邓恩桉（Eucalyptus dunnii）人工幼龄林土壤酶活性对模拟硫、氮复合沉降的响应

为探究南方人工林生态系统土壤酶活性对硫、氮复合沉降的响应机制,本研究采用二元二次正交回归旋转设计方法,设置16个硫、氮复合沉降处理组和1个空白对照组,研究1 a硫、氮复合沉降下邓恩桉人工幼龄林土壤上层(0~20 cm)和下层(20~40 cm)的酸性磷酸酶、脲酶、蔗糖酶和过氧化氢酶活性与硫、氮复合沉降之间关系,并建立回归模型。对17组数据进行单因素方差分析(one-way ANOVA),结果显示除上、下层过氧化氢酶活性组间差异均不显著外(p>0.05),酸性磷酸酶、脲酶和蔗糖酶活性组间均存在差异显著的土壤分层(p<0.05)。利用土壤分层中差异显著的酸性磷酸酶、脲酶和蔗糖酶活性进行分析、建模,结果表明:酸性磷酸酶仅对氮沉降的独立效应响应显著,与空白对照组相比,氮沉降抑制酸性磷酸酶活性;脲酶仅对硫沉降和氮沉降的独立效应响应显著,且脲酶活性在硫、氮沉降下降低,以氮沉降抑制作用最强;蔗糖酶对硫、氮沉降的独立效应和交互作用均响应显著,表现出硫、氮沉降抑制蔗糖酶活性的特征。研究表明,1 a硫、氮沉降抑制邓恩桉人工幼龄林红壤表层(0~40 cm)的土壤酶活性,引起土壤肥力降低。

Responses of Soil Enzymes Activities to Simulated Sulfur and Nitrogen Complex Depositions in A Young Eucalyptus dunnii Plantation

In order to explore response mechanism of enzymes activity to sulfur and nitrogen complex depositions in Southern plantation ecosystems, this study used quadratic rotating orthogonal regression designs method and set 16 sulfur, nitrogen complex depositions treatments groups and a control group to explore the relations between soil acid phosphatase, urease, invertase and catalase activity and sulfur, nitrogen depositions in the upper soil stratification(0-20 cm)and lower soil stratification(20-40 cm)of a young Eucalyptus dunnii plantation, and the regression models were established. Using 17 sets of data to make one-way ANOVA, the results showed except the catalase activity differences between groups in upper soil stratification and lower soil stratification were all not significant(p>0.05), acid phosphatase, urease and invertase activity all existed one significant differences stratification between groups in soil(p>0.05). Using acid phosphatase, urease and invertase whose differences were significant in soil stratification to make regression analysis, the results showed acid phosphatase only responded to nitrogen deposition independent effect significantly, compared with the control group, the nitrogen deposition inhibited acid phosphatase activity; urease only responded to sulfur, nitrogen deposition independent effect significantly, and urease activity decreased under sulfur, nitrogen depositions, and independent effect of nitrogen deposition was stronger; invertase activity responded to sulfur, nitrogen deposition independent effects and interactions all significantly, showing sulfur, nitrogen depositions inhibited invertase activity. This study showed 1a sulfur, nitrogen depositions decreased soil enzymes activity in red soil stratification(0-40 cm)in young Eucalyptus dunnii plantation and caused soil fertility to reduce.