热平衡技术与气孔计法测定沙生植物蒸腾

应用热平衡技术和气孔计对沙漠人工植被区的油蒿与柠条的蒸腾速率进行了观测，然后以叶面积作为纯量尺度转换后进行比较. 结果表明:油蒿的蒸腾速率明显高于柠条，受近地面的微气象条件的影响，两种植物蒸腾速率和气孔导度的变化步调高度一致. 土壤干旱不但使蒸腾速率峰值提前，而且造成植物通过叶片蒸腾散失水分滞后于吸水约2 h. 气孔计法测定的蒸腾速率利用多项式拟合后的日变化曲线均达到显著水平（P0.05），对多项式积分求得日蒸腾量；然后同热平衡法测定的日蒸腾量比较后认为，两者之间没有差异（P0.05）. 从而说明，以叶面积作为纯量，对植物蒸腾从叶片水平到单株水平的尺度转换是可行的. 

Measurement on the transpiration of xerophils in the desert area with steady state porometer and stem heat balance technique

The transpiration of Artemisia ordosica Krasch.and Caragana korshinskii Kom.in the revegetated area was investigated with the porometer and the stem heat balance technique.Measurements from both methods were compared after they were scaled based on the leaf area. Results showed that the transpiration rates of A.ordosica were higher than those of C.korshinskii,but their diurnal variation trends were highly consistent.The drier soil makes the peak of daily transpiration rate occurring earlier than the usual,and results in about two hours postponement of water loss through transpiration than water uptaking.The polynomial simulation results of diurnal transpiration variation with porometer reach significant level(P<0.05).The daily transpiration amounts from both methods were obtained by integration of the transpiration rates,and showed no significant difference(P>0.05),which indicates the feasibility of scaling transformation from leaf level up to individual level based on leaf area.