岩溶湿地和稻田的土壤酶活性与CO2和CH4排放特征

【目的】探究土地利用变化对湿地土壤酶活性和温室气体排放之间关系的影响。【方法】以会仙岩溶湿地为研究样点,以湖泊湿地和其相邻的稻田为研究对象,采用比色法和静态暗箱法分别测定水稻整个生育期内主要土壤酶的活性及CO₂和CH₄的排放,并对二者之间的关系进行分析。【结果】稻田土壤的β-葡萄糖苷酶、纤维素酶、蔗糖酶、几丁质酶、脲酶和碱性磷酸酶活性均高于湖泊湿地,高出幅度为11.8%—32.7%。稻田CO₂和CH₄排放通量分别为255.9—789.7和-0.41—1.74 mg·m^-2·h^-1,平均值分别为445.8和0.42 mg·m^-2·h^-1,低于天然湖泊湿地。与湖泊湿地相比,稻田CO₂和CH₄排放总量分别降低了22.3%和83.3%,而增温潜势（GHGs,含N₂O）降低了29.6%。相关性结果显示,CO₂排放通量与β-葡萄糖苷酶、纤维素酶、蔗糖酶和几丁质酶活性呈显著负相关关系,CH₄排放通量与6种土壤酶活性显著负相关（P<0.05）。【结论】在会仙岩溶湿地系统中,天然的湖泊湿地转变为稻田可显著提高土壤酶活性,同时降低CO₂和CH₄的排放量,有利于微生物碳利用率的提高和土壤碳的封存。

Characteristics of Soil Enzyme Activities and CO2 and CH4 Emissions from Natural Wetland and Paddy Field in Karst Areas

【Objective】 The purpose of this study was to explore the impacts of land-use change on the relationship between soil enzyme activities and greenhouse gas emissions of wetlands. 【Method】 Huixian karst wetland and the top soil (0-20 cm) from a lake wetland and its adjacent paddy fields were used as a research site and research objects, respectively. The soil enzyme activities and CO₂ and CH₄ emissions were detected with colorimetric method and static-chamber method, respectively.【Result】The results showed that the activities of β-glucosidase, cellulase, invertase, chitinase, urease and alkaline phosphatase in the paddy soil were all higher than those in the lake wetland, with a range of 11.8%-32.7%. The fluxes of CO₂ and CH₄ from the paddy field were 255.9-789.7 mg·m^-2·h^-1and -0.41-1.74 mg·m^-2·h^-1, respectively. The average values of CO₂ and CH₄ fluxes from the paddy field were 445.8 and 0.42 mg·m^-2·h^-1, respectively, which were lower than those in the lake wetland. Compared with the lake wetland, the amount of CO₂ and CH₄ emissions from the paddy field were decreased by 22.3% and 83.3%, respectively, while the GHGs (including N₂O) was decreased by 29.6%. Correlation analysis showed that the CO₂ flux was significantly negatively correlated with the activities of β-glucosidase, cellulase, invertase and chitinase, while the CH₄ flux was significantly negatively correlated with 6 soil enzyme activities (P<0.05).【Conclusion】The above results indicated that the conversion of a natural lake wetland into a paddy field had significantly increased soil enzyme activities and decreased the emissions of CO₂ and CH₄ at the same time, which was conductive to the improvement of microbial carbon-use-efficiency and the sequestration of soil carbon in Huixian karst wetland.