Method for determining minimum ideal width of urban ecological corridor based on functional connectivity
By constructing a comprehensive resistance surface and circuit theory, combined with a piecewise linear regression model, the minimum ideal width of urban ecological corridors is determined, which solves the problem of strong subjectivity in width setting in existing technologies. This achieves the effect of both meeting ecological function requirements and saving land in the construction of ecological corridors in areas with scarce land resources.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-09-29
- Publication Date
- 2026-03-20
AI Technical Summary
Existing technologies lack a quantitative reflection of the relationship between corridor width and connectivity when determining the width of urban ecological corridors, resulting in a high degree of subjectivity in width setting and making it difficult to save land resources while meeting ecological function requirements.
Using a functional connectivity-based approach, the current proximity centrality of the path with the minimum cumulative resistance is calculated by constructing a comprehensive resistance surface and circuit theory. Combined with a piecewise linear regression model, the minimum ideal width of the ecological corridor is determined, taking into account the migration needs of focal species and land use costs.
This approach enables a quantitative reflection of the relationship between corridor connectivity benefits and land costs under land use constraints, determines the minimum ideal width, avoids the subjectivity of width setting, meets ecological function requirements, and saves land resources.
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Figure CN115577835B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of urban ecological planning and construction, and particularly relates to a method for determining minimum ideal width of urban ecological corridor based on function connection degree. BACKGROUND
[0002] Urban ecological corridor refers to a collection of strip or linear ecological spaces with certain width and connectivity in urban area, which is mainly composed of green land, forest land, grassland, wetland, water area, garden land, farmland and other spaces with significant ecological function, and is an important part of urban ecological network. Building an efficient and economical urban ecological corridor system can effectively connect scattered ecological sources, limit urban disorderly expansion, protect urban biodiversity and enhance ecological service function, and is of great significance for coordinating the contradiction between ecological protection and urban development and maintaining a healthy and stable urban ecological security pattern.
[0003] The width of ecological corridor is affected by many factors such as focal species, vegetation composition (including vegetation structure, density, coverage, etc.), dominant function, surrounding land use, corridor length, social and economic level, and climate conditions. How to determine the width of the corridor in highly urbanized areas is a difficult and important point in the construction of ecological corridors. A too narrow corridor has small connection degree and large edge effect, and the habitat and survival value of animals and plants is low, and the ecological service function is limited. The larger the width of the corridor, the higher the connection degree and ecological service function in general, but a too wide corridor occupies a large area of land, which is in sharp conflict with the shortage of urban land resources. In land resource scarce urban areas, ecological corridors often serve multiple focal species, and different focal species have different requirements for the width of the corridor. Therefore, it is necessary to determine the minimum ideal width of the ecological corridor to meet the ecological function requirements and reduce the occupation of land resources.
[0004] Currently, there are two main methods to determine the width of the ecological corridor: one is to extract the minimum cumulative resistance path through the MCR model, and then set a uniform width on both sides of the path to determine the spatial range; the other is to determine the corridor level based on the importance of river, road network and other infrastructure corridors, land use scale and land status, etc.
[0005] Both of the above two methods have the problem of subjective width setting, and cannot quantitatively reflect the relationship between the width of the corridor and the connectivity. Among different connectivity indicators, the functional connectivity can reflect the degree of landscape promoting or hindering the movement of target species or ecological processes between source areas, and is the core indicator of representing the effective connectivity of ecological corridors. Therefore, a method for determining the minimum ideal width of the urban ecological corridor meeting the ecological function demand and the minimum land area is needed, which can guarantee the functional connectivity of the corridor and realize the saving of urban land resources. SUMMARY
[0006] In order to achieve the above technical purpose, the present application provides a minimum ideal width determination method of urban ecological corridor based on functional connectivity, which firstly determines the object city focus species to be protected, constructs a comprehensive resistance surface, determines the minimum cumulative resistance path and the suitable path space range between different important ecological source areas based on the MCR model; then calculates the current adjacent centrality of the minimum cumulative resistance path based on the connectivity model of the circuit theory, determines the effective corridor, and calculates the current density of each pixel in the suitable path space range between all source areas, which represents the probability of the focus species passing through the pixel, i.e. the functional connectivity; thirdly, for each effective corridor, a multi-stage buffer zone with different widths is set in the GIS software based on the minimum cumulative resistance path, and the cumulative value of the current density of all pixels in the buffer zone is calculated; and the ratio of the cumulative value of the current density to the corridor land area, i.e. the connectivity benefit-cost ratio, is calculated; finally, the piecewise linear regression model is adopted to extract the only inflection point of the piecewise linear regression curve of the "width-connectivity benefit-cost ratio" of the urban ecological corridor, and the width value corresponding to the inflection point is the minimum ideal width of the urban ecological corridor under the constraint of the land scale.
[0007] The technical purpose of the present application is realized by the following technical scheme:
[0008] The minimum ideal width determination method of urban ecological corridor based on functional connectivity comprises ecological source site screening and comprehensive resistance surface construction, and the minimum cumulative resistance model is used to simulate and extract the minimum cumulative resistance path and the suitable path space range between the ecological source sites based on the ecological source sites and the comprehensive resistance surface;
[0009] The circuit theory is used to calculate the current adjacent centrality of each minimum cumulative resistance path, determine the effective corridor, calculate the current density of each pixel in the suitable path space range between all ecological source sites, and for each effective corridor, a multi-stage buffer zone with different widths is made based on the minimum cumulative resistance path, the cumulative value of the current density of all pixels in each stage buffer zone is calculated, and the ratio of the cumulative value of the current density to the corridor land area is calculated;
[0010] For each valid corridor, a scatter plot is drawn with the width as the horizontal coordinate and the ratio of the accumulated value of the current density under the corresponding width to the land area of the corridor as the vertical coordinate. For each valid corridor, a unique unknown breakpoint is extracted in the scatter plot based on a piecewise linear regression model, i.e., the intersection point of the front and back two linear regression models. The width value corresponding to the intersection point is the minimum ideal width of the urban ecological corridor under the constraint of the land use scale.
[0011] Further, the piecewise linear regression model formula is as follows:
[0012] BCRC=I+αW+β(W-ψ)+,
[0013] Wherein, BCRC is the benefit-cost ratio of connectivity, W is the corridor width, I is the intercept of the regression model, a is the slope of the first linear regression, β is the slope difference of the two linear regressions, (a+β) is the slope of the second linear regression, and ψ is the width of the corridor at the breakpoint.
[0014] Further, when screening the valid corridors, based on the ecological source and the comprehensive resistance surface, the current adjacent centrality of each minimum cumulative path is simulated by using the circuit theory. In the GIS software, the minimum cumulative resistance paths are graded according to the central value of each minimum cumulative resistance path, and the valid corridors are extracted by setting a level threshold.
[0015] Further, when screening the ecological source, the following steps are included:
[0016] Step 1, obtaining the spatial distribution data of the object city present green patch;
[0017] Step 2, cutting and aggregating the obtained object city present green patch in the GIS software, and screening to obtain the candidate ecological source;
[0018] Step 3, determining the focus species to be protected in the object city, constructing the urban ecological source screening index system by comprehensively considering the human ecological livability and the habitat demand of the focus species, dividing the importance level of the candidate ecological source, and selecting the ecological source according to the importance level.
[0019] Further, when constructing the comprehensive resistance surface, the present land use type is combined with other resistance factors to construct a resistance factor table, and the other resistance factors include at least one of the distance from the ecological source, the distance from the trunk road, the distance from the trunk river, the population density, the vegetation quality, the elevation, and the slope. The resistance factor table is valued, and the raster layers of each resistance factor are spatially overlaid based on the GIS software to obtain the comprehensive resistance surface.
[0020] Further, when making the multi-level buffer zone of the ladder width, the minimum cumulative resistance path is taken as the center, the starting width is set, and the width is increased by the same amount step by step to the set termination width based on the starting width.
[0021] Compared with the prior art, the present application has the beneficial effects that:
[0022] 1. The minimum ideal width determination method of the urban ecological corridor based on the functional connectivity degree of the present application adopts a piecewise linear regression model to establish a mathematical model between the benefit cost of the connectivity degree and the width of each effective corridor, quantitatively reflects the relationship between the connectivity degree benefit obtained by the urban ecological corridor construction under different widths and the land cost, and extracts the intersection of the linear regressions of the two sections based on the piecewise linear regression model in the scatter plot to further determine the ideal width value that meets the ecological function demand and has the minimum land area under the constraint of the land scale, thereby avoiding the strong subjectivity problem in the determination of the corridor width.
[0023] 2. The present application comprehensively uses the minimum cumulative resistance model (MCR model) and the circuit theory, the MCR model can effectively extract the minimum path of the cumulative resistance between different source lands, and the connectivity degree model based on the circuit theory uses the random flow characteristics of electrons in the circuit to simulate the migration and diffusion process of focal species in the landscape, the current density can represent the landscape elements or "pinch point" areas (the pinch point area is a region with a larger current density in the corridor) that have an important influence on the functional connectivity degree, and can be used as a data basis for determining the reasonable width of the ecological corridor. BRIEF DESCRIPTION OF DRAWINGS
[0024] Figure 1 is the technical flow chart for determining the minimum ideal width of the urban ecological corridor of the present application.
[0025] Figure 2 is the minimum cumulative resistance path and the suitable path space range between the important ecological source lands in the embodiment of the present application.
[0026] Figure 3 is the current density grid chart of each pixel in the suitable path space range between all source lands in the embodiment of the present application.
[0027] Figure 4 is the schematic diagram of the multi-level buffer zone of a single corridor relying on the minimum cumulative resistance path with different widths in the embodiment of the present application.
[0028] Figure 5 is the piecewise linear regression result schematic diagram of the "width-connectivity degree benefit cost ratio" of a single corridor in the embodiment of the present application. DETAILED DESCRIPTION
[0029] The technical solutions of the present application will be further described below in combination with specific embodiments:
[0030] The minimum ideal width determination method of the urban ecological corridor based on the functional connectivity degree, taking the Minhang District of Shanghai as an example, as shown in the figure, the method comprises the following steps: Figure 1
[0031] Step 1, obtaining the spatial distribution data of the object city's current green land patches, including park green land, protective green land, accessory green land, regional green land and square land;
[0032] The skilled person collects and prepares green land distribution data, land use data, renewable land data, urban development boundary vector data, digital elevation data (DEM data), traffic station data, summer NDVI index, summer daytime land surface temperature, holiday population heat map, and other vector or raster spatial data in Minhang District of Shanghai and its surrounding urban areas, wherein the resolution of the raster data is not less than 30m, and a city geographic information database is established.
[0033] Step 2, cutting and aggregating the obtained object city's current green land patches in the GIS (Geographic Information System) software, and screening to obtain the candidate ecological source;
[0034] In the GIS software, the current green land patches within the administrative boundary of Minhang District and its surrounding 5km buffer zone are cut, the aggregation surface tool is used to classify and aggregate the current green land patches with a Euclidean distance of 10m or less, and the aggregated green land patches are screened according to the area threshold of 0.05 square kilometers within the administrative boundary and 0.3 square kilometers within the buffer zone, as the candidate ecological source.
[0035] As an optimization, by including the current green land patches within the 5km buffer zone of Minhang District into the object city's current green land patches for cutting, aggregation and screening, the constructed ecological corridor can better connect important ecological spaces inside and outside the city, and enhance the protection effect of urban biodiversity.
[0036] Step 3, determining the focus species to be protected in the object city, constructing an ecological source screening index system by comprehensively considering human ecological livability and habitat requirements of the focus species, and screening the ecological source according to the importance level, as follows:
[0037] Humans, small mammals (yellow weasels, hedgehogs) and amphibians and reptiles (frogs, lizard feet) are the three major categories of focus species served by the Minhang District urban ecological corridor. Considering the human ecological livability and habitat requirements of the focus species, an index system for screening the ecological source of Minhang District is constructed as shown in Table 1, and the index calculation and assignment are performed. The indexes include: green land service coverage radius, green land service facility supporting, green land actual use level, green land space accessibility, green land habitat quality, green land vegetation quality, green land connectivity importance, and green land heat island effect mitigation.
[0038] The AHP hierarchical analysis method is used to set the corresponding weight for each index in Table 1. Based on the GIS platform, the raster layers of each index score are weighted and superimposed according to the set index weight, and the operation result is reclassified to obtain the social-ecological composite function importance level (1-10 level) of each block of the selected ecological source area. The selected source area with a comprehensive score in the top 30% is screened out, and a total of 92 ecological source areas are obtained.
[0039] In addition to the green source area, the important rivers flowing through Minhang District, Huangpu River, Suzhou River, Dianpu River and other water surface and tidal wetlands with an area greater than 0.05 square kilometers are taken as blue source areas into the source area system, and are spatially superimposed with the green source area extracted in the above step in the GIS software, and finally together constitute the important ecological source area required to be connected by the ecological corridor of Minhang District, and a total of 103 ecological source areas are obtained.
[0040]
[0041]
[0042] Step 4, for the construction of urban ecological corridor and the calculation of functional connection degree, the setting of comprehensive resistance surface not only needs to consider the hindering effect of different land use types on human slow walking and animal migration, but also needs to pay attention to the resistance difference of urban vegetation coverage, social and economic conditions and artificial disturbance intensity on the movement of focal species. The resistance factor table is constructed by combining the resistance factor of the present land use type of the object city with other resistance factors, and the resistance factors in the resistance factor table are valued; the raster layers of each resistance factor are spatially superimposed based on the GIS software to obtain the comprehensive resistance surface;
[0043] Considering the needs of human slow walking and the migration of wild animals to be protected, the comprehensive resistance factor table (shown in Table 2) is constructed by combining the present land use type of Minhang District with other resistance factors, and the other resistance factors are at least one of the distance from the ecological source area, the distance from the trunk road, the distance from the trunk river, the population density, the vegetation quality, the elevation and the slope (the elevation and the slope are obtained by acquiring the digital elevation model (DEM) data in the GIS software), and in this embodiment, the resistance factors include land use type, distance from ecological source area, distance from trunk road, distance from trunk river, population density, vegetation quality and six resistance factors.
[0044]
[0045]
[0046]
[0047] Note: In Table 2, under the background of land use reduction in Shanghai, 198 plots and 195 plots are land use reduction plots in Minhang District, among which 198 plots are mainly used for land reclamation, and 195 plots are mainly used for urban renewal and transformation and upgrading. In this embodiment, both 198 plots and 195 plots are renewable land.
[0048] For the land use resistance factor, the current land use type map is taken as the base map, and superimposed are, for example, highways, railways, urban renewal land, etc. According to relevant research results and combined with the actual situation of Minhang District, the ecological resistance is mainly considered, and the land suitability for corridor construction is also considered. The resistance is valued. Among them: in the ecological space, the ecological resistance of forest land, green land, wetland, grassland and garden land is relatively small, and the resistance is valued between 1-30; rivers, lakes and reservoirs are usually difficult to cross, and the resistance is valued as 500; in the non-ecological space, the ecological resistance of residential land, road land, industrial land and storage land is relatively high, and the resistance is valued between 50-100; non-ecological space with high ecological resistance, such as highways and high-speed railways, is valued as 1000; urban renewable land in industrial land, such as 195 plots and 198 plots in Minhang District of Shanghai, has a higher possibility of being converted into green land or forest land, and the resistance is valued lower than general industrial land, which is 30 and 50 respectively.
[0049] For the distance from the ecological source, the distance from the trunk road and the distance from the river, the Euclidean distance of each pixel to the source, the trunk road and the trunk river boundary is calculated by using GIS software, and then it is classified and valued. Considering the need for urban ecological corridor construction to connect important ecological sources, and usually relying on trunk roads and trunk rivers for construction and implementation, the closer the distance of the pixel to the ecological source, the road or the river, the lower the resistance value.
[0050] The population density and vegetation quality are classified and valued by using the population heat map and NDVI index map of the object city (Table 2). Urban ecological corridor construction should avoid densely populated urban areas, so the higher the population density, the higher the resistance value. At the same time, urban ecological corridor construction should also make full use of existing urban vegetation, so the higher the NDVI index, the lower the resistance value.
[0051] The AHP hierarchical analysis method is used to determine the weight of each resistance factor, and the resistance factor table is formed. Based on GIS software, the determined index weight is used to spatially weight and superimpose each resistance factor grid layer, so as to form a comprehensive resistance grid map (comprehensive resistance surface). The resolution of the comprehensive resistance surface grid map should not be higher than 30m, and in this embodiment, the resolution of the comprehensive resistance surface grid map is 10m.
[0052] Step 5: Based on important ecological source areas and the comprehensive resistance surface, simulate and extract the minimum cumulative resistance path and suitable path spatial range between any two important ecological source areas using the Minimum Cumulative Resistance (MCR) model. The MCR model can simulate the minimum cumulative resistance path with the shortest cost-weighted distance (CWD) between two source areas.
[0053]
[0054] Where i represents the i-th landscape unit, j represents the j-th ecological source area, m represents the total number of landscape units, n represents the total number of ecological source areas, and D ij R represents the spatial distance between the j-th ecological source area and the i-th landscape unit. i Let f represent the resistance value corresponding to the i-th landscape unit, and let f represent the positive correlation between the minimum cumulative resistance and the ecological process.
[0055] The suitable path space is the area between two ecological source sites comprised of all pixels whose CWD (cumulative resistance) is no higher than the CWD shear threshold compared to pixels on the path with the minimum cumulative resistance. Within this space, the CWD between the two ecological source sites may not be the shortest, but it is suitable for the target species, thus enabling passage and migration. Different species have different requirements for corridor width. Given the scarcity of urban land resources, urban ecological corridors must be intensive and efficient. The minimum width required by different species should be determined based on a comprehensive consideration of these factors.
[0056] In setting the maximum length and minimum width parameters of the corridor, according to technical standards and literature, the minimum width values for corridors requiring passage or migration by humans, small mammals, and amphibians and reptiles are 15m, 60m, and 30m, respectively. The CWD corresponding to a width of 30m is used as the CWD shear threshold for urban ecological corridor construction in this embodiment. cut At the same time, the CWD corresponding to a length of 3km is taken as the maximum CWD of the corridor. max CWD shear threshold = W min ×R mean W min R is the preset minimum width of the corridor. mean It is the average resistance value in the composite resistance surface; CWD max =L max ×R mean , where L max R is the preset maximum length of the corridor. mean It is the average resistance value in the composite resistance surface; through calculation, the average resistance value of all pixels in the composite resistance surface is 50, therefore, CWDcut and CWD max respectively 1500 and 150000, and based on this the minimum cumulative resistance path of Minhang District not more than the preset maximum length and its suitable path space range are extracted.
[0057] The corridor path with the Euclidean distance not more than one grid length is removed, and a total of 211 corridor paths in Minhang District and its surrounding 5km buffer zone are obtained, and the total area of the suitable path space range is 66.34 square kilometers.
[0058] Step 6, based on the important ecological source and the comprehensive resistance surface, the current flow betweenness centrality (CFBC) of each minimum cumulative path is simulated according to the circuit theory. The circuit theory regards the landscape surface as a conductive surface, and uses the characteristics of the random flow of electrons in the circuit to simulate the migration and diffusion process of species individuals or genes in the landscape. CFBC can be used to measure the importance of a path to maintaining the connectivity of the entire network, and can be used to determine the priority of the corridor constructed relying on the path. In the GIS software, the minimum cumulative resistance paths are classified according to the size of the centrality value of each minimum cumulative resistance path;
[0059] In the GIS software, the minimum cumulative resistance paths are classified according to the size of the centrality value of each minimum cumulative resistance path, and the classification map of all cumulative resistance paths based on CFBC is obtained. In this embodiment, the minimum cumulative resistance paths are classified into three priority levels according to the size of the current flow betweenness centrality (CFBC) value of each minimum cumulative resistance path, wherein: the first priority corridor path has a CFBC range of 256.6-2029.1, a total of 68 paths; the second priority corridor path has a CFBC range of 146.9-256.6, a total of 71 paths; and the third priority corridor path has a CFBC range of 1.2-146.9, a total of 72 paths. The corridor paths of the first two priority levels are reserved as effective corridor paths, and the suitable path space range thereof is extracted.
[0060] Step 7, based on the important ecological source and the comprehensive resistance surface, the electrical current density (ECD) of each pixel in the above suitable path space range between all sources is calculated by using the circuit theory. ECD can be used to simulate the probability that an electron (i.e. a focal species) passes through a certain landscape element (or pixel) by random walk in a circuit composed of resistors (conducting elements) connecting all nodes (i.e. ecological sources). The higher the electrical current density, the higher the functional connectivity.
[0061] The important ecological sources within the boundary of the administrative boundary of the target city region, the minimum cumulative resistance path and the suitable path space range, and the current density distribution map within the suitable path space range are extracted using the vector data of the administrative boundary of the target city region. Figure 2 As shown in FIG. 6, Minhang District contains 59 green sources and 11 blue sources; there are 169 effective corridors, including 56 first priority corridors and 64 second priority corridors; the total area of the suitable path range of the effective corridors is 41.14 km 2 , accounting for about 11.02% of the total area of Minhang District. As shown in FIG. 7, the minimum current density of the pixels within the suitable path range of the effective corridors is 0, and the maximum current density is 3256.86. Figure 3
[0062] Step 8, for each effective corridor within the administrative boundary of the target city region, based on the resolution (10 m) of the current density grid map, taking the minimum cumulative resistance path as the center, taking 10 m (20 m on both sides) as the starting value, 300 m (600 m on both sides) as the ending value (the limit width under the constraint of urban land scale), and 10 m as the interval, a multi-level buffer zone with a width of 20-600 m on both sides is made (part of the width buffer zone between sources 18 and 38 is shown in FIG. 8). Figure 4
[0063] Step 9, based on the above multi-level buffer zone, the cumulative value (benefit of connectivity, BC) of the current density of all pixels within each width buffer zone is calculated, and then the ratio of the benefit of connectivity to the land area of the corridor (construction cost, CC) is calculated, that is, the benefit cost ratio of connectivity (BCRC).
[0064] Step 10, for each effective corridor within the administrative boundary of the target city region, taking the width (Width, W) as the horizontal coordinate and the benefit cost ratio of connectivity (BCRC) of the urban ecological corridor under the corresponding width as the vertical coordinate, a "width-benefit cost ratio of connectivity" scatter plot is drawn (the scatter plot of the "width-benefit cost ratio of connectivity" of the ecological corridor between sources 18 and 38 is shown in FIG. 9). Figure 5
[0065] Step 11, for each effective corridor within the administrative boundary of the target city region, using the above "width-benefit cost ratio of connectivity" scatter plot, based on the piecewise linear regression model, the only unknown breakpoint in the piecewise linear regression is extracted, that is, the intersection point of the two linear regressions before and after the breakpoint.
[0066] The formula of the piecewise linear regression model is as follows:
[0067] BCRC = I + aW + b(W - y) + e
[0068] Where BCRC is the benefit-cost ratio of connectivity, W is the corridor width, I is the intercept of the regression model, a is the slope of the first linear regression, b is the slope difference of the two linear regressions, (a+b) is the slope of the second linear regression, and y is the corridor width at the break point.
[0069] Take the ecological corridor between source 18 and 38 as an example, the results of the piecewise linear regression fitting of the "width-connectivity benefit-cost ratio" scatter plot are shown in Table 3, the degree of freedom of the regression model is 45, the standard error of the residual is 0.03985, the coefficient of determination is 0.9744, the adjusted coefficient of determination is 0.9722, and the fitting effect of the simulation parameters reaches a very significant level (p<0.001).
[0070]
[0071] Step 12, for each valid corridor within the administrative boundary of the target city area, the width value corresponding to the unique break point generated by the above piecewise linear regression is assigned. Take the ecological corridor between source 18 and 38 as an example, the minimum ideal width value of this corridor is 104.3 meters (width at the break point). And complete the determination of the minimum ideal width of all valid corridors within the administrative boundary of the target city area according to this method. Figure 5 Step 13, determine the minimum ideal width of each valid corridor within the administrative boundary of the target city area according to the above method.
[0072] This embodiment is only a further explanation of the present application and is not a limitation of the present application. Those skilled in the art can make non-creative modifications to this embodiment according to needs after reading this specification, but as long as it is within the scope of the claims of the present application, it is protected by the Patent Law.
Claims
1. A method for determining the minimum ideal width of urban ecological corridors based on functional connectivity, characterized in that, This includes the screening of ecological source areas and the construction of comprehensive resistance surfaces. Based on the ecological source areas and comprehensive resistance surfaces, the minimum cumulative resistance model is used to simulate and extract the minimum cumulative resistance paths and suitable path spatial ranges between ecological source areas. Using circuit theory, the current proximity centrality of each path with minimum cumulative resistance is calculated to determine the effective corridor; the current density of each cell within the suitable path space between all ecological source areas is calculated; for each effective corridor, a multi-level buffer zone with stepped width is constructed with the path with minimum cumulative resistance as the center, the cumulative value of the current density of all cells in each level buffer is calculated, and the ratio of the cumulative value of the current density to the corridor land area is calculated. For each effective corridor, a scatter plot is drawn with width as the x-axis and the ratio of the cumulative current density at the corresponding width to the corridor's land area as the y-axis. For each effective corridor, a unique unknown inflection point is extracted from the scatter plot based on a piecewise linear regression model; this inflection point is the intersection of two consecutive linear regression models. The width value corresponding to this intersection point is the minimum ideal width of the urban ecological corridor under land use constraints. The formula for the piecewise linear regression model is as follows: BCRC=I+αW+β(W-ψ) + , Where BCRC is the connectivity benefit-cost ratio, W is the corridor width, I is the intercept of the regression model, α is the slope of the first linear regression, β is the difference in slopes between the two linear regressions, (α+β) is the slope of the second linear regression, and ψ is the corridor width where the inflection point is located.
2. The method for determining the minimum ideal width of urban ecological corridors based on functional connectivity as described in claim 1, characterized in that, When selecting effective corridors, based on the ecological source area and the comprehensive resistance surface, the current proximity centrality of each minimum cumulative resistance path is simulated using circuit theory. In the GIS software, the minimum cumulative resistance paths are classified according to the centrality value of each minimum cumulative resistance path, and effective corridors are extracted by setting level thresholds.
3. The method for determining the minimum ideal width of urban ecological corridors based on functional connectivity as described in claim 1, characterized in that, The selection of ecological source areas includes the following steps: Step 1: Obtain spatial distribution data of existing green space patches in the target city; Step 2: In GIS software, the existing green space patches of the target city are cropped and aggregated to select candidate ecological source areas; Step 3: Identify the key species to be protected in the target city, construct an urban ecological source area screening index system that integrates human ecological livability and the habitat needs of key species, classify the candidate ecological source areas according to their importance level, and select ecological source areas according to their importance level.
4. The method for determining the minimum ideal width of urban ecological corridors based on functional connectivity as described in claim 1, characterized in that, When constructing the comprehensive resistance surface, the existing land use type is combined with other resistance factors to construct a resistance factor table. Other resistance factors include at least one of the following: distance from ecological source area, distance from main road, distance from main river, population density, vegetation quality, elevation, and slope. Values are assigned to the resistance factor table, and the comprehensive resistance surface is obtained by spatially overlaying the raster layers of each resistance factor using GIS software.
5. The method for determining the minimum ideal width of urban ecological corridors based on functional connectivity as described in claim 1, characterized in that, When creating a multi-level buffer zone with stepped width, set the starting width with the path of minimum accumulated resistance as the center, and gradually increase the width by the same amount at each level until the set ending width.