在三江平原选择 3种不同类型的湿地:永久积水的漂筏苔草沼泽、季节性积水的小叶章草甸和无积水的恢复湿地.从 2002年 7月到 10月对漂筏苔草沼泽进行了土壤碳排放的观测, 2002年 8月中旬至 10月对小叶章草甸和恢复湿地进行了土壤碳排放的观测.观测结果表明,不同湿地类型下土壤 CO2和 CH4排放具有明显的差异,同段时期内 (2002年 8月中旬到 10月底 )土壤 CH4排放通量为小叶章草甸 (14.3 mg· m-2· h-1)>漂筏苔草沼泽 (7.9 mg· m-2· h-1)>恢复湿地 (-0.015 mg· m-2· h-1), CO2排放速率表现为小叶章草甸 (384.9 mg· m-2· h-1)>恢复湿地 (345.6 mg· m-2 · h-1)>漂筏苔草沼泽 (117.6 mg· m-2· h-1).温度是导致漂筏苔草沼泽和小叶章草甸土壤 CO2和 CH4的排放季节变化的主要驱动因子,也是恢复湿地土壤 CO2排放季节变化的主要驱动因子,但对其 CH4氧化吸收影响不明显.地表积水深度与漂筏苔草沼泽以及小叶章草甸土壤 CO2和 CH4排放均呈负相关,温度和积水深度的综合作用决定了漂筏苔草沼泽和小叶章草甸土壤 CO2和 CH4排放的季节变化特征.
A field experiment was conducted to measure CO2 and CH4 emissions f rom three types of wetlands including Carex pseudocuraica marsh, Calamagrostis a ngustifolia meadow and construction wetland in the Sanjiang Plain. Of all, Carex pseudocuraica marsh was long-waterlogged wetland, Calamagrostis angustifolia meadow was short-waterlogged wetland and construction wetland was non-waterl ogged wetland. CO2 and CH4 emissions were measured during July and October in 20 02 from Carex pseudocuraica marsh soil, and during August and October in 2002 fr om Calamagrostis angustifolia meadow and construction wetland soil. The results indicated that there were distinct differences on CO2 and CH4 emissions among th e three types of wetland soils. During the same period, i.e. during August and O ctober soil CH4 flux was Calamagrostis angustifolia meadow (14.3 mg·m-2·h-1) > Carex pseudocuraica marsh (7.9 mg·m-2·h-1) > construction wetlan d (-0.015 mg·m-2·h-1). Soil CO2 emission rate was Calamagrostis angust ifolia meadow (384.9 mg·m-2·h-1) > construction wetland (345.6 mg·m-2·h-1) > Carex pseudocuraica marsh (117.6 mg·m-2·h-1). Temperature w as a key factor affecting CO2 and CH4 emission rates from Carex pseudocuraica ma rsh and Calamagrostis angustifolia meadow, and also was a key factor affecting C O2 emission rates. The effect of temperature on CH4 uptake rates from the constr uction wetland depended on the scope of the temperature. When it was higher than ten degrees, the correlations between the CH4 uptake rates and temperatures wer e positively significant, but when it was lower than ten degrees, the correlatio ns between them were not significant. Water table was another important factor a ffecting CO2 and CH4 emission rates. The correlation coefficients between water table and CO2 and CH4 emission rates were both negative in Carex pseudocuraica m arsh and Calamagrostis angustifolia meadow, which demonstrated more CH4 could be oxidized going through the deeper water and less CO2 production because of the restricti
Journal of Agro-Environment Science( J. Agro-Environ. Sci.)