乌珠穆沁伏沙区近40年沙漠化时空变化特征分析

Analysis of Spatial-temporal Changes of Aeolian Desertification in the Ujumqin Sinking Sand Areas over the Past 40 Years

沙漠化是干旱、半干旱草原区严重的生态环境问题,尤其在伏沙区,因风蚀或人为破坏导致的伏沙显化现象日益增多。因此,准确掌握其演变过程及成因,对抑制伏沙活化、沙漠化防治具有重要意义。笔者以乌珠穆沁伏沙区霍尔其格沙地为例,基于Landsat系列卫星影像数据为主要数据源,分析了近40年来沙漠化土地的时空变化特征。结果表明:(1)近40年来,研究区沙漠化呈逆转趋势,主要逆转类型是重度沙漠化和严重沙漠化土地,但两者仍是研究区主要的沙漠化土地类型;(2)严重沙漠化土地集中分布在研究区的南侧,2003年之后开始变得零星分布;重度沙漠化土地主要分布于研究区中部;中度沙漠化土地集中分布于研究区西北部;轻度沙漠化土地刚开始呈带状分布于严重沙漠化土地的南侧边缘,从2007年开始逐渐分布在研究区中部和南部大部分区域;(3)近40年来,霍尔其格沙地的严重、重度沙漠化土地主要通过边缘扩张进行。从扩张方向来看,方形沙地的各类型沙漠化土地重心向沙地中央逐渐集中,且向逆转的方向发展;而圆形沙地的重心向东北移动,有向该方向扩张的趋势。研究结果可以为伏沙区风沙化治理和区域生态环境恢复重建提供决策依据。

Aeolian desertification is a serious ecological environmental issue in arid and semi-arid grasslands,es⁃pecially in the sinking sand area,where the sinking sand manifestation caused by wind erosion or human destruc⁃tion is increasing.Therefore,it is of great significance to accurately understand its evolution process and causes for sinking sand control and desertification prevention and protection.Taking the Holchig sandy land in the Ujumqin desert as an example and Landsat series satellite image data as the main data source,the spatio-tempo⁃ral changes of desertification land over the past 40 years were analyzed in this article.The research showed that:(1)The desertification trend in the study area had reversed over the past 40 years.The main types of reversal were severe desertification and heavily desertified land,both of which are still the main types of desertified land in the study area.(2)Severely desertified land was distributed mainly in the southern part of the study area and has become sporadically distributed since 2003.Heavily desertified land was mainly distributed in the central part of the study area.Moderately desertified land was concentrated in the northwest of the study area.Mildly de⁃sertified land initially showed a belt-like distribution on the southern edge of severely desertified land,but it has gradually spread to most areas in the central and southern parts of the study area since 2007.(3)Over the past 40 years,severe desertification and heavily desertified land in the Holchig sandy land have mainly expanded through edge expansion.In terms of expansion direction,the focus of each type of desertified land in the square sandy land gradually concentrated to the center of the sandy land and developed in the reverse direction,while the focus of the circular sandy land has moved to the northeast with a tendency to expand in that direction.The research findings can provide a decision-making basis for the control of desertification and the restoration and re⁃construction of the regional ecological environment in sinking sand areas.