Spatial and temporal evolution of vegetation and topographic differentiation in Minjiang River basin based on MODIS-NDVI
Minjiang River is one of the important branches of the Yangtze River system,which flows through the western Sichuan Plateau and the Sichuan Basin.As one of the important ecological indicators,studying the spatial and temporal variation of vegetation in Minjiang River basin will help to understand the ecological environment of the basin and provide reference for subsequent ecological management.Based on the MODIS-NDVI dataset and DEM data of Minjiang River basin from 2003 to 2021,the spatial and temporal evolution of vegetation cover in the Minjiang River basin and the influence of topographic factors on its change trend by means of spatial analysis techniques,Hurst index,linear trend analysis and coefficient of variation were analyzed.The results showed that:(1)The average NDVI value ranged from 0 to 0.9 during the study period.The NDVI value in the upper and middle reaches of the river basin were higher than that in the lower reaches,and the overall vegetation cover of the Minjiang River basin showed a fluctuating upward trend with a growth rate of 2.4％/1 0 a.(2)The areas with increasing and decreasing vegetation cover in the Minjiang River basin accounted for 84.49％and 15.51％,respectively.The valley areas of the western Sichuan Plateau and the non-urban areas of the Sichuan basin showed a significant increasing trend.Those with decreasing trends were mainly located in the new urban areas of Chengdu city expanding outward,Meishan city and Deyang city.(3)The areas with high volatility were mainly distributed in the high-elevation mountains of the western Sichuan Plateau and in Chengdu city,while low volatility mainly occured in the relatively low-elevation areas of the western Sichuan Plateau,where the vegetation was more stable.(4)Future changes in vegetation cover showed a continuous decrease mainly in the new urban areas of Chengdu city,which were expanding outward.Those with persistent increases were mainly in the non-urban areas of the Sichuan basin and the river valley areas of the western Sichuan Plateau.(5)Elevation and slope were the main factors affecting vegetation change,and the correlation between slope direction and vegetation change did not show a clear pattern.
Minjiang River basinNDVIvegetation coverspatial and temporal variation
万方数据
维普
