【摘要】 湿地以常年性或周期性积水为特征,而水分条件的改变可直接影响湿地生态系统的结构和功能。为探究淹水条件对土壤酶活性的影响以及驱动酶活性变化的因素,在青海湖鸟岛地区选择长期淹水、周期性淹水和很少淹水的湿地,比较了土壤化学性质、微生物生物量碳氮以及酶活性的差异。结果表明:周期性淹水的湿地土壤β-葡萄糖苷酶、纤维二糖酶和甘氨酸氨基肽酶的活性较长期淹水的湿地分别下降了24.01%、18.80%和2.96%;而很少淹水的湿地较周期性淹水的湿地分别下降了33.65%、18.84%和63.47%。周期性淹水与长期淹水湿地的土壤N-乙酰氨基葡萄糖苷酶和亮氨酸氨基肽酶活性显著高于很少淹水的湿地,而很少淹水的湿地土壤碱性磷酸酶和酚氧化酶活性最高。冗余分析发现,土壤易氧化碳、全氮、有机碳、微生物生物量碳氮、水溶性有机氮与土壤酶活性显著相关,其中,有机碳与纤维二糖酶活性的相关性较高;易氧化碳能很好地解释β-葡萄糖苷酶、N-乙酰氨基葡萄糖苷酶和甘氨酸氨基肽酶活性的变化。总的来说,长时间淹水更有利于碳氮的积累,提高水解酶活性。更多还原

【Abstract】 Wetland is characterized by permanent or seasonal inundation,whose structure and function are directly influenced by the changes of flooding conditions. To investigate the effects of flooding conditions on soil enzyme activities and identify the driving factors,we used three kinds of plots with different flooding conditions( long-term flooded wetlands,periodically flooded wetlands and seldom flooded wetlands) in the Bird Island of Qinghai Lake. Soil chemical properties,soil microbial biomass carbon and nitrogen,and soil enzyme activities were analyzed. The results showed that,compared to the long-term flooded wetland,the activities of β-glucosidase,cellobiase,and glycine aminopeptidase in the periodically flooded wetland decreased by 24. 01%,18.80% and 2.96%, respectively. The activities of those enzymes decreased by 33. 65%,18.84%,and 63. 47% in the seldom flooded wetlands,compared with the periodically flooded wetland,respectively. The activities of N-acetylglucosaminidase and leucine aminopeptidase were significantly higher in periodically flooded wetland and long-flooded wetland than in the seldom flooded wetlands. However,the activities of alkaline phosphatase and phenol oxidase were the highest in the seldom flooded wetlands. Results of redundancy analysis showed that readily oxidizable carbon,total nitrogen,organic carbon,microbial biomass carbon and nitrogen,and dissolved organic nitrogen were significantly correlated with the changes of soil enzyme activities.Among them,soil organic carbon was responsible for the variability in cellobiase activity,whereas the activities of β-glucosidase,N-acetylglucosaminidase and glycine aminopeptidase were well explained by readily oxidizable carbon. Our results indicate that imposing flood was more conducive to the accumulation of carbon and nitrogen,and thus increased the activities of several hydrolases.更多还原