A method for identifying nodes on critical paths of coastal migration corridors

Abstract

The present invention relates to a method for identifying nodes along critical paths in coastal flyways. The method comprises the following steps: extracting core habitats for migratory waterbirds and constructing a migratory resistance surface; establishing a critical migratory path based on the core habitats and migratory resistance surface; and identifying key nodes along the critical migratory path. Key nodes include migratory joints and migratory obstacles. The present invention provides a comprehensive coastal flyway route and key node identification technology system, enabling accurate and reliable identification of key paths and nodes.

Description

Technical Field

[0001] The present invention relates to the technical field of coastal wetland protection and management, and in particular to a method for identifying nodes of a key path of a coastal migration channel. Background Art

[0002] Circuit theory model is one of the common methods to identify and construct migration channels. In a circuit environment, electric charges are in a state of random motion, and the movement patterns of species in nature are similar to the flow of electric charges. Therefore, the current theory can better present the random walk characteristics of migratory species. This theory regards migratory animals in the landscape as randomly moving electrons, different landscapes as conductive surfaces with different resistances, and core habitats as power sources. It simulates the migration channels of migratory animals by observing the movement of electrons on the conductive surface. Specifically, it regards the landscape as a conductive surface, and with the help of circuit theory, abstracts the heterogeneous landscape into a circuit composed of a series of nodes and resistors, where the nodes represent the core habitats or source areas. According to Ohm's law in physics, in the same circuit, the current in the conductor is proportional to the voltage across the conductor and inversely proportional to the resistance of the conductor. Therefore, the current between two nodes can be expressed by the following formula:

[0003]

[0004] Where I is the current between nodes, V is the voltage, and R e Is the effective resistance. e It is an important indicator to measure the degree of isolation between nodes, that is, the more node connection paths, the greater the R e The basic concepts and ecological significance of circuit theory are shown in Table 1. Table 1 shows the basic concepts and ecological significance of circuit theory.

[0005] Table 1

[0006]

[0007]

[0008] Circuit theory still has problems and shortcomings. Currently, most technologies for identifying and constructing migratory corridors based on circuit theory are primarily used to study the migration and dispersal of rare mammalian species and the connectivity of their habitats. Applications to identifying migratory waterbird routes are limited, and most are limited to identifying animal migration corridors in certain regions. Applications to large-scale, cross-scale, and multi-species migration corridors are limited. Furthermore, few technologies integrate multiple natural and human factors to construct migratory corridors. Furthermore, there is a lack of verification of the results with actual tracking data.

[0009] Circuit theory simplifies the ecological landscape into a network model of "nodes" and "resistors", which cannot fully reflect the diverse biological behaviors, dynamic environments and complex ecological interactions in real ecosystems, because species determine their migration routes based on their migration experience rather than moving randomly like electrons.

[0010] The accurate setting of the resistance surface directly affects the accuracy of migratory route simulations. However, the reality is that there is no unified standard for the selection and weighting of resistance factors in ecological resistance surfaces. Resistance factors are usually assigned based on expert opinion or literature reviews, which is highly subjective. Moreover, due to the difficulty in obtaining relevant data, the construction of resistance surfaces cannot fully reflect the resistance conditions in the real world. Species may also try to find multiple "optimal" paths due to unfamiliarity with the landscape. If a species' activity area is limited or does not include certain land-use types, it is unlikely to cross these land-use types during migration. Species can easily cross unsuitable habitats to reach suitable habitats during their spread. For birds, unsuitable habitats have less resistance and negative impact on their movement, so birds have more potential corridors. Summary of the Invention

[0011] In order to overcome the shortcomings of the current background technology in terms of small application scale and limited application in the identification of bird migration channels, the present invention provides a complete coastal migration channel route and key node identification technology system to achieve the effect of accurate and reliable identification of key paths and nodes.

[0012] To achieve the above object, the present invention provides the following solutions:

[0013] A method for identifying nodes on a critical path of a coastal migration channel includes:

[0014] Extract the core habitats of migratory waterbirds and construct migration resistance surfaces;

[0015] Establishing a critical migration path based on the core habitat and the migration resistance surface;

[0016] Key nodes are identified through the migration key path; wherein the key nodes include: migration joint points and migration obstacle points.

[0017] Optionally, extracting the core habitat of the migratory waterbirds includes:

[0018] Obtaining the activity area of the migratory waterbirds and using the activity area as the waterbird habitat;

[0019] The inner area of the waterbird habitat with a target length from the edge is regarded as an important habitat, the connectivity probability after the important habitat is removed is calculated, and the change in the connectivity probability is used as a measure of the importance of the important habitat to maintaining landscape connectivity;

[0020] A degree threshold is preset, the importance is compared with the degree threshold, and the importance higher than the degree threshold is taken as the core habitat.

[0021] Optionally, the activity area includes: aquaculture land, salt pans and tidal flats.

[0022] Optionally, constructing the migration resistance surface includes:

[0023] Screen multiple influencing factors, assign values to the multiple influencing factors, use hierarchical analysis method to determine the weights of the multiple influencing factors, perform weighted summation on each influencing factor, and establish the migration resistance surface of the migratory waterbirds moving within the habitat under multiple influencing factors.

[0024] Optionally, the multiple influencing factors include: natural environmental factors, biological factors and human interference factors.

[0025] Optionally, the formula for establishing the migration resistance surface of the migratory waterbirds moving within the habitat under multiple influencing factors is:

[0026]

[0027] Among them, R represents the resistance value of migratory waterbirds, n represents the total number of influencing factors, and Val i Represents the resistance value of the influencing factor i, W i Represents the weight of each impact factor.

[0028] Optionally, identifying the migration joint includes:

[0029] Based on the critical migration path, the route width is determined, and the migration joint points are identified by using grid center analysis to simulate the path of other core habitats with a single core habitat.

[0030] Optionally, identifying the migration obstacle point includes: setting detection parameters of a detection device, and using the set detection device to identify the migration obstacle point.

[0031] Optionally, the detection parameters include: a minimum detection radius, a maximum detection radius and a radius step value.

[0032] The beneficial effects of the present invention are:

[0033] The present invention compares the key migration paths and key nodes on the identified migration corridor with the bird trajectories tracked by actual satellites, and verifies the migration route results based on the degree of overlap between the two. The migration paths identified by the present invention are completely consistent with the actual satellite tracking data. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 This is a flow chart of a method for identifying nodes on a critical path of a coastal migration channel according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] like Figure 1 As shown, this embodiment discloses a method for identifying nodes of a critical path of a coastal migration channel, including: extracting the core habitat of migratory waterbirds and constructing a migration resistance surface; establishing a critical migration path based on the core habitat and the migration resistance surface; identifying key nodes through the critical migration path; wherein the key nodes include: migration joint points and migration obstacle points.

[0039] Furthermore, extracting the core habitat of migratory waterbirds includes: obtaining the activity area of migratory waterbirds and taking the activity area as the waterbird habitat; taking the internal area of the waterbird habitat with a target length from the edge as the important habitat, calculating the connectivity probability after the important habitat is removed, and taking the change in connectivity probability as a measure of the importance of the important habitat for maintaining landscape connectivity; presetting a degree threshold, comparing the importance with the degree threshold, and taking the importance higher than the degree threshold as the core habitat; the activity area includes: aquaculture land, salt fields and mudflats.

[0040] Taking the importance above the degree threshold as the core habitat includes: screening the area with dPC>1 as the core habitat.

[0041] Specifically, the core habitat extraction of the migration corridor:

[0042] Core habitats are crucial for maintaining ecological functions and processes. They serve as important habitats for native species and are crucial for safeguarding ecosystem services, maintaining their integrity and connectivity. They also provide a wealth of products for human production and life. These habitats exhibit good habitat quality and landscape connectivity. When identifying core habitats, it is necessary to comprehensively assess the ecosystem's ability to withstand disturbances (i.e., ecological and environmental sensitivity) in the face of human activities and changes in the natural environment, consider the interrelationships between different ecosystem services or ecological elements, and select large, continuous patches whenever possible to maximize ecological benefits.

[0043] Aquaculture sites, salt pans, and mudflats are key areas for migratory coastal waterbirds to rest, feed, and breed, while other land uses, such as construction land and cultivated land, are unsuitable for waterbird activity. Therefore, we identified three land use types—aquaculture sites, salt pans, and mudflats—as waterbird habitats, and identified the inner area within 100 meters of the habitat edge as critical habitat. To ensure that the core habitat had a certain carrying capacity, we excluded smaller critical habitats. We calculated the change in connectivity probability after removing these critical habitats to measure their importance in maintaining landscape connectivity. Highly important habitats were then selected as core habitats for migratory waterbirds.

[0044] Calculating the connectivity probability after important habitats are removed involves:

[0045] The calculation formulas of the probability of connectivity (PC) and the importance of the patch (dPC) are as follows:

[0046]

[0047] where n is the total number of landscape patches; nlij is the number of connections between patch i and patch j; ai and aj represent the areas of patch i and patch j, respectively; Pij* is the maximum probability of direct diffusion of species between patch i and patch j; AL is the total area of the landscape; and PCremove is the value of the landscape connectivity index after patch i is removed from the landscape.

[0048] Probability of connectivity refers to the probability of successfully establishing a connection between nodes in a random network. dPC measures the importance of a patch in maintaining landscape connectivity by measuring the change in PC after a patch is removed. A larger value indicates a node's greater contribution to the overall landscape.

[0049] Furthermore, constructing a migration resistance surface includes: screening multiple influencing factors, assigning values to the multiple influencing factors, using the hierarchical analysis method to determine the weights of the multiple influencing factors, performing weighted summation on each influencing factor, and establishing a migration resistance surface for migratory waterbirds moving within their habitats under multiple influencing factors; the multiple influencing factors include: natural environmental factors, biological factors, and human interference factors.

[0050] Specifically, the migration resistance surface is constructed:

[0051] The resistance surface reflects the flow trends of ecological flows, indirectly illustrating species' migration choices and quantifying the degree of resistance to species dispersal. Its accurate setting directly impacts the accuracy of migratory route simulations. Typically, factors are assigned values based on their impact on species, both natural and human, and then weighted to construct a resistance surface.

[0052] A variety of influencing factors were screened, including natural environmental factors (altitude, slope, and land use type); biological factors (vegetation coverage); and human interference factors (distance to roads and distance to human settlements). All influencing factors were assigned values, and the analytic hierarchy process was used to determine the weights of each influencing factor, thus establishing a multi-level evaluation structure model. The weighted sum of each influencing factor was used to establish the resistance surface formula for migratory waterbirds moving within their habitat under various influencing factors, as follows:

[0053]

[0054] Where R is the resistance value of migratory waterbirds, n represents the total number of influencing factors, and Val i is the resistance value of influencing factor i, W i is the weight of each influencing factor.

[0055] Furthermore, identifying migration nodes includes: determining the route width based on the key migration path, and using grid center analysis to simulate the path of other core habitats with a single core habitat to identify migration nodes.

[0056] Furthermore, identifying the migration obstacle points includes: setting detection parameters of the detection equipment, and using the set detection equipment to identify the migration obstacle points; the detection parameters include: a minimum detection radius, a maximum detection radius, and a radius step value.

[0057] Specifically, critical path identification:

[0058] This example constructs flyways by establishing networks and graphical connections. Flyways are migratory pathways connecting waterbird habitats. They connect isolated key habitat patches, maintain the flow of matter and energy, and enable the diffusion, migration, and exchange of matter and energy, thereby promoting the sustainable development of plant and animal resources. Flyways are a crucial component of establishing an ecological security framework and an effective way to address ecosystem fragmentation. Flyway construction utilizes network and graphical connections.

[0059] Specifically, key nodes are identified:

[0060] The key nodes of the migration route are divided into pinch points and barrier points. Nodes refer to locations on the migration route that play a key role in ecological processes such as biological migration.

[0061] 1. Migration joints:

[0062] A pinch point refers to an area with high habitat quality and low resistance value. When the resistance value of an area is low, waterbirds are more likely to pass through this area or it is extremely frequent. Or this area is a must-pass place for waterbirds to migrate and there is no other alternative route. If this area is destroyed, it may cut off the routes between core habitats, resulting in a decrease in the overall landscape connectivity. Such areas are called pinch points.

[0063] When identifying migratory nodes along a flyway, the weighted cost distance (cost-weighted corridor width), or route width, represents the range of "route width" within which the analysis is conducted. Based on the habitat requirements of waterbirds and the results of flyway identification, a corridor width of 20,000 meters was selected. Two analysis modes are available: adjacent pair analysis and raster centrality analysis. However, the adjacent pair analysis model yields regions of limited value to the overall landscape pattern, as organisms can bypass other core habitats. Therefore, a raster centrality analysis model was used. This model is further divided into pairwise and all-to-one models. The pairwise model simulates the path between all pairs of core habitats to determine the degree of obstruction during animal movement; the all-to-one model simulates the path from one core habitat to all other core habitats. The all-to-one model was ultimately chosen for migratory node identification.

[0064] 2. Migration Obstacle Points

[0065] Barrier points refer to areas where the movement of species between habitats is greatly hindered. After restoration, the overall connectivity of the region can be improved, and they are priority areas for ecological restoration.

[0066] The landscape resistance value within the detection radius is replaced with the minimum value of the resistance surface, and the improvement score of the migration route is analyzed. The larger the improvement score, the greater the degree of obstacle in this area.

[0067] The minimum detection radius is an integer multiple of the pixel resolution, typically 2-3 times. For example, if the pixel size is 30, the minimum radius is 60 or 90. Similarly, the maximum detection radius is an integer multiple of the pixel resolution, typically 10 times. The radius step value is the radius increment for each analysis: (maximum - minimum) / step size = an integer.

[0068] The key migration paths and key nodes on the migration corridor identified using this method will be compared with the bird trajectories in the literature and actual satellite tracking, and the migration route results will be verified based on the degree of overlap between the two.

[0069] Coastal migration routes, ecological nodes, and ecological barriers were identified, with 40 core habitats primarily located in the Bohai Rim, Yellow Sea, and East China Sea regions. The land use type of these core habitats is primarily coastal tidal flats, primarily along the Bohai Rim, East China Sea, and Yellow Sea coasts. This is consistent with previous satellite tracking data and studies of shorebird staging sites. The 71 identified flyways fully matched actual satellite tracking data, with 49 of these routes being frequently used by migrating birds, and 22 (30.98%) being less frequently used. Further analysis revealed that migratory birds concentrated on flyways with an average resistance index (the ratio of the total resistance overcome by the migration to the length of the flyway) between 17 and 27, indicating that birds prefer routes with lower average resistance during migration. Flyway nodes were primarily located in the Bohai Rim region and along the coasts of Zhejiang and Fujian provinces, while migratory barriers were primarily located in Nantong, Jiangsu Province, and along the coasts of Zhejiang and Fujian provinces.

[0070] This embodiment discloses a method for identifying nodes on a critical path of a coastal migration corridor, including:

[0071] 1. Extraction of core habitats along the migration corridor:

[0072] Three land use types, namely aquaculture land, salt pan and mudflat, were selected as waterbird habitats. The inner area 100 m from the edge of the habitat was selected as the important habitat. In order to ensure that the core habitat has a certain carrying capacity, the area less than 2 km was excluded. 2The importance of important habitats for maintaining landscape connectivity was measured by calculating the change in the probability of connectivity after these important habitats were removed, and the important habitats with higher importance were selected as the core habitats for migratory waterbirds.

[0073] 2. Construction of migration resistance surface:

[0074] Through literature review, we identified six influencing factors: natural environmental factors (altitude, slope, and land use type); biological factors (vegetation coverage); and human disturbance factors (distance to roads and distance to human settlements). We assigned values to all of these factors and used the analytic hierarchy process (AHP) to determine their weights (Table 2). This led to the development of a multi-level evaluation model. By weighting each factor and summing it, we established the resistance surface for migratory waterbirds moving within their habitat under these multiple factors:

[0075]

[0076] Where R is the resistance value of migratory waterbirds, n represents the total number of influencing factors, and Val i is the resistance value of influencing factor i, W i is the weight of each influencing factor.

[0077] As shown in Table 2, Table 2 sets the resistance values for each influencing factor:

[0078] Table 2

[0079]

[0080]

[0081] 3. Critical path identification: Use network and graphic connections to construct migration routes.

[0082] 4. Migration joints:

[0083] When identifying migration nodes along a flyway, a route width of 20,000 meters was selected. Two analysis modes are available: adjacent pair analysis and raster centrality analysis. However, the regions identified in the adjacent pair analysis mode are not of great significance to the overall landscape pattern, as organisms can bypass other core habitats. Therefore, the raster centrality analysis mode was chosen. This mode is further divided into pairwise and all-to-one modes. The pairwise mode simulates the path between all pairs of core habitats to determine the degree of obstruction during biological movement; the all-to-one mode simulates the path from one core habitat to all other core habitats. The all-to-one mode was ultimately used to identify migration nodes.

[0084] 5. Migration obstacles:

[0085] When identifying migration obstacles, set the minimum detection radius to an integer multiple of the pixel resolution, generally 2-3 times. For example, if the pixel size is 30, the minimum radius is 60 or 90. Similarly, the maximum detection radius is an integer multiple of the pixel resolution, generally 10 times. The radius step value is the radius increment for each analysis, (maximum - minimum) / step length = an integer. When identifying migration obstacles on the migration route, based on the habitat requirements of waterbirds and the identification results of the migration route, the minimum detection radius is finally selected as 500 meters, the maximum detection radius is selected as 1500 meters, and the radius step value is 500 meters.

[0086] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for identifying nodes on a critical path of a coastal migration channel, characterized in that: include: Extract the core habitats of migratory waterbirds and construct a migration resistance surface: Obtaining the activity area of the migratory waterbirds and using the activity area as the waterbird habitat; The inner area of the waterbird habitat with a target length from the edge is regarded as an important habitat, the connectivity probability after the important habitat is removed is calculated, and the change in the connectivity probability is used as a measure of the importance of the important habitat to maintaining landscape connectivity; Preset a degree threshold, compare the importance with the degree threshold, and take the importance higher than the degree threshold as the core habitat; Screening multiple influencing factors, assigning values to the multiple influencing factors, using a hierarchical analysis method to determine the weights of the multiple influencing factors, performing a weighted summation on each influencing factor, and establishing a migration resistance surface for the migratory waterbirds moving within the habitat under the multiple influencing factors; Establishing a critical migration path based on the core habitat and the migration resistance surface; Through the migration key path, key nodes are identified; wherein the key nodes include: migration joint points and migration obstacle points.

2. The method for identifying nodes of a critical path of a coastal migration channel according to claim 1, characterized in that: The activity areas include: aquaculture sites, salt pans and tidal flats.

3. The method for identifying nodes of a critical path of a coastal migration channel according to claim 1, characterized in that: The multiple influencing factors include: natural environmental factors, biological factors and human interference factors.

4. The method for identifying nodes of a critical path of a coastal migration channel according to claim 1, characterized in that: The formula for establishing the migration resistance surface of migratory waterbirds moving within their habitat under various influencing factors is: Among them, R represents the resistance value of migratory waterbirds, n represents the total number of influencing factors, and Val i Represents the resistance value of the influencing factor i, W i Represents the weight of each impact factor.

5. The method for identifying nodes of a critical path of a coastal migration channel according to claim 1, characterized in that: Identifying the migration joints includes: Based on the critical migration path, the route width is determined, and the migration joint points are identified by using grid center analysis to simulate the path of other core habitats with a single core habitat.

6. The method for identifying nodes of a critical path of a coastal migration channel according to claim 1, characterized in that: Identifying the migration obstacle point includes: setting detection parameters of a detection device, and using the set detection device to identify the migration obstacle point.

7. The method for identifying nodes of a critical path of a coastal migration channel according to claim 6, characterized in that: The detection parameters include: a minimum detection radius, a maximum detection radius, and a radius step value.

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