油松人工林的能量平衡和蒸发散

Energy Balance and Evapotranspiration Observation in A Chinese Pine Plantation

本文用Bowen比能量平衡方法和空气动力学方法分析了一片油松人工林分的微气象学观测资料。在生长季内,油松林冠的日平均反射率为10～11％,透射率15～21％。林分的植被贮热通量和林地土壤热通量分别为净辐射的2.5％和8％。林冠表面层日平均Bowen比变动于0.2～1.1,生长季平均为0.7。由能量平衡计算,油松林睛天的蒸发散速率为3.6mm/d,日中最大可达0.7mm/h,整个生长季平均为3.1mm/d,其中林地蒸发0.4mm/d,林木蒸腾2.7mm/d。空气动力学方法的结果与能量平衡法有较大差异。

Micrometeorological data recorded on a Chinese pine (Pinus tabulaeformis carr.) plantation were analysed by the Bowen ratio energy balance and the aerodynamic method. In the growing season, the daily mean albedo of the canopy was 10-11 percent, and the transmissiyity was 15-20 percent. The heat fluxes stored in plant, Jp, and in soil, G, were about 2.5% and 8% of net radiation, respectively. The daily mean Bowen ratio of the canopy surface layer varied from 0.2 to 1.1, in the entire growing season,with an average of 0.7. In sunny days, the evapotranspi-ration of the plantation, as calculated by energy balance method, was 3.6mm water/d, in midday with a maxium value rising to 0.7mm/h. The average evapotranspiration in the entire growing season was 3.1mm/d, of which,evaporation from the forest floor was 0.4mm/d and transpiration of the trees was 2.7mm/d. There was a large discrepancy between the results obtained by energy balance method and by aerodynamic method.