Abstract
植被类型及淹水带来的干湿交替过程是影响温室气体排放的重要因素.本文通过原状土柱模拟实验，模拟西洞庭湖水文节律变化对不同土壤-植被系统温室气体排放的影响.利用静态箱-气相色谱法研究不同植被-土壤类型（芦苇湿地、灰化苔草湿地和刚砍伐的杨树林湿地）在季节性淹水条件下的CO<sub>2</sub>、CH<sub>4</sub>和N<sub>2</sub>O的排放通量变化，并探讨了在水位变化的情况下，不同植被-土壤类型对全球增温潜势的贡献.结果表明：在不同的水文条件下，芦苇湿地的CO<sub>2</sub>排放通量均显著高于苔草和杨树林湿地；淹水过程导致3种植被类型覆盖湿地CO<sub>2</sub>排放通量显著降低，甲烷排放通量升高，其中芦苇湿地CH<sub>4</sub>排放通量升高显著，苔草和杨树林湿地CH<sub>4</sub>排放通量升高不明显；水文变化及植被类型对N<sub>2</sub>O排放通量的影响不显著；不同植被类型湿地对全球增温潜势的贡献为：芦苇 > 杨树林 > 苔草，分别为16191.3、3405.6和1883.1 kg/hm<sup>2</sup>.本研究结果表明在西洞庭湖湿地恢复过程中，不再人为增大芦苇湿地面积，将杨树林湿地恢复为苔草湿地，更有利于降低湿地恢复过程中温室气体的排放.;Seasonal flooding and vegetation types are the main drivers of greenhouse gases fluxes in wetland ecosystems. In this study, undisturbed soil column simulation experiments were carried out to study the effects of hydrological regime on the emission of greenhouse gases from wetlands dominated by different types of vegetation in west Lake Dongting. Three types of vegetation were tested, i.e. Phragmites australis, Carex cinerascens and Populus deltoides. Static opaque chamber/gas chromatography method was used to measure the flux of CO<sub>2</sub>, CH<sub>4</sub> and N<sub>2</sub>O from wetlands with different vegetation types under the same dry-wet treatment. The results showed that the contributions of wetland to global warming potential were 16191.3, 3405.6 and 1883.1 kg/ha<sup>2</sup> for wetlands dominated by P. australis, P. deltoides and C. cinerascens, respectively. Specifically, CO<sub>2</sub> flux from P. australis wetland was significantly higher than that from C. cinerascens and P. deltoides wetlands, and flooding resulted in a significant decrease in CO<sub>2</sub> emission regardless of vegetation type. Flooding significantly increased methane emission from P. australis wetland but the increase was not significant for C. cinerascens and P. deltoides wetlands. For N<sub>2</sub>O emission, the effects of both flooding and vegetation types were not significant. The results of this study indicate that the current wetland restoration program in west Lake Dongting, such as curbing the expanding of P. australis and converting P. deltoides wetland to C. cinerascens wetland, could potentially reduce its contribution to global warming.
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