Carbon Storage Of Natural Wetland Ecosystem In Southern Daxing’an Mountains Of China

Although the wetlands only accounts for a very small part of the global land ground, while it commonly is a important carbon sink of the land ecosystems. The ecosystem carbon storage (vegetation C storage and soil organic C storage), carbon sequestration and net primary productivity of five types of natural wetland (hassock wetland, shrubs wetland, Alnus sibirica var. hirsuta wetland, Betula platyphylla wetland and Larix gmelinii wetland) were studied by using Multi N/C3100, HT1300Solids Module (Analytik Jena AG, Germany) and the sample tree analysis method in Daxing’anling of northeast China, so as to evaluate the carbon sinks of natural wetlands quantitatively and reveal the influences of environmental gradients on wetland carbon sinks. The results showed that:(1) The vegetation carbon storage of five wetland types varied from0.48±0.08to8.33±0.66kg C·m-2, which took on rising trends along the water environmental gradient from marsh to forest. And herb layer dominated in vegetation carbon storage of hassock wetland (67.6%) compared to the litter layer; shrub layer dominated in shrubs wetland (76.7%) compared to the litter layer (13.7%) and herb layer (9.6%); tree layer dominated in forested wetlands(86.4%-93.6%), litter layer in a subordinate position(4.8%～9.3%), herb and shrub layer took very small part of vegetation carbon storage (1.2%～4.3%).(2) The soil organic carbon storage of five wetland types varied from19.21±6.17to38.28±4.86kg C·m-2, which took on lowering trends along this environmental gradient, the primary cause was the distribution differences of soil organic carbon storage in0-40cm soil layer, and0-40cm soil layer dominated in hassock wetland, while0-30cm soil layer dominated in shrubs wetland and three kinds of forested wetland.(3) The ecosystem carbon storage of these wetland types varied from27.54±7.16to38.76±4.58kg C·m-2, which nearly took on constant trends along this environmental gradient, and the soil C pool all dominated in five kinds of ecosystem C pool (95.4%-98.8%) Compared to the vegetation C pool (1.2%～4.6%); the soil C pool all dominated in three kinds of forested wetland ecosystem C pool (69.8%～88.4%) yet, but there was a substantial increase in proportion of vegetation C pool (11.6%～30.3%).(4) The net primary productivity (NPP)of five wetland types varied from0.68±0.10to1.08±0.12kg·m-2·a-1, NPP of Alnus sibirica var. hirsuta wetland was the highest, that of Larix gmelinii wetland was the lowest, and NPP of others were in the middle level, and they generally were lower than that of the temperate forested wetlands, but higher than that of the cold temperate larch forest.(5) The vegetation net carbon sequestration (VNCS) of five wetland types varied from 0.32±0.09to0.51±0.06kg·m-2·a-1and VNCS of Alnus sibirica wetland was the highest (which was higher than the average of global vegetation net carbon sequestration), VNCS of shrubs wetland and Betula platyphylla wetland were in the middle level (reached or approached the average VNCS of global vegetation), VNCS of hassock wetland and Larix gmelinii wetland were lowest (but slightly lower than the average VNCS of global vegetation), therefore, five types of natural wetlands all have strong carbon sink function in Daxing’anling of northeast China.