| The large-scale exploitation and utilization of land resources resulted from human being has caused serious damage to the land ecological environment and restricted the sustainable utilization of land resources.The evaluation of ecological security of Chengdu Plain is helpful to provide reference for environmental management and reasonable planning land use.Chengdu plain is both in economic and cultural the most developed regions in Sichuan Province,and also is the largest plain in Southwest of China.This paper,relying on the"Key Laboratory of the Ministry of education"and the National Natural Science Fund project,and the Chengdu plain area is selected as the research area.The objectives of this study were to create the land use database based on 2000~2015 a Landsat TM/ETM+/Landsat8 OLI_TRIS images,statistics,and 3S technology;to evaluate ecological security following the build the evaluation index system,based on P-S-R model and selected 17 indicators in Chengdu plain area;to analyze the driving forces based on the Geodetector.The results showed that:(1)Land use is mainly cultivated land and woodland,and there are obvious changes between different parts of the land.Forestland and cultivated land account for more than85%of the total land area.In quantity change,the area of cultivated land decreased year by year(152.80×10~4hm~2?136.86×10~4hm~2?121.75×10~4hm~2?115.02×10~4hm~2),the construction land increased year by year(10.13×10~4hm~2?15.53×10~4hm~2?20.36×10~4hm~2?32.10×10~4hm~2),woodland increased at first and then decreased(83.50×10~4hm~2?98.66×10~4hm~2?106.12×10~4 hm~2?101.21×10~4hm~2),water,grassland and unused land changed little.(2)The conversion of land use types to each other,and the total amount of transformation is 79.34×10~4hm~2 within 15 years in space change.Construction land is mostly converted from cultivated land in Chengdu,Leshan,Mianyang etc.,the conversion between cultivated land and woodland is also obvious,which often occurs in the west of the plain.The conversion of water into cultivated land and construction land is mainly around the central city area.Grassland conversion to woodland mainly occurs in western mountainous areas,These areas are less affected by human beings,and are naturally converted from natural disasters and environmental restoration.(3)The ecological security situation is good as a whole,but the ecological safety index is decreasing.The ecological security index were 0.575 and 0.563 from 2000 to 2015,The unsafe(0.14×10~4hm~2?4.36×10~4hm~2)?less safety(3.42×10~4hm~2?19.17×10~4hm~2),area increased slowly,The safety area increased first and then decreased,and the critical safety and safer area decreased slowly;In the 4 period of study,the ranking of various levels of ecological security is:critical safety>safer>safety>less safe>unsafe.(4)There are differences in ecological security in all districts and counties.Not safe,less safe,safety critical areas are mainly distributed in Chengdu,Mianyang,Meishan,etc.These cities are economically developed,and the ecological environment is affected by the urban development;The safer and safety areas are mainly distributed in the plains and the mountains,for example Jiangyou,Dujiangyan,Dayi,Qionglai etc,As an ecological barrier,it plays an important role in maintaining the ecological security of the Chengdu plain.(5)The influence of driving force factors on ecological safety is different,and the major driving force factors are as follows:human disturbance index?regional development index?degree of land use?ecological environment elasticity?ecosystem service value?relief ampliftude etc.,some driving forces have a significant impact on ecological security.The highest region of ecological safety index is distributed in different range of every driving force factor,and the higher the driving factor index is,the more safe the ecology is,but the other opposite.There is an interaction effect between each driving factor,which will increase or weaken the explanatory power to the ecological security. |
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