不同退耕年限下菜子湖湿地土壤酶活性变化

摘要

选取菜子湖区不同退耕年限(3、7、9、11、21 a)湿地为研究对象，以仍耕作油菜地和原始湿地为参照，分析了退耕还湖后湿地土壤过氧化氢酶、蔗糖酶、磷酸酶和脲酶活性特征，探讨了退耕还湖后湿地土壤酶活性变化规律。结果表明：相对于仍耕作油菜地，退耕后湿地土壤过氧化氢酶活性表层与亚表层均表现为退耕3~7 a降低，退耕9~21 a升高趋势；表层土壤蔗糖酶活性呈现退耕3 a升高退耕7 a降低退耕9~11 a升高退耕21 a降低的趋势，而亚表层土壤退耕3年急剧升高，而后呈降低的趋势；表层土壤磷酸酶活性则呈现退耕3~11 a逐渐升高，而后逐渐降低的趋势，而亚表层土壤则表现为退耕3~7 a降低退耕9~11 a升高退耕21 a降低的趋势；退耕后湿地表层土壤脲酶活性表现为退耕3 a降低，退耕7~9 a升高，退耕11~21 a降低趋势，亚表层则呈现退耕3 a升高，而后逐渐降低的趋势；退耕21 a湿地土壤4种酶活性均与原始湿地仍存在显著性差异。退耕后水文条件的改变和植被的恢复致使土壤酶来源、酶促反应底物与产物和土壤环境因子变化，进而影响退耕后湿地土壤酶活性变化。%The activities of soil catalease, invertase, phosphatase and urease were investigated in wetlands under various ages (3, 5, 7, 9, 11 and 21a) of returning farmland to lake (RFL), rape field and native wetland in the Caizi Lake region, Anhui Province. The results indicated that all soil enzyme activities changed along the period of RFL. Compared to rape field, catalease activities of surface and subsurface soils decreased during the 3-7a of RFL, and increased during the 9-21a of RFL. Invertase activities of surface soil increased during the 3a of RFL, declined after 7a of RFL, increased again during the 9-11a of RFL and increased again after 21a of RFL, while invertase activities of subsurface soil increased sharply during the 3a of RFL and then deceased gradually. Phosphatase activities of surface soil increased during the 3-11a of RFL and then decreased gradually, while phosphatase activities of subsurface soil decreased during the 3-7a of RFL, increased during the 9-11a of RFL and declined again after 21a of RFL. Urease activities of surface soil declined during the 3a of RFL, increased during the 7-9a of RFL and decreased again during the 11-21a of RFL, while urease activities of subsurface soil increased during the 3a of RFL and then decreased gradually. Moreover, all soil enzyme activities showed significant difference between wetlands with 21a of RFL and natural wetland. The changes of all soil enzyme activities were attributed to the shift of soil physical and chemical property due to the changes of hydrological condition and vegetation recovery status during the period of RFL.