干旱区生态环境知识资源中心

Partitioning evapotranspiration (ET) into its components reveals details of the processes that underlie ecosystem hydrologic budgets and their feedback to the water cycle. We measured rates of actual evapotranspiration (ETa), canopy transpiration (T-c), soil evaporation (E-g), canopy-intercepted precipitation (E-l), and patterns of stomatal conductance of the desert shrub Calligonum mongolicum in northern China to determine the water balance of this ecosystem. The ETa was 251 +/- 8 mm during the growing period, while E-l, T-c and E-g accounted for 3.2%, 63.9%, and 31.3%, respectively, of total water use (256 +/- 4 mm) during the growing period. In this unique ecosystem, groundwater was the main water source for plant transpiration and soil evaporation, T-c and exceeded 60% of the total annual water used by desert plants. ET was not sensitive to air temperature in this unique desert ecosystem. Partitioning ET into its components improves our understanding of the mechanisms that underlie adaptation of desert shrubs, especially the role of stomatal regulation of Tc as a determinant of ecosystem water balance. (C) 2016 Elsevier B.V. All rights reserved.