中文摘要：

以洞庭湖区退田还湖后不同恢复模式下（恢复自然水域、种植芦苇、种植杨树）的典型堤垸（青山垸、官垸和小集成）为研究对象，通过与相邻堤垸农田生态系统（水田、旱田）土壤中蔗糖酶、脲酶、磷酸酶和过氧化氢酶活性的比较，揭示不同退田还湖模式下土壤酶活性的变化及其与土壤化学特性的相关关系．结果表明：与水田、旱田相比，在表层土壤中，以种植杨树为恢复方式的小集成样地的过氧化氢酶活性显著增加，其他酶活性无显著变化；以种植芦苇为恢复方式的官垸样地的蔗糖酶和磷酸酶活性有所下降，其他酶活性无显著变化；恢复自然水域的青山垸样地中，除磷酸酶活性下降外，其他酶活性没有表现出明显的差异性．相关分析表明，土壤有机质含量与4种酶活性均表现出显著的正相关关系（P〈0．01），说明退田还湖后系统恢复模式导致的土壤有机质含量的变化是土壤酶活性变化的主要原因．

英文摘要：

To reveal the effects of different restoration modes after returning farmland to lake on the soil biological characteristics in Dongting Lake area, the activities of soil saccharase, urease, phos-phatase, and catalase at three typical sites （Xiaojicheng, Guanyuan, and Qingshanyuan） were studied. At the Xiaojicheng site where poplar was planted, soil catalase activity increased significantly, but the activities ＇of other three test enzymes had no significant change. At the Guanyuan site where reed was planted, the activities of soil saccharase and phosphatase had somewhat decrease, and those of urease and catalase had less change. At the Qingshanyuan site where natural water area was restored, the test enzyme activities had less changes except that the phosphatase activity decreased. Correlation analysis showed that the test enzyme activities had significant positive correlations with soil organic matter content （P 〈 0. 01 ）, illustrating that the changes in the soil organic matter content under different restoration modes could be the main cause inducing the changes in soil enzyme activity.