浑善达克沙地沙质荒漠化过程与动态评估

Sandy desertification process and dynamic assessment in Hunshandake sandland

在人类活动相对频繁的干旱、半干旱地区,沙质荒漠化制约当地生产生活的主要环境问题之一。文中以MODIS NDVI数据为基础,以2000年荒漠化现状为初始状态,采用逐时段累计方法分析了2000年以来浑善达克沙地沙质荒漠化时空动态。研究结果表明浑善达克沙地整体变化幅度在2697km^2,5个时段统计学变异系数为3.0%。统计学分析解释了不同沙丘类型分布面积以固定沙丘变异系数最高为42.3%,半固定沙丘分布面积变化最小(变异系数为23.8)。从沙质荒漠化逆转区与降水量等值线空间关系来看,年降水量差异不是制约荒漠化逆转的限制因素,浑善达克沙地稳定区+逆转区的面积占主导地位,占总面积的82.8%(±4.7%)。在影响沙质荒漠化动态因素方面,年均气温对半流动沙丘面积分布有较大影响(在0.1水平上),年降水量对半固定沙丘有较大影响(在0.05水平上),而牲畜头数(羊单位)与不同类型沙丘面积分布没有显著关系。总的来看,在研究时段内浑善达克沙地总体相对稳定,尚未发生明显的沙质荒漠化扩展。

Sandy desertification,which was induced by frequent human activity in arid and semi-arid zone,is one of principal environment problems to restrict production and livelihood for local people.Taking the desertification situation of 2000 as an initial status in Hunshandake sandland,we employed gradatim accumulative statistical method to analyze the desertification dynamics in temporal and spatial scale based on MODIS NDVI data from 2000 to 2017.Results showed that rangeability of distribution area of Hunshandake sandland scope was 2697 km^2 during study period and variable coefficient was 3.0%on five periods.In terms of the different sand-dune distribution area,statistical analysis indicated that fixed sand-dune had maximum variable coefficient as 42.3%and semi-fixed sand-dune had minimum variable coefficient on five periods.As to the relationship between the changeover area of the desertification and precipitation isoline in spatial aspect,annual precipitation variation was not restriction factor for the desertification changeover in Hunshandake sandland,and the stable area and changeover area dominated as 82.8%(±4.7%)of total area in all change types.In terms of the impact factor of the desertification dynamic mechanism,mean annual air temperature had significant effect on semi-shifting sand-dune area at 0.1 level and annual precipitation had significant effect on semi-fixed sand-dune area at 0.05 level,respectively.Meanwhile,livestock number(sheep unit)had not significant relation with different sand-dune areas.In general,desertification of Hunshandake sandland in study period was relatively stable and not extended obviously.