Study On CO₂ Flux Of Surface Interface And Rate Of Organic Carbon Accumulation In Peatland

Research was conducted to estimate surface CO₂ flux and organic carbon accumulating rate of typical peatland in Longgang volcano group. Jinchuan Peatland, lies in Longwan National Nature Reserve in Jilin province, was selected as research area. Two dominant communities (Carex schmidtii community and Betula ovilifolia-Carex schmidtii community) of Jinchuan peatland were taken as research object. The research was based on on a great amount of investigation, observation and experiments in field, analysis and experiments in labortory. The observation and experiments falls into four parts. The first was to test the photosynthesis and respiration rate of dominant species (Carex schmidtii and Betula ovilifolia) in dominant communities. The second was to observe the respiration rate of peatland soil. The third was to measure the biomass of dominant communities in the peatland. The forth was to monitor the decomposing rate of dominant species litters. The results showed that the CO₂ flux of peatland surface-layer interface is quite different not only between day and night, but also among seasons. The CO₂ flux that peatland absorbs from air is controlled by photosynthesis of peatland plant, it is zero at night and none plant growing seasons. The CO₂ flux that peatland releases to air is determined by the two factors, ie. respiration of vegetation and soil. For Jinchuan peatland, the seasonal changes of CO₂ flux of surface interface is as follows: in July, the absorbing flux is 38.18 t·d^-1,the releasing flux is 16.55 t·d^-1; in August, the absorbing flux is 34.6 t·d^-1,the releasing flux is 12.6 t·d^-1;in September, the absorbing flux is 11.49 t·d^-1,the releasing flux is 10.92 t·d^-1. The difference between CO₂ absorbing flux and CO₂ releasing flux changes in different seasons. In the stage of plant fast growing, peatland is the sink of CO₂. But when plants stop growing, peatland turns to be the source of CO₂. For Jinchuan peatland in 2004, the Carex schmidtii community absorbed 12.1122 gCO₂·m^-2·d^-1 in July and 20.1347 gCO₂·m^-2·d^-1 in August, and released 1.2583 gCO₂·m^-2·d^-1 in September; the Betula ovilifolia-Carex schmidtii community absorbed 37.6868 gCO₂·m^-2·d^-1 in July, 35.2998 gCO₂·m^-2·d^-1 in August and 10.1617 gCO₂·m^-2·d^-1 in September. In Jinchuan peatland, the organic carbon accumulating rate of leaves of in Carex schmidtii community and Betula ovilifolia community respectively were 19.09 g·m^-2·a^-1 and 16.06 g·m^-2·a^-1. Total organic carbon (TOC) accumulation of leaves of Carex schmidtii and Betula ovilifolia was 18.58t. Consequently, Jinchuan peatland still maintains the function of being sink of CO₂ under serious interference from mankind.