沙漠及绿洲不同覆被下大气CO_2浓度的梯度变化

Vertical Variations of Atmospheric CO_2 Concentration over Desert and Oases with Different Cover

运用美国生产的开环气体交换系统LI 6 40 0便携式光合作用测定系统 ,研究了沙漠及绿洲不同覆被下大气CO2 浓度的梯度变化。结果表明 ,2 0 0 1年巴丹吉林沙漠南缘大气CO2 浓度为 36 6 μmol·mol-1,秋季大气CO2 浓度梯度在 1～ 10m高度范围内为 0 ,CO2 浓度与气温呈线形正相关 ,相关系数为 0 .87;与空气相对湿度呈线形负相关 ,相关系数为 - 0 .86。秋季绿洲区CO2 浓度高于沙漠区 ,人类活动向大气排放CO2 ,是绿洲区CO2 浓度高于沙漠区的主要原因。绿洲不同覆被类型其CO2 浓度梯度明显不同 ,影响CO2 浓度梯度的主要因素为 :人类活动、覆被变化、气象因子。覆被变化研究得出 ,杨树林初秋光合作用最强时在 10m高度范围内CO2 浓度可降低 2 2 μmol·mol-1;另外得出 ,降雨能够明显降低空气CO2

The LI-6400 Portable Photosynthesis System, produced by USA, was used to study the vertical variation of atmospheric CO 2concentration over desert and oases with different cover. The results showed that atmospheric CO 2concentration was 366 μmol·mol -1 over the southern edge of the Badain Jaran Desert in 2001. In autumn, the CO 2concentration gradient was 0 within 1～10 m height. The CO 2concentration was positively correlated with air temperature (correlative coefficient 0.87). But the CO 2concentration was negatively correlated with air relatively humidity and the coefficient was 0.86. In autumn, the CO 2 concentration over oasis region was higher. The key cause is the CO 2 emission of human activity. The CO 2 concentration gradients over oases with different vegetation cover were conspicuous different. The key factors are human activity, vegetation cover change and meteorological factor. In early autumn, the CO 2 concentration could be decreased by 2.2μmol·mol -1 at 10 m height when photosynthesis of Populus gansuensis was the greatest. Certainly, CO 2 concentration decreased obviously when precipitation.