Stable Isotope Study On The Process Of Soil Water Transport And Change In Peak Forest-lake Basin

Soil water is an important link in the process of water circulation,the study of soil moisture composition and transportation has theoretical and practical significance for the effective use of soil water and groundwater,in this paper,the forest basin area of Yunnan pine forest,secondary forest,thicket three different vegetation cover sample for the research object,the use of statistical software Excel for the preliminary processing of data,The characteristics of soil moisture content and stable isotope change in each soil layer are analyzed and mapped by software Grapher.The relationship between different water samples D and ¹⁸O of different water bodies is based on correlation analysis and regression analysis,and iso Source model is used to analyze the proportion of plant utilization of potential water sources.Based on the analysis of 200 different water samples collected in the research area in 2014-2015,the following conclusions are obtained:?1?The local atmospheric precipitation line in the study area is?D=7.68?¹⁸O+11.29?R²=0.99,n=12?in the atmospheric precipitation range of¹⁸O-14.4 to 7.5 degrees,D average-7.1 degrees;The surplus d value showed significant seasonal changes,with lower rainy seasons and higher dry seasons.The temperature effect is very weak,and the precipitation effect is very weak.?2?The water content characteristics of the three kinds of soil are shown to be higher than the dry season during the rainy season,higher than the surface,and the secondary forest,yunnan pine forest and thickets.The linear correlation between soil water 18O and d in the study area is remarkable,and the fitting curve equation is?D=7.23?¹⁸O-6.81,R²=0.96,n=140.Atmospheric precipitation,pre-rain soil water and shallow groundwater are the main potential sources of soil moisture.?3?Yunnan pine rainy season soil water¹⁸O surface variation coefficient is greater than deep,the dry season deep soil water ¹⁸O variation is the largest of each habitat,the other layers are small,the matrix flow mixing effect is strong,the piston flow is mainly the upper layer of priority flow;The degree of variation in the dry season is low,the lowest value appears deep,the transport mode is mainly piston flow,the surface soil water ¹⁸O variation degree of the surface water of the season of the thickets is large,the variation degree of the surface and deep soil water¹⁸O is low,the mixing effect is strong,the soil water piston flow and the priority flow coexist,mainly the priority flow supply.?4?The use of water from different plants also has an impact on soil water redistribution.The hydraulic boost of plant roots can make the plant pass the dry season smoothly.With the restoration of vegetation communities,Yunnan pine forests and secondary forests in the higher stage of ecological restoration tend to use stable water sources such as surface karst water than thickets,be more adaptable to karst environment,be less stressed by water,and gradually decrease the heterogeneity of soil water.