| The construction of regional ecological network can improve the landscape connectivity among the increasingly fragmented ecological patches due to urbanization,which is of great significance to the overall protection of natural resources and regional ecological security.Guiyang,as one of the central cities in the karst area of southwest China,is a typical karst mountain city with less construction land,more concentrated development and fragile ecological environment.Guiyang,as one of the central cities in the karst area of southwest China,is a typical karst mountain city with less construction land,while it also has more concentrated development and fragile ecological environment.According to the landscape characteristics of the mountain cities in karst areas,in order to alleviate the contradiction between ecological protection and economic development in the karst mountain cities,this paper explores their ecological network construction mode and the role of the mountain ecological patches in the construction of the ecological network.The results of this study will provide a basis and reference for the spatial pattern optimization and green space system planning of karst mountain cities.Taking the municipal district of Guiyang as an example,it used Morphological Spatial Pattern Analysis(MSPA)to analyze the dynamic change of landscape Pattern.Based on the spatiotemporal changes of ecological source patches,ecological corridors and ecological nodes,the problems existing in the urbanization process of the ecological network in Guiyang municipal district were analyzed.The key connecting corridors and nodes of ecological network identification at two levels of"municipal district-built-up area"were overlaid to find out the breaking points of ecological network,which can be reconstructed by increasing the ecological source area,identifying the ecological buffer zone,repairing the breaking point,constructing the footstone patch,and determining the width and buffer distance of the ecological corridor.The results are as follows:(1)The patches in the core area of ecological land in the northeast of Guiyang City were concentrated and the area was the largest,while the patches in the middle were sporadic and the area was small.From 2013 to 2018,the patches in the core area of the ecological land tended to be fragmented,and the patches were obviously island-oriented.Patches in the ecological core areas of Baiyun District,Guanshanhu District,Huaxi District,Wudang District and Yunyan District were fragmented to varying degrees under the influence of urbanization,also the landscape connectivity between patches was reduced.The small ecological core area in Nanming District has a certain amount of increase,but the increased patches were not concentrated.The spatial distribution of patches in the ecological core area was not obvious in 2013,showing a random distribution pattern.While the spatial distribution of patches in the ecological core area depicted a positive correlation in 2018,implying an agglomeration effect.(2)From 2013 to 2018,the importance index of ecological source patches decreased,and the size of the patches decreased,and the north-south differentiation trend was obvious;Three nodes of ecological source area were reduced in the middle of the study area,with a reduced area of 126.00km~2.The patches of ecological source area were increased in the west of Guanshanhu District and the north of the Yunyan District,with an area of 10.48km~2,but the new patches of ecological source area were small and fragmented.The distribution of high nuclear density in the ecological corridors in the study area was uniform in 2013,and the nuclear density in the northern area was higher than that in the southern and central areas.While the distribution difference was great in 2018.The high nuclear density values were concentrated in the north of the study area,less in the south and middle of the study area,and scarce in the east.The high kernel nuclear values of the ecological corridor were concentrated from the middle to the edge of the study area.From 2013 to 2018,the scale of ecological nodes in Baiyun District decreased the most,while that in Wudang District increased the most.(3)The ecological source areas of the built area were mainly distributed in the Yunyan District,Nanming District and Guanshanhu District,covering 10comprehensive parks in the built area.The number of extremely crucial,important and general corridors in the built-up area was 37,113 and 227,respectively.The extremely crucial corridors were mainly distributed in the central part of the built-up area,but few were distributed in the south and north of the built-up area.There was an obvious fault between the southern source patch and other patches,also no connected corridors were formed.There are 25 first-class ecological nodes and 17 second-class ecological nodes in the built-up area.There are 10 ecological corridors connecting the ecological network between the administrative area and the built-up area of Superposition City,with a length of 2.52 km and an area of 2.27 km~2.There are 5overlapping nodes between the two scales.(4)After having optimization,there were 9 new ecological sources in the ecological network,and the area of ecological buffer zone was 671.72 km~2,accounting for 26.3%of the study area.Eleven new vital ecological corridors were added,and the nuclear density of potential ecological corridors increased as a whole,and the high value areas were evenly distributed.The important ecological corridors in 2018,the newly added important ecological corridors,and the overlaid corridors of built-up areas along with municipal districts will be regarded as the first level ecological corridors after optimization,also the remaining potential ecological corridors will be regarded as the second level ecological corridors.The optimal width of the ecological corridor in the study area was determined to be 30-100 m,and 200 m was determined as the diffusion distance of the ecological corridor buffer.Forty-nine ecological fracture points were identified,of which two were located on the connecting corridor.Four"stepping stone"patches were identified based on the long ecological corridor,the urban district and the built-up area. |
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