干旱区生态环境知识资源中心

Plant transpiration plays a key role in sand-binding zones, but obtaining accurate estimates at an integrated leaf-individual-canopy scale is difficult. In this study, transpiration rates of two typical xerophytic shrubs, Caragana korshinskii and Artemisia ordosica, were investigated during the growing season (April-October) from 2008 to 2012 in the Tengger Desert, a revegetated desert area in China. Gas exchange techniques, sap flow measurements, and the crop evapotranspiration minus micro-lysimeter method were used to evaluate plant transpiration. Transpiration data were subsequently compared with the dynamical normalized leaf area-based extrapolation. The results indicated that at leaf level, the transpiration rates of C. korshinskii and A. ordosica were 2.67 and 4.51 mmol H2O m(-2) s(-1), respectively. The sap flow rates were 0.071 and 0.086 g h(-1) cm(-2) at the tree level, and the transpiration rates were 0.42 and 0.35 mm d(-1) at the stand level. The total seasonal transpiration of the two xerophytic shrubs reached 71.79 and 55.62 mm, representing approximately 48.4 and 37.5% of the total rainfall over this period. Direct measurements of plant transpiration and upscaling transpiration from leaf level to the stand level exhibited good correspondence, which verified that leaf area was a reliable representation of scaled transpiration, especially in arid desert regions.