干旱区生态环境知识资源中心

The seasonal and diurnal variation in transpiration rate and stomatal conductance of four dominant shrub species (Caragana intermedia, Hippophae rhamnoides, Hedysarum leave, Salix psammophyla) planted in schemes designed to restore vegetation and conserve water in the arid soils of northwest China were studied. Transpiration rates were measured at the leaf scale using a porometer and then combined with data on leaf area, leaf mass, and remotely sensed information on shrub stand size, to scale-up the leaf-based estimates to the individual and stand scale. The results showed that the leaf daily transpiration rates per dry leaf mass of H. leave and H. rhamnoides was greater than that of C. intermedia and S. psammophyla. For C. intermedia, the most drought-adapted species at the individual plant scale, has the lowest daily transpirational water consumption (2808 g). The total diurnal transpirational water consumption of three shrubs stands at the Wufendi small catchment was 74 tonnes of water in August 2002. C. intermedia is a more suitable species for planting in ecological restoration schemes in chestnut soils in northwest China. However, for long-term ecosystem stability and health at the catchment scale, a more diverse selection of shrubs should be used in the eco-reclamation programs.