2001-2016年三峡库区植被变化及其气候驱动因子分析

Vegetation Changes in the Three Gorges Reservoir Area from 2001 to 2016 and the Analysis of Its Climate Driving Factors

三峡库区植被的变化及其对气候因子的响应能够反映库区生态系统状况。因此,以MOD13Q1数据和32个气象站的气象资料为数据源,研究了三峡库区2001-2016年季节合成植被指数(SINDVI)的时空变化,并对库区NDVI(归一化差异植被指数)的气候驱动因子进行了分析。研究显示:1)三峡库区近16年来SINDVI呈增长趋势,其重心存在西移趋势。库区高植被覆盖区SINDVI保持稳定或增强,低植被覆盖区则进一步降低且波动更大。2)三峡库区月最大NDVI与温度的(偏)相关性高于降水,且偏相关系数表现出农作物>草甸与灌木>阔叶林>针叶林的规律。驱动力分析表明,库区大部分区域主要受温度影响,受温度和降水共同影响的区域多为农作物种植区。总体而言,三峡库区月最大NDVI对气候因子的响应具有明显的植被类型差异及空间异质性。

The Three Gorges Reservoir Area is an important ecological barrier in southwest of China.Vegetation changes and their responses to climatic factors can reflect the status of the ecosystem in the Three Gorges Reservoir Area.Therefore,taking MOD13 Q1 data of 250 m spatial resolution and meteorological data of 32 meteorological observatories in the Three Gorges Reservoir Area and its surrounding areas as data source,the spatial and temporal variation of SINDVI(seasonally integrated normalized difference vegetation index) in the Three Gorges Reservoir Area from 2001 to 2016 was studied and its climate driving factors were analyzed using trend analysis and correlation analysis methods.The results show that:1) SINDVI shows a trend of increasing in the Three Gorges Reservoir Area in the past 16 years.The higher SINDVI regions tend to move west.2) The higher SINDVI regions are mainly distributed in the eastern,northern and southern parts of the Three Gorges Reservoir Area,and their vegetation cover keeps stable or becomes higher.However,SINDVI values are getting lower and the vegetation cover fluctuates more due to frequent human activities in the western and the Yangtze River bank.3) The correlation between monthly maximum NDVI and temperature in the Three Gorges Reservoir Area is higher than that between monthly maximum NDVI and precipitation,and the partial correlation coefficient shows the law of crops > grassland and shrubs > broadleaf forest > coniferous forest.The driving force analysis shows that the crop area in the Three Gorges Reservoir Area is mostly affected by both temperature and precipitation,while the woodland,shrubbery and grassland are mostly affected by temperature.In general,the monthly maximum NDVI response to climatic factors in the Three Gorges Reservoir Area has obvious differences in vegetation types and spatial heterogeneity.It is also necessary to consider different time scales and more influence factors for further study.