Spatial-temporal Dynamic Change Of Land Desertification In The Inner Mongolia Section Of The Yellow River Basin Based On The Geodetector Method

Desertification is the land degradation in arid,semi-arid and partly sub-humid areas caused by human overuse or harsh natural conditions.The Mongolian section of the Yellow River basin is an important ecological barrier and one of the most serious desertification areas in north China,so it is very urgent to control desertification in this area.In this study,the Inner Mongolia section of the Yellow River Basin was selected as the research area.Landsat remote sensing images of six periods from 1995 to 2020 were used as data sources,and the vegetation coverage index was used to classify desertification types,and the spatial pattern and evolution characteristics of desertification were analyzed using ENVI5.3 and Arc GIS10.2 platforms.In addition,climate,natural and economic index data were obtained extensively,and the spatial differentiation characteristics and driving forces of desertification degree in the Mongolian section of the Yellow River basin were explained by using geographic detector model.The main conclusions are as follows:(1)Desertification in the study area showed a trend of reversal in the last 25 years.Desertification land mainly expanded from 1995 to 2000;From 2000 to 2005,with the implementation of a series of ecological engineering projects,vegetation gradually recovered and desertification was reversed.After 2005,the extremely severe desertification showed an increasing trend,but the non-desertification area continued to increase.By 2020,mild desertification and non-desertification increased by 3765.36km2 and 4927.48km2 respectively,and extremely severe desertification decreased by 1853.31km2.The spatial distribution of land desertification gradually decreased from west to east.During the monitoring period,the desertification land conversion of different grades in the Mongolian section of the Yellow River Basin mainly occurred between extremely severe desertification,severe desertification and moderate desertification.(2)From the dynamic attitude of desertification types,it can be seen that the dynamic attitude of extremely severe desertification land fluctuated positively,negatively,positively and negatively from 1995 to 2020.In the last two periods,mild desertification increased the most area and the most dynamic attitude(8.26% and 5.50%).In the first three periods,the area of non-desertification changed very slowly,and in the last two periods,the area continued to increase and the growth rate continued to accelerate,and the dynamic attitude was positive(3.34%,4.71%),which changed from extremely slow growth to slow growth.The slow growth of mild and non-desertified land reflects the difficulty and long cycle of desertified land control.(3)The comprehensive driving mechanism of spatial differentiation is as follows:population > dryness > moisture index > annual mean precipitation > soil type > elevation >land use > accumulated temperature(≥10℃)> accumulated temperature(≥0℃)> GDP >annual mean temperature > topographic features.The spatial differences of desertification in the study area are mainly determined by population density,moisture index,dryness and annual average precipitation,and their factor interpretation power is more than 25%.Most of the driving factors showed mutual enhancement or nonlinear enhancement,and the wetting index and soil had the strongest interaction explanatory power,with q value of 0.459.The spatial differentiation of desertification in The Mongolian section of the Yellow River Basin is the result of interaction of multiple driving factors.