Constructing Ecological Security Pattern In Mianning County

The ecological security pattern is of great significance for maintaining the natural ecological process,ensuring biological security and urban ecological security.Mianning County is located in the transition zone between the western Sichuan plateau and the mountains.It has complex geologic conditions,frequent geological hazards and fragile ecological environment.In recent years,with the acceleration of urbanization,human activities such as mining and urban construction have increased,causing serious ecological and environmental problems.Ecological spaces such as forests,grasslands and waters have shrunk,the composition of the land cover and spatial structure have changed,and the biological diversity has been threatened.Taking Mianning County as an example,this paper discussed the application of morphological spatial analysis,connectivity index,circuit theory,shortest path and other methods to construct the ecological security pattern based on the theory of landscape ecology,so as to provided references for territorial and spatial plan,ecological environment protection,natural resource management in Mianning County.The research results are as follows:(1)The land use structure of Mianning County is reasonable.The area of different land use types in Mianning County is ranked as forest land>grassland>cultivated land>construction land,and forest land accounts for 70.75%of the total area,followed by grassland and cultivated land,which accounted for 10.69%and10.40%respectively.Mianning County is rich in vegetation and high quality for forest land,NDVI value range is 0-0.78,about 52%area is more than 0.55.(2)Mianning County has a relatively low overall ecological security.The important ecological zone and ecological risk zone of Mianning County were identified based on the ecological service and ecological sensitivity level,as well as the ecological security level of Mianning County was determined.The area of low and relative low ecological security area is about 1976.15km~2,accounting for 44.71%of the total area.The low ecological security is mainly distributed in the western mountainous areas of Mianning County,with frequent geological hazards and serious soil erosion problems.The area with high ecological security accounts for only 6.29%,with an area of 278.22 km~2,and is mainly located in the plain area.The important ecological service areas and the ecological risk areas have similar distribution location,which are mainly distributed in mountainous areas.(3)Thirty-seven patches of important ecological sources were identified to build two types of ecological networks:land and water.Morphological spatial pattern analysis and classification were conducted on the high-quality forest,important ecological service function areas and ecological sensitive areas to identify the core and bridge areas.By using Conefor 2.6 software,three kinds of indices,i.e.integrated connectivity index(IIC),possible connectivity index(PC)and patch importance index(d I),were selected to analyze the connectivity of core areas.Seventeen patches with high quality and twenty patches with high connectivity were selected as the ecological source.Eighty-two land ecological corridors were identified based on the circuit theory and minimal cost path.Thirty-six important corridors,Thirty-six ecological pinch points,and sixty-eight ecological barrier points were selected based on circuit density of Linkage Mapper.It was found that important ecological corridors are mainly located in the areas with dense patches in the middle of Mianning County.And most of the ecological pinch points and barrier points are located in the edges of patches,roads,rivers,and ecological sensitive areas.The Yalongjiang River and the Anning River in Mianning County were selected as first-level water corridors,and seven main branches of the Anning River and the Yalongjiang River were selected as second-level water corridors to construct Mianning County waters and land ecological network.(4)The ecological security pattern of"Three Mountains,Two Networks,and Multi-Areas"was constructed by integrating the information of ecological security elements,and protection measures were also proposed.Based on the identification results of ecological service function types and ecological sensitive types,as well as the data of protection areas,the main ecological function zones were delineated;the land and water corridors were graded to form an ecological security pattern of“Three Mountains,Two Networks,and Multi-Areas".According to the idea of classified management of natural resources,the proposal of“Three Districts and Three Lines”space management was put forward.The ecological space should be classified and managed according to four categories.The first type of ecological space is strictly protected ecological space such as national nature reserve.The second type of ecological space mainly refers to non-core areas of nature reserves and water source protection areas.The third type of ecological space includes animal habitats,rivers,ecological corridors,etc.The fourth type of ecological space is urban parks,wedge-shaped green land,and green belt within the boundary of urban development.