Construction Of Ecological Network In Tumen River Basin Based On Circuit Theory

With the rapid development of social economy,people increase the development and use of land use,which leads to the deterioration of ecological environment,the fragmentation of habitat patches,and the decline of ecosystem services,biodiversity and other ecological problems.Therefore,scientific and reasonable construction of ecological network is helpful to optimize ecological security pattern,improve the quality of natural ecosystem,and strengthen the sustainable development of ecosystem.Tumen River Basin in China is an important node of China’s"Northeast Forest Belt",and also an important part of the Silk Road"Russia,Russia,North Korea and Mongolia"international passage.The region contains a variety of ecosystem services such as soil and water conservation,carbon storage and biodiversity maintenance.However,due to the long-term over-exploitation and utilization of its ecosystem for economic development,a series of ecological problems such as weakened connectivity between habitat patches and decreased biodiversity have been caused.Therefore,the selection of ecological source areas and the construction of ecological network in the Tumen River Basin are helpful to realize the pattern of regional ecological security and provide scientific basis for the optimization strategy of ecological security.In this study,the Tumen River Basin in China was selected as the research area to comprehensively evaluate the ecosystem services of the Tumen River Basin based on the basic paradigm of ecological security pattern construction.On this basis,the region with the highest comprehensive ecosystem service level was selected as the ecological source area,and the ecological resistance surface was established by calculating the habitat quality of the Tumen River Basin,and the ecological corridor,ecological pinch and obstacle area were identified by using the least path method and circuit theory to construct the ecological network of the Tumen River Basin.Finally,the natural breakpoint method was used to divide ecological pinch points and obstacle points into key areas,restoration areas and improvement areas,and put forward optimization strategies and suggestions for ecological safety network.The main conclusions are as follows:(1)In the study area,the ecosystem comprehensive service level of forest land,grassland and wetland is the highest,showing a three-point distribution.Carbon fixation,soil conservation and habitat quality are similar in spatial distribution.They all diffuse from the construction land with the lowest ecosystem service level to the surrounding,passing through cultivated land,forest land and ecosystem service level gradually.Biodiversity is higher in mountains than in basins,and water conservation is gradually decreasing from upstream to downstream.(2)The ecological source patches in the western Part of the Tumen River Basin are abundant and seriously fragmented,but the connectivity between large patches is strong.In contrast,the ecological connectivity in the eastern part of the study area is weak.Coniferous forest contributed more to ecological connectivity than other landscape types.The second is broadleaf forest.(3)There were 20 ecological sources in tumen River Basin with a total area of 2743.92 km~2,accounting for 11.89%of the total area of the study area.35 ecological corridors were identified,with a total length of 864.812 km.There are 17 potential corridors with a total length of 839.097 km;There are 31 ecological"pinch points",covering an area of 416.88 km~2;There were 44 ecological obstacle spots,covering an area of 266.39 km~2.(4)Based on the construction of ecological network,key areas,protected areas,restoration areas,improvement areas,protection corridors and restoration corridors are divided.31 key areas,with a total area of 416.88 km~2;There are 23 improved areas with a total area of 103.62 km~2;Twenty-one restoration areas,with a total area of 162.77 km~2;There are 20 protected areas with a total area of2743.92 km~2;14 protected corridors,with a total length of 839.107 km;Nine corridors were restored,with a total length of 679.599 km.(5)Based on the ecological security pattern of the Tumen River Basin,ecological protection suggestions were put forward for key areas,protected areas,restored areas,improved areas,protected corridors and restored corridors.