A Method for Constructing Urban Green Space Ecological Networks Based on Ecological Security Patterns

Abstract

This invention relates to a method for constructing an urban green space ecological network based on an ecological security pattern. The method involves acquiring spatial distribution data of existing green space patches in a target urban area, extracting candidate urban ecological source areas, and then screening to obtain important urban ecological source areas. It combines existing land use types with other resistance factors to construct a comprehensive resistance surface. Based on important ecological source areas and the comprehensive resistance surface, a minimum cumulative resistance model is used to simulate the minimum cumulative resistance path and suitable path spatial range of potential ecological corridors. Based on circuit theory, the minimum cumulative resistance path is classified, and effective corridors are determined according to the level, with their suitable path spatial ranges extracted. Supplementary ecological nodes are identified. The suitable path spatial ranges of important ecological source areas, effective corridors, and supplementary ecological nodes are superimposed to form an urban green space ecological network. This invention provides a basis for the formulation and implementation of relevant plans, effectively improving the ecological service efficiency of green spaces, maintaining urban ecological balance, and improving the urban living environment.

Description

Technical Field

[0001] This invention relates to the field of urban ecological planning and construction technology, specifically to a method for constructing an urban green space ecological network based on an ecological security pattern. Background Technology

[0002] Urban green spaces are a vital component of the urban ecosystem and the only negative feedback subsystem that performs the function of "absorbing pollution and releasing fresh air." They play a crucial role in addressing prominent urban ecological and environmental problems, improving the living environment, meeting recreational needs, and reshaping the harmonious relationship between humans and the land. As my country's economy gradually enters a stage of high-quality development, traditional green space system planning, primarily based on area and spatial layout, can no longer meet the needs of building ecologically livable cities. Constructing a continuous, complete, and efficient urban green space ecological network formed by a systematic connection of "source areas + corridors + nodes" is of great significance for curbing disorderly urban spatial development, improving the urban ecological environment, raising the standard of living, and protecting biodiversity.

[0003] The urban green space ecological network mainly refers to the network system formed by connecting urban and municipal green spaces, woodlands, wetlands, and other natural ecological protected areas through linear corridors with a certain degree of connectivity, such as ecological corridors, green spaces, and biological stepping stones. It is a multi-layered, multi-functional, multi-scale, multi-landscape, and multi-benefit complex ecosystem. The purpose of its construction is to protect the natural attributes of the ecological environment, improve biodiversity, and enhance landscape quality, so as to meet the needs of a healthy and efficient living environment and the harmonious and sustainable development of humans and nature.

[0004] Currently, the construction of ecological networks based on ecological security patterns in my country is mostly focused on provincial, municipal, or watershed scales. Source areas are screened through ecological importance or sensitivity analysis, and potential corridors are identified using cumulative resistance models. In source area identification, research and practice on larger-scale ecological network construction are more focused on species protection, with less consideration given to the human-centered socio-ecological complex functions of urban green spaces. In corridor path extraction, existing methods still rely on traditional conservation biology or landscape ecology theories, focusing more on the protection of existing ecological spaces and lacking consideration for the necessity and suitability of urban ecological restoration. Furthermore, there is a lack of quantitative methods for identifying necessary supplementary ecological protection or restoration nodes in cities, in addition to source areas. Therefore, there is an urgent need for a method for constructing urban green space ecological networks based on ecological security patterns, providing scientific and technological support for the planning and implementation of green space ecological networks within urban development boundaries. Summary of the Invention

[0005] To achieve the above-mentioned technical objectives, this invention provides a method for constructing an urban green space ecological network based on an ecological security pattern. Through important source site screening, comprehensive resistance surface construction, optimal corridor path and suitable range extraction, corridor centrality calculation and path optimization, and supplementary node identification, a green space ecological network consisting of "source site + corridor + node" is finally formed, which can effectively maintain the ecological security pattern of the target city.

[0006] The technical objective of this invention is achieved through the following technical solution:

[0007] A method for constructing an urban green space ecological network based on an ecological security pattern, which includes the following steps:

[0008] Step 1: Obtain spatial distribution data of existing green space patches in the target city;

[0009] Step 2: In GIS software, the existing green space patches of the target city are cropped and aggregated to select candidate ecological source areas;

[0010] Step 3: Construct an ecological source area screening index system, classify the candidate ecological source areas according to their importance level, and screen out important ecological source areas;

[0011] Step 4: Combine the current land use type of the target city with other resistance factors to construct a resistance factor table, and assign values ​​to the resistance factors in the resistance factor table; use GIS software to spatially overlay the raster layers of each resistance factor to obtain a comprehensive resistance surface.

[0012] Step 5: Based on important ecological sources and comprehensive resistance surfaces, simulate and extract the minimum cumulative resistance path and suitable path spatial range between any two important ecological sources according to the minimum cumulative resistance model;

[0013] Step 6: Based on important ecological sources and comprehensive resistance surfaces, simulate the current proximity centrality of each minimum cumulative resistance path according to circuit theory; classify the minimum cumulative resistance paths according to the centrality value of each path in GIS software, determine the effective corridors according to the level, and extract the suitable path spatial range.

[0014] Step 7: Taking all intersections of the path with minimum cumulative resistance as the object, extract the intersections with more than two connecting paths. Draw a circular region with the extracted intersections as the center, and calculate the proportion R of the circular region where ecological protection and restoration can be implemented.

[0015]

[0016] Among them, Area eco It is the total area of ​​ecological space. re It is the total area of ​​the updatable space, Areatotal It is the total area of ​​the circular region;

[0017] Based on the preset threshold of R, the intersection of the minimum cumulative resistance path with more than 2 connecting paths within the threshold range is selected and used as a supplementary ecological node.

[0018] Step 8: Spatial overlay of the appropriate path spatial range of important ecological sources and effective corridors, as well as supplementary ecological nodes, in GIS software; extract the source areas, corridors, and nodes within the boundary range using the administrative boundary vector data of the target city area to complete the construction of the green space ecological network of the target city.

[0019] Furthermore, in step 1, the spatial distribution of existing green space patches in the target city includes park green space, protective green space, ancillary green space, regional green space, and plaza land.

[0020] Furthermore, step 1 also includes cropping, aggregating, and screening existing green space patches within the surrounding area of ​​the target city into existing green space patches of the target city.

[0021] Furthermore, in step 4, the resistance factor includes at least land use type.

[0022] Furthermore, the resistance factors also include at least one of the following: distance from the ecological source, distance from the main road, distance from the main river, population density, vegetation quality, elevation, and slope.

[0023] Furthermore, the minimum cumulative resistance model is MCR.

[0024]

[0025] 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.

[0026] Furthermore, the suitable path space range is defined as all pixels between two target ecological source areas that do not exceed the cost-weighted distance shear threshold (CWD) compared to those on the path with the minimum cumulative resistance. cut The space composed of pixels.

[0027] Furthermore, CWD cut =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.

[0028] Furthermore, determining the appropriate path spatial range also includes using a preset CWD (Central Pathway). max Filter out paths whose length exceeds the set value, 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.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] 1. This invention is applicable to the systematic construction of green space ecological networks within urban development boundaries, ultimately forming an urban ecological security pattern consisting of "source areas + corridors + nodes". It plays an important role in restricting disorderly urban spatial development, improving the urban ecological environment, enhancing the living standards of residents, and protecting biodiversity.

[0031] 2. Incorporating the surrounding areas of the target city into the systematic construction of the green space ecological network can fully reflect the connection between the internal and external regions, reflect the coupling relationship between the city and the regional ecology, and enhance the systematicness, integrity and effectiveness of the network construction.

[0032] 3. In the process of selecting source sites, the social-ecological complex functions of urban green spaces should be taken into account in a comprehensive manner, with the primary goal of meeting the needs of human ecological livability, while also considering the protection of the habitats of key species.

[0033] 4. In constructing resistance surfaces and extracting pathways, the primary focus is on human needs for slow-moving recreation, while also considering the migration and movement of key species, and combining current land use with other resistance factors. For resistance assignment to land use types, ecological obstruction is the main consideration, while also taking into account the suitability of land use for corridor construction, reflecting the connection between the scientific and practical processes.

[0034] 5. The spatial range of suitable paths with similar passage functions was simulated and extracted, rather than determining the spatial range by setting a uniform width on both sides of the path with the least cumulative resistance. The above spatial range also provides a spatial data foundation for further improving and delineating the control boundaries of urban ecological corridors, and ultimately enabling their implementation.

[0035] 6. By introducing current proximity centrality, the importance of each path with minimum cumulative resistance to maintaining the overall network connectivity can be calculated, which helps to accurately grasp the spatial distribution of higher-priority ecological corridors, further reducing the redundancy of MCR model simulation results and reducing construction costs.

[0036] 7. Based on the intersection of the minimum cumulative resistance paths of the effective corridor, a circular area of ​​a certain radius is extracted, and the proportion of space within the circular area that can be used for ecological protection and restoration is analyzed. The ecological nodes extracted in this way not only play an important role in improving the overall connectivity of the system, but also have high construction feasibility. Attached Figure Description

[0037] Figure 1 This is a flowchart of the construction process of an urban green space ecological network based on an ecological security pattern, as presented in this invention.

[0038] Figure 2 This is a distribution map of important ecological sources in the embodiments of the present invention.

[0039] Figure 3 This is the minimum cumulative path distribution map in this embodiment of the invention.

[0040] Figure 4 This is a suitable path space range diagram in the embodiments of the present invention.

[0041] Figure 5 This is the minimum cumulative path level map in this embodiment of the invention.

[0042] Figure 6 This is a corridor path priority distribution diagram in an embodiment of the present invention.

[0043] Figure 7 This is a supplementary ecological node distribution map in the embodiments of the present invention.

[0044] Figure 8 This is a diagram showing the results of the urban green space ecological network in an embodiment of the present invention. Detailed Implementation

[0045] The technical solution of the present invention will be further described below with reference to specific embodiments:

[0046] This embodiment of the method for constructing an urban green space ecological network based on an ecological security pattern takes Minhang District of Shanghai as an example. Minhang District is located in the central part of Shanghai, at 31°5′N, 121°25′E, with a total area of ​​372.56 square kilometers. Minhang District has a flat terrain with a ground elevation of 3.3–4.8 meters. The Huangpu River runs through Minhang District, and the Wusong River, Dianpu River, Dazhi River, and other major water systems, along with more than 200 rivers within the district, form a river network. As of the end of 2017, Minhang District had jurisdiction over 9 towns and 4 subdistricts. At the end of 2019, the district's permanent resident population was 2,549,300, of which 1,251,400 were non-local residents.

[0047] like Figure 1 As shown, the method includes the following steps:

[0048] Step 1: Obtain the spatial distribution data of existing green space patches in the target city. The spatial distribution data of existing green space patches includes: park green space, protective green space, ancillary green space, regional green space and square land.

[0049] Technical personnel collect and prepare vector or raster spatial data such as green space distribution data, land use data, renewable land data, urban development boundary vector data, digital elevation model (DEM data), transportation station data, summer NDVI index, summer daytime surface temperature, and holiday population heat map of Minhang District and its surrounding urban areas in Shanghai. The resolution of the raster data is no less than 30m, and a city geographic information database is established.

[0050] Step 2: In GIS (Geographic Information System) software, the existing green space patches of the target city are cropped and aggregated to select candidate ecological source areas;

[0051] In GIS software, existing green space patches within the administrative boundary of Minhang District and its surrounding 5-kilometer buffer zone were clipped. Using a clustering tool, existing green space patches with a Euclidean distance of less than 10 meters were clustered. These clustered green space patches were then filtered according to a 0.3 square kilometer area threshold within the 0.05 square kilometer buffer zone within the administrative boundary, serving as potential ecological source areas. By incorporating existing green space patches within the 5-kilometer buffer zone surrounding Minhang District into the existing green space patches of the target city through clipping, clustering, and filtering, the constructed green space ecological network better connects important ecological spaces both inside and outside the city, further enhancing the network's systematicity and integrity.

[0052] Step 3: Construct an ecological source area screening index system, classify candidate ecological source areas according to their importance level, and screen out important ecological source areas, such as... Figure 2 As shown;

[0053] With the primary goal of meeting human ecological living needs, while also considering the habitat and survival needs of small mammals (weasels, hedgehogs) and amphibians and reptiles (frogs, sauropods, etc.), an indicator system for screening ecological source areas in Minhang District was constructed, as shown in Table 1. The indicators include: green space service coverage radius, green space service potential, actual green space usage level, green space accessibility, green space habitat quality, green space vegetation quality, importance of green space connectivity, and green space mitigation of the urban heat island effect. The methods in Table 1 were used to calculate and assign values ​​to these indicators.

[0054] The Analytic Hierarchy Process (AHP) was used to assign corresponding weights to the above indicators (Table 1). Based on the GIS platform, the raster layers of each indicator score were weighted and overlaid using the pre-set indicator weights. The results were then reclassified to obtain the socio-ecological composite functional importance level (levels 1-10) for each candidate ecological source area. The candidate source areas with the top 30% comprehensive scores were selected, totaling 92.

[0055] In addition to green source areas, important rivers flowing through Minhang District, such as the Huangpu River, Suzhou River, and Dianpu River, as well as ponds and wetlands with an area of ​​more than 5 hectares, are included as blue source areas in the source area system. These blue source areas are then spatially overlaid with the green source areas extracted in the above steps in GIS software, ultimately forming a total of 103 important ecological source areas required for the construction of the urban green space ecological network.

[0056]

[0057]

[0058] Step 4: For the construction of green space ecological networks, the setting of resistance surfaces needs to consider not only the hindering effects of different land use types on human slow-moving activities and animal migration, but also the differences in resistance to the aforementioned ecological flows caused by urban vegetation cover, socio-economic conditions, and the intensity of human disturbance. A resistance factor table is constructed by combining the current land use type of the target city with other resistance factors, and values ​​are assigned to the resistance factors in the table. Using GIS software, the raster layers of each resistance factor are spatially overlaid to obtain a comprehensive resistance surface.

[0059] Based primarily on the needs of human slow-moving recreation, while also considering the migration needs of small mammals and amphibians and reptiles, a resistance factor table (Table 2) is constructed by combining the current land use types of Minhang District with other resistance factors. The mandatory resistance factor is land use type, which, in addition to land use type, includes 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 (elevation and slope are calculated in GIS software by acquiring Digital Elevation Model (DEM) data). In this embodiment, the resistance factors include six resistance factors: land use type, distance from ecological source area, distance from main road, distance from main river, population density, and vegetation quality.

[0060] For land use resistance factors, the current land use vector map is used as the basis, overlaid with areas such as highways, railways, and urban renewal land. Based on relevant research findings and combined with the actual situation in Minhang District, resistance values ​​are assigned primarily based on ecological resistance, while also considering the suitability of land use for corridor construction. Specifically: In ecological spaces, woodlands, green spaces, wetlands, grasslands, and orchards have relatively low ecological resistance, with resistance values ​​ranging from 1 to 30; rivers, lakes, and reservoirs are generally difficult to cross, with a resistance value of 500. In non-ecological spaces, residential land, road land, industrial and mining land, and warehousing land have relatively high ecological resistance, with values ​​ranging from 50 to 100; non-ecological spaces with high ecological resistance, such as highways and high-speed railways, are assigned a value of 1000; urban renewal land within industrial and mining land, such as plots 195 and 198 in Minhang District, Shanghai, have lower resistance values ​​than general industrial and mining land, at 30 and 50 respectively, due to their higher potential for conversion into green spaces or woodlands.

[0061] For the distances to ecological source areas, main roads, and rivers, GIS software was used to calculate the Euclidean distance from each pixel to the boundary of the source area, main road, and main river, respectively, and then these distances were classified and assigned resistance values. Considering that the construction of urban ecological corridors needs to connect important ecological source areas, and that they are usually constructed and implemented along main rivers and main roads, the closer a pixel is to the aforementioned source area, road, or river, the lower its resistance value.

[0062] Population density and vegetation quality were classified and assigned resistance values ​​using population heat maps and NDVI index maps of the target cities, respectively (Table 2). Urban ecological corridor construction should avoid densely populated urban areas; therefore, higher population density corresponds to higher resistance values. Simultaneously, urban ecological corridor construction should make full use of existing urban vegetation; therefore, higher NDVI index corresponds to lower resistance values.

[0063] Using the Analytic Hierarchy Process (AHP), weights were assigned to the above indicators to form a resistance factor table. Figure 2 Based on GIS software, the raster layers of each resistance factor are spatially weighted and superimposed using the set weights of the indicators to determine the comprehensive resistance raster map (comprehensive resistance surface) for humans and the focus species respectively. The resolution of the comprehensive resistance surface raster map should not be higher than 30m. In this embodiment, the resolution of the comprehensive resistance raster map is 10m.

[0064]

[0065]

[0066]

[0067] Note: In Table 2, under the background of reducing industrial land use in Shanghai, plots 198 and 195 are both reduced industrial and mining land plots in Minhang District. Plot 198 is mainly used for land reclamation, while plot 195 is mainly used for urban renewal and transformation and upgrading. In this embodiment, both are renewable land.

[0068] Step 5: Based on important ecological source areas and comprehensive resistance surfaces, and using the Minimum Cumulative Resistance (MCR) model, simulate and extract the minimum cumulative resistance path and suitable path spatial range between any two target ecological source areas, such as... Figure 3 and Figure 4 As shown; the MCR model can simulate the minimum cumulative resistance path with the shortest cost-weighted distance (CWD) between two source locations:

[0069]

[0070] 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.

[0071] The suitable path space is defined as the area between two ecological source sites comprised of all pixels whose CWD (cumulative resistance) shear threshold is no higher than that of 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 to use, thus enabling passage and migration. This spatial range also provides a spatial data foundation for the subsequent delineation of the control boundaries of urban ecological corridors and their eventual implementation. Different species have different requirements for corridor width. Due to the scarcity of urban land resources, urban ecological corridors must be intensive and efficient, and the minimum width required to meet the needs of different species must be determined based on a comprehensive consideration of these factors.

[0072] 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 for 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 This is the average resistance value across the composite resistance surface; calculations show that the average resistance value of all pixels in the composite resistance surface is 50. Therefore, CWD cut and CWD max The values ​​are 1500 and 150000 respectively, and based on this, the spatial range of corridors and their suitable paths in Minhang District that do not exceed the preset maximum length is extracted.

[0073] After excluding corridor paths with a distance of no more than one grid length in the European style, a total of 211 corridor paths were obtained within the Minhang District and its surrounding 5-kilometer buffer zone. The total suitable spatial range of these paths is 66.34 square kilometers, accounting for approximately 14.94% of the total area of ​​Minhang District.

[0074] Step 6: Based on important ecological sources and comprehensive resistance surfaces, simulate the current flow betweenness centrality (CFBC) of each minimum cumulative resistance path using circuit theory. Circuit theory treats the landscape surface as a conductive surface and uses the random flow of electrons in a circuit to simulate the migration and diffusion of individual species or genes in the landscape. CFBC can be used to measure the importance of a path in maintaining the connectivity of the entire network and can be used to determine the priority of corridors constructed based on that path. In GIS software, the minimum cumulative resistance paths are classified according to their centrality values.

[0075] In GIS software, each path with minimum cumulative resistance is classified according to its centrality, resulting in a tiered map of all cumulative resistance paths based on Current Proximity Centrality (CFBC). In this embodiment, each path with minimum cumulative resistance is divided into three priority levels based on its CFBC value. Figure 5 and Figure 6 As shown, the CFBC range of priority corridor paths is 256.6-2029.1, totaling 68 paths; the CFBC range of priority corridor paths is 146.9-256.6, totaling 71 paths; and the CFBC range of priority corridor paths is 1.2-146.9, totaling 72 paths. The corridor paths of the first two priority levels are retained as valid corridor paths, and their suitable path spatial ranges are extracted.

[0076] Step 7: Using all intersections of the minimum cumulative resistance paths of the effective corridors as the target, extract intersections with more than two connecting paths in the GIS software. Exclude all intersections within a 500-meter radius of the source area. Draw a circular area with a radius of 50 meters centered on the extracted intersections. In the GIS software, overlay the resulting circular area with the land use status map of Minhang District, extract the current land use within the circular area, and calculate the spatial proportion R of each circular area suitable for ecological protection and restoration.

[0077]

[0078] Among them, Area eco It is the total area of ​​ecological space. re Area is the total area of ​​renewable space within non-ecological spaces. total It is the total area of ​​the circular region;

[0079] The threshold for R is preset at 50%. Intersections of all paths with the minimum cumulative resistance within this threshold range are selected and incorporated as supplementary ecological nodes into the green space ecological network system. Furthermore, based on the cost-effectiveness principle, for two or more adjacent nodes within 500 meters, only one node is retained based on spatial location and land use composition, resulting in a total of 21 nodes. Figure 7 As shown.

[0080] Step 8: Spatially overlay the suitable path spatial ranges of important ecological source areas and effective corridors, as well as supplementary ecological nodes, in GIS software. Extract the source areas, corridors, and nodes within the boundary range using the administrative boundary vector data of the target city area to complete the construction of the target city's green space ecological network. For example... Figure 8 As shown, the network contains 59 green source areas and 11 blue source areas; there are 169 effective corridor paths, including 56 first-priority paths and 64 second-priority paths; the total suitable corridor path range area of ​​the effective corridors is 41.14 km². 2 It accounts for approximately 11.02% of the total area of ​​Minhang District, with an additional 12 nodes.

[0081] This embodiment is merely a further explanation of the present invention and is not intended to limit the present invention. Those skilled in the art can make non-inventive modifications to this embodiment as needed after reading this specification, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for constructing an urban green space ecological network based on an ecological safety pattern, characterized in that, The method comprises the following steps: Step 1, obtaining spatial distribution data of object city current green land patches; Step 2, cutting and aggregating the obtained object city current green land patches in the GIS software, and screening to obtain a candidate ecological source; Step 3, constructing an ecological source screening index system, classifying the importance level of the candidate ecological source, and screening an important ecological source; the index includes: green land service coverage radius, green land service potential, green land actual use level, green land spatial accessibility, green land habitat quality, green land vegetation quality, green land connectivity importance, and green land heat island effect mitigation; Step 4, combining the object city current land use type with other resistance factors to construct a resistance factor table, and assigning values to the resistance factors in the resistance factor table; based on the GIS software, the grid layers of each resistance factor are spatially superimposed to obtain a comprehensive resistance surface; the other resistance factors include at least one of the following: distance from the ecological source, distance from the trunk road, distance from the trunk river, population density, vegetation quality, elevation, and slope; Step 5, based on the important ecological source and the comprehensive resistance surface, the minimum cumulative resistance path and the suitable path space range between any two important ecological sources are simulated and extracted according to the minimum cumulative resistance model; Step 6, based on the important ecological source and the comprehensive resistance surface, the current proximity center of each minimum cumulative path is simulated according to the circuit theory; in the GIS software, the minimum cumulative resistance path is classified according to the size of the center value of each minimum cumulative resistance path, the effective corridor is determined according to the level, and the suitable path space range thereof is extracted; Step 7, taking all intersection points of the minimum cumulative resistance path as objects, extracting the intersection points with more than 2 connection paths, and drawing a circular area with the extracted intersection point as the center, calculating the space proportion R of the circular area that can be implemented for ecological protection and restoration, wherein Area eco is the total area of the ecological space, Area re is the total area of the renewable space, Area total is the total area of the circular region; According to the threshold value of the preset R, the intersection points of the minimum cumulative resistance path with more than 2 connection paths in the threshold range are screened out as supplementary ecological nodes; Step 8, spatially superimposing the important ecological source, the suitable path space range of the effective corridor and the supplementary ecological node in the GIS software, extracting the source, the corridor and the node within the boundary range thereof by using the object city regional administrative boundary vector data, and completing the construction of the target city green land ecological network.

2. The method for constructing an urban green space ecological network based on an ecological security pattern according to claim 1, characterized in that, In the step 1, the spatial distribution of the object city current green land patches includes park green land, protection green land, accessory green land, regional green land and square land. 3.The method according to claim 2, wherein, In the step 1, the current green land patches within the surrounding range of the object city are also included in the object city current green land patches for cutting, aggregation and screening. 4.The method according to claim 1, wherein, In step 3, when screening the important ecological source, the AHP hierarchical analysis method is used, the corresponding weight is set for each index, the weighted superposition operation is performed on the grid layer of each index score, and the operation result is reclassified to obtain the social-ecological composite function importance level of each candidate ecological source; the green source is screened according to the comprehensive score; Then, the river, the water surface of pit and pond with area greater than 5 ha and the tidal wetland are taken as the blue source into the source system, and the green source extracted is overlaid with the blue source in the GIS software, which finally forms the important ecological source for the construction of urban green ecological network.

5. The method according to claim 1, wherein, The minimum cumulative resistance model is MCR, where i is the ith landscape unit, j represents the jth source, m represents the total number of landscape units, n represents the total number of sources, D ij represents the spatial distance between the jth source and the ith landscape unit, R i represents the resistance value corresponding to the ith landscape unit, and f represents the positive correlation between the minimum cumulative resistance and the ecological process. 6.The method of claim 1, wherein, The suitable path space ranges from the space of all pixels not higher than the cost-weighted distance cut-off threshold CWD compared to the pixels on the minimum cumulative resistance path between the two target ecological source areas cut .

7. The method according to claim 6, wherein, CWD cut = W min × R mean where W min is the preset corridor minimum width, and R mean is the average value of resistance in the integrated resistance surface. 8.The method of claim 6, wherein, Also included in determining the appropriate path space range is by preset CWD max Eliminate paths with length exceeding a set value, CWD max = L max x R mean , where L max is the preset maximum length of the gallery, and R mean is the average resistance in the integrated resistance surface.

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