| With rapid economic development and increasing human interference with ecosystems,land development and land use patterns have undergone significant changes,leading to irrational ecological space distribution,landscape fragmentation and degradation of ecosystem services,putting enormous pressure on resources and the environment and threatening ecosystem security.Northwestern Jilin is one of the most important agricultural areas in China,located in the transition zone between the horqin sands and the Songnun plain,and the ecosystem in the area is extremely fragile due to climate fluctuations,soil salinization,and disturbances from human activities.Optimizing the spatial pattern of landscape ecological security can restore ecosystem functions,improve ecological stability and protect biodiversity,effectively alleviate the contradiction between economic development and ecological protection,and provide an important spatial way to safeguard and manage regional ecological security.Based on the above knowledge,this paper takes the city of Baicheng in northwestern Jilin as an example,firstly analyzes the spatial and temporal characteristics of land use in Baicheng from 1954 to 2020,and explores the relationship with the driving factors;on this basis,it selects ecological spatial evaluation indicators that can represent the characteristics of the ecological environment in Baicheng,and evaluates the characteristics of ecosystem services and ecological sensitivity in Baicheng;furthermore,based on the morphological spatial analysis method,it examines The core area changes from 1954 to 2020 in Baicheng City were examined and the connectivity index was analyzed.The ecological security pattern is identified by using circuit theory and minimum cumulative resistance model,and this is used to optimize the ecological space of Baicheng city and put forward corresponding rationalization suggestions.The main part has 4 chapters with the following main findings.（1）Based on six periods of land use data from 1954 to 2020,Arc GIS spatial analysis and SPSS principal component analysis were applied.The results show that:（1）The land use types in Baicheng City are mainly arable land,accounting for more than 41%of the total area,the saline land has increased the most,with an increase of 4370.62km~2,and the medium-coverage grassland has decreased the most drastically,in which there is a frequent two-way transformation between dry land,medium-coverage grassland,saline land and marshland.（2）The single land use dynamic attitude of different land types in descending order is:paddy land>forest land>saline land>urban land,and the land use dynamic attitude shows a trend of first decreasing and then slowly increasing the overall decrease.In terms of spatial distribution,the active areas of dynamic attitudes are mainly found around the construction land.（3）The change of land types showed a spatially concentrated distribution trend from northwest to southeast,with a trend of gradually decreasing coverage.The center of gravity of cultivated land and swampy land shifts most obviously.（4）Regional economic demand,demographic factors,and farming and grazing are the main drivers of land use change in White City.（2）A comprehensive evaluation of the spatial coupling relationship between the importance of ecosystem services and ecological sensitivity in White City.Habitat quality,biodiversity,water production,soil and water conservation in the selected importance according to the ecological characteristics of the city of White;The evaluation indexes of soil wind erosion,water erosion,salinization and sanding in sensitivity identify and grade the ecological function areas and ecological risk areas in Baicheng City.It is found that:the overall ecological spatial service function of Baicheng City is at a moderate to low level,and the areas with high comprehensive evaluation of ecological spatial service function only account for 8.69%of the total area of Baicheng City,these areas have high vegetation coverage,and the area occupied by water and grassland is extensive,and most of them are within the scope of nature reserves.（3）The MSPA method was applied to analyze the patch area,scale and distance thresholds of ecological land in White City to obtain the appropriate source site size.The study found that the edge width of 60 cm is suitable for the White City landscape connectivity analysis.the core area in 2020 is reduced by 1.1 times the area in 1954,shifting mainly to non-ecological land.By setting different distance thresholds to analyze the index variation,the optimal distance threshold was obtained as 2000m.Based on the 2020 land use data,40 ecological patches with core area>10km~2 and d IIC and d PC>0.1 were screened as partial ecological source sites,with a total area of 3737.92km~2.（4）The ecological network was constructed based on the spatial structure pattern of"source-corridor-node",and the ecological spatial pattern was identified.The results showed that 55 ecological source patches in Baicheng City were screened,accounting for 14.59%of the total area of Baicheng City.One hundred and twenty-two potential ecological corridors were identified,consisting of both terrestrial and water corridors,and the corridors’orientation had a high coincidence with the change in the elliptical direction of the standard deviation of land use in White City;47 key ecological corridors were selected from them,and the corridor landscape types were mainly arable land.Eighty-one ecological pinch points and 54 barrier points were obtained.These ecological components interact with each other to form an ecological network structure that is"face to face,dotted and interwoven".（5）Optimizing the spatial elements of the White City on the basis of the ecological network,dividing the ecological space into ecological core areas,ecological buffer areas,ecological staggered areas,and production and living areas,accounting for 32.99%,28.60%,13.68%,and 9.10%of the total area of the study area,respectively.According to the current development goals of Baicheng City and related planning documents,the ecological spatial structure layout of"two cores,two corridors,three zones,four belts,and one loop"was re-optimized,and corresponding protection strategies were proposed. |
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