Study On Landscape Ecological Risk Assessment And Influencing Factors Of The Yangtze River Economic Belt Based On Land Use Change

The Yangtze River Economic Belt has been an important population and industrial agglomeration area in my country since ancient times.With the increase of population density and development intensity in the region,the problem of human-land contradiction has intensified.In the new era,the national development orientation of “do not engage in large-scale development,focus on large-scale protection” has made balancing land ecosystem protection and regional economic sustainable development an important challenge for the development of the Yangtze River Economic Belt in the new era.Therefore,this article takes the Yangtze River Economic Belt as the object of study.Firstly,based on the four phases of land use data in 1990,2000,2010 and 2018,with the help of improved land use change models to analyze the land use structure,dynamics and transfer characteristics of the region;Secondly,use change as an inducement to construct a landscape ecological risk assessment model,explore the temporal and spatial distribution characteristics of landscape ecological risk in the region and the transformation trend of each risk level;Thirdly,use the geographically weighted regression model to explore the main influencing factors and space of the spatial differentiation of landscape ecological risk Different functions;Finally,based on the research results,suggestions on land use optimization and landscape ecological risk management in the Yangtze River Economic Belt are put forward.The main conclusions are as follows:(1)From 1990 to 2018,the land use in the Yangtze River Economic Belt was dominated by forest land and cultivated land,and its comprehensive dynamics showed an increasing development trend year by year.Among them,the dynamic degree of construction land is4.16%,and the expansion trend is the most significant.Its sources are mainly cultivated land(The contribution rate was 78.92%)and woodland(The contribution rate was 14.70%).The conversion areas are concentrated in the suburbs of Jiangsu,northern Zhejiang,and northern Anhui,and form sub-core areas in the suburban areas of each core city;the outflow area of cultivated land is the largest,with a dynamic degree of-0.21%,and 56.43% and 21.35% of the area transferred out to forest land and construction land,respectively.The areas that flow to forest land are mainly distributed in The middle and upper reaches of the Yangtze River,while the areas that flow to construction land are mainly distributed in the Yangtze River Delta;the area of grassland has also decreased to a certain extent,with a dynamic degree of-0.21%,mainly flowing to woodland and cultivated land,and the outflow area is mainly distributed in the border area of western Sichuan and the junction of Yunnan-Guizhou.Agricultural reclamation in the middle and upper reaches and the expansion of construction land in the middle and lower reaches have made the trend of fragmentation of cultivated land and grassland degradation in the region increasingly prominent.(2)From 1990 to 2018,the overall landscape ecological risk index of the Yangtze River Economic Belt rose from 13.41 to 14.16,showing a small increase.High landscape ecological risk areas are mainly distributed in Shanghai,Nanjing and Hangzhou,northern Jiangsu,Huainan City,Jianghan Plain,etc.;Higher landscape ecological risk areas are mainly distributed in eastern Jiangsu,central and northern Anhui,and the plains and basins in the upper and middle reaches Regions: The medium and low landscape ecological risk areas are the most widely distributed,mainly in the mountainous areas of the upper and middle reaches.Among them,the landscape pattern changes during 1990-2000 were relatively small;The landscape pattern evolution from 2000-2010 and 2010-2018 was more intense,and the period from 2000 to 2010 belonged to the stage of strong increase in risk level,and the ecological risk of landscape from 2010 to 2018 was in the middle.The upper reaches of the region have changed to a good state,but the risk levels in the Yangtze River Delta and Jianghan Plain have shown an upward trend.(3)The analysis of driving factors shows that the intensity of the impact on the landscape ecological risk of the Yangtze River Economic Belt is in the order of river and lake density,average slope,proportion of secondary industry output value,urbanization rate,average annual precipitation,and population density.Among them,the slope and average annual precipitation show a negative correlation effect with landscape ecological risk,and the absolute value of the regression coefficient shows the spatial distribution characteristics of decreasing from the downstream area to the upstream area;On the contrary,the density of rivers and lakes,the proportion of the output value of the secondary industry,and the population Density has a positive correlation with landscape ecological risks.The proportion of the output value of the secondary industry and the intensity of population density on landscape ecological risks show an enhanced spatial distribution law from downstream areas to upstream areas.The density of rivers and lakes has an effect on landscape ecological risks.The effect intensity presents the spatial distribution characteristics of “high in the middle and south and low in the east and west”;The urbanization rate is negatively correlated with landscape ecological risks in the upper and middle regions,while it is positively correlated with landscape ecological risks in the lower and upper reaches.The intensity of the action is higher than that in the middle and lower reaches.The different intensities and spatial differences of the impact factors can provide a reference for the management of landscape ecological risks according to local conditions.