Spatial Heterogeneity Assessment Of Urban Ecological Quality Based On Remote Sensing Index And Geographic Spatial Analysis

Rapid urbanization and industrialization have promoted social and economic development and improved people’s living standards.It have also been accompanied by large-scale land development and unreasonable land use,resulting in many ecological and environmental issues,such as urban heat island,severe landscape fragmentation,reduced biodiversity and resource shortages.How to construct an ecological security pattern scientifically and reasonably,coordinate the contradiction between ecological protection and economic development,and solve ecological environmental problems has become a current research hots pot.This study uses Pingtan County,a coastal city in Fujian Province,China as the research area.Based on the Landsat 8 OLI remote sensing image data in 2013 and 2017,the remote sensing ecological index（RSEI）model was used to extract the four degrees of greenness,humidity,dryness and heat.It uses principal component analysis（PCA）method to generate RSEI.Then,using a 500m×500m cell grid as the standard,the Moran index model was used to analyze the spatial auto correlation of the RSEI index in the two periods.Finally,select land use cover data,road data,and population data as independent variable factors,and use least square regression（OLS）and geographically weighted regression（GWR）to establish global and local fitting models of RSEI indicators,and model them based on the GWR model.The spatial distribution map of the combined coefficients is used to further evaluate the spatial heterogeneity relationship between the RSEI index and influencing factors such as land use,road density and population density.The main research results obtained are as follows:（1）The RSEI value of the study area increased from 0.449 in 2013 to 0.525 in 2017,and the overall ecological environment has improved.Among them,the greenness index has the greatest impact on the improvement of RSEI,which mainly benefits from the large-scale increase in the vegetation coverage of newly-added land along the northwestern coast.The science,technology,culture and education district in the Pingtan Comprehensive Experimental Zone has risen steadily,indicating that the new district pays attention to the protection of the ecological environment in the development planning and construction process,and relevant policies have been effectively implemented;due to the expansion of the central city,new constructions close to the drinking water source The ecological quality of land used has declined in recent years,and it is necessary to strengthen monitoring of changes in this area.（2）The spatial distribution of RSEI has obvious spatial autocorrelation,which is prominently manifested in that the high clustering gradually develops toward the edge of the city,and the low cluster gradually develops toward the city center.There is a strong spatial heterogeneity in the ecological quality of the study area.The impervious surface,road density,and population density in the land cover type can reduce the RSEI index,and the forest land in the land cover type can increase the RSEI index.The relationship between RSEI and influencing factors shows local variation characteristics as the spatial position changes.（3）The fitting and accuracy of the geographically weighted regression model is better than that of the global model.The R²_adjof the global model is 0.769,the AIC is-3468,the RMSE is 0.015,the geographically weighted regression model R²_adjis 0.822,the AIC is-3621,and the RMSE is 0.002.According to the model fitting results,geographically weighted regression has higher verification accuracy and better fitting results.