Isotopic Characteristics Of Different Water Bodies And Vegetation Water Use Strategies In The Southern Hunshandake Sandy Land

Hunshadak Sand is the important ecological protection barrier in my country to prevent invasion from Central Asian Grassland and the West of Sharms.In recent years,local governments have been planted in terms of local conditions,planting a large amount of drought-donated trees,shrubs and various pastures.Windproof sand and other aspects play an important sense.This article is based on the south margin of Hunshada Sand,vegetation,Qingyang and Huiliu as the research object,using stable isotope trace technology,multi-linear hybrid model and Bayesian model,analysis of vegetation in different seasons and different The moisture source and water use efficiency of the growth period,and combined with the study area for many years of atmospheric hydrogen oxygen and oxyhydride stabilize the isotope data and meteorological data,the precipitation isotope characteristics of the south edge of Hunshadak Sand.In order to provide reasonable reference and theoretical basis for structural optimization of the Sandy artificial protective forest ecosystem.The main research results are as follows:(1)According to the isotope observation data from 2014 to 2019,the atmospheric precipitation equation line in the study area is obtained:?D=7.29?¹⁸O+0.96(R²=0.88),the rain experienced a strong secondary evaporation process during the fall;the rainy season(6-9)Month)isotope values are relatively enriched,and dry season(from October to April of the following year)isotope values are relatively depleted,showing the characteristics of seasonal changes of"high in summer and low in winter",and there are significant differences on both the annual and seasonal scales.The temperature effect does not show the rainfall effect;the d value during the deuterium surplus during the summer monsoon is generally less than 10‰,and the d value during the winter monsoon is generally greater than 10‰,and it shows a"V"-shaped change characteristic during the year.(2)The range of hydrogen and oxygen isotope variation in different water bodies is:atmospheric precipitation>soil water>stem water>groundwater,and the average size of the two forest lands is:atmospheric precipitation>stem water>soil water>groundwater,showing that atmospheric precipitation is in When replenishing soil water and groundwater,it is subjected to strong evaporation and fractionation;the intercept and slope of the soil moisture evaporation line of the poplar forest land are larger than that of the yellow willow forest land,because the soil moisture evaporation of the green poplar forest land is more than that of the yellow willow forest land.It is strong and shows that the movement of soil water in the forests of poplar woods is faster than that of the forests of yellow willows,which makes the effect of evaporation and fractionation more intense and indirectly aggravates this difference.(3)Combining direct comparison method,multiple linear mixed model and Bayesian model to analyze the variation of vegetation water sources during the year.The two types of vegetation mainly use 0-40cm to obtain surface soil water.When the surface soil water is insufficient to maintain the normal growth of plants,The lateral roots can be used to absorb the soil water in the middle and deep layers.At the same time,the strong main roots can also be used to absorb a small amount of groundwater to maintain their normal growth.(4)The variation range of ?¹³C value of green poplar is-25.28‰?-28.54‰,the variation range of?¹³C value of yellow willow sun leaf is-26.10‰?-28.98‰,and the variation range of?¹³C value of yellow willow shade leaf surface is-26.10‰?-29.68‰.The water use efficiency(WUE)of the two types of vegetation are basically the same,showing a"U"-shaped change feature,the size is:green poplar woodland>sunny leaf surface yellow willow woodland>shade leaf surface yellow willow woodland,on a seasonal scale Above,the water use efficiency of the two types of vegetation is higher in the dry season than in the rainy season.This is because the vegetation has increased the water use efficiency in response to water stress.