Abstract: In desert environment, water is the principal factor affecting plant distribution,and the plants with different life forms have different water sources.As hydrogen stable isotopes are prone to fractionation in salt-tolerant and drought-tolerant plants,so,in this study,oxygen isotope ratios (δ¹⁸O) were measured for xylem water of five typical plant species,soil moisture in different soil layers and groundwater in the east Junggar Basin.The five typical plant species were Haloxylon ammodendron,H.persicum,Convolvulus tragacanthoides,Reaumuria soongonica and Anabasis salsa respectively.The IsoSource model was used to calculate the possible ranges of potential water sources used by the five typical plant species.The proportional similarity index(SPI) was used to analyze the water use relationship among different plant species.The result showed that the five typical plant species used mainly soil water but had different water uptake soil layers.H.ammodendron and H.persicum used mainly deep soil water (140-200 cm in depth),their soil water use proportions were 73%-87% and 43%-74% respectively,and the water uptake soil depthvaried in a range of 140-160 cm.R.soongonica used mainly soil water in depth of 0-80 cm,its soil water use proportion varied in a range of 49%-85%,and the water uptake soil depth was 60-80 cm.A.salsa and C.tragacanthoides used mainly soil water in depth of 0-60 cm,their soil water use proportions were 80%-91% and 24%-79%,and the water uptake soil depths were 20-40 cm and 40-60 cm,respectively.There were water use competition between H.ammodendron and H.persicum and between A.salsa and C.tragacanthoides.This study could help us to know more about the adaption of plant species in desert environment.

Key words: desert plant species, soil moisture content, proportional similarity index, stable isotope, water source, Xinjiang