Ecological security pattern risk assessment method based on finite element simulation

Abstract

The invention discloses an ecological security pattern risk assessment method based on finite element simulation, and belongs to the technical field of ecological security pattern risk assessment, and the method comprises the following steps: S1, constructing an ecological security pattern; s2, discretizing the ecological corridor; s3, expressing the internal condition of the ecological corridor by using a landscape pattern index, and obtaining the material attribute of the three-dimensional model by converting the landscape pattern index; s4, extracting normalized vegetation indexes and traffic network density data in a preset range of the ecological corridor, and converting the data into external loads after processing; s5, constraint is applied to the three-dimensional model corresponding to the ecological source land and the three-dimensional model corresponding to the pedal stone; s6, constructing four scenes based on the three-dimensional model, and performing finite element simulation on the four scenes; and S7, making an ecological security pattern optimization strategy based on results of multi-scenario analysis and finite element simulation. And the risk assessment of the ecological space is carried out by using theoretical methods such as stress and deformation of three-dimensional mechanics, so that the method has relatively high innovativeness and practicability, and has unique protection value.

Description

Technical Field

[0001] The present invention relates to the technical field of ecological security pattern risk assessment, and in particular to an ecological security pattern risk assessment method based on finite element simulation. Background Art

[0002] Many small ecological sources are scattered, lack the connection of ecological corridors, and do not consider the overall ecological protection. Building a regional ecological security pattern (ESP) has become one of the ways to solve this problem.

[0003] ESP refers to the potential ecological spatial pattern composed of key areas, important locations and ecological networks in the landscape to ensure ecological security. The construction and optimization of ESP is crucial to the coordination of regional ecological protection and economic growth. After a long period of development, a construction paradigm of ESP has been formed with "identification of ecological sources, construction of resistance surfaces, and extraction of corridors" as the main theoretical framework. There are three main methods to identify ecological sources: ① Directly select nature reserves or ecological protection red lines as ecological sources. ② Extract ecological sources based on the importance of ecosystem services or ecological sensitivity. ③ Identify ecological sources based on morphological spatial pattern analysis. Organisms will migrate when the ecological environment changes or they are threatened, and they will be hindered by natural or man-made obstacles during the migration process. The resistance surface is a representation of the resistance encountered by species during migration. The resistance factor usually selects natural factors that can reflect natural conditions (land use type, elevation, slope, etc.) and human factors that reflect human activities (such as the distance from highways, railways and residential areas, etc.), which constitute an ecological resistance factor indicator system. Ecological corridors are connecting corridors between ecological sources. They provide channels for biological migration and material and energy exchange by connecting ecological sources and bypassing areas of high ecological resistance. As a key component of ESP, it connects different ecological sources and plays a key role in maintaining the stability and health of the ecosystem. The extraction of ecological corridors generally adopts methods such as the minimum cumulative resistance model and circuit theory. Using the Circuitscape software based on circuit theory and the pinch mapper tool, a current density map is created to extract high-value areas as ecological pinch points, that is, areas where species are more likely to migrate or where there is no alternative path. Ecological barrier points refer to areas between patches with greater resistance to biological movement. Removing such areas can significantly improve biological flow and landscape connectivity within the corridor. However, traditional ecological corridor research methods, such as the minimum cumulative resistance model and circuit theory model, although they have significant effects in determining the scope of ecological corridors and identifying barrier points in ecological corridors, cannot quantitatively assess the risks of ESP, and it is difficult to accurately quantify risks and provide targeted protection strategies.

[0004] By introducing finite element simulation into the study of ecological problems, the risk issues of ESP can be quantitatively analyzed. Finite element simulation is a method of numerical analysis, which is widely used in mechanical design and construction. It is a numerical method that regards a continuum as a discretized set of several finite-sized units to solve the thermal, mechanical, and electromagnetic problems of the continuum. Its basic idea is to discretize the continuous solution area into a combination of a finite number of units that are connected to each other in a certain way. Finite element simulation can be used to consider the interaction between various structural units and analyze the stress, deformation and stability of the structure under different working conditions. This kind of detailed analysis helps to optimize the structural design and improve the performance and safety of the structure. It is precisely because of this feature that the introduction of finite element simulation into the study of ESP can accurately analyze the structure of the ecological corridor, thereby determining the weak points of the ecological corridor and realizing accurate optimization of ESP.

[0005] The optimization mode in the past is often large-scale, which is difficult to meet the requirements of accurate optimization and easily causes waste of resources. Therefore, adding stepping stones is an effective method to solve the waste of resources in ecological protection. Stepping stones are small patch habitats that can be temporarily inhabited by organisms during migration and diffusion. Adding stepping stones between unconnected patches can increase the connectivity of the landscape. However, for the stepping stones that play an important role in ESP, the impact of their setting on the ecological corridor and the surrounding ecological environment is not in-depth enough and lacks scientific planning. In the past, the addition of stepping stones was blind, and the middle part of the ecological corridor was generally selected as a stepping stone. By analyzing the entire ESP structure through finite element simulation, the weak points of the ecological corridor can be accurately located and then stepping stones can be added, and the protection effect of stepping stones on ESP and the impact on the surrounding ecological corridors can be analyzed. Therefore, the invention is based on finite element simulation. Compared with the previous research method of ESP, it can not only accurately locate the weak points of the ecological corridor to conduct risk assessment on ESP, but also scientifically plan the addition of stepping stones. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide an ecological security pattern risk assessment method based on finite element simulation.

[0007] The objective of the present invention is achieved through the following technical solutions: The present invention discloses an ecological security pattern risk assessment method based on finite element simulation, comprising the following steps: S1. Determine the ecological source area based on the MSPA method, construct the ecological resistance surface, extract the ecological corridor, and build the ecological security pattern; S2. Discretization of ecological corridors, establishment of three-dimensional models of ecological corridors with different cross-sections to express the heterogeneity within the ecological corridors; S3. Use the landscape pattern index to express the internal situation of the ecological corridor, and obtain the material properties of the three-dimensional model by transforming the landscape pattern index; S4, extracting the normalized vegetation index and traffic network density data within the preset range of the ecological corridor, processing them, and converting them into external loads; S5, impose constraints on the three-dimensional models corresponding to the ecological source and stepping stones respectively; S6. Construct four scenarios based on the three-dimensional model and perform finite element simulation on the four scenarios; S7. Based on the results of multi-scenario analysis and finite element simulation, formulate an optimization strategy for the ecological security pattern.

[0008] Furthermore, step S1 specifically includes: converting land use data into binary data through a morphological spatial pattern analysis method, and dividing it into foreground and background, wherein the foreground includes areas with biological potential, and the background is other areas except the foreground; processing the foreground and background through Guidos analysis software, and selecting the core area as the ecological source; constructing an ecological resistance surface, wherein the ecological resistance surface includes natural factors and human factors, wherein the natural factors include the normalized vegetation index and terrain, and the resistance surface is modified by assigning corresponding weights, and the resistance value range is set to [1, 500]; determining the specific scope of the ecological corridor through a circuit theory model; and constructing an ecological security pattern.

[0009] Preferably, step S2 specifically includes: establishing a first ecological corridor three-dimensional model according to the ecological corridor obtained in step S1, and then dividing the first ecological corridor three-dimensional model into n second ecological corridor three-dimensional models, wherein the width and height of the cross-section of the second ecological corridor three-dimensional model are within a preset range.

[0010] Preferably, step S3 specifically includes: calculating the landscape pattern index within the ecological corridor buffer zone, the landscape pattern index including patch richness, effective grid size, connectivity index, landscape shape index, maximum patch index and patch type area, normalizing all data after the calculation is completed, and determining the weights corresponding to all data through the hierarchical analysis method to obtain the material properties of the second ecological corridor three-dimensional model, the material properties including Young's modulus, bulk modulus and Poisson's ratio.

[0011] Preferably, step S4 specifically includes: constructing a buffer zone based on the ecological corridor, extracting the normalized vegetation index and traffic road network density data in the buffer zone, and sorting and normalizing the normalized vegetation index and traffic road network density data, and using the processed normalized vegetation index and traffic road network density data as the load data of the second ecological corridor three-dimensional model; specifically including: adding the first normalized vegetation index within the left range of the buffer zone with the first normalized vegetation index within the right range of the buffer zone, and using the result as the second normalized vegetation index within the left range of the buffer zone; adding the first traffic road network density value within the right range of the buffer zone with the first traffic road network density value within the left range of the buffer zone, and using the result as the second traffic road network density value within the right range of the buffer zone; the raster data on both sides of the corridor can be obtained; based on the raster data and the corresponding coordinate values, a load is applied to the corresponding position of the second ecological corridor three-dimensional model; and the goal of converting relevant indicators in the geographic space into corresponding indicators in the field of mechanics is achieved.

[0012] Preferably, step S5 specifically includes: constraining the three-dimensional models corresponding to the ecological source and the stepping stones, specifically including, performing surface constraints on the surface of the three-dimensional model, that is, the displacement of the three-dimensional model corresponding to the ecological source in the X, Y, and Z directions is zero; wherein, the stepping stones have a constraining effect on the ecological corridor in the X direction, and have no constraining effect in other directions.

[0013] Preferably, step S6 specifically includes: performing finite element simulation on a mechanical three-dimensional model constructed based on real geographic spatial data, wherein different units of the mechanical three-dimensional model generate strains of different sizes and directions according to the magnitude of their respective stresses, obtaining stress and strain data of the ecological corridor, and evaluating the risk of the ecological corridor by analyzing the stress and strain data results; constructing four scenarios based on the three-dimensional model, including a natural development scenario, adding stepping stones, ecological corridor destruction, and adding stepping stones after ecological corridor destruction, comparing the stress and strain changes of the ecological corridor under different scenarios, and studying the protective effect of the stepping stones and the impact of destroying the ecological corridor on other ecological corridors.

[0014] Preferably, step S7 specifically includes: projecting the ecological risk problems in the geographic space into the three-dimensional mechanical space according to the finite element simulation results and multiple scenario analyses, and displaying the ecological risk areas in the real world according to the mechanical deformation; formulating corresponding optimization strategies for ecological corridors with different risk levels, specifically including: for corridors whose risk levels exceed the preset range, improving their stability by adding stepping stones, but taking into account the impact on adjacent corridors; taking repair measures for damaged corridors; strengthening protection for corridors whose risk levels are within the preset range; at the regional level, rationally planning the layout of ecological corridors according to the analysis of finite elements, establishing protection buffer zones, and controlling the interference of human activities on ecological corridors, so as to ensure the stability of the regional ecological security pattern.

[0015] The beneficial effects of the present invention are: 1) Traditional ecological corridor research has shortcomings in risk assessment, and mostly relies on complex networks or simple spatial analysis. This method introduces the finite element method into ecological corridor risk assessment for the first time, and proposes an ecological security pattern risk assessment method based on finite element simulation. Finite element simulation is a numerical method that treats a continuum as a discretized set of several finite-sized units to solve the continuum. From a mechanical perspective, the risk is quantified by solving the corridor stress and deformation through finite element simulation. Corridors with higher risks and potential risk corridors can be identified, providing a basis for accurately locating key protection areas, which is helpful for formulating targeted ecological protection measures, establishing nature reserves, and carrying out ecological restoration projects. Traditional methods tend to focus on large-scale protection, which aggravates the irrational allocation of resources. This method can change the lack of targeting of traditional large-scale ecological protection strategies, reasonably allocate protection resources, concentrate resources on high-risk corridors, improve ecological protection efficiency, achieve maximum ecological benefits with minimum investment, and maintain regional ESP stability.

[0016] 2) Stepping stones are crucial to the stability of the ecosystem and the migration of organisms, but previous studies lacked in-depth exploration of the impact of their setting, and most of them were empirical layouts, without analyzing their role in the stability of the ecological corridor from a mechanical perspective. Based on finite element simulation and multi-scenario analysis, this study analyzed the role of stepping stones from a mechanical perspective for the first time, showing the protective effect of stepping stones at different locations of the ecological corridor, and revealing the inherent mechanism of stepping stones to improve the overall structural stability of the ecological corridor by constraining the nodes in a single direction. Based on multi-scenario comparative analysis, the protective role of stepping stones in maintaining the stability of ESP in the case of ecological corridor destruction is revealed. At the same time, the present invention also analyzes the possible adverse effects of stepping stones on adjacent ecological corridors, which provides guidance for the scientific planning and layout of stepping stones, avoids negative impacts, and achieves sustainable development of ecosystems.

[0017] 3) Break through the limitations of traditional methods, introduce finite element simulation in mechanics into ESP research, and open up new research perspectives and methods. Take the peak cluster depression as a case area to analyze the risks of the ecological corridor from the perspective of stress and strain. Use finite elements to analyze the case area, and apply loads to the three-dimensional model of the case area. The load here is the NDVI and traffic road network density data extracted in the ecological corridor buffer zone. Through these two raster data and combined with the corresponding coordinates, the three-dimensional model can be accurately loaded, so as to obtain the stress and strain data of the three-dimensional model. Areas with large strain and stress can be accurately located, and the corresponding areas are risk areas and potential risk areas, so that accurate protection and risk warning can be carried out, proving the feasibility of exploring ecological problems from a mechanical perspective. Although there are limitations to interdisciplinary integration, it provides innovative ideas for subsequent research, promotes the development of multidisciplinary cross-disciplinary research in the field of ecology, and helps to discover more ecological laws and new ways to solve practical problems.

[0018] 4) The heterogeneity inside the ecological corridor is expressed with the help of different cross-sections and materials of the three-dimensional model. The internal characteristics of the ecological corridor are mapped into material properties in the finite element. This discretization idea just echoes the idea of ​​discretizing the whole unit and solving it separately to approximate the real value in the finite element simulation. Specifically, the 12 ecological corridors in the case area are discretized into 42 three-dimensional models, and different material properties are assigned to them according to the landscape pattern index in the buffer zone of the ecological corridor and the hierarchical analysis method. This method can objectively show the real situation inside the ecological corridor in the finite element simulation.

[0019] 5) The study constructed a complete ESP risk assessment and optimization system, which uses finite element simulation to conduct risk assessment and optimization strategy formulation for ESP. The system is highly systematic and process-oriented, which can improve research efficiency and accuracy. Its good scalability and versatility can be applied to ecological research in different regions, providing strong technical support for global ecological protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the steps of an ecological security pattern risk assessment method based on finite element simulation according to an embodiment of the present invention; Figure 2 A schematic diagram of the spatial pattern of ecological sources, resistance surfaces and ecological corridors in a case area of ​​an ecological security pattern risk assessment method based on finite element simulation according to an embodiment of the present invention; Figure 3 A schematic diagram of a transformation method of constraints of an ecological security pattern risk assessment method based on finite element simulation according to an embodiment of the present invention; Figure 4It is a schematic diagram of finite element result processing of a case area of ​​an ecological security pattern risk assessment method based on finite element simulation in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0022] The existing method for studying the ecological security pattern (ESP) is to analyze the overall topological structure based on a complex network. The present invention introduces mechanical thinking into ecological research. Through finite element simulation, the risks and potential risk areas of ESP can be accurately located, thereby achieving precise optimization. The abstract concept of ecological corridor is converted into a specific three-dimensional model structure and simulated by the finite element method. The geographic spatial indicators are converted into mechanical indicators, and the risk assessment of the corridor model is completed through finite element simulation. The present invention discloses an ecological security pattern risk assessment method based on finite element simulation. It is the first time that finite element simulation has been used to model, evaluate and optimize ecological corridors, which brings many pioneering and practical advantages to the field of ecological protection. The specific steps of the ecological security pattern risk assessment method based on finite element simulation are shown in the schematic diagram. Figure 1 As shown, the present invention can be divided into the following aspects: constructing ESP, data conversion and processing, imposing constraints, finite element simulation, and multi-scenario analysis and optimization, which specifically include the following steps: S1. Determine the ecological source area based on the MSPA method, construct the ecological resistance surface, extract the ecological corridor, and build the ecological security pattern; S2. Discretization of ecological corridors, establishment of three-dimensional models of ecological corridors with different cross-sections to express the heterogeneity within the ecological corridors; S3. Use the landscape pattern index to express the internal situation of the ecological corridor, and obtain the material properties of the three-dimensional model by transforming the landscape pattern index; S4, extracting the normalized vegetation index and traffic network density data within the preset range of the ecological corridor, processing them, and converting them into external loads; S5, impose constraints on the three-dimensional models corresponding to the ecological source and stepping stones respectively; S6. Construct four scenarios based on the three-dimensional model and perform finite element simulation on the four scenarios; S7. Based on the results of multi-scenario analysis and finite element simulation, formulate an optimization strategy for the ecological security pattern.

[0023] Exemplarily, taking the peak cluster depression in Yunnan, Guizhou and Guizhou as an example, step S1 specifically includes: converting land use data into binary data through morphological spatial pattern analysis method, and dividing it into foreground and background, the foreground includes areas with biological potential, and the background is other areas except for the foreground. In this embodiment, the foreground selects woodlands and grasslands with greater biological potential, and the background includes other areas in the ecological protection area except for the foreground; processing the foreground and background through Guidos analysis software, and selecting the core area as the ecological source; constructing an ecological resistance surface, which is composed of natural factors such as normalized vegetation index and terrain, and human factors, and assigning corresponding weights to the resistance surface for correction. The resistance value range is set to [1, 500]. The resistance factor and resistance value settings of the case area in this embodiment are shown in Table 1; determining the specific scope of the ecological corridor through the circuit theory model; and constructing an ecological security pattern. The spatial pattern of the ecological source, resistance surface and ecological corridor in the case area is shown in Table 1. Figure 2 shown.

[0024] Table 1: Resistance factor and resistance value settings for case areas Exemplarily, step S2 specifically includes: establishing a first ecological corridor three-dimensional model according to the ecological corridor obtained in step S1, and then dividing the first ecological corridor three-dimensional model into n second ecological corridor three-dimensional models, wherein the width and height of the cross section of the second ecological corridor three-dimensional model are within a preset range. The preset range is a range pre-set according to the working environment and is not limited to a specific range. Discretization of ecological corridors: The ecological corridor is a strip-shaped channel that connects the ecological source to realize the flow of species. The interior of the ecological corridor is heterogeneous, and this method characterizes this heterogeneity by establishing a second ecological corridor three-dimensional model of different cross sections. In this embodiment, the 12 ecological corridors in the case area are finally divided into a total of 42 second ecological corridor three-dimensional models, and the width of the cross section of the second ecological corridor three-dimensional model ranges from 30-50m, and the height of the cross section is uniformly set to 5m. This method can characterize the differences within the same corridor to approximate the internal situation of the ecological corridor in real conditions. The principle of finite element simulation is to discretize the three-dimensional model into smaller and simpler domains, which we call units. The calculation is completed by combining and solving the equations of all units in the three-dimensional model. The ecological corridor in the case area is discretized into 42 second ecological corridor three-dimensional models, which is similar to the method of discretizing the three-dimensional model into small units and then solving them in the finite element principle.

[0025] Exemplarily, step S3 specifically includes: calculating the landscape pattern index within the ecological corridor buffer zone, the landscape pattern index includes patch richness, effective grid size, connectivity index, landscape shape index, maximum patch index and patch type area, normalizing all data after the calculation is completed, and determining the weights corresponding to all data through the hierarchical analysis method to obtain the material properties of the second ecological corridor three-dimensional model, the material properties include Young's modulus, bulk modulus and Poisson's ratio. Finite element-oriented corridor property transformation: The heterogeneity within the ecological corridor can be expressed not only by the difference in cross-sections, but also by different material properties. In this embodiment, there are AL, a total of 12 ecological corridors in the case area, and the 12 ecological corridors are divided into 42 sections. The number of each section is shown in Table 2. In this study, the landscape pattern indexes in the case area were calculated, including patch richness (PR), effective grid size (MESH), connectivity index (CONNECT), landscape shape index (LSI), maximum patch index (LPI) and patch type area (CA). After the calculation, the obtained data were normalized, and the weights of each index were determined by the analytic hierarchy process, and then the material properties of the ecological corridor were obtained by comprehensive calculation. The material properties of different corridors are shown in Table 2, where AL corresponds to the material properties of the 12 ecological corridors in the case area, and other is the material property of the ecological source. The properties of the material include Young's modulus, bulk modulus and Poisson's ratio. Young's modulus is a physical quantity that describes the ability of solid materials to resist deformation; bulk modulus is a type of elastic modulus, which is used to reflect the macroscopic properties of the material, that is, a physical quantity of the relationship between the volume strain and the average stress of the object; Poisson's ratio refers to the ratio of the lateral normal strain to the axial normal strain when the material is under unidirectional tension or compression. These three properties can effectively describe the mechanical properties of the material.

[0026] Table 2: Material properties of different corridors in the case area Material Young's modulus Poisson's ratio Bulk modulus Material Young's modulus Poisson's ratio Bulk modulus A1 9.44E+10 0.3 7.91E+10 E1 2.10E+11 0.3 1.75E+11 A2 3.56E+11 0.3 2.97E+11 E2 3.42E+11 0.3 2.85E+11 A3 5.16E+11 0.3 4.30E+11 E3 2.80E+11 0.3 2.80E+11 A4 3.04E+11 0.3 2.53E+11 F1 3.64E+11 0.3 3.03E+11 B1 3.39E+11 0.3 2.82E+11 F2 5.23E+11 0.3 4.36E+11 B2 4.19E+11 0.3 3.49E+11 G1 4.01E+11 0.3 3.35E+11 B3 3.76E+11 0.3 3.13E+11 G2 4.14E+11 0.3 3.45E+11 B4 5.49E+11 0.3 4.58E+11 H1 4.74E+10 0.3 3.95E+10 B5 3.34E+11 0.3 2.78E+11 H2 2.70E+11 0.3 2.25E+11 B6 3.52E+11 0.3 2.93E+11 H3 4.56E+11 0.3 3.80E+11 B7 4.68E+11 0.3 3.90E+11 H4 2.08E+11 0.3 1.73E+11 B8 5.58E+11 0.3 4.65E+11 H5 2.21E+11 0.3 1.84E+11 C1 4.84E+11 0.3 4.03E+11 I1 3.10E+11 0.3 2.85E+11 C2 6.54E+11 0.3 5.45E+11 J1 2.88E+11 0.3 2.40E+11 C3 5.76E+11 0.3 4.80E+11 J2 2.90E+11 0.3 2.42E+11 C4 4.56E+11 0.3 3.80E+11 K1 4.34E+11 0.3 3.62E+11 C5 3.58E+11 0.3 2.98E+11 K2 5.88E+11 0.3 4.90E+11 D1 3.35E+11 0.3 2.79E+11 K3 3.86E+11 0.3 3.22E+11 D2 4.81E+11 0.3 4.01E+11 L1 2.94E+11 0.3 2.45E+11 D3 5.54E+11 0.3 4.62E+11 L2 5.14E+11 0.3 4.28E+11 D4 6.15E+11 0.3 5.12E+11 Other 2.00E+11 0.3 1.67E+11 D5 5.55E+11 0.3 4.63E+11 Exemplarily, step S4 specifically includes: constructing a buffer zone based on the ecological corridor, in this embodiment, constructing a 500m buffer zone around the ecological corridor, extracting the normalized vegetation index (NDVI) and traffic road network density data in the buffer zone, and sorting and normalizing the normalized vegetation index and traffic road network density data, and using the processed normalized vegetation index and traffic road network density data as the load data of the second ecological corridor three-dimensional model; specifically including: adding the first normalized vegetation index within the left range of the buffer zone with the first normalized vegetation index within the right range of the buffer zone, and using the result as the second normalized vegetation index within the left range of the buffer zone; adding the first traffic road network density value within the right range of the buffer zone with the first traffic road network density value within the left range of the buffer zone, and using the result as the second traffic road network density value within the right range of the buffer zone; obtaining the raster data on both sides of the corridor; applying loads at the corresponding positions of the second ecological corridor three-dimensional model based on the raster data and the corresponding coordinate values; achieving the goal of converting relevant indicators in the geographic space into corresponding indicators in the field of mechanics.

[0027] Exemplarily, step S5 specifically includes: setting constraints on ecological sources and stepping stones. Since ecological sources are patches that play an important radiation role in ESP, their stability and sustainability are good and not easily damaged. Therefore, the three-dimensional model individuals corresponding to the ecological source are constrained, that is, the ecological source constrains the overall structure of the three-dimensional model. Specifically, the surface of the three-dimensional model is constrained, that is, the displacement of the three-dimensional model of the ecological source in the X, Y, and Z directions is zero. The schematic diagram of the constraint conversion is shown in the figure below. Figure 3 As shown in the figure, since the area where the stepping stones are located is relatively fragmented, its ecological stability and sustainability are weaker than those of the ecological source area. Therefore, the constraint of the stepping stones on the corridor is defined as zero displacement in the X direction and freedom in the Y and Z directions. That is, the stepping stones only have a constraint effect on the ecological corridor in the X direction, and have no constraint effect in other directions.

[0028] Exemplarily, step S6 specifically includes: multi-scenario analysis, finite element simulation based on the mechanical three-dimensional model constructed based on real geographic spatial data, different units of the three-dimensional model will produce strains of different sizes and directions according to the magnitude of their respective stresses, and then obtain the stress and strain data of the ecological corridor. The schematic diagram of the finite element result processing of the case area is shown in Figure 4As shown. By analyzing the stress and strain results, the risk of the ecological corridor is evaluated. For example, the area with large deformation and stress concentration has relatively high risk. Four scenarios are set: natural development, adding stepping stones, corridor destruction, and adding stepping stones after corridor destruction. ① Natural development scenario: analysis of the case area; ② Adding stepping stones: adding stepping stones in the high-risk area of ​​the ecological corridor, which is the area with large stress and strain; ③ Ecological corridor destruction: based on the natural development scenario, it is assumed that a certain ecological corridor is destroyed; ④ Adding stepping stones after ecological corridor destruction: adding stepping stones in the high-risk area after a certain ecological corridor is destroyed. Compare the stress and strain changes of the ecological corridor under different scenarios, and study the protective effect of stepping stones and the impact of ecological corridor destruction on other ecological corridors. In the scenario of ecological corridor destruction, we will suppress the model of the corresponding ecological corridor so that the ecological corridor cannot play a role in the structure, and the others will not change. For adding stepping stones, it is achieved by constraining the nodes in the ecological corridor model. The previous node of the constraint model, that is, the degree of freedom of the node in the X direction is 0. Through the multi-scenario comparison method, the overall stability and risk of a certain ecological corridor in the ESP can be evaluated, as well as the optimization effect of the stepping stone, and it can be specially protected in the subsequent optimization strategy.

[0029] Exemplarily, step S7 specifically includes: projecting the ecological risk problem of the geographic space into the three-dimensional mechanical space according to the finite element simulation results and multi-scenario analysis, so as to intuitively display the ecological risk area in the real world according to the mechanical deformation. Formulate corresponding optimization strategies for ecological corridors with different risk levels. For corridors whose risk level exceeds the preset range, such as corridors with large deformation and stress concentration, their stability can be improved by adding stepping stones, but the impact on adjacent corridors needs to be considered comprehensively; for damaged corridors, repair measures are taken; for corridors with risk levels within the preset range, protection is strengthened. The preset range is a range pre-set according to the working environment, and is not limited to a specific range. At the regional level, the layout of the ecological corridor is reasonably planned according to the finite element analysis, a protection buffer zone is established, and the interference of human activities on the ecological corridor is controlled to ensure the stability of the regional ecological security pattern (ESP).

[0030] Specifically, based on the case area ESP, a series of unique method steps such as material property assignment, constraint setting, and load setting in finite element simulation constitute a complete technical process. These steps cooperate with each other to form a set of operational ESP risk assessment and optimization methods, using theoretical methods such as stress and deformation of three-dimensional mechanics to conduct risk assessment of ecological space, which is highly innovative and practical. Use finite element simulation technology in ESP risk assessment. Including converting ecological corridors into three-dimensional models for simulation analysis, converting geographical indicators into indicators in mechanics, obtaining stress and strain data through finite element simulation to assess risks, and using simulation results to guide ESP optimization. This interdisciplinary technology application brings new perspectives and methods to ecological research and has unique protection value. The key to the present invention lies in the overall technical framework of using finite element simulation methods to assess and optimize the risks of ecological security patterns; the idea of ​​converting regional ecological attributes into three-dimensional mechanical attributes, and converting geographical ecological indicators into mechanical indicators; the idea of ​​combining the idea of ​​interaction between multiple forces in mechanics with the interaction of multiple factors in ecological security; the idea of ​​using finite element simulation to conduct multi-scenario assessment of corridor risks.

[0031] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. An ecological security pattern risk assessment method based on finite element simulation, characterized in that: The following steps are involved: S1. Determine the ecological source area based on the MSPA method, construct the ecological resistance surface, extract the ecological corridor, and build the ecological security pattern; S2. Discretization of ecological corridors, establishment of three-dimensional models of ecological corridors with different cross-sections to express the heterogeneity within the ecological corridors; S3. Use the landscape pattern index to express the internal situation of the ecological corridor, and obtain the material properties of the three-dimensional model by transforming the landscape pattern index; S4, extracting the normalized vegetation index and traffic network density data within the preset range of the ecological corridor, processing them, and converting them into external loads; S5, impose constraints on the three-dimensional models corresponding to the ecological source and stepping stones respectively; S6. Construct four scenarios based on the three-dimensional model and perform finite element simulation on the four scenarios; S7. Based on the results of multi-scenario analysis and finite element simulation, formulate an optimization strategy for the ecological security pattern.

2. The method for ecological security pattern risk assessment based on finite element simulation according to claim 1 is characterized in that: Step S1 specifically includes: converting land use data into binary data through morphological spatial pattern analysis method, and dividing it into foreground and background, wherein the foreground includes areas with biological potential, and the background is other areas except for the foreground; processing the foreground and background through Guidos analysis software, and selecting the core area as the ecological source; constructing an ecological resistance surface, wherein the ecological resistance surface includes natural factors and human factors, wherein the natural factors include normalized vegetation index and terrain, and assigning corresponding weights to the resistance surface for modification, and the resistance value range is set to [1, 500]; determining the specific scope of the ecological corridor through the circuit theory model; and constructing an ecological security pattern.

3. The method for ecological security pattern risk assessment based on finite element simulation according to claim 2 is characterized in that: Step S2 specifically includes: establishing a first ecological corridor three-dimensional model according to the ecological corridor obtained in step S1, and then dividing the first ecological corridor three-dimensional model into n second ecological corridor three-dimensional models, wherein the width and height of the cross section of the second ecological corridor three-dimensional model are within a preset range.

4. The method for ecological security pattern risk assessment based on finite element simulation according to claim 3 is characterized in that: Step S3 specifically includes: calculating the landscape pattern index within the ecological corridor buffer zone, the landscape pattern index including patch richness, effective grid size, connectivity index, landscape shape index, maximum patch index and patch type area, normalizing all the data after the calculation is completed, and determining the weights corresponding to all the data through the hierarchical analysis method to obtain the material properties of the second ecological corridor three-dimensional model, the material properties including Young's modulus, bulk modulus and Poisson's ratio.

5. The method for ecological security pattern risk assessment based on finite element simulation according to claim 4 is characterized in that: Step S4 specifically includes: constructing a buffer zone based on the ecological corridor, extracting the normalized vegetation index and traffic road network density data in the buffer zone, sorting and normalizing the normalized vegetation index and traffic road network density data, and using the processed normalized vegetation index and traffic road network density data as the load data of the second ecological corridor three-dimensional model; specifically includes: adding the first normalized vegetation index within the left range of the buffer zone with the first normalized vegetation index within the right range of the buffer zone, and using the result as the second normalized vegetation index within the left range of the buffer zone; adding the first traffic road network density value within the right range of the buffer zone with the first traffic road network density value within the left range of the buffer zone, and using the result as the second traffic road network density value within the right range of the buffer zone; obtaining the raster data on both sides of the corridor; applying loads at the corresponding positions of the second ecological corridor three-dimensional model based on the raster data and the corresponding coordinate values; and achieving the goal of converting relevant indicators in the geographic space into corresponding indicators in the field of mechanics.

6. The method for ecological security pattern risk assessment based on finite element simulation according to claim 5 is characterized in that: Step S5 specifically includes: constraining the three-dimensional models corresponding to the ecological source and the stepping stones, specifically including: performing surface constraints on the surface of the three-dimensional model, that is, the displacement of the three-dimensional model corresponding to the ecological source in the X, Y, and Z directions is zero; wherein, the stepping stones have a constraining effect on the ecological corridor in the X direction, and have no constraining effect in other directions.

7. The method for ecological security pattern risk assessment based on finite element simulation according to claim 6 is characterized in that: Step S6 specifically includes: performing finite element simulation on a mechanical three-dimensional model constructed based on real geographic spatial data, wherein different units of the mechanical three-dimensional model generate strains of different sizes and directions according to the magnitude of their respective stresses, obtaining stress and strain data of the ecological corridor, and evaluating the risk of the ecological corridor by analyzing the stress and strain data results; constructing four scenarios based on the three-dimensional model, including a natural development scenario, adding stepping stones, ecological corridor destruction, and adding stepping stones after ecological corridor destruction, comparing the stress and strain changes of the ecological corridor under different scenarios, and studying the protective effect of stepping stones and the impact of destroying the ecological corridor on other ecological corridors.

8. The method for ecological security pattern risk assessment based on finite element simulation according to claim 7 is characterized in that: Step S7 specifically includes: projecting the ecological risk problems in the geographic space into the three-dimensional mechanical space according to the finite element simulation results and various scenario analyses, and displaying the ecological risk areas in the real world according to the mechanical deformation; formulating corresponding optimization strategies for ecological corridors with different risk levels, specifically including: for corridors whose risk levels exceed the preset range, improving their stability by adding stepping stones, but taking into account the impact on adjacent corridors; taking repair measures for damaged corridors; strengthening protection for corridors whose risk levels are within the preset range; at the regional level, rationally planning the layout of ecological corridors according to the analysis of finite elements, establishing protection buffer zones, and controlling the interference of human activities on ecological corridors, so as to ensure the stability of the regional ecological security pattern.

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