Evaluation And Pattern Optimization Regulation Of Ecological Security In Xiangxiang City Based On Random Forest Model

In the process of rapid urbanization,as an important agricultural product producing area and an important ecological value area,the low mountain and hilly area in the south of the Yangtze River in China is facing the problems of land use and ecological security,such as the increase of construction land,the decrease of cultivated land,the degradation of ecological environment,and the tension between human and land.In this study,Xiangxiang City,a typical county-level city located in the middle of Hunan Province,was selected as the research object.On the basis of 50 m grid,the random forest model is introduced.Based on the ecological importance,ecological sensitivity and ecological resistance,the ecological security evaluation model is constructed to identify the spatial pattern of Xiangxiang City’s ecological security level and analyze the differences of regional ecological security to identify the main factors affecting the level of ecological security.Combined with the minimum cumulative resistance model,the ecological corridor and ecological node were identified to construct the ecological security pattern.In this study,the random forest model was introduced to analyze the ecological security level of Xiangxiang City,and the ecological security pattern was constructed.At the same time,the importance of ecological security evaluation factors was ranked.The main conclusions are as follows.(1)The random forest ecological security evaluation model constructed in this study,through sample learning and classification test of test samples,found that the random forest classification model has high accuracy.Among them,the sample training accuracy of the model is98.01%,the test accuracy is 95.53%,and the ecological red line at all levels of Xiangxiang City is in good agreement with the ecological security evaluation results.(2)The ecological security level of Xiangxiang City is in the middle and low level,accounting for 84.33%.The ecological security level has the characteristics of uneven spatial distribution,which is higher in the West and north than in the East and south,higher in the hilly area than in the plain,and higher in the mountainous area than in the urban area.At present,the contradiction between economic development and ecological environment protection in Xiangxiang City is that the ecological security of the main urban area with more construction land and some suburban towns such as Dongjiao Township and quantang town is low;The low mountain and hilly areas with more ecological land,less developed traffic network and more stable ecological environment have relatively high ecological security.(3)The results show that the main factors affecting the ecological security level of Xiangxiang City are biodiversity,distance from highway,distance from river,land use type,soil layer thickness,soil erodibility,ecological risk,and so on The degree of rocky desertification and other factors have a relatively small impact on the evaluation of ecological security level.(4)Based on the random forest model and the minimum cumulative resistance model,the ecological security pattern of Xiangxiang City was identified,which was composed of ecological source,ecological corridor and ecological node.Among them,the main ecological sources are the mountains,forests and waters in the West and south of the county,including Shuifumiao Wetland Park,Baozhong mountain and Mao Gong mountain;The ecological corridor includes river corridor and ecological resistance corridor.The urban ecological corridor connects the ecological areas such as Shuifumiao Wetland Park and Baozhong mountain,and the important water systems such as Lianshui and the East and west main streams of Shishi river.By setting up ecological nodes,the ecological corridor of the city was improved to improve the integrity of the ecosystem in the low mountains and hills.