Responses of soil temperature in wetland ecosystem to air temperature and their effects on CO2 emission
通过2年的野外定位观测，研究了沼泽湿地土壤温度对气温变化的响应特征，以及土壤温度对沼泽湿地植物土壤系统CO2排放的影响，并对CO2排放的季节性变化进行模拟计算.结果表明，随融冻作用开始，沼泽湿地土壤温度对气温变化的响应强度不断增大，根层土壤温度与气温间呈显著指数关系（R2=0.94，P<0.01），但不同深度土壤温度对气温变化的响应强度存在一定的差异，表现为随土壤深度的增加，二者之间的相关系数变小，土壤温度对气温的响应强度减弱.沼泽湿地植物土壤系统CO2排放与根层土壤温度有关，二者呈显著指数相关关系（R2=0.84,P<0.01），利用模型模拟计算出沼泽湿地2003年生长季植物土壤系统CO2排放通量平均值为664.5±213.9 mg·m-2·h-1，野外定位观测值为634.0±227.7 mg·m-2·h-1，二者之间差值不大，表明利用此方法可以对沼泽湿地生长季CO2排放进行估算.
Through two years located field observation,this paper studied the responses of marsh soil temperature to air temperature and the effects of soil temperature on CO2 emission from marsh soil-vegetation system,and calculated the seasonal variation of CO2 emission.The results showed that from the beginning of thawing,an increasing trend of soil temperature was exerted by the change of air temperature,and there was a significant exponential correlation between soil temperature in root layer and air temperature (R2=0.94,P<0.01).Despite of the decreased responses of soil temperature to air temperature with increasing soil depth,the CO2 emission from marsh soil-vegetation system was strongly exponentially correlated with soil temperature in root layer (R2=0.84,P<0.01).An improved model equation was used for calculating the mean CO2 efflux from marsh soil-vegetation system during the growth season in 2003,and the calculated CO2 efflux was 664.5±213.9 mg·m-2·h-1,approaching the value of located field observation (634.0±227.7 mg·m-2·h-1),indicating that this model equation was effective to evaluate the CO2 emission from marsh during growth season.
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