Monitoring Of Vegetation Change In Beijing-Tianjin-Hebei And Exploration Of The Climatic And Non-climatic Influential Factors Based On Remote Sensing

This study used long-term remote sensing data,climate data and field survey data,etc.,combined with spatial analysis,statistics and other technical methods to completely quantitatively reveal the spatial and temporal change trends of vegetation in the Beijing-Tianjin-Hebei(BTH)region from 2000 to 2018 at pixel scale,and explored the influencing factors of climate and non-climate.It provides scientific guidance of ecological protection,restoration,and optimal management at regional scale for the BTH integration strategy,and provides important regional-scale insights for studying global change.The main results are as follows:(1)This study used the least squares method to linearly fit MODIS EVI to obtain the spatio-temporal change trend of EVI from 2000 to 2018 in the BTH region.The results showed that from 2000 to 2018,the vegetation in the BTH region showed a greening trend,which was basically distributed in the mountainous areas in the north and west.Vegetation degradation has occurred locally,appeared in the plains.(2)This study used the correlation analysis and regression analysis of EVI and climatic factors to probe the correlation relationship between them.The results showed that in most areas of the BTH region,warm and wet climate has promoted the growth of vegetation,but the excessive temperature or precipitation has inhibited vegetation growth.The results of the EVI residual trend indicated that vegetation changes in the most of the area of the BTH region were dominated by climatic factors,but in the BTH metropolitan area with rapid urban development,non-climate factors were a type of factors that cannot be ignored that could affect vegetation changes.(3)This study purposed a relative greening effectiveness value,combining with the Hurst index calculated by rescaled range analysis method,remote sensing interpretation and field survey results,to prove that many national and regional forestry projects implemented in the BTH region achieved good results as a whole.However,the EVI changes in the implementation area of the Beijing-Tianjin sandstorm source project reflected by the Hurst index is unstable.This indicated that in the implementation of forestry projects,scientific planning should be carried out,the types of vegetation should be optimized,the trees and trees should be suitable,and the management and cultivation of existing vegetation should be strengthened.(4)This study used the observation data of nitrogen deposition in the North China Plain for the first time and calculated their correlation relationship with EVI changes.The results showd that human activities represented by urban expansion,industrial and agricultural activities have a negative impact on the growth of vegetation,combining with the land use transfer matrices.