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利用涡度相关法和波文比——能量平衡法,对西藏拉萨附近的小麦农田进行了能量物质交换的观测试验。结果表明:拉萨地区小麦群体的净光合作用明显高于平原地区。群体的光合作用随着净辐射的增加而线性增加,当净辐射超过700W/m~2左右时,其增加速率开始下降。农田群体的光合水分利用效率日出后不久达最大值,在整个白天呈下降趋势,日落前后到达最低点。拉萨地区的净辐射能和小麦群体的蒸散量也都明显的高于平原地区,但在下午日落前的几个小时内,净辐射及蒸散强度以拉萨地区为最小,华北平原地区为最大。
Using the eddy covariance method and the Bowen ratio-energy balance method, the experiment of exchanging energy materials was carried out on the wheat farmland in Lhasa, Tibet. The results showed that the net photosynthesis of wheat in Lhasa was significantly higher than that in the plain. Photosynthesis increased linearly with the increase of net radiation. When the net radiation exceeded 700W / m ~ 2, the rate of increase began to decrease. The photosynthetic water use efficiency of farmland groups reached their maximum value shortly after sunrise, decreasing throughout the day and reaching the lowest point before and after sunset. Net radiation and wheat evapotranspiration in Lhasa were also significantly higher than those in the plains, but the net radiation and evapotranspiration were the lowest in Lhasa and the largest in the North China Plain within a few hours before sunset in the afternoon.