Study On The Construction Of Landscape Ecological Security Pattern And Restoration Countermeasures Of Obstacle Areas In The Three Gorges Reservoir Area Based On Circuit Theory

With the acceleration of urbanization and the frequent activities of human beings,the land use structure has changed greatly,resulting in the degradation of regional ecosystem services and biodiversity and other ecological and environmental problems,which threaten the regional ecological and environmental security.Ecological security pattern is one of the three strategic ways of territorial space development and protection in China.The construction and improvement of regional ecological security pattern is crucial to maintaining regional species diversity,habitat integrity and stability of various ecological processes,and is also an important measure to achieve sustainable urban development.Therefore,taking the Three Gorges Reservoir Area as the research object,this paper judged and analyzed the ecological security problems of the Three Gorges Reservoir area by analyzing the dynamic changes of land landscape types,landscape pattern changes and temporal and spatial changes of landscape ecological security from2000 to 2020.According to "source identification-resistance surface building corridor extracted-pinch,barrier point recognition,obstacle region extraction,ecological restoration zone identification" research steps to construct landscape ecological security pattern of the three gorges reservoir area,then according to the results of the analysis on the landscape ecological security pattern of the three gorges reservoir area and identify the key ecological restoration area,puts forward the three gorges reservoir area landscape ecological security from different angles to repair strategies,And summarize the suggestions.The main conclusions are as follows:（1）In the analysis of landscape types,agricultural landscape and forest landscape have always been the main landscape types in the Three Gorges Reservoir area from 2000 to 2020;In the past 20 years,the area of agricultural landscape and grassland landscape has decreased by 810.17 ㎞~2 And 1677.72 ㎞~2;The area of forest land landscape,water landscape and construction landscape increased by 357.28 ㎞~2、365.46 ㎞~2 And 1769.18 ㎞~2,On the whole,the landscape type and area of the reservoir area change significantly.（2）In the results of landscape pattern analysis,the agricultural landscape patch density and the number of patches in the Three Gorges Reservoir area remained the largest in each period under the scale of landscape types,and increased significantly in 2015,making the patches more fragmented;The LPI value of forest landscape is more than 19.60 every year,which is significantly higher than other landscape types.It is the dominant landscape in the reservoir area;The AI value of the construction landscape changes most obviously,rising from 93.612to95.6849,indicating that the fragmentation of the construction landscape is small and the degree of agglomeration is high.The value of tag and AI on the landscape level scale decreased as a whole,while the value of PD and SHDI increased as a whole,It indicates that the fragmentation degree of the whole landscape patch in the study area is enhanced.（3）From 2000 to 2020,the level of landscape ecological security in the study area remained high,and the spatial distribution characteristics of "low in Northwest and high in Southeast" were maintained.The spatial distribution law of low safety areas is obvious,which is mainly located near the urban area,while the high safety areas are concentrated in contiguous areas,which are mainly located in areas with more forest landscape.In the past 20 years,the area of low safety area has increased by 2.01%,the area of lower safety area has decreased by 9.58%,the area of medium safety area has increased by 4.33%,the area of higher safety area has decreased by 2.65%,and the area of high safety area has increased by 5.9%.On the whole,the landscape ecological security of the Three Gorges Reservoir area has been improved to a certain extent.（4）The results of landscape ecological security pattern in the Three Gorges Reservoir Area Based on circuit theory show that;From 2000 to 2020,the ecological source of the reservoir area is concentrated in the northeast and Southeast.By 2020,its scope will be reduced to a certain extent,and the area will be reduced by 2574.32 ㎞~2。 The resistance is mainly low,and the ecological corridors,ecological pinch points and obstacles are mainly distributed in the northeast and northwest of the reservoir area.In2015,the area of ecological sources in the west of the reservoir area decreased significantly,with the largest number of key ecological corridors,69 in total,with a total length of 1484.82 ㎞ and the largest number of ecological obstacles,118.The stability of landscape ecological security pattern decreased in that year.（5）The results of the ecological restoration area identified by the superposition analysis of the obstacle area show that the total area of the ecological restoration area in the study area is 512.24 ㎞~2,It accounts for 0.89% of the total area of the reservoir area.Among the three types of restoration areas,the area of important ecological restoration areas accounts for the largest,accounting for 239.54 ㎞~2,The area of key ecological restoration area is 103.10 ㎞~2,The general ecological restoration area is 169.6 ㎞~2.In terms of spatial distribution,key and important ecological restoration areas are mainly distributed in the northwest of Banan,the middle of Fuling,the east of Kaizhou and the middle of Wanzhou.General ecological restoration areas are mainly distributed in the east of Yubei,the north of Changshou,the middle of Wanzhou and the northwest of Banan.Within the scope of ecological restoration area,agricultural landscape and forest landscape are the main landscape types of the restoration area,followed by construction landscape and water landscape.（6）In terms of the Restoration Countermeasures of the ecological restoration area: for the key ecological restoration area,we can return some low-quality cultivated land to forest or optimize the types of crops,and carry out green space construction in the process of urban construction,so as to improve the vegetation coverage within the urban space and reduce the ecological resistance in the restoration area;Important ecological restoration areas can adopt the development of ecological agriculture,carry out the transformation of sloping farmland,optimize the layout of forest land and water area,and form the landscape resource pattern of belt,piece and network;General ecological restoration areas should strengthen their ecological maintenance and construction,reduce the impact of human activities and improve the connectivity of various landscape patches.