炼山对巨桉人工幼林土壤酶活性和有效养分的影响

Effects of Control Burning on Soil Enzyme Activity and Nutrients Availability of A Eucalyptus grandis Plantation in Sichuan Basin

为了解传统营林方式炼山对巨桉（Eucalyptus grandis）人工林土壤生态过程的影响，根据巨桉生长特性和当地气候环境，在四川盆地典型巨桉人工林地研究了春季炼山后夏季、秋季和次年春季土壤水解酶、氧化还原酶活性以及土壤有效养分质量分数的变化及其相互关系。结果表明：炼山后的各个季节土壤酸性磷酸酶活性均显著小于未炼山林地．夏季炼山林地土壤转化酶和脲酶活性与未炼山林地无显著差异，秋季炼山林地土壤转化酶活性明显较低，但次年春季土壤转化酶和脲酶活性显著高于未炼山林地。炼山后夏季0～20cm土壤和秋季〉20～40cm土壤过氧化氢酶活性显著降低，但秋季0～20cm土壤过氧化氢酶活性显著增加。此外，炼山后的巨桉林地各土壤酶活性与土壤有机质、有效养分质量分数的关系较未炼山林地更加紧密。可见，炼山对巨桉人工幼林土壤酶活性的负面影响主要表现在当年炼山后的夏季和秋季。

The experiment was conducted to investigate the effects of control burning on soil ecological process in the Eucalyptus grandis plantation in Sichuan basin, several soil hydrolase and oxidoreductase activities in summer, autumn and next spring after a control burning in spring. The soil acid phosphatase activity in the plantation after control burning is lower than that in non-burning plantation. Soil invertase and urease activities show few differences in summer after control burn- ing between the plantations with control burning and non-burning. Soil invertase activity in control burning plantation is lower in autumn after control burning compared with non-burning plantation, but the soil invertase and urease activities in control burning plantation are higher in next spring. Nevertheless, control burning shows a decrease effect on soil peroxi- dase activity in the investigated seasons after control burning. Control burning decreases soil catalase activity in 0-20 cm soil layer in summer and in 20-40 cm soil layer in autumn after control burning, but increases soil catalase activity in 0- 20 cm soil layer in autumn. There are closer relationships between soil enzyme activities and the contents of soil organic carbon and available nutrients in control burning plantation than those in non-burning plantation. The negative effects of control burning on soil enzyme activity are in summer and autumn after control burning in E. grandis plantation.