Study On Scale Difference And Coordination Of Ecological Security Pattern In Shiyang River Basin

Under the trend of rapid urbanization,the problem of "population,resources and environment" has become increasingly prominent.High-intensity land development and land use mode have worsened the originally fragile ecological environment,severely damaged the structure and function of the ecosystem,and caused a series of ecological and environmental problems.Ecological security pattern optimization,as an important way to maintain national ecological security,is of great significance to maintain the integrity of ecosystem structure and process,improve ecosystem service capacity,balance the contradiction between ecology and economic development,and is an important way to solve ecological environmental problems and guarantee regional ecological security.Compared with the eastern regions with good ecological environment,the ecological environment of Shiyang River Basin is sensitive and fragile.The complex coupling system of multi-factors in the basin makes the construction of ecological security pattern exist in a cross-scale and multi-level system.At different scales,landscape elements,pattern and process have certain differences.It is of great significance for the optimization of watershed territorial spatial planning and ecological sustainable development to scientifically identify the scale differences of watershed ecological security pattern and promote the coordinated optimization of different scales.Taking Shiyang River Basin as a typical case,based on multi-source data of land use,soil and vegetation,and using Arc GIS,Fragstats 4.2,Guidos Toolbox,Conefor Sensinode and other software,Using morphological spatial pattern analysis(MSPA),minimum cumulative resistance model(MSPA),landscape index and social network analysis,the ecological security patterns of Shiyang River basin scale and Minqin county scale were firstly constructed.Then,according to the landscape ecology theory,the difference of ecological security pattern and scale between Shiyang River Basin and Minqin County was analyzed from three aspects of patch type level,landscape level and network structure.Finally,based on the scale difference of ecological security pattern,the coordinated optimization of shiyang River Basin and Minqin county pattern was carried out,and the coordinated optimization strategy of land ecological security pattern was proposed from the perspectives of source,corridor and node.The main conclusions are as follows:(1)based on land use landscape basal analysis,selection of shiyang river basin scale and minqin county scale as a case study area,according to "general source-compose corridor-node" ecological security pattern to build model,using the method of spatial pattern analysis(MSPA)form ecological source identification,using minimum cumulative resistance model identify potential ecological corridor,Ecological nodes were extracted from corridor intersections.The ecological security pattern of shiyang River Basin was identified as "34 sources,71 corridors and 34 points",showing a "T" shaped spatial distribution characteristic of concentrated southern area,loose central and northern area,and from south to north.The ecological security pattern in Minqin county is characterized by "17 sources,21 corridors and 13 points",showing the spatial distribution characteristics of overall looseness and local agglomeration in the north and south.(2)At the level of patch types,the green landscape types dominated by forest and grassland accounted for 27.55% of the total area of the Shiyang River Basin,and the patch aggregation degree was high.However,the grassland landscape patches were affected by the expansion of cultivated land and construction land,and the fragmentation degree was high and the edge effect was strong.The landscape types in Minqin county were mainly desert landscape,and the patch aggregation degree was the highest.The green landscape type dominated by forest and grassland only accounted for6.41% of the total area of the county,and the patch fragmentation was serious and the edge effect was strong.At the landscape level,the landscape types in shiyang River Basin are diverse and uniform,and the ecological environment is relatively stable.However,the landscape fragmentation level is relatively high due to the influence of the southern mountainous terrain.The ecological environment in Minqin county was sensitive and fragile due to the disturbance of sandstorm activities,and the patch spread degree of desert landscape was high,the diversity and evenness of landscape composition were low.From the perspective of ecological security pattern network structure,the α index,β index,γ index and network density of shiyang River Basin are0.6,2.09,0.7 and 0.51,respectively.The ecological network structure is complex and highly connected,and the centrality of ecological source area is the highest in the southern part of shiyang River Basin.The spatial pattern of point outgo and point ingo was "upstream ecological source,middle ecological transfer and downstream ecological succession",and there were four core aggregation subgroups.The size and structure of the subgroups in the southern part of the basin were relatively perfect and closely connected,while the relationship between the subgroups in the upstream and middle and lower reaches was relatively weak.Minqin county ecological security pattern of alpha index was 0.43,beta,gamma index for 1.62 to 0.46,the network density is 0.3,ecological network structure is relatively simple,the weak connectivity,red cliff mountain reservoir in southern and northern white alkali lake wetland center degree is higher,ecological radiation ability is stronger,has four core condensing subgroup,subgroup size and structure is relatively simple,And the correlation between subgroups is weak.(3)Based on the difference of ecological security pattern scale,the ecological security pattern of Shiyang River Basin and Minqin County was co-optimized respectively,and finally formed an ecological security optimization pattern of "34sources,82 corridors and 38 points" in Shiyang River Basin and "17 sources,29 corridors and 21 points" in Minqin County.Second,from the ecological source,ecological corridor,from three aspects of ecological node,put forward the "source mountain ecological protection,ecological transfer repair,desert oasis region ecological undertake governance" of the functional partition optimization strategy and strengthening ecological source protection,appropriate to establish ecological corridor,optimize,and repair the structure of the ecological nodes connected optimization strategy.