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(P0.05).The daily transpiration amounts from both methods were obtained by integration of the transpiration rates,and showed no significant difference(P0.05),which indicates the feasibility of scaling transformation from leaf level up to individual level based on leaf area.