Water Sources Of Two Shrub Species In The Mu Us Desert

The intense evaporation and limited rainfall in desert regions result in the shortage of water resources,which largely affects the survival of plants and the distribution of vegetation.Flexible water use strategies are of great significance for plants in desert regions to adapt to the arid climate environment.The availability of soil water,precipitation,groundwater,and the water use dynamics of plants is very important for ecosystem functions.However,how desert plants use these water sources is unclear.This studyinvestigated the use of water sources?soil water,precipitation,and groundwater?of two sand-fixing shrub species?Caragana korshinskii and Salix psammophila?in the Mu Us Desert,using stable isotope tracing The main results and conclusions are as follows:?1?There was a large fluctuation in?¹⁸O and?²H in precipitation in the Mu Us Desert.The?2H in soil water had a minor change in 0-120 cm layer,and the?18O decreased significantly with increasing depth.In growing season,the?18O and?2H values in the xylem water of C.korshinskii and S.psammophila showed a trend of increase,decrease,and reaching the maximum in July.?2?Soil water was the main water source for C.korshinskii and S.psammophila in the Mu Us Desert,accounting for 83%and 89.1%,respectively.C.korshinskii and S.psammophila had a different soil layer of water absorption that C.korshinskii tended to use soil water in 40-80 cm,accounting for35.34%,while S.psammophila mainly used soil water in 0-60 cm,accounting for 64.28%.?3?In whole growing season,whether in dry or rainy season,C.korshinskii and S.psammophila mainly relied on deeper soil water?80-120 cm?that did not significantly change.In the rainy season,the contribution rate of soil water in the shallow layer?0-60 cm?to C.korshinskii and S.psammophila had a significant change,and the contribution rate of shallow soil water?0-10 cm?increased;but the contribution rate of soil water in 40-60 cm to C.korshinskii decreased,while that in 20-40 cm to S.psammophila decreased.?4?To conclude,C.korshinskii tends to absorb soil water in the deeper layer?40-60 cm?than S.psammophila.During the rainy season,water use layers of C.korshinskii and S.psammophila lift from0-40 cm)to 0-10 cm;however,water use below 80 cm of the two shrub species does not change.By analyzing the water sources and stable isotope values of C.korshinskii and S.psammophila,the results preliminarily revealed the water sources of the two sand-fixing shrub species C.korshinskii and S.psammophila as well as the seasonal dynamics of soil water.The findings help to fully understand the water use strategies and environmental adaptability of desert plants,thereby providinga theoretical basis for the selection of sand-fixing plant species in arid regions.