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Inner Mongolia Normal University (2021)

Spatiotemporal Variation of Soil Moisture and Its Effect on Grassland Vegetation Phenology in the Mongolian Plateau

王佳新

Titre : Spatiotemporal Variation of Soil Moisture and Its Effect on Grassland Vegetation Phenology in the Mongolian Plateau

Auteur : 王佳新

Grade : Master 2021

Université : Inner Mongolia Normal University

Résumé partiel
As an important part of the global energy cycle,soil moisture is a key parameter describing the exchange of moisture and energy between land and atmosphere.It has a major impact on the earth’s water cycle,energy balance and climate change.Soil moisture can also provide an important source of water and energy for the growth and development of plants,and the phenological characteristics of vegetation will also provide corresponding feedback to adapt to changes in soil moisture.Therefore,based on the GLDAS soil moisture data,GIMMS NDVI and MODIS NDVI data,and meteorological data from 1982 to 2019,this paper uses linear regression analysis,trend analysis,cumulative Logistic curve curvature extreme value method and correlation analysis to analyze the soil moisture time and space in the Mongolian Plateau.Changes and their impact on grassland vegetation phenology were studied,and the following conclusions were obtained :(1)From 1982 to 2019,the soil moisture of 0~10cm(SM1)in the Mongolian Plateau showed an insignificant increase at a rate of 0.002 m3/m3/10 a,and the mutation time occurred around 2012 ;10~40cm(SM2)soil The rate of water change is-0.004 m3/m3/10 a,with a significant decreasing trend and abrupt changes around 1996.In spring and winter,SM1 soil moisture showed a significant increasing trend ;in summer and autumn,SM1 soil moisture showed an insignificant decreasing trend.The soil moisture of SM2 showed a decreasing trend in different seasons.In addition,the annual variation of soil moisture in the deep layer is smaller than that of the shallow layer.The annual average soil moisture at different depths shows a gradual decrease in space from northeast to southwest and presents a pattern of relatively high soil moisture values on the periphery of the plateau and relatively low internal soil moisture values.The soil moisture of SM1 and SM2 have good consistency in spatial distribution.The area of SM1 showing an increasing trend accounts for about 71.89%,including the Altai Mountains,the Yinshan Mountains and the Daxingan Mountains in the east.The area showing a decreasing trend of SM2 accounts for about 66.13%,distributed in the northern part of Hangai Mountain,Sayan Mountains and Horqin Sandy Land.(2)The vegetation return period(SOS)of the Mongolian Plateau from 1982 to 2019 was mainly concentrated from late April to mid-May,accounting for about 70.41% of the study area.Over the years,SOS has shown an advance trend at a rate of 1.09 d/10 a,accounting for about80.23%.On the whole,the emergence time of vegetation SOS is desert grassland,meadow grassland,typical grassland and alpine grassland.

Mots clés : Mongolian Plateau ;soil moisture ;vegetation phenology ;correlation analysis ;time lag correlation analysis ;

Présentation (CNKI)

Page publiée le 11 novembre 2021