植物生长季退化草毡寒冻雏形土CO2释放特征

对中国科学院海北高寒草甸生态系统定位站地区退化草毡寒冻雏形土CO₂释放的全天候连续观测结果表明,退化草毡寒冻雏形土CO₂的释放有明显的日变化和季节动态,日最大释放速率出现于12:00～14:00,最小释放速率出现于6:00～8:00;植物生长季的最大振幅为462.49mg·m^-2·h^-1(8月18日),最小振幅为114.97mg·m^-2·h^-1(5月9日),CO₂释放速率白天大于夜晚.不同物候期CO₂释放速率亦不同,草盛期>枯黄期>返青期.最大日均值为480.76mg·m^-2·h^-1(8月18日),最小日均值为140.77mg·m^-2·h^-1(5月9日).释放速率与气温、地表温度及土壤5cm地温均呈显著或极显著相关关系,表明温度是决定CO₂释放速率季节变化的首要因素.

CO2 flux characteristics from degenerated mat cryo-sod soil during plant growing period

The carbon dioxide (CO₂) emission rate was studied in the degenerated mat cryo sod soil covered with alpine Kobresia humilis meadow at the Haibei alpine meadow ecosystem research station, with CID 301ps CO₂ analytical instrument during plant growth period (May-Sep, in1998). The results showed that the CO₂ emission rate had obvious daily variation and seasonal dynamics. The maximum rate of CO₂ emission appeared at 12:00～14:00, and the minimum rate appeared at 6:00～8:00. The max daily amplitude was 462.49 mg·m^-2·h^-1,while the minimum daily amplitude was 114.97 mg·m^-2·h^-1 .The CO₂ emission rate varied with phonological periods, and the order was exuberance>withering>green up. The maximum daily average value was 480.76 mg·m^-2·h^-1 (Aug.18th), and the minimum daily average value was 140.77 mg·m^-2·h^-1 (May.9th). Correlation analysis showed that there was a significant relationship between CO₂ emission rate and air temperature, soil surface temperature and soil temperature in 5 cm, 10 cm, 15 cm, 20 cm,and 30 cm. Temperature was the dominant factor that affected the CO₂ emission rate in degenerated mat cryo sod soil.