西北干旱半干旱区NDVI季节性变化及其影响因素

Seasonal changes of NDVI in the arid and semi-arid regions of Northwest China and its influencing factors

研究植被的动态变化及其影响因素,不仅能够揭示植被覆盖动态变化特征与气候变化之间的响应机制,同时对区域的植被恢复以及生态可持续具有重要意义。本文基于MODIS遥感卫星数据,借助变异系数、趋势分析、相关分析与Hurst指数探究了2000—2020年西北干旱半干旱区植被覆盖逐季变化特征、影响因素及未来趋势。结果表明:(1)归一化植被指数(Normalized DifferenceVegetationIndex,NDVI)空间变异程度在冬季偏高,且高波动主要分布在新疆与内蒙古大兴安岭的草地与未利用地区域。(2)NDVI随季节波动较大,在林地与耕地最为明显。(3)NDVI主要为改善趋势,其中,春季改善面积最大(84.63%),冬季最小(72.52%),且林地改善最为显著。(4)各季度NDVI均受地表温度与降水量影响(Significance=0.05),且夏季地表温度与冬季降水量逐年递增对植被生长具有抑制作用。(5)未来NDVI主要呈改善趋势。值得注意的是,退化区域零星分布于新疆塔里木盆地、准噶尔盆地等地区。本研究旨在为西北干旱半干旱区的生态修复与治理,以及局部气候暖湿化的应对提供理论参考。

The study of vegetation dynamics and its influencing factors can reveal the response mechanism between vegetation cover dynamics and climate change and has important significance for regional vegetation restoration and ecological sustainability.Based on MODIS multitemporal remote sensing satellite data,this study investigated the quarterly changes in vegetation cover in the arid and semi-arid regions of Northwest China from 2000-2020 using variation coefficient,Theil-Sen median trend analysis,Mann-Kendall significance test,correlation analysis,and Hurst index.The study found that:(1)The spatial variability of the Normalized Difference Vegetation Index(NDVI)was high in winters,and the high fluctuation areas were mainly in the grasslands and unused land areas in the Daxinganling region of Xinjiang and Inner Mongolia.(2)NDVI fluctuates more with the seasons and is most obvious in forests and cultivated areas.(3)NDVI is mainly improving,with the largest improvement in springs(84.63%),the smallest in winters(72.52%),and the most significant improvement in the woodland areas.(4)Surface temperature and precipitation influenced NDVI in all seasons(Significance=0.05),with precipitation changes significantly affecting NDVI trends in summers and weakly during winters and surface temperature changes significantly affecting NDVI trends in springs and weakly in autumns.(5)The future NDVI also mainly shows an improving trend,with an area of 70.89%;notably,the degraded areas are sporadically distributed in the Tarim and Junggar Basins of Xinjiang.This study’s results provide theoretical references for ecological restoration and management in the arid and semi-arid regions of Northwest China and the response to local climate warming and humidification.