干旱区生态环境知识资源中心

Water relation characteristics of the desert legume Alhagi sparsifolia were investigated during the vegetation period from April to September 1999 in the foreland of Qira oasis at the southern fringe of the Taklamakan Desert, Xinjiang Uygur Autonomous Region of China. The seasonal variation of predawn water potentials and of diurnal water potential indicated that Alhagi plants were well water supplied over the entire vegetation period. Decreasing values in the summer months were probably attributed to increasing temperatures and irradiation and therefore a higher evapotranspirative demand. Data from pressure-volume analysis confirmed that Alhagi plants were not drought stressed and xylem sap flow measurements indicated that Alhagi plants used large amounts of water during the summer months. Flood irrigation had no influence on water relations in Alhagi probably because Alhagi plants produced only few fine roots in the upper soil layers. The data indicate that Alhagi sparsifolia is. a drought-avoiding species that utilizes ground water by a deep roots system, which is the key characteristic to adjust the hyper-arid environment. Because growth and survival of Alhagi depends on ground water supply, it is important that variations of ground water depth are kept to a minimum. The study will provide a theoretical basis for the restoration and management of natural vegetation around oasis in and regions.