关键词: 沙漠, 绿洲, CO₂浓度, 土地覆被, 小气候

Abstract: The LI-6400 Portable Photosynthesis System, produced by USA, was used to study the vertical variation of atmospheric CO₂concentration over desert and oases with different cover. The results showed that atmospheric CO₂concentration was 366 μmol·mol-1 over the southern edge of the Badain Jaran Desert in 2001. In autumn, the CO₂concentration gradient was 0 within 1~10 m height. The CO₂concentration was positively correlated with air temperature (correlative coefficient 0.87). But the CO₂concentration was negatively correlated with air relatively humidity and the coefficient was 0.86. In autumn, the CO₂ concentration over oasis region was higher. The key cause is the CO₂ emission of human activity. The CO₂ 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 CO₂ concentration could be decreased by 2.2μmol·mol-1 at 10 m height when photosynthesis of Populus gansuensis was the greatest. Certainly, CO₂ concentration decreased obviously when precipitation.

Key words: desert, oasis, CO₂ concentration, land cover, microclimate