Spatial Pattern Evolution And Future Trend Prediction Of Ecological Networks In Jinan In The Context Of Rapid Urbanization

With rapid urbanization,urban land use has undergone drastic changes,resulting in serious damage to urban landscape ecology,fragmentation of ecological patches and reduction of biodiversity,which has a significant impact on sustainable urban development.The 19 th Party Congress included the construction of ecological civilization into the "two hundred years" goal,and the latest 14 th Five-Year Plan further emphasizes the importance of strengthening ecological restoration and environmental protection in accordance with local conditions,and promoting integrated urban and rural design.The construction of ecological networks can connect important or fragmented ecological patches into a whole,which is an important way to protect the integrity of urban ecosystem structure and function.Therefore,exploring the spatial pattern evolution of urban ecological networks,predicting and analyzing the future change trends of urban ecological networks and optimizing them can provide references for scientific planning of urban land and balancing economic development and ecological protection.This thesis takes Jinan,a typical rapidly urbanizing area in the lower reaches of the Yellow River Basin,as an example,and conducts a study on ecological network construction and future trend prediction based on Landsat images,natural environment,and socioeconomic data for the years 2000,2010,and 2020.Firstly,the land use change characteristics of Jinan City in the past two decades are quantitatively described based on the land use dynamic attitude and land use transfer matrix,and the landscape index based on the moving window method is used to visually analyze the landscape pattern evolution characteristics of Jinan city.Second,an ecological resistance surface construction method based on the SAVEE model was proposed,and the evolution of the spatial pattern of the ecological network in Jinan was simulated by coupling the MSPA model,MCR model,and gravity model.Thirdly,the spatial pattern of land use in Jinan in 2030 under three different development scenarios,including natural development scenario,urban development scenario,and ecological protection scenario,was simulated based on the PLUS model,and the future evolution trend of the ecological network in Jinan was predicted.Finally,based on the results of the aforementioned study,a comprehensive optimization strategy for ecological networks that takes into account the differences in urban-rural gradient spatial zoning is proposed,and ecological protection and restoration measures tailored to local conditions are given to construct an ecological security pattern in Jinan.The main conclusions are as follows:(1)During the period from 2000 to 2020,the rapid growth of urbanization rate and the complex and diverse changes in land use transfer in Jinan city led to a sudden increase in the spatial aggregation of construction land and an intensification of landscape fragmentation around the town.The analysis of the results of landscape pattern evolution reveals that the landscape fragmentation is relatively high in the whole Jinan city,which significantly reduces the landscape connectivity.However,at the same time,the development of townships in the northern area has little impact on the overall landscape connectivity in the north.(2)The ecological resistance surface obtained from the proposed SAVEE model can effectively retain the characteristics of each resistance factor,and the simulated ecological corridors,ecological pinch points and ecological obstacle points are more in line with the actual situation of the natural background,especially the river corridors have the best effect.The ecological network structure in Jinan has been deteriorating and then improving over the past two decades,and the distribution and area of ecological obstacle points have been increasing and then decreasing,while ecological pinch points have been degrading,and the ecological restoration work has been effective in maintaining the ecological network.However,the overall distribution of ecological network elements in Jinan is extremely uneven,with a lack of ecological sources and ecological corridors in the north and poor ecological connectivity in the north-south direction.(3)The land use structures under the three different development scenarios of natural development scenario,urban development scenario and ecological protection scenario are similar,but the scale of land use change is significantly different.The ecological network structure under the natural development scenario becomes worse compared to 2020,the ecological network structure under the urban development scenario is the worst,and the ecological network structure under the ecological protection scenario is more complete,so limiting the conversion of ecological land to construction land can help improve the ecological security level of the region.(4)The proposed comprehensive optimization strategy of ecological network with urbanrural gradient spatial zoning can take into account the comprehensive benefits of urban development and ecological protection.The optimized ecological sources are reasonably distributed,the spatial structure of the ecological network is improved,and the complexity and connectivity are significantly enhanced,which has a positive effect on maintaining the overall ecological network cycle in Jinan.Based on the optimization of ecological elements,the Jinan ecological security pattern of "two belts,three zones and five corridors" is constructed,which promotes the sustainable development of the city while maintaining the integrity and stability of the ecosystem.