| QiXingHe nature reserve is one of the preserved natural wetlands in Sanjiang Plain wetland, which has less human intervention, with good representation. The research adopts enclose chamber-gas chromatograph technique, through combining field-situ monitoring and laboratory analysis of samples method, to analyze the spatial and temporal variation of the vegetation growing season CO2emissions with natural wetlands and wetlands of different ages farmland to wetland, and to study the temperature, soil temperature, soil volumetric water content, soil PH and other environmental factors are how to affect CO2emissions flux.The results indicate:CO2emission fluxes have significant seasonal variations of vegetation growing season in Qixinghe wetland. Every point of CO2emissions in2011are significantly higher than it in2012. The maximum CO2emissions are in August with higher temperature. In the growing season of vegetation, CO2emissions of5-year-cropland-to-wetland Calamagrostis angustifolia wetland range from44.85to884.99mg·m-2·h-1, CO2emissions of natural reed wetland range from38.89to1415.62mg·m-2·h-1, CO2emissions of10-year-cropland-to-wetland reed wetland range from60.34to1933.30mg·m-2·h-1, CO2emissions of10-year-cropland-to-wetland Calamagrostis angustifolia wetland range from45.08to1163.94mg·m-2·-h-1.The order of CO2emissions fluxes is:10-year-cropland-to-wetland reed wetland (3#)> natural reed wetland (2#)>10-year-cropland-to-wetland Calamagrostis angustifolia wetland(4#)>5-year-cropland-to-wetland Calamagrostis angustifolia wetland(1#). The overall difference is not significant from every samples, but CO2emissions of5-year-cropland-to-wetland Calamagrostis angustifolia wetland has significant difference from10-year-cropland-to-wetland reed wetland(P<0.05).CO2fluxes and the atmospheric temperature has significant positive correlation in natural reed wetland and10-year-cropland-to-wetland Calamagrostis angustifolia wetland(P<0.05), but CO2fluxes and the atmospheric temperature has not correlation in5-year-cropland-to-wetland Calamagrostis angustifolia wetland and10-year-cropland-to-wetland reed wetland. In5-year-cropland-to-wetland Calamagrostis angustifolia wetland,10-year-cropland-to-wetland reed wetland and10-year-cropland-to-wetland Calamagrostis angustifolia wetland, CO2fluxes and5cm,10cm,15cm soil temperature show significant positive correlation(P<0.01). CO2fluxes and5cm soil temperature also show significant positive correlation(P<0.05) in natural reed wetland. But with depth studies show that CO2fluxes and soil temperature are not positive or negative correlation simply, it has positive correlation in a temperature range, and it has negative correlation beyond some range. In5cm soil depth, the maximum CO2emissions temperature ranges from17.4to22.2℃, in10cm soil depth, the maximum CO2emissions temperature ranges from15.2to21.2℃, in15cm soil depth, the maximum CO2emissions temperature ranges from11.2to19.0℃.The correlation of CO2flux and5cm,15cm soil volumetric water content is not significant in every samples, but CO2flux and soil volumetric water content has significantly negative correlation in10cm depth soil. The soil of Qixinghe wetland is weak acid, in the range of4.3to7.0. CO2flux and soil PH has positive correlation in the range of4.3to6.3, and has negative correlation in the range of6.3to7.0. The maximum of organic carbon content is45.33g·kg-1, and the minimum is32.69g·kg-1. Overall, the content of soil organic carbon of Qixinghe wetland in the Sanjiang plain region is in a medium level. In this study, the correlation between CO2flux and soil organic carbon content is not significant. Finally, based on principal component analysis, we obtain the linear regression equation between CO2flux and environmental factors. |
