黑河上游高寒草地蒸散发日变化及其影响因子分析

基于箱式气体交换观测原理,采用Li-8100A通量自动测量系统测定了黑河上游高寒草地群落蒸散发量,并采用相关系数和通径系数分析了高寒草地蒸散发日变化与环境因子的关系。观测结果显示:Li-8100A能够较好地观测草地群落的蒸散发日变化过程;生长季旺盛期晴天高寒草地蒸散发日变化呈单峰变化;有草覆被和没有草覆被样点之间存在较大差异,通过两者之间差值可将植物蒸腾和土壤蒸发区分开来。相关系数和通径系数分析显示,影响高寒草地蒸散发日变化最大的影响因子是空气温度,其次是土壤水分和风速,而土壤温度、太阳辐射主要是通过空气温度而间接影响蒸散发速率日变化。

Daily variation of evapotranspiration rate of alpine grassland and analysis of its environmental factors in upper reach of Heihe River

Based on the theory of gas exchange measurement of chamber system, the paper used Li-8100A automated soil CO₂ flux system to measure the diurnal evapotranspiration of alpine meadow community in the upper reach of Heihe River. The relationship between the diurnalvariation of evapotranspiration rate and environmental factors was represented by the correlation coefficient and path coefficients. The result shows that the Li-8100A can be effectively used to measure the changes of diurnal evapotranspiration rate.The variation of alpine meadow evapotranspiration rate appears single-peak changing tendency over time in a sunny day.There are larger difference between the sample with grass land and that with bare land;the difference of the two could be considered as the grass transpiration. The correlation coefficient and path coefficients between the evapotranspiration rate and environmental factors indicated that the air temperature has the strongest positive effect on evapotranspiration rate, the subsequent factors is soil moisture and wind speed. In addition, the soil temperature, solar radiation have indirect effect on evapotranspiration rate through the change of air temperature.