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Northwest A&F University (2020)

Responses of Soil Moisture Estimated from CRNP to Vegetation Types in A Small Watershed on the Loess Plateau

王秋铭;

Titre : Responses of Soil Moisture Estimated from CRNP to Vegetation Types in A Small Watershed on the Loess Plateau

Auteur : 王秋铭;

Grade : Doctoral Dissertation 2020

Université : Northwest A&F University

Résumé partiel
Soil water is a principal component of Earth’s water,playing an important role in the processes of energy exchange between the surface and the atmosphere and a variety of scale of water sports,and also is the main limiting factor for plant growth and development on the Loess Plateau.The spatiotemporal changes of soil water have important effects on soil erosion,coupled transport of water-heat-solutes,and material migration in the soil-vegetation-atmosphere continuum.The distribution and consumption intensity and depth of soil water are different due to different soil texture,vegetation types and allocation modes,which leads to the significant spatial differentiation of soil water on the Loess Plateau.In turn,the spatial and temporal distribution of soil water on the Loess Plateau determines the spatial distribution of vegetation types and their growth conditions.Therefore,the spatial and temporal distribution of soil water must be followed in order to ensure the sustainability of vegetation restoration.This study explores the changing process and distribution of soil water content(SWC)in 3 plots with different soil texture and different vegetation types on the Loess Plateau,so as to provide a scientific basis for the sustainable utilization of soil water in the Loess Plateau.The SWC and its distribution were measured by Cosmic-ray neutron probe(CRNP)and TDR sensors.The biomass and vegetation water content were measured by Unmanned Aerial Vehicle(UAV).The changing process of biomass was modeled by SPACSYS model.The spatial and temporal distribution of SWC and its interaction with vegetation were analyzed and the main conclusions are as follows :(1)In 2016 and 2017,changing processes of SWC measured by the CRNP and TDR sensors in loamy-sand hill plot(LSH),silty-loam dam plot(SLD)and sandy-loam slope plot(SLS)were consistent and the coefficient of the linear relationships between CRNP-SWC and TDR-SWC is the order:SLS>LSH>SLD.And the accuracy of the CRNP was verified by the oven-dried method(RMSE=0.068 cm3 cm-3).CRNP-SWC shows a similar trend over time and is very sensitive to changes of SWC.The effects of soil texture on CRNP can be ignored.(2)The average SWC at a depth of 0~30 cm of three plots during the growing season was moderate variability and the order of varisions of SWC in 3 plots is SLS>LSH>SLD.The Spearman’s rank correlation coefficient was low in the early period of the measurement and was high after July,indicating a stronger temporal stability of spatial patterns for 3 plots in the late period.And the correlation coefficient of each measurement date in the SLD sample plot is basically the highest value.The numbers of dry(MRD<0)and wet(MRD>0)spots in the three plots are approximately the same,but LSH and SLS deviate to a greater extent from the MRD=0 line,especially the wet points,indicating that wet spots in the two plots have a higher degree of deviation

Mots clés : SOIL WATER CONTENT; SPATIAL AND TEMPORAL DISTRIBUTION; CRNP MEASUREMENT; SPACSYS;

Présentation (CNKI)

Page publiée le 15 juin 2021