荒漠河岸柽柳(Tamarix chinensis)灌丛的能量平衡特征

用涡度相关法对新疆塔里木河下游荒漠河岸柽柳(Tamarix chinensis)灌丛进行了1个生长季的实验观测,利用同步气象资料探讨了干旱胁迫环境下柽柳灌丛的近地面微气象和能量平衡特征,并运用普通最小二乘法线性回归及能量平衡比率法对比分析了不同天气条件下柽柳的日能量平衡变化和分配的差异。结果表明:观测期内柽柳灌丛的能量平衡闭合率为72.3%,地表能量通量和能量分配特征呈明显的单峰型二次曲线,地表净辐射通量和潜热通量是柽柳灌丛生长季的主要能量收入项和支出项;生长季内柽柳灌丛的能量平衡残差出现系统性、正负交替的日循环规律;在不同天气条件下,能量的分配转化和平衡程度均有明显差异,晴天的能量闭合状况好于阴天、降雨及扬沙天气,白天好于夜间;能量平衡比率在日出前与日落后的变化显著,且出现瞬时能量过闭合现象。受光合作用的影响,能量平衡闭合程度及碳通量的变化与不同天气下的温度及水分密切相关。

Characteristics of Energy Balance of Riparian Tamarix Shrubs in Desert

In this research, the lower reaches of Tarim River, Xinjiang, was taken as target area and Tamarix shrubs were observed with the eddy covariance method during a whole growing season. Based on the synchronous meteorological data, the ground micrometeorological and energy balance of Tamarix shrubs under the drought stress environment were discussed; the differences between diurnal variations of energy balance and energy partitioning in different weather conditions were analyzed by using the ordinary least squares linear regression and the energy balance ratio method. The results showed that: the energy balance radio of Tamarix shrubs during the observation period was 72.3%, and the diurnal variation of surface energy flux and energy allocation trend appeared a single peak quadratic curve. R_n and LE was important energy income and expenditure terms of Tamarix shrubs, respectively. Energy balance residuals appeared systematic diurnal cycle alternating with negative and positive value. There was a significant difference in conversion of energy allocation and energy balance under different weather condition; the energy closure condition of fine day was better than the cloudy, rainy and windy day; and it was better during the day time than night. There was a significant change in the energy balance radio between before sunrise and after sunset and appeared instantaneous energy closure phenomenon. By affecting of photosynthesis, the magnitude of energy balance closure degree and changes of carbon flux had close relations with the air temperature and moisture degree under the different weather condition. These results suggested that the main reason which was resulted in the imbalance of energy balance radio was the underestimation of carbon flux.