Node identification method for critical path of migratory flight channel in coastal zone

Abstract

The invention relates to a coastal zone migratory flight channel key path node identification method comprising the following steps: extracting a core habitat of a migratory waterfowl, and constructing a migratory flight resistance surface; establishing a migratory flight key path based on the core habitat and the migratory flight resistance surface; identifying a key node through the migratory flight key path; wherein the key nodes comprise migratory flight nodes and migratory flight obstacle points. The invention provides a set of complete coastal zone migratory flight channel route and key node identification technology system, and the effect of accurately and reliably identifying key paths and nodes is realized.

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 critical 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 the 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 conductive surfaces. Specifically, the landscape is regarded as a conductive surface, and with the help of circuit theory, the heterogeneous landscape is abstracted into a circuit composed of a series of nodes and resistors, where the nodes represent the core habitat or source. 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 there are, the greater the R e The lower the value, the lower the value. 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] At present, circuit theory still has problems and shortcomings. At present, most of the technologies for identifying and constructing migration corridors based on circuit theory are mainly used to study the migration and dispersal of rare mammal species and the connectivity of their habitats. They are rarely used in the identification of migratory waterfowl routes. Most of them are limited to the identification of animal migration corridors in some areas. There are few applications for large-scale, cross-scale, and multi-species migration corridors. There are few aspects that integrate the changes of multiple natural and human factors to construct migration corridors, and there is a lack of verification of the results obtained 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 the migratory route simulation, but the reality is that there is no unified standard for the selection and weight allocation of resistance factors for ecological resistance surfaces in academia. Resistance factors are usually assigned based on expert opinions or literature reviews, so they are highly subjective. In addition, due to the difficulty in obtaining relevant data, it is difficult to fully reflect the resistance situation in the real world by constructing a resistance surface. Species may also try to find multiple "optimal" paths because they are unfamiliar with the landscape environment. If the activity area of ​​a species is rare or does not include certain land use types, they are unlikely to cross these land use types during their movement. Species can easily cross unsuitable habitats to reach suitable habitats during the diffusion process. For birds, unsuitable habitats have lower resistance and negative impacts 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, such as small application scale and less 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 of a critical path of a coastal migration channel, comprising:

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

[0015] Based on the core habitat and the migration resistance surface, establish a key migration path;

[0016] Through the migration critical path, key nodes are identified; wherein the key nodes include: migration joint points and migration obstacle points.

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

[0018] Acquiring the activity area of ​​the migratory waterfowl and using the activity area as the waterfowl habitat;

[0019] The inner area of ​​the water bird habitat with a target length from the edge is taken 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 for 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 sites, salt pans and tidal flats.

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

[0023] Screen a variety of 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 the 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 point includes:

[0029] According to the critical migration path, the route width is determined, and the migration nodes 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 according to 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 drawings required for use in the embodiments will be briefly introduced below. 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 creative labor.

[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 be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work 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 sites, salt pans and tidal flats.

[0040] Taking the importance degree 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 of key significance in maintaining ecological functions and processes. They are important habitats for local species and are essential for ensuring ecosystem services, maintaining their integrity and connectivity. They can also provide rich products for human production and life. Such habitats have good habitat quality and landscape connectivity. When identifying core habitats, it is necessary to comprehensively assess the ecosystem's ability to resist interference (i.e., ecological and environmental sensitivity) under human activities and changes in the natural environment, consider the relationships between different ecosystem services or various ecological elements, and try to select large areas of continuous patches to maximize ecological benefits.

[0043] Aquaculture land, salt pans and tidal flats are the main areas for coastal migratory waterbirds to stop, forage and breed, while other land uses such as construction land and cultivated land are not suitable for waterbird activities. Therefore, three land use types, namely aquaculture land, salt pans and tidal flats, were used as waterbird habitats, and the inner area 100 meters away from the edge of the habitat was used as an important habitat. In order to give the core habitat a certain carrying capacity, the important habitats with smaller areas were excluded. The importance of the important habitat 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.

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

[0045] The calculation formulas of the possible connectivity index (Probability of connectivity, PC) and the patch importance value (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 possibility of direct diffusion of species between patch i and patch j; AL is the total area of ​​the landscape; PCremove is the value of the possible connectivity index of the landscape 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 refers to the change in PC after a patch is removed to measure the importance of the patch in maintaining landscape connectivity. The larger the value, the greater the contribution of the node to the overall landscape.

[0049] Furthermore, constructing the 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 the migration resistance surface of migratory waterbirds moving within the habitat 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 trend of ecological flow, reflects the migration selection of species from the side, and is used to quantify the degree of obstruction in the diffusion of species. Its accurate setting directly affects the accuracy of migratory route simulation. Usually, each influencing factor is assigned a value according to the degree of influence of natural and human factors on the species, and then the resistance surface is constructed by superimposing them according to a certain weight.

[0052] A variety of influencing factors were screened out, including natural environmental factors (altitude, slope and land use type); biological factors (vegetation coverage) and human interference factors (road distance and distance from human settlement), etc. All influencing factors were assigned values, and the weight of each influencing factor was determined using the hierarchical analysis method to establish 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 in the habitat under multiple 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 according to 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 embodiment constructs a migration route by establishing a network and graphic connection. The migration route is a migration channel connecting waterfowl habitats. The migration route connects isolated key habitat patches, maintains the flow of materials and energy, and can meet the diffusion, migration and exchange of materials and energy, thereby promoting the sustainable development of animal and plant resources. It is an important part of the construction of an ecological security pattern. The construction of a migration route is an effective way to solve the fragmentation of the ecosystem. Use the establishment of a network and graphic connection to construct a migration route.

[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 the 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 small, waterbirds are more likely to pass through this area or it is very 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, the routes between core habitats may be cut off, resulting in a decrease in the overall landscape connectivity. Such areas are called pinch points.

[0063] When identifying migration nodes on the migration route, the weighted cost distance (cost-weighted corridor'width'), that is, the route width, indicates that the analysis is performed within the range of "how wide the route is". According to the habitat requirements of waterfowl and the identification results of the migration route, the corridor width is selected as 20,000 meters. There are two analysis modes: adjacent core habitat pair analysis (adjacentpair) and raster centrality analysis (raster centrality). However, in the adjacent core habitat pair analysis mode, the area sought is not of great value to the overall landscape pattern, and organisms can bypass other core habitats. Therefore, the raster centrality analysis mode is used for analysis. This mode is divided into two types: pairwise and all-to-one. The pairwise mode refers to the degree of obstruction in the process of biological movement. The path simulation is performed between all paired core habitats; the many-to-one mode is to simulate the path of one core habitat to all other core habitats. Finally, the many-to-one mode is selected for the identification of migration nodes.

[0064] 2. Migration obstacles

[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, usually 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, usually 10 times. The radius step value is the radius increment for each analysis, (maximum - minimum) / step = an integer.

[0068] The key migration paths and key nodes on the migration corridor identified by this method are compared with the literature and the bird trajectories tracked by actual satellites, and the migration route results are verified based on the degree of overlap between the two.

[0069] The number of core habitats in the coastal zone migration routes, ecological nodes and ecological barriers is 40, mainly distributed in the Bohai Sea Rim, the Yellow Sea and the East China Sea. The land use type of the core habitat is mainly coastal tidal flats, mainly distributed along the Bohai Sea Rim, the East China Sea and the Yellow Sea coast. This is basically consistent with the satellite tracking data of previous years and the research results of plovers and sandpipers; the 71 migration routes identified are completely consistent with the actual satellite tracking data, of which 49 routes are high-frequency routes used by migratory birds, and 22 (30.98%) are relatively low-frequency routes. Further analysis found that migratory birds concentrated on using migration routes with an average resistance index (the ratio of the total resistance overcome by migration to the length of the migration route) between 17 and 27, indicating that birds prefer routes with lower average resistance when migrating. Migration nodes are mainly in the Bohai Sea Rim, Zhejiang Province and Fujian Province, and migration barriers are mainly in Nantong City, Jiangsu Province, Zhejiang Province and Fujian Province.

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

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

[0072] Three land use types, namely aquaculture land, salt pan and tidal flat, 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 areas with an area less than 2 km were excluded. 2The importance of important habitats for maintaining landscape connectivity was measured by calculating the change in 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] By consulting the literature, a total of 6 influencing factors were screened out, including natural environmental factors (altitude, slope and land use type); biological factors (vegetation coverage) and human interference factors (road distance and distance from human settlement). All influencing factors were assigned values, and the weight of each influencing factor was determined by the hierarchical analysis method (Table 2), and a multi-level evaluation structure model was established. The weighted sum of each influencing factor was used to establish the resistance surface formula for migratory waterbirds moving in the habitat under multiple influencing factors as follows:

[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 value of 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 the migration nodes on the migration route, the route width is selected as 20,000 meters. There are two analysis modes: adjacent core habitat pair analysis (adjacentpair) and raster centrality analysis (raster centrality). However, in the adjacent core habitat pair analysis mode, the area sought is not of great value to the overall landscape pattern, and organisms can bypass other core habitats. Therefore, the raster centrality analysis mode is selected for analysis. This mode is divided into two modes: pairwise and all-to-one. The pairwise mode refers to the degree of obstruction in the process of biological movement. The path simulation is carried out between all paired core habitats; the all-to-one mode is to simulate the path of one core habitat to all other core habitats, and finally the all-to-one mode is selected for the identification of 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 waterfowl 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 only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for identifying nodes of a critical path of a coastal migration channel, characterized in that: include: Extract the core habitats of migratory waterbirds and construct migration resistance surfaces; Based on the core habitat and the migration resistance surface, establish a key migration path; Through the migration critical 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 core habitats for migratory waterbirds include: Acquiring the activity area of ​​the migratory waterfowl and using the activity area as the waterfowl habitat; The inner area of ​​the water bird habitat with a target length from the edge is taken 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 for maintaining landscape connectivity; 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.

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

4. The method for identifying nodes of a critical path of a coastal migration channel according to claim 1, characterized in that: Constructing the migration resistance surface includes: A variety of influencing factors are screened, values ​​are assigned to the various influencing factors, the weights of the various influencing factors are determined using the hierarchical analysis method, the weighted sum of each influencing factor is performed, and the migration resistance surface of the migratory waterbirds moving within the habitat under the various influencing factors is established.

5. The method for identifying nodes of a critical path of a coastal migration channel according to claim 4, characterized in that: The multiple influencing factors include: natural environmental factors, biological factors and human interference factors.

6. The method for identifying nodes of a critical path of a coastal migration channel according to claim 4, characterized in that: The formula for establishing the migration resistance surface of migratory waterbirds moving within the 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.

7. 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: According to the critical migration path, the route width is determined, and the migration nodes are identified by using grid center analysis to simulate the path of other core habitats with a single core habitat.

8. 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.

9. The method for identifying nodes of a critical path of a coastal migration channel according to claim 8, characterized in that: The detection parameters include: a minimum detection radius, a maximum detection radius and a radius step value.

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