Research on the shift change of vegetation greenness line in the Loess Plateau based on GEE
The temporal and spatial evolution patterns of the vegetation greenness index and its spatial distribution in the Loess Plateau hold significant scientific importance in gaining comprehensive insights into the dynamic changes of vegetation and assessing the effectiveness of ecological restoration.Although previous studies have explored the factors influencing spatiotemporal variations in vegetation greenness,the limited spatial resolution of remote sensing products poses challenges in capturing fine-scale characteristics and dynamic shifts in vegetation greenness lines.In the study,the Google Earth Engine(GEE)cloud platform,combined with a series of Landsat remote sensing images,is used to calculate the Normalized Difference Vegetation Index(NDVI),Enhanced Vegetation Index(EVI),along with their Vegetation Greenness Lines,as indicators to characterize the spatiotemporal evolution of vegetation greenness during the growing season on the Loess Plateau from 1987 to 2020.The results show that the annual average growth rates of NDVI and EVI in the Loess Plateau were 0.0042a-1(P＜0.01)and 0.0023a-1(P＜0.01)from 1987 to 2020,respectively.Notable,the average growth rates after the year 2000 were approximately three to four times higher than those observed before 2000.In terms of spatial distribution,the trends in NDVI and EVI predominantly exhibited significant and highly significant increases,with respective area percentages of 78.78％and 69.21％.Over the period from 1987 to 2020,the vegetation greenness lines VGLNDVI and VGLEVI exhibited a northward movement in the Loess Plateau at rates of 5.52 and 4.59 km/year,respectively.Over the same period,the average northward movements for VGLNDVI and VGLEVI were 173.93km and 131.62km,respectively.The most significant northward shift was primarily observed between 2005 and 2010,with the largest movement of the VGLNDVI and VGLEVI occurring in the Yulin and Yan'an areas of Shaanxi Province,northwest Shanxi Province,and central and southern Inner Mongolia,reaching maximum distances of 532.12km and 471.57km,respectively.
NETL
NSTL
万方数据
维普
