The Study On Water Source And Water Using Efficiency Of Salix Gordejevii In Otinday Sandland

As the global water shortage becomes more and more serious,the rational allocation of water resources in arid and semi-arid regions is particularly important.the dominant shrubs salix gordejevii of the Hunshandake Sandland was selected as research object.Based on the carbon and oxygen isotope tracing technique,analyze the relationship between local atmospheric precipitation,soil water,groundwater,atmospheric water vapor of isotope and meteorological factors.Combined with multi-source linear mixed model and Bayesian model,the water source and water use efficiency of salix gordejevii in different stages were analyzed,which provided a scientific basis for realizing optimal allocation of water resources,improving desertification and restoring local vegetation and ecosystem.The main research results are as follows:(1)Analyze the monthly variation characteristics of hydrogen and oxygen isotopes in different water bodies.The results show that:The difference in isotope value of each water body is as follows:Salix gordejevii branches>Silicon surface soil water>back side soil water>atmospheric precipitation>groundwater>atmospheric water vapor.By studying the relationship between the isotope values of various water bodies and temperature?precipitation,it is found that the atmospheric precipitation,atmospheric water vapor ?D,?18O values are positively correlated with temperature,and there is a positive correlation between groundwater and burial depth.The ?D and ?18O values of salix gordejevii stem water were positively correlated with precipitation,and the values of ?D and ?18O of atmospheric water vapor were negatively correlated with precipitation.(2)The visual method and the multi-source linear mixed model and the Bayesian model were used to qualitatively and quantitatively determine the water source of the salix in each month,and the water use pattern of the salix was summarized.In the 4-5months,the salix mainly absorbed the middle and deep water.In the 6-8months,due to the increase of precipitation,Salix mainly used precipitation and surface soil water after precipitation.In the 9-10months,salix mainly absorbed the middle and upper soil water,and it was also possible to absorb deep soil water with depth,and it was also possible to use groundwater.(3)The ?13C value of the sunny surface of the salix leaves varied from-28.34‰ to-26.49‰,while the ?13C value of the back sunny surface ranged from-29.16‰ to-26.96‰in 2018.The monthly change showed a trend of decreasing first and then increasing.There were also characteristics of high dry season and low rainy season.There was no correlation between the ?3C value and the temperature of the day,and it was negatively correlated with precipitation.The WUE ranges of the sunny and the back-faced salix were 84.83-155.23 mmol C·mol-1H2O and 72.30-153.75 mmol C·mol-1 H2O respectively;the average values were 124.22 and 116.80 mmol C·mol-1 H2O respectively.It can be seen from the WUE value that the salix has a high water use efficiency.