Spatial-temporal Variations Of Sandy Desertification And Causes In The Ujumqin Sinking Sand Area In The Last 40 Years

Aeolian desertification has become a challenging issue that directly impacts global and regional economic and social development as well as food security.The Ujumqin Grassland,one of the best-preserved typical grasslands in China,has been facing increasingly severe problems such as desertification,vegetation degradation,and sand dune activation in recent years due to climate change and rapid socio-economic development.Compared to the large-scale desertification of the Holchig Grassland,the degree of desertification in the Ujumqin Grassland is relatively mild,making it somewhat easier to reverse and restore.Therefore,it is urgent to prevent further desertification before the cost of restoration exceeds feasibility or the opportunity to take action is lost.Understanding the current state and spatiotemporal evolution patterns of Aeolian desertification land on the Ujumqin Grassland,and accurately comprehending the impacts of natural and human factors on its desertification,is of paramount significance for the ecological protection and management of the sandy land.This study took the Hoerqige sandy land,which has been largely Aeolian desertification in the sand-buried area of the Ujumqin Grassland,as the research area.Using Landsat TM/ETM+/OLI remote sensing images as data sources and combining natural and human factors,we explored the spatiotemporal evolution rules and causes of Aeolian desertification land over the past 40 years.The following conclusions were obtained:(1)In terms of temporal changes,the development of desertification land in the study area in the past 40 years shows a pattern of "recovery(1987-1995)-expansion(1995-1999)-recovery(1999-2003)-expansion(2003-2015)-recovery(2015-2022)",with an overall trend of reversal.The main types of reversal are severe desertification and extremely severe desertification,which still account for a large proportion and are the main types of desertification land in the study area.(2)Sand prevention measures should be taken in the peripheral areas of severely Aeolian desertification land in the middle of the research area.(3)In terms of spatial changes,the expansion of desertification land in the research area is mainly edge expansion,followed by infilling and enclave expansion.In terms of the direction of expansion,the center of gravity of desertification land in square-shaped sandy areas gradually moves towards the center of the sand,indicating that desertification is gradually shrinking and improving.However,the center of gravity of circular sandy areas is moving northeast,indicating a trend towards expansion in that direction.(4)In terms of driving forces,under the background of climate change,human factors in the Holchig Sandy Land are the main driving force leading to the desertification land changes in the study area.