阿拉善高原植被覆盖动态监测与驱动因素分析

阿拉善高原作为我国生态环境重度危急区，定期评价植被动态变化对区域生态环境保护和建设、保障北方地区生态安全及维护社会经济可持续发展具有极其重要的作用。利用遥感影像和气象数据，辅以趋势分析、重标极差及偏相关分析等方法，从全区及旗县尺度对2000-2015年阿拉善高原植被覆盖时空变化及其影响因素进行分析研究。从时间变化特征来看，额济纳旗、阿拉善右旗、阿拉善左旗植被覆盖度均呈增加趋势，其中，阿拉善左旗植被覆盖度最高。总体而言，近16 a阿拉善高原植被覆盖度呈现改善趋势，但以低植被覆盖区为主，植被覆盖区域占阿拉善高原总面积的24.77%。从空间分布特征来看，阿拉善高原植被覆盖具有明显的空间差异，具有东南部高，西北部低的分布特征。Hurst指数表明阿拉善高原植被覆盖度未来变化趋势为东南部持续改善，西北部严重退化。从驱动因子来看，植被覆盖对降水和潜在蒸散存在时滞效应。此外，阿拉善高原植被覆盖度的增加与当地牲畜数量的下降具有负相关关系。

Spatial-temporal Changes and Driving Factors of Vegetation Coverage in the Alxa Plateau From 2000 to 2015

It has important significance to periodically evaluate the vegetation changes to reconstruct the regional ecological environment,protect the ecological security of the Northern region and maintain the sustainable development of society and economy because Alxa Plateau is a serious ecologically fragile area in China.Using remote sensing images and climate data,we investigated the changes of normalized difference vegetation index (NDVI) in the growing seasons and its response to climate changes in the Alxa Plateau based on the trend analysis,Hurst index and partial correlation analysis,aiming to analyze the spatial-temporal changes of vegetation coverage and its driving factors in the Alxa Plateau between 2000 and 2015 from two dimensions.From the point of temporal changes,vegetation coverage presented an increasing trend in the Ejina Banner,Alxa Right and Left Banner.In contrast,vegetation coverage of Alxa Left Banner was the highest.In summary,the vegetation coverage in the Alxa Plateau showed a trend of improvement and was dominated by low coverage and the vegetation coverage area accounted for 24.77% of the total area by the end of 2015.From the point of spatial changes,there were obvious regional differences in vegetation coverage.The vegetation coverage presented an increase trend in the southeast and a decrease trend in the northwest.Hurst index showed that the improving trend was mainly found in the Alxa Right and Left Banner,while the serious degradation trend was mainly distributed in Ejina Banner.From the point of driving factors,the response of vegetation coverage to precipitation and potential evapotranspiration had time lag.In addition,there was a significant positive correlation between declining of livestock quantity and improving of vegetation coverage.