Abstract: With four perennial plant species (Populus euphratica Oliv.,Tamarix ramosissima Ledeb., Calligonum caput medusae Schrenk. and Alhagi sparsifolia Shap.) in the southern fringe of Takelamakan Desert as test objects, the variation characteristics of their main water relation parameters P₁₀₀ (osmotic potential at maximum turgor), P₀ (osmotic potential at zero turgor), e_max(maximum cell elasticity modulus), and RWC_a (cell relative water content at incipient plasmolysis) in growth period were analyzed based on pressurevolume curves (P-V curves). In the meantime, the predawn water potential of test species was measured, and the soil water content was monitored. As for the ability of maint
aining turgor at low water potential, it was in order of T. ramosissima>P. euphratica>A. sparsifolia>C. caputmedusae. The common response of the four species to water stress was to keep relatively high water content when incipient plasmolysis occurred. As for the mechanisms of droughtendurance, C. caput medusae and A. sparsifolia belonged to the type of keeping high water potential to delay dehydration, while P. euphratica and T. ramosissima belonged to the type of keeping low water potential to endure dehydration. Among the four species, A. sparsifolia had the highest predawn water potential, while T. ramosissima had the lowest one. C. caput medusae and P. euphratica had a stable predawn water potential during its growth period. The variation tendency of predawn water potential was consistent with the change characteristics of water relation parameters of the species. No signs of serious drought stress were observed in any of the test species
 during their growth period. Irrigation had no significant effects on the water relation parameters of test species, suggesting that the four pe
rennial plant species were well adapted to the harsh environmental condition. The root systems of the species could access groundwater to satisfy their large demands for water. To protect the root systems of the species and to maintain a stable groundwater level would be the most important prerequisite for the restoration and reestablishment of the perennial plant species.

Key words: Hongchiba/Wuxi county, Aerial-sowing afforestation, Controlled burning, Ecological restoration, Species diversity, Pinus armandii