高寒湿地生态系统土壤有机物质补给及地-气CO_2交换特征

The Features of Soil Organic Matters Supplement and CO_2 Exchange between Ground and Atmosphere in Alpine Wetland Ecosystem

海北高寒湿地植物地上、地下生物现存量较高，2004年海北高寒湿地植物净初级生产力为1799．7gC·m^-2．由于家畜对湿地植物采食量低，每年将有大量的枯黄植物残留于地表，表现出地上、地下生物量以及苔鲜均成为土壤有机物质的补给源．由于区域温度低，积水严重，对植物残体分解缓慢，导致湿地土壤有机质含量很高，形成了厚达2m左右的泥炭层．观测结果表明，海北高寒湿地净生态系统CO2交换量具有明显的季节变化，年内4月和10月存在两个CO2释放高峰期，夏季的7～8月为一个强吸收期，全年来看为一个巨大的碳源．2004年净生态系统年碳交换量为76．7gC·m^-2．计算结果表明，植被的呼吸消耗量每年为1199．8gC·m^-2，其植物总固碳量为2999．5gC·m^-2，而土壤呼吸为1876．4gC·m^-2．

The aboveground and belowground biomass is quite large and the net primary productivity is 1799. 7 gC · m^-2 in Haibei alpine wetland ecosystem. Because less of the biomass is eaten by livestock, there are a lot of dead plants remained in the surface every year, which shows that the aboveground and belowground biomass and mosses are the supplement of soil organic matters. Meanwhile, the soil organic matter is rich and the turf layer is thick, because of lower temperature, more seeper and less decomposition of the plant leaves.It is found that the net CO2 exchange in alpine wetland ecosystem has an obvious seasonal change and is a great carbon source, with two release maxima in April and October, and a strong absorption in July- August. The net ecosystem CO2 exchange was 76.7 gC · m^-2 in 2004. The plant respiration quantity, ecosystem carbon fixation and soil respiration are 1199.8, 2999.5 and 1867.4 gC·m^-2, respectively.