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sur le développement des zones arides et semi-arides

Titre : Study on the Effect of Vegetation Restoration on Soil Moisture on the Loess Plateau

Auteur : 刘粲

Grade : Master 2022

Université : Hebei GEO University

Résumé partiel
Loess Plateau is located in semi-arid and semi-humid areas,with special soil structure and deep water table,so soil water is very important for vegetation growth.Since 1999,the Loess Plateau has been carrying out the project of returning farmland to forest（grass）.During the implementation of the project,the fallow vegetation may overconsume soil water and cause ecological environment changes.Therefore,it is significant to study the influence on soil water during the vegetation restoration process.In this study,based on remote sensing monitoring land use/cover and soil moisture fusion product data,land use transfer matrix,transfer mapping and change magnitude were used to analyze the spatial and temporal changes of land use on the Loess Plateau from 2000 to 2020,and the Theil-Sen Median slope estimation and Mann-Kendal trend analysis were used to study the spatial and temporal changes of soil water on the Loess Plateau from 2000 to 2020.The spatial and temporal changes of land use on the Loess Plateau from 2000 to 2020 were studied,based on which the effects of vegetation restoration on soil moisture on the Loess Plateau were further analyzed.The main results obtained are as follows（1）The changes of arable land,forest land and unused land on the Loess Plateau from2000 to 2020 are obvious,with arable land decreasing by 12,918 km 2（accounting for 6%of the total arable land area）,forest land increasing by 3,232 km 2（accounting for 6%of the total arable land area）,shrubs increasing by 555 km 2（accounting for 1.4%of the total shrub area）,and unused land decreasing by 1,982 km 2（accounting for 5%of the total unused land area） ;during the recent During the last 20a,arable land mainly shifted to grassland,with an area of 58,576km 2（28%of the total arable land area）,mainly in the semi-arid central Shaanxi and Shanxi ;forest land mainly shifted to grassland and arable land,with an area of10,599km 2（20%of the total forest land area）and 6,890km 2（13%of the total forest land area）,mainly in the semi-arid and semi-humid areas ;shrubland mainly shifted to grassland,with an area of 11,088 km 2（13%of the total area of shrubland）.km 2（28%of the total shrubland area）,mainly in Yan’an City,Shanxi Province,and Shanxi Province in the semi-arid zone ;grassland is mainly transferred to cropland,with an area of 54,923 km 2（28%of the total grassland area）.km 2（21%of the total area of grassland）,mainly located in semi-arid areas,and the transfer of unused land mainly to grassland,with a transfer area of10,278 km 2（24%of the total area of unused land）,mainly occurring in Inner Mongolia and eastern Qinghai to grassland.（2）Soil moisture in the Loess Plateau showed an overall increasing trend(4.9×10-4yr-1)during the growing season from 2000 to 2020,and soil moisture trends in all climatic zones were consistent with the Loess Plateau,with an overall increasing trend,but with slightly different rates of rise,with the semi-arid zone being the fastest(6.1×10-4yr-1),the arid zone the second fastest(4.4×10-4yr-1),and the semi-humid zone the slowest(1.8×10-4yr-1).Soil moisture in the Loess Plateau in spring,summer,autumn and winter show fluctuating rising trend,but the rising rate is slightly different,from large to small,spring＞summer＞autumn＞winter ;soil moisture in the growing season of the Loess Plateau from 2000 to2020 showed rising trend in 73%of the area,rising area of 459809km 2,mainly in Gansu,Ningxia and part of Inner Mongolia region.Among them,23%of the regions showed a highly significant rising trend,with a regional area of 142,370 km 2,mainly distributed in Ningxia,Gansu and Qinghai regions.

Mots clés : Land cover ;soil moisture ;Vegetation restoration ;Loess Plateau ;

Présentation (CNKI)