Abstract: In order to study the activities and dynamic characteristics of soil invertase and amylase during the process of vegetation degradation (Non-degradation,Light degradation,Moderate degradation,and Heavy degradation),the filed experiments were conducted in marsh meadow of Gahai wetland in Gannan state,Gansu province. The main results were as following:the average activity values of invertase and amylase activities in 0~100 cm layers varied in different stages of vegetation degradation of marsh meadow,following the order of CK (Non-degradation) > SD (Light degradation) > MD (Moderate degradation) > HD (Heavy degradation). With the increasing of soil layers,the activity of invertase significantly decreased (P<0.05),while the activity of amylase decreased fluctuantly. The activities of enzymes in the surface soil (0~20 cm) accounted for more than 60% of the total activities of each enzyme. The activities of invertase and amylase showed the obvious dynamic characteristics with time in all stages of vegetation degradation. The average activity of invertase in different months was the highest in June (47.07 mg·g^-1) and the lowest in August (22.69 mg·g^-1). The average activity of amylase was the highest in July,85.18 mg·g^-1,while the activity values in other months were low. Correlation analysis showed that soil organic carbon was significantly correlated with invertase and amylase (P<0.01),and soil water content was only significantly correlated with invertase (P<0.01). The results showed that the vegetation degradation in Gahai wetland significantly affects soil invertase and amylase activities,reduces the efficiency of enzymatic reaction,and leads to the deterioration of wetland soil environment.

Key words: Marsh meadow, Vegetation degradation, Soil invertase, Soil amylase

摘要： 以尕海湿地不同植被退化程度样地（未退化CK、轻度退化SD、中度退化MD及重度退化HD）为研究对象，采用野外采样与室内试验结合的方法，研究尕海湿地植被退化过程中土壤蔗糖酶和淀粉酶活性分布特征及动态变化。结果表明：尕海湿地4种植被退化阶段0~100 cm土层中2种酶活性均值表现为CK > SD > MD > HD。随土层深度增加，同一退化程度蔗糖酶活性显著降低（P<0.05），淀粉酶活性呈波动性降低趋势；表层（0~20 cm）土壤中2种酶的活性值占各自总值的60%以上。不同月份蔗糖酶活性均值6月最高（47.07 mg·g^-1），8月最低（22.69 mg·g^-1）；淀粉酶活性均值7月最高（85.18 mg·g^-1），其它月份值较低。相关性分析表明，土壤有机碳与2种酶之间相关性极显著（P<0.01）；土壤含水量仅与蔗糖酶间有极显著相关关系（P<0.01）。说明尕海湿地植被退化显著影响2种酶的活性，降低了酶促反应的效率，导致湿地土壤环境恶化。

关键词: 沼泽化草甸, 植被退化, 土壤蔗糖酶, 土壤淀粉酶