基于茎干液流法和涡度相关法的小叶锦鸡儿(Caragana microphylla)群落蒸散特征

运用Dynamax茎流测量系统、涡度相关系统、气象-土壤环境观测系统进行连续观测,利用基径横截面积对单枝茎干液流进行尺度扩展,得到科尔沁沙地小叶锦鸡儿(Caragana microphylla)群落蒸腾量(T),并与涡度相关系统观测的蒸散发量(ET)进行对比,详细分析了小叶锦鸡儿群落T与ET的变化特征以及群落水分收支状况。结果表明:(1)小叶锦鸡儿群落T、ET日变化趋势基本一致,均值分别为1.61 mm·d-1、2.43 mm·d-1;(2)T、ET日内变化曲线分别呈宽幅单峰型、钟型分布,日累积量均呈"S"型增长趋势;(3)不同天气条件下T、ET日变化峰型各异,峰值及总量变化水平晴天高于阴雨天;(4)不同降水事件中,降雨时间不同导致T启动时间推迟或结束时间提前,ET发生时间降水前后无显著差异;降雨量P≤10 mm或P>20 mm时,雨后T有所降低,10 mm

Transpiration and Evapotranspiration of Caragana microphylla Community Measured with the Sap Flow and Eddy Covariance Methods

Horqin sandy land is one of the most typical desertification areas in North China, and Caragana microphylla is the typical vegetation in desert area. We measured transpiration and evapotranspiration of C. microphylla with packaged sap flow gauges and an eddy covariance system in Horqin sandy land. The basal diameter was used to scale the single stem flow to transpiration of C. microphylla. In contrast, the characteristics of transpiration(T) and evapotranspiration(ET), and water budget of the community were analyzed in detail. The results showed that:(1) the daily changes of T and ET of C. microphylla community were basically consistent, the daily mean values were 1.61 mm·d-1 and 2.43 mm·d-1, respectively;(2) the daily variation curves of T and ET were wide and single peak type and clock type, and the daily accumulative process curves showed a "S" type growth trend;(3) in different weather conditions, the peaks of T and ET daily changes were different. The change level of total amount is higher than that of cloudy and rainy days;(4) in different precipitation events, the rainfall time varies lead to T start time or end time changed, there is no significant difference of ET occurrence time before and after rainfall;when P≤10 mm or P>20 mm, T has decreased after rainfall, 10 mm