疏勒河上游高寒草甸生态系统CO2通量观测研究

采用涡动相关技术对2009,2010和2011年疏勒河上游高寒草甸生态系统CO₂通量观测和分析表明,疏勒河上游高寒草甸生态系统CO₂通量具有明显的日变化和年变化特征,6月、7月和8月为CO₂的强吸收期,4月、5月和10月为CO₂的强释放期。计算得到3年的CO₂净吸收量分别为134.5,151.3和194.4 g CO₂/m²,平均吸收量为160.0 g CO₂/m²,在区域起着碳汇的作用。生长季节,净生态系统交换量(net ecosystem CO₂ exchange, NEE)与温度、降水量、相对湿度以及地表长波辐射呈负相关,气温在0~7℃范围内NEE随气温增加线性减小,当温度大于7℃时,NEE随温度的增加而增大;非生长季节,NEE与温度、降水量、相对湿度以及地表长波辐射呈正相关。当地表反射率在0.2左右,NEE呈现快速增长趋势,当反射率超过0.3时,NEE接近最大值,并保持稳定。

Observations and study on the CO2 flux in an alpine meadow ecosystem in the upper reaches of the Shule River Basin

An eddy covariance observation system was established for providing continuous measurements on CO₂ fluxes in an alpine meadow ecological system at the upper reach of the Shule River Basin from 2009 to 2011. Obvious seasonal and inter-annual variations of CO₂ flux were observed. The months, June, July and August, were the strongest absorption period for CO₂ while April, May and October were the strongest release period for CO₂. The net exchange of CO₂ in the three years was 134.5, 151.3 and 194.4 g CO₂/m², respectively, and the mean value was 160.0 g CO₂/m². This indicates that the alpine meadow system played an important role as a carbon sink. During the growing season, the correlations between CO₂ net exchange and the temperature, precipitation, relative humidity, and surface long wave radiation were all negative. When the temperature was higher than 7℃, the CO₂ net exchange increased as temperature increased. In the dormant season, the correlations between CO₂ net exchange and the temperature, precipitation, relative humidity, and surface long wave radiation were all positive. When the surface reflectivity was about 0.2, the trend of the CO₂ net exchange increased fast. When the surface reflectivity was more than 0.3, the CO₂ net exchange reached a maximum and then remained stable.