Abstract:Root distribution of three desert shrubs, Tamarix ramosissima Ledeb., Haloxylon ammodendron (C. A. Mey.) Bunge and Reaumuria soongorica (Pall.) Maxim. were investigated under co-occurring conditions using whole root system excavation method. Assimilatiion shoot water potential and transpiration rate were monitored during the wet-dry circle induced by rain events. Leaf-specific apparent hydraulic conductance and the index of water stress impact for the three species were calculated from shoot water potential and transpiration rate. The results showed that the root system of T. ramosissima mainly distributed at 50 to 310cm below soil surface, with average total absorbing root surface area at 302492cm2 per plant; The root system of H. ammodendraom distributed at 0 to 250cm below soil surface with average total absorbing root surface area at 12847.3 cm2 per plant; The root system of R. soongorica distributed at 0-80cm, with average total absorbing root surface area at 361.8 cm2. The root distribution shows that, T. ramosissima uses the ground water as the main water resource; H. ammodendraom uses both ground water and rain water; R. soongorica uses rain water only. During the wet-dry cycle induced by raining events, hydraulic parameters of T. ramosissima showed no responses to precipitation. R. soongorica responded most significantly, the responses of H. ammodendraom were in between. In conclusion, the plant responses towards rain events closely related to their root distribution and plant water-use strategy. Under the scenario of the predicted precipitation changes in the future, the discrepancy of root distribution will partially determine the position of the studied species in water resource competition. Species that have the superior root morphological plasticity, such as H. ammodendron, will have significant advantage in competing for water resources.