A risk assessment method for ecological security pattern based on finite element simulation

Abstract

The present invention discloses a risk assessment method for ecological security pattern based on finite element simulation, belonging to the technical field of risk assessment of ecological security pattern, and comprising the following steps: S1, constructing an ecological security pattern; S2, discretizing ecological corridors; S3, expressing the internal situation of ecological corridors with landscape pattern indices, and obtaining the material properties of the three-dimensional model by transforming the landscape pattern indices; S4, extracting the normalized difference vegetation index and traffic road network density data within the preset range of ecological corridors, and converting them into external loads after processing; S5, applying constraints to the three-dimensional models corresponding to ecological source areas and stepping stones respectively; S6, constructing four scenarios based on the three-dimensional model, and performing finite element simulation on the four scenarios; S7, formulating an optimization strategy for the ecological security pattern based on the results of multi-scenario analysis and finite element simulation. Using theoretical methods such as stress and deformation in three-dimensional mechanics to conduct risk assessment of ecological space has high innovation 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 particularly relates to an ecological security pattern risk assessment method based on finite element simulation. Background Art

[0002] Many small ecological source areas are scattered and lack the connection of ecological corridors. The construction of the regional ecological security pattern (ESP) without considering the overall ecological protection has become one of the methods to solve this problem.

[0003] ESP refers to the potential ecological spatial pattern composed of key areas, important positions, and ecological networks that ensure ecological security in the landscape. The construction and optimization of ESP are crucial for coordinating regional ecological protection and economic growth. After a long time of development, a construction paradigm of ESP has been formed with the main theoretical framework of "identifying ecological source areas, constructing resistance surfaces, and extracting corridors". There are mainly three methods for identifying ecological source areas: ① directly selecting nature reserves or ecological protection red lines as ecological source areas; ② extracting ecological source areas based on the importance of ecosystem services or ecological sensitivity; ③ identifying ecological source areas based on morphological spatial pattern analysis. Organisms will migrate when the ecological environment changes or they are threatened. During the process of species migration, they will be hindered by natural or human factors. The resistance surface is a representation of the resistance encountered during species migration. The resistance factors usually select natural factors (land use type, elevation, slope, etc.) that can reflect natural conditions and human factors (such as the distance from highways, railways, and residential areas) that reflect human activities to form an ecological resistance factor index system. An ecological corridor is a connecting corridor between ecological source areas, which provides a passage for biological migration and material and energy exchange by connecting ecological source areas and bypassing areas with high ecological resistance. As a key part 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 uses methods such as the minimum cumulative resistance model and circuit theory. Using the Circuitscape software and the pinch point mapper tool based on circuit theory, a current density map is created to extract high-value areas as ecological pinch points, that is, areas where the possibility of species migration passing through is relatively high or there is no alternative path. Ecological barrier points refer to areas with relatively large resistance to biological movement between patches. Removing such areas can significantly improve the biological flow and landscape connectivity within the corridor. However, traditional ecological corridor research methods, such as the minimum cumulative resistance model and the circuit theory model, although having significant effects in determining the scope of ecological corridors and identifying the barrier points of ecological corridors, cannot quantitatively evaluate the risks of ESP, and it is difficult to accurately quantify the risks and provide targeted protection strategies.

[0004] Introducing finite element simulation into the study of ecological problems can quantitatively analyze the risk issues of ESP. Finite element simulation is a numerical analysis method that is widely used in mechanical design and construction. It is a numerical method that regards a continuum as a discretized set of a number of finite-sized unit bodies to solve the thermal, mechanical, and electromagnetic problems of the continuum. Its basic idea is to discretize the continuous solution domain 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, analyze the stress, deformation, and stability of the structure under different working conditions. This kind of refined analysis helps to optimize the structure design and improve the performance and safety of the structure. It is precisely such characteristics that introducing 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 then achieving precise optimization of ESP.

[0005] The past optimization models are often large-scale, difficult to meet the requirements of precise optimization, and prone to 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 dispersal. Adding stepping stones between unconnected patches can increase the connectivity of the landscape. However, the research on the impact of the setting of stepping stones, which play an important role in ESP, on the ecological corridor and the surrounding ecological environment is not deep enough, and there is a lack of scientific planning. In the past, the addition of stepping stones was blind. Generally, the middle part of the ecological corridor was selected as the 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 the stepping stones on ESP and the impact on the surrounding ecological corridor can be analyzed. Therefore, the invention is based on finite element simulation. Compared with the previous research methods 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 a risk assessment method for ecological security pattern based on finite element simulation.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] The present invention discloses a risk assessment method for ecological security pattern based on finite element simulation, including the following steps:

[0009] S1. Determine ecological source areas based on the MSPA method, construct an ecological resistance surface, extract ecological corridors, and construct an ecological security pattern;

[0010] S2. Discretization of ecological corridors, establishing 3D models of ecological corridors with different cross-sections to express the heterogeneity within ecological corridors;

[0011] S3. Expressing the internal situation of ecological corridors using landscape pattern indices and obtaining the material properties of 3D models by transforming landscape pattern indices;

[0012] S4. Extracting the normalized difference vegetation index and traffic road network density data within the preset range of ecological corridors, processing them, and transforming them into external loads;

[0013] S5. Applying constraints to the 3D models corresponding to ecological source areas and stepping stones respectively;

[0014] S6. Constructing 4 scenarios based on the 3D models and conducting finite element simulations on the 4 scenarios;

[0015] S7. Formulating optimization strategies for ecological security patterns based on the results of multi-scenario analysis and finite element simulations.

[0016] Furthermore, step S1 specifically includes: converting land use data into binary data through the 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 the foreground; processing the foreground and background through Guidos analysis software and selecting the core area as the ecological source area; constructing an ecological resistance surface, which includes natural factors and human factors. The natural factors include the normalized difference vegetation index and terrain, and the resistance surface is corrected by assigning corresponding weights, with the resistance value range set as [1, 500]; determining the specific range of ecological corridors through the circuit theory model; constructing an ecological security pattern.

[0017] Preferably, step S2 specifically includes: establishing a first 3D model of ecological corridors according to the ecological corridors obtained in step S1, and then dividing the first 3D model of ecological corridors into n second 3D models of ecological corridors, where the width and height of the cross-sections of the second 3D models of ecological corridors are within the preset range.

[0018] Preferably, step S3 specifically includes: calculating the landscape pattern indices within the buffer range of ecological corridors. The landscape pattern indices include patch richness, effective mesh size, connectivity index, landscape shape index, largest patch index, and patch type area. All the calculated data are normalized, and the weights corresponding to all the data are determined through the analytic hierarchy process to obtain the material properties of the second 3D models of ecological corridors. The material properties include Young's modulus, bulk modulus, and Poisson's ratio.

[0019] Preferably, step S4 specifically includes: constructing a buffer zone based on the ecological corridor, extracting the normalized difference vegetation index (NDVI) and traffic road network density data within the buffer zone, and sorting and normalizing the NDVI and traffic road network density data, and using the processed NDVI and traffic road network density data as the load data of the second three-dimensional model of the ecological corridor; specifically including: adding the first NDVI within the left range of the buffer zone to the first NDVI within the right range of the buffer zone, and using the obtained result as the second NDVI within the left range of the buffer zone; adding the first traffic road network density value within the right range of the buffer zone to the first traffic road network density value within the left range of the buffer zone, and using the obtained result as the second traffic road network density value within the right range of the buffer zone; thus, the grid data on both sides of the corridor can be obtained; based on the grid data and their corresponding coordinate values, applying loads at the corresponding positions of the second three-dimensional model of the ecological corridor; achieving the goal of converting relevant indicators in the geographical space into corresponding indicators in the field of mechanics.

[0020] Preferably, step S5 specifically includes: constraining the three-dimensional models corresponding to the ecological source areas and stepping stones, specifically including surface constraints on the surfaces of the three-dimensional models, that is, the displacements of the three-dimensional model corresponding to the ecological source area in the X, Y, and Z directions are all zero; among them, the stepping stone has a constraining effect on the ecological corridor in the X direction and has no constraining effect in other directions.

[0021] Preferably, step S6 specifically includes: performing finite element simulation on the mechanical three-dimensional model constructed based on real geographical space data, where different units of the mechanical three-dimensional model generate strains of different magnitudes and directions according to the magnitudes of their respective stresses, obtaining the stress and strain data of the ecological corridor, and evaluating the risk of the ecological corridor by analyzing the results of the stress and strain data; constructing four scenarios based on the three-dimensional model, including natural development scenario, adding stepping stones, ecological corridor damage, and adding stepping stones after ecological corridor damage, comparing the stress and strain changes of the ecological corridor under different scenarios, and studying the protection effect of stepping stones and the impact of damaging an ecological corridor on other ecological corridors.

[0022] Preferably, step S7 specifically includes: according to the finite element simulation results and various scenario analyses, projecting the ecological risk problems in the geospatial space into the three-dimensional mechanical space, 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 with risk levels exceeding the preset range, improving their stability by adding stepping stones, but the impact on adjacent corridors needs to be comprehensively considered; for damaged corridors, taking repair measures; for corridors with risk levels within the preset range, strengthening protection; at the regional level, according to the analysis of the finite element, reasonably planning the layout of ecological corridors, establishing protection buffers, and controlling the interference of human activities on ecological corridors to ensure the stability of the regional ecological security pattern.

[0023] The beneficial effects of the present invention are:

[0024] 1) There are shortcomings in the traditional ecological corridor research in terms of risk assessment, mostly relying on complex networks or simple spatial analysis. This method first introduces the finite element method into the ecological corridor risk assessment and proposes a risk assessment method for the ecological security pattern based on finite element simulation. Finite element simulation is a numerical method that regards a continuum as a discrete set of a number of finite-sized unit bodies to solve the continuum. From the mechanical perspective, the stress and deformation of the corridor are solved through finite element simulation to quantify the risk. Corridors with higher risks and potential risk corridors can be identified, providing a basis for accurately positioning key protection areas, helping to formulate targeted ecological protection measures, establishing nature reserves, and carrying out ecological restoration projects. Traditional methods tend to large-scale protection, exacerbating the unreasonable allocation of resources. By this means, the situation that the traditional large-scale ecological protection strategy lacks pertinence can be changed, the protection resources can be reasonably allocated, the resources can be concentrated on high-risk corridors, the ecological protection efficiency can be improved, the maximum ecological benefit can be achieved with the minimum investment, and the stability of the regional ESP can be maintained.

[0025] 2) Stepping stones are crucial for the stability of the ecosystem and the migration of organisms. However, previous studies have lacked in-depth exploration of the impact of their settings, mostly being empirical layouts and not analyzing the principle of their role in the stability of ecological corridors from the mechanical level. This study, based on finite element simulation and various scenario analyses, first analyzes the role of stepping stones from the mechanical perspective, shows the protection effects of stepping stones on different positions of ecological corridors, and reveals the internal mechanism by which stepping stones improve the overall structural stability of ecological corridors through single-direction constraints on nodes. Based on multi-scenario comparative analysis, the protective role of stepping stones in maintaining the stability of the ESP in the case of ecological corridor damage is revealed. At the same time, the present invention also analyzes the possible adverse effects of the setting of stepping stones on adjacent ecological corridors, which provides guidance for the scientific planning and layout of stepping stones, avoids negative impacts, and realizes the sustainable development of the ecosystem.

[0026] 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. Taking peak cluster depressions as the case area, analyze the risks of ecological corridors from the perspectives of stress and strain. Use finite element to analyze the case area, apply loads to the 3D model of the case area. Here, the loads are the NDVI and traffic road network density data extracted from the buffer zone of the ecological corridor. Through these two raster data and combined with the corresponding coordinates, the loads can be accurately applied to the 3D model, thereby obtaining the stress and strain data of the 3D model. The areas with larger strain and stress can be accurately located, and the corresponding areas are the risk areas and potential risk areas, so as to carry out precise protection and risk early warning, proving the feasibility of exploring ecological problems from the mechanical perspective. Although there are limitations in interdisciplinary integration, it provides innovative ideas for subsequent research, promotes the development of multidisciplinary cross-research in the ecological field, and helps to discover more ecological laws and new ways to solve practical problems.

[0027] 4) Express the heterogeneity inside the ecological corridor by means of the cross-sections and materials of different 3D models. And map the internal characteristics of the ecological corridor as the material properties in the finite element. This discretization idea exactly corresponds to the idea of discretizing the overall elements and solving them separately in the finite element simulation to approximate the true value. Specifically, 12 ecological corridors in the case area are discretized into 42 3D models, and different material properties are assigned to them according to the landscape pattern index in the buffer zone of the ecological corridor and by means of the analytic hierarchy process. Such a method can objectively display the real situation inside the ecological corridor in the finite element simulation.

[0028] 5) The research constructs a complete set of ESP risk assessment and optimization system, that is, the whole process of risk assessment and optimization strategy formulation for ESP by means of finite element simulation. This system has a high degree of systematicness and process flow, which can improve the 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 work. Brief Description of the Drawings

[0029] Figure 1 It is a schematic diagram of the steps of a method for risk assessment of ecological security pattern based on finite element simulation according to an embodiment of the present invention;

[0030] Figure 2 It is a schematic diagram of the spatial pattern of ecological source areas, resistance surfaces and ecological corridors in the case area of a method for risk assessment of ecological security pattern based on finite element simulation according to an embodiment of the present invention;

[0031] Figure 3 It is a schematic diagram of the conversion method of constraints of a method for risk assessment of ecological security pattern based on finite element simulation according to an embodiment of the present invention;

[0032] Figure 4 Schematic diagram of finite element result processing for the case area of a method for ecological security pattern risk assessment based on finite element simulation according to an embodiment of the present invention. Detailed implementation manners

[0033] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0034] The existing methods for studying the ecological security pattern (ESP) analyze the overall topological structure based on complex networks. The present invention introduces the thinking of mechanics into the study of ecology. Through finite element simulation, the risks and potential risk areas of ESP can be accurately located, and then a method for precise optimization can be achieved. The abstract concept of ecological corridor is transformed into a specific three-dimensional model structure and simulated by the finite element method. Geospatial indicators are transformed into mechanical indicators, and the risk of the corridor model is evaluated through finite element simulation. The present invention discloses a method for ecological security pattern risk assessment based on finite element simulation, which is the first to use finite element simulation to model, evaluate and optimize ecological corridors, bringing many pioneering and practical advantages in many aspects to the field of ecological protection. The schematic diagram of the specific steps of the method for ecological security pattern risk assessment based on finite element simulation is as Figure 1 shown. The present invention can be divided into several aspects such as constructing ESP, data conversion and processing, applying constraints, finite element simulation, and multi-scenario analysis and optimization, and specifically includes the following steps:

[0035] S1. Determine ecological source areas based on the MSPA method, construct an ecological resistance surface, extract ecological corridors, and construct an ecological security pattern;

[0036] S2. Discretize the ecological corridors, establish three-dimensional models of ecological corridors with different cross-sections to express the heterogeneity inside the ecological corridors;

[0037] S3. Express the internal situation of the ecological corridors with landscape pattern indices, and obtain the material properties of the three-dimensional models by transforming the landscape pattern indices;

[0038] S4. Extract the normalized difference vegetation index and traffic road network density data within the preset range of the ecological corridors, process them, and transform them into external loads;

[0039] S5. Apply constraints to the three-dimensional models corresponding to the ecological source areas and stepping stones respectively;

[0040] S6. Construct 4 scenarios based on the three-dimensional models and perform finite element simulation on the 4 scenarios;

[0041] S7. Based on the results of multi-scenario analysis and finite element simulation, formulate an optimization strategy for the ecological security pattern.

[0042] Exemplarily, taking the peak cluster depressions in the Yunnan-Guizhou-Guangxi region as an example, step S1 specifically includes: converting the land use data into binary data through the 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 the foreground. In this embodiment, the foreground selects forest land and grassland with relatively large biological potential, and the background includes other areas except the foreground in the ecological protection area; 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 the normalized difference vegetation index and terrain, and human factors, and correcting the resistance surface by assigning corresponding weights, and setting the resistance value range as [1, 500]. The resistance factors and resistance values of the case area in this embodiment are set as shown in Table 1; determining the specific scope of the ecological corridor through the circuit theory model; constructing the ecological security pattern. The spatial patterns of the ecological source, resistance surface, and ecological corridor in the case area are as Figure 2 shown.

[0043] Table 1: Setting of resistance factors and resistance values in the case area

[0044]

[0045] Exemplarily, step S2 specifically includes: establishing a three-dimensional model of the first ecological corridor according to the ecological corridor obtained in step S1, and then dividing the three-dimensional model of the first ecological corridor into n three-dimensional models of the second ecological corridor, where the width and height of the cross-section of the three-dimensional model of the second ecological corridor are within a preset range. The preset range is a range preset according to the working environment and is not limited to a specific range. Discretization of the ecological corridor: The ecological corridor is a strip-shaped passage that connects ecological source areas to achieve the flow of species. The interior of the ecological corridor is heterogeneous, and this method characterizes this heterogeneity by establishing three-dimensional models of the second ecological corridor with different cross-sections. In this embodiment, 12 ecological corridors in the case area are finally divided into a total of 42 three-dimensional models of the second ecological corridor. The width of the cross-section of the three-dimensional model of the second ecological corridor ranges from 30 to 50 m, and the height of the cross-section is uniformly set to 5 m. Through this method, the differences existing within the same corridor can be characterized to approximate the internal situation of the ecological corridor under real conditions. The principle of finite element simulation is to discretize a three-dimensional model into smaller and simpler domains, which we call elements. By combining and solving the equations on all elements of the three-dimensional model, the calculation is completed. Discretizing the ecological corridors in the case area into 42 three-dimensional models of the second ecological corridor is exactly similar to the method of discretizing a three-dimensional model into small elements and then solving it in the finite element principle.

[0046] Exemplarily, step S3 specifically includes: calculating the landscape pattern indices within the ecological corridor buffer zone, where the landscape pattern indices include patch richness, effective grid size, connectivity index, landscape shape index, largest patch index, and patch type area; normalizing all the calculated data; and determining the weights corresponding to all the data through the analytic hierarchy process to obtain the material properties of the second ecological corridor three-dimensional model, where the material properties include Young's modulus, bulk modulus, and Poisson's ratio. Transformation of corridor properties for finite elements: For the heterogeneity within the ecological corridor, it can be characterized not only by differences in cross-sections but also by different material properties. In this embodiment, there are a total of 12 ecological corridors from A to L in the case area, which are divided into 42 segments, and the numbers of each segment are shown in Table 2. In this study, the landscape pattern indices in the case area were calculated, including patch richness (PR), effective grid size (MESH), connectivity index (CONNECT), landscape shape index (LSI), largest patch index (LPI), and patch type area (CA). After the calculation, the obtained data was normalized, and the analytic hierarchy process was used to determine the weights of each index. Then, the material properties of the ecological corridor were comprehensively calculated. The material properties of different corridors are shown in Table 2, where the properties corresponding to A - L are for the 12 ecological corridors in the case area, and "other" are the material properties of the ecological source areas. 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 a solid material to resist deformation; bulk modulus is a type of elastic modulus that reflects the macroscopic properties of a material, that is, a physical quantity representing the relationship between the volume strain and the average stress of an object; Poisson's ratio is the ratio of the transverse normal strain to the axial normal strain when the material is unidirectionally tensioned or compressed. Through these three properties, the mechanical properties of the material can be effectively described.

[0047] Table 2: Material properties of different corridors in the case area

[0048] 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

[0049] Exemplarily, step S4 specifically includes: constructing a buffer zone based on the ecological corridor. In this embodiment, a 500m buffer zone is constructed around the ecological corridor, and the normalized difference vegetation index (NDVI) and traffic road network density data within the buffer zone are extracted. Then, the NDVI and traffic road network density data are sorted and normalized, and the processed NDVI and traffic road network density data are used as the load data for the second ecological corridor three-dimensional model. Specifically, it includes: adding the first NDVI within the left range of the buffer zone to the first NDVI within the right range of the buffer zone, and the resulting value is used as the second NDVI within the left range of the buffer zone; adding the first traffic road network density value within the right range of the buffer zone to the first traffic road network density value within the left range of the buffer zone, and the resulting value is used as the second traffic road network density value within the right range of the buffer zone. In this way, the raster data on both sides of the corridor can be obtained. Based on the raster data and their corresponding coordinate values, loads are applied at the corresponding positions of the second ecological corridor three-dimensional model, achieving the goal of converting relevant indicators in the geographical space into corresponding indicators in the mechanical field.

[0050] Exemplarily, step S5 specifically includes: setting constraints for ecological source areas and stepping stones. Since the ecological source areas are patches that play an important radiation role in the ESP and have good stability and sustainability and are not easily damaged, the corresponding three-dimensional model individuals of the ecological source areas are constrained, that is, the ecological source areas play a constraining role in the overall structure of the three-dimensional model. Specifically, surface constraints are imposed on the surface of the three-dimensional model, that is, the displacements of the ecological source area three-dimensional model in the X, Y, and Z directions are all zero. The schematic diagram of the constraint conversion is as Figure 3 shown. Since the area where the stepping stones are located is relatively fragmented and its ecological stability and sustainability are weaker than those of the ecological source areas, the constraint of the stepping stones on the corridor is defined as having zero displacement in the X direction and being free in the Y and Z directions, that is, the stepping stones only have a constraining effect on the ecological corridor in one direction (X), and have no constraining effect in other directions.

[0051] Exemplarily, step S6 specifically includes: multi-scenario analysis. Finite element simulation is carried out on the mechanical three-dimensional model constructed based on real geographical space data. Different units of the three-dimensional model will generate strains of different magnitudes and directions according to the magnitudes of their respective stresses, and then the stress and strain data of the ecological corridor are obtained. The schematic diagram of the finite element result processing in the case area is as Figure 4As shown. By analyzing the stress and strain results, the risks of ecological corridors are evaluated. For example, areas with larger deformation and stress concentration have relatively higher risks. Four scenarios are set: natural development, adding stepping stones, corridor damage, and adding stepping stones after corridor damage. ① Natural development scenario: Analyze the case area; ② Adding stepping stones: Add stepping stones in the high-risk areas of the ecological corridor, and the high-risk areas are those with larger stress and strain; ③ Ecological corridor damage: On the basis of the natural development scenario, assume that a certain ecological corridor is damaged; ④ Adding stepping stones after ecological corridor damage: Add stepping stones in the high-risk areas after a certain ecological corridor is damaged. Compare the stress and strain changes of the ecological corridor under different scenarios to study the protection effect of stepping stones and the impact of ecological corridor damage on other ecological corridors. In the scenario of ecological corridor damage, we will suppress the model of the corresponding ecological corridor so that it cannot play a role in the structure, and the others remain unchanged. For adding stepping stones, it is achieved by constraining the nodes in the ecological corridor model. Constraining one node on the model means that the degree of freedom of this node in the X direction is 0. Through the method of multi-scenario comparison, the stability and risk of a certain ecological corridor in the ESP to the whole can be evaluated, as well as the optimization effect of stepping stones can be evaluated, and special protection can be carried out in the subsequent optimization strategy.

[0052] Exemplarily, step S7 specifically includes: According to the finite element simulation results and multi-scenario analysis, project the ecological risk problems in the geographical space into the three-dimensional mechanical space to visually display the ecological risk areas in the real world according to the mechanical deformation. Develop corresponding optimization strategies for ecological corridors with different risk levels. For corridors with risk levels exceeding the preset range, such as corridors with larger deformation and stress concentration, etc., their stability can be improved by adding stepping stones, but the impact on adjacent corridors needs to be comprehensively considered; for damaged corridors, take repair measures; for corridors with risk levels within the preset range, strengthen protection. The preset range is a range preset according to the working environment, and is not limited to a specific range. At the regional level, reasonably plan the layout of ecological corridors according to the finite element analysis, establish a protection buffer zone, and control the interference of human activities on ecological corridors to ensure the stability of the regional ecological security pattern (ESP).

[0053] 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.

[0054] 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, including natural development scenario, adding footsteps Stone, ecological corridor destruction, and adding stepping stones after ecological corridor destruction, and finite element simulations were performed for 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.

Images