailing dump

To evaluate the ameliorative effects of Miscanthus floridulus, a well known heavy metal-tolerant plant species, a bare mine tailing site (control site) and four mine tailing sites (RI, RII, RIII and RIV) inhabited by Miscanthus floridulus on the mine tailing sand were chosen for determining soil microbial biomass, respiration rate and enzyme activities, and the relationships between the microbial parameters. The results showed that except for the pH, soil organic carbon, total nitrogen, total phosphorus, NH₄⁺-N, NO₃^--N, available phosphorus, aggregate stability and maximum water holding capacity significantly increased (P < 0.05) with the inhabitation of M. floridulus, while total or DTPA-extractable heavy metal contents significantly decreased (P < 0.05). The inhabitation of M. floridulus signiciantly enhanced soil microbial carbon, nitrogen, phosphorus, basal respiration rate, substrate induced respiration rate and ten enzyme activities, but declinded the phenol oxidase activity and the respiration quotient (P < 0.05). The principal components analysis (PCA) showed that soil microbial parameters, physico-chemical and heavy metal properties all significantly discriminated. The canonical correlation analysis (CCA) showed that the net microbial parameters were positively related to the soil physico-chemical properties (except for pH), but negatively related to the heavy metal contents.