Regional Comparison of Changes in NDVI in Arid Regions of Central Asia
China's Xinjiang and the five Central Asian countries belong to the Asian arid region,but there are huge differences in social and economic development conditions and land use between them,which may have a significant impact on vegetation changes.Based on Google Earth Engine(GEE),this paper used the average Normalized vegetation index(NDVI)in MODIS NDVI product MOD13Q1 in the vegetation growing seasons from 2000 to 2020 to compare and analyze the spatial-temporal changes of NDVI in the five Central Asian countries and China's Xinjiang,using Sen's slope and Mann-Kendall test.Based on meteorological data,land use data and socio-economic data,a multiple linear regression model was developed to analyze the factors affecting NDVI change.The results showed that:(1)From 2000 to 2020,the vegetation NDVI in the arid regions of Central Asia showed an overall fluctuating upward trend.The overall growth rate of vegetation NDVI in Xinjiang was 2.9×10-3 a-1,which was higher than the overall growth rate in Central Asia,which was 0.6×10-3 a-1.(2)From a spatial perspective,the variation of vegetation NDVI in the arid areas of Central Asia is obviously different.In the five Central Asian countries,the areas with improved vegetation NDVI account for 25.9%of the region,and degraded areas account for 8.78%.The improved areas are the grassland in northeastern Central Asia,and the degraded areas are distributed in the grassland regions in northwest Central Asia and in cultivated lands in the north.The area of improved vegetation in China's Xinjiang accounts for 37.72%,while degraded areas only account for 0.46%.(3)Vegetation NDVI is affected by various factors such as climate,topography and human activities.Rising temperatures inhibit vegetation growth in arid areas of Central Asia,while increased precipitation is beneficial to vegetation growth.Elevation significantly affects vegetation growth.Rational use of land and investment in irrigation facilities by Humans play a positive role in vegetation restoration.Research shows that there are obvious differences between the five Central Asian countries and China's Xinjiang.The vegetation improvement in China's Xinjiang is significantly better than that of the five Central Asian countries.Changes in vegetation NDVI are affected by both natural factors and human activities,and regional heterogeneity and the synergy of multiple influencing factors need to be comprehensively considered.Therefore,considering the interaction effects of these factors in the model,the relationships among variables can be explained more accurately.
arid region of Central Asianormalized difference vegetation index(NDVI)regional differencespatio-temporal dynamicsGoogle Earth Engine(GEE)
万方数据
维普
