Method for identifying strip mine area reference ecosystem based on normal distribution function

Abstract

The invention discloses a method for identifying a strip mine area reference ecosystem based on a normal distribution function, and belongs to the technical field of ecological restoration. Dividing a degradation area around the open pit coal mine into a protection and restoration area, and dividing the dumping site into an ecological reconstruction area; defining different types of reference ecosystems for the two regions on the basis of considering the succession law of the ecosystems, the spatial position of the waste dump and the ecological restoration direction, and identifying target regions of the various types of reference ecosystems; calculating the ecological system quality of each pixel in the target area by integrating remote sensing calculation results of various ecological parameters; normal distribution function fitting is carried out on the ecosystem quality of all pixels in each target area; and extracting pixels of ecological system quality in each target area, and carrying out spatial aggregation to obtain a reference ecological system. The remote sensing technology is utilized, statistics, ecology and mining knowledge are combined, and a reference ecological system can be quickly and accurately established for ecological restoration engineering of the open pit coal mine.

Description

Technical Field

[0001] This invention relates to a method for identifying reference ecosystems in open-pit mines based on a normal distribution function, belonging to the field of ecological restoration technology. Background Technology

[0002] Currently, a reference ecosystem refers to an area that can serve as a target or benchmark for ecological restoration. It can be used to diagnose the degree of ecological degradation, set reasonable goals for ecological restoration projects, or evaluate the effectiveness of such projects. More than ten national standards and norms requiring the use of reference ecosystems have been promulgated. Therefore, the research and use of reference ecosystems are receiving close attention at the national level.

[0003] The prior art disclosed in publication number CN115346122A presents a method for selecting reference ecosystems for ecological restoration areas based on remote sensing technology. This method divides the ecological restoration area into different ecological types based on nationally published climate, vegetation, soil, and landform zoning data. Hydrological analysis and vegetation community clustering analysis are performed on the areas where each ecological type is located, further subdividing each ecological type into different assessment units. Using remote sensing technology, the ecosystem quality of all assessment units is calculated from four aspects: ecosystem structure, function, stability, and intensity of human disturbance. The assessment units of each ecological type are ranked from highest to lowest ecosystem quality, and the assessment units with the highest quality in the top t% (5≤t≤10%) are selected as the reference ecosystems for that ecological type. However, this method requires setting different assessment units, resulting in low ecosystem identification efficiency. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for identifying reference ecosystems in open-pit mines based on a normal distribution function, achieving accurate, rapid, and objective identification of reference ecosystems.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for identifying a reference ecosystem in an open-pit mine based on a normal distribution function, comprising the following steps: S1. Degraded areas around open-pit coal mines are designated as protection and restoration areas, and spoil heaps are designated as ecological reconstruction areas; S2. Define different types of reference ecosystems for the two regions and determine the target areas for each type of reference ecosystem; S3. Calculate the ecosystem quality of each pixel within the target area by integrating remote sensing calculation results of multiple ecological parameters; S4. Fit the ecosystem quality of all pixels in each target area using a normal distribution function to obtain the fitting parameters; S5. Extract the pixels that meet the conditions and perform spatial aggregation. The aggregation result is the reference ecosystem.

[0006] Furthermore, considering the laws of ecosystem succession, the spatial location of the spoil heap, and the direction of ecological restoration, the protection and restoration area is divided into two types of reference ecosystems: herbaceous reference ecosystem and woody reference ecosystem. Based on the boundary of the target mining area, the area where herbaceous plants are located within a 10 km radius of the target mining area is extracted as the target area for identifying the herbaceous reference ecosystem, and the area where woody plants are located is extracted as the target area for identifying the woody reference ecosystem. Based on remote sensing images, the spoil heap area is delineated from the open-pit coal mine using visual interpretation methods, which is the ecological reconstruction area of ​​the open-pit coal mine.

[0007] Furthermore, the ecological reconstruction area corresponds to three types of reference ecosystems: platform grassland reference ecosystem, platform forest reference ecosystem, and slope reference ecosystem. The target mining area and N mining areas closest to the target mining area that underwent ecological restoration projects 5 years ago are selected (N≥3). Using historical remote sensing images of these areas, specific areas D that underwent ecological restoration 5 years ago are extracted from the spoil heaps of these mining areas through visual interpretation. Area D is then divided into platform area D-1 and slope area D-2. The grassland area extracted from platform area D-1 is used as the target area D-1-1 for identifying the platform grassland reference ecosystem, and the forest area extracted from platform area D-1 is used as the target area D-1-2 for identifying the platform forest reference ecosystem. Slope area D-2 is used as the target area for identifying the slope reference ecosystem.

[0008] Furthermore, five target areas were established for each type of reference ecosystem: herbaceous reference ecosystem, woody reference ecosystem, platform grassland reference ecosystem, platform forest reference ecosystem, and slope reference ecosystem. Based on remote sensing technology, the ecological parameters of these five target areas in August of the current year or the previous year were calculated: vegetation cover, leaf area index, biomass, chlorophyll content, and soil moisture. The calculated results of the ecological parameters for each target area were normalized and then added together with a weight of 3:2:2:1:2 to obtain the ecosystem quality Q of all pixels in each target area. The ecosystem quality Q of all pixels in the five target areas was then normalized.

[0009] Furthermore, the min-max method was used to normalize the ecosystem quality Q of all pixels in each target area to the range of 0-1: , In the formula, FVC refers to vegetation cover, LAI refers to leaf area index, Biomass refers to biomass, C refers to chlorophyll content, and SMC refers to soil moisture.

[0010] Furthermore, the ecosystem quality Q of all pixels in each target area is extracted, and the extraction results of each target area are fitted with a normal distribution function to obtain the mean μ and standard deviation σ of the normal distribution function.

[0011] Furthermore, the normal distribution function fitting process is as follows: First, the ecosystem quality of all pixels in each target area should be extracted, and its frequency distribution histogram should be plotted. The horizontal axis of the histogram represents the ecosystem quality Q, and the vertical axis represents the number of pixels. Then, the normal distribution function f(x) of the frequency distribution histogram of each target area should be calculated using the following formula: .

[0012] Furthermore, pixels with ecosystem quality located in [μ+σ-z, μ+σ+z] within each target area are extracted, with a z-value of 0.005. The extracted pixels are then spatially aggregated, and the aggregated result is the reference ecosystem for each target area.

[0013] Furthermore, the spatial aggregation process for the extracted pixels is as follows: using the polygon aggregation tool in ArcGIS software, the distance parameter is set to 10 m; the aggregated patches are sorted from largest to smallest area, and the top 5 patches are extracted from each target area; it is then determined whether the area of ​​each extracted patch is ≥400 m². 2 If yes, the current patch is the reference ecosystem for each target area; if no, the z value in the range [μ+σ-z, μ+σ+z] is increased by 0.001, and this step is repeated until the judgment result is yes.

[0014] A computer device includes a processor and a memory, the processor being electrically connected to the memory, the memory being used to store instructions and data, and the processor being used to execute the method for identifying a reference ecosystem in an open-pit mine based on a normal distribution function as described in any one of claims 1-9.

[0015] Beneficial Effects: This invention, based on ecosystem succession theory and the actual conditions of open-pit mine ecological restoration projects, defines different types of reference ecosystems for different areas (protected restoration area - herbaceous reference ecosystem, protected restoration area - woody reference ecosystem, ecological reconstruction area - platform grassland reference ecosystem, ecological reconstruction area - platform forest reference ecosystem, and ecological reconstruction area - slope reference ecosystem), and determines the target areas for each type of reference ecosystem. Then, remote sensing technology is used to calculate various ecological parameters and ecosystem quality. Finally, based on Gaussian distribution function and spatial aggregation technology, various types of reference ecosystems are identified. Compared with existing technologies, this invention integrates relevant knowledge from ecology, statistics, and mining science, considers the actual conditions of ecological restoration projects, and ensures the objective and accurate identification of reference ecosystems in open-pit mines. Simultaneously, the use of remote sensing technology ensures rapid identification of reference ecosystems. Attached Figure Description

[0016] Figure 1 This is a flowchart of the method for identifying reference ecosystems in open-pit mines based on the normal distribution function, as described in this invention.

[0017] Figure 2 This is a schematic diagram illustrating the division of the ecological reconstruction zone and the protection and restoration zone in an embodiment of the present invention.

[0018] Figure 3 This is the fitting result of the normal distribution function of the ecosystem quality of all pixels in the protected restoration area - herbaceous plant area in the embodiment of the present invention. Detailed Implementation

[0019] The invention will now be further described with reference to the accompanying drawings.

[0020] Example: The following example uses an open-pit coal mine located in Jungar Banner, Inner Mongolia Autonomous Region, China as the implementation object. The following steps are used to establish a reference ecosystem for the open-pit coal mine.

[0021] like Figure 1 As shown, this invention discloses a method for identifying reference ecosystems in open-pit mines based on a normal distribution function, the steps of which are as follows:

[0022] Step 1: Identify target areas for various types of reference ecosystems. Based on the mine boundary A of the open-pit coal mine, use the buffer function in ArcGIS software to obtain a buffer zone B with a buffer radius of 10 km. Erase A from B to obtain region C. Download the Sentinel-2 remote sensing image of region C from August 2025. Using visual interpretation, subdivide region C as a protection and restoration area into herbaceous plant area C-1 and woody plant area C-2; C-1 is the target area for identifying herbaceous reference ecosystems, and C-2 is the target area for identifying woody reference ecosystems. Based on the remote sensing image, use visual interpretation to delineate the spoil heap area in the open-pit coal mine, which is the ecological reconstruction area of ​​the open-pit coal mine, such as... Figure 2 As shown.

[0023] Step Two: Select the open-pit coal mine and three nearby coal mines that underwent ecological restoration projects five years prior. Using historical remote sensing imagery (Sentinel-2 from August 2020), extract specific areas (D) from the spoil heaps of these four coal mines that underwent ecological restoration in 2020 through visual interpretation. Divide area D into platform area D-1 and slope area D-2. Since the restoration directions of the spoil heap platforms include woodland and grassland, the visual interpretation method of remote sensing imagery is still used. The grassland area is extracted from D-1 as the target area D-1-1 for identifying the platform grassland reference ecosystem, and the woodland area is extracted from D-1 as the target area D-1-2 for identifying the platform woodland reference ecosystem. Slope area D-2 is used as the target area for identifying the slope reference ecosystem. Through these operations, the reference ecosystems are divided into multiple types, and target areas for each type are obtained. C-1, C-2, D-1-1, D-1-2, and D-2 are the target areas for the following ecosystems: the protection and restoration zone - herbaceous reference ecosystem, the protection and restoration zone - woody reference ecosystem, the ecological reconstruction zone - platform grassland reference ecosystem, the ecological reconstruction zone - platform forest reference ecosystem, and the ecological reconstruction zone - slope reference ecosystem, respectively. The degraded area surrounding the mine (protection and restoration zone) is indirectly affected by coal mining; therefore, ecological restoration activities in this area can refer to natural areas within a 10 km radius of the mine. The spoil heap (ecological reconstruction zone) is directly affected by coal mining, resulting in drastic changes to its topography, making restoration to a natural state difficult. Therefore, the ecological reconstruction zone uses areas on surrounding mine spoil heaps that have been restored for more than 5 years with good results as a reference. The protection and restoration zone and ecological reconstruction zone in this embodiment are as follows: Figure 2 As shown. Simultaneously, considering the successional patterns of natural ecosystems, reference ecosystems at different successional stages (herbaceous succession stage and woody succession stage) are established for the protection and restoration area. For the ecological reconstruction area, multiple types of reference ecosystems are established considering different locations (platforms and slopes) and different restoration directions (grassland, woodland) of the spoil heap. This step comprehensively considers self-design theory, anthropogenic design theory, ecosystem succession theory in restoration ecology, and the actual situation of mine ecological restoration, scientifically dividing the types of reference ecosystems and target areas.

[0024] Step 3: Remote sensing estimation of various ecological parameters in the target areas. These parameters include vegetation cover, leaf area index (LAI), biomass, chlorophyll content, and soil moisture. Vegetation cover was calculated using a pixel-based bisection model; leaf area index and chlorophyll content were calculated using the Prosail radiative transfer model; soil moisture was calculated using the Oh model; and biomass was calculated using an empirical model. Vegetation cover, leaf area index, chlorophyll content, and biomass were calculated using Sentinel-2 remote sensing imagery from August 2025, while soil moisture was calculated using Sentinel-1 remote sensing imagery from February 2025. After normalizing the calculation results of each ecological parameter, the ecosystem quality Q was calculated using the following formula: FVC refers to vegetation cover, LAI to leaf area index, Biomass to biomass, C to chlorophyll content, and SMC to soil moisture. Finally, the min-max method was used to normalize the ecosystem quality Q of each target area to between 0 and 1. .

[0025] Step 4: Extract the ecosystem quality of all pixels within each target area and plot a frequency distribution histogram. The horizontal axis of the histogram represents ecosystem quality, and the vertical axis represents the number of pixels. Fit the histogram with a normal distribution function. Taking the herbaceous plant area of ​​the conservation and restoration zone as an example (i.e., target area C-1), the normal distribution function fitting result is as follows: Figure 3 As shown. The normal distribution function is Where μ = 0.324 and σ = 0.142. Following this method, normal distribution functions are fitted sequentially to other target regions.

[0026] Step 5: Extracting Pixels and Spatial Aggregation: Taking the herbaceous plant area of ​​the protection and restoration zone as an example (i.e., target area C-1), extract pixels in target area C-1 whose ecosystem quality falls within the range of [0.324+0.142-0.005, 0.324+0.142+0.005]. Similarly, perform the same operation on other target areas. This operation uses a normal distribution function to describe the distribution of ecosystem quality among pixels in the target area. Integrating the normal distribution function yields the cumulative distribution function, which takes the form of an S-shaped growth curve. According to statistical knowledge, μ+σ corresponds to the 84.14% position of the cumulative distribution curve. Simultaneously, μ+σ also corresponds to the inflection point of the S-shaped growth curve, transitioning from a rapid growth phase to a slow growth phase. Taking the pixel ranking 84.14% of ecosystem quality as the reference ecosystem ensures that the reference ecosystem has high ecosystem quality while avoiding excessively high ecosystem quality that would hinder the achievement of ecological restoration goals. This operation utilizes statistical knowledge to achieve precise and objective location of the reference ecosystem within the target area. Finally, the extracted pixels within each target area are spatially aggregated. Using the area aggregation tool in ArcGIS 10.7, the distance parameter is set to 10 m, meaning that two pixels more than 10 m apart cannot be aggregated into the same patch. The aggregated patches are then sorted by area from largest to smallest, and the top 5 patches are extracted from each target area. It is then determined whether the area of ​​all extracted patches is ≥400 m². 2 If yes, the aforementioned patches serve as the reference ecosystems for each target area; if no, the z-value is increased by 0.001, and step five is repeated until the result is yes. Through the above operations, multiple types of reference ecosystems are established for this open-pit coal mine. Each type of reference ecosystem has multiple instances and a certain area. The average value of multiple reference ecosystems is used as the final result, effectively reducing the problems caused by spatial heterogeneity. Figure 3 As shown.

[0027] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0028] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any minor modifications, equivalent substitutions, and improvements made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for identifying a reference ecosystem in an open pit mine area based on a normal distribution function, characterized by, The method comprises the following steps: S1, dividing the degraded area around the open-pit coal mine into a protection and restoration area, and dividing the dump into an ecological reconstruction area; S2, defining different types of reference ecosystems for the two areas, and determining the target areas of each type of reference ecosystem; S3, comprehensively calculating the remote sensing results of multiple ecological parameters to calculate the ecosystem quality of each pixel in the target area; S4, fitting the ecosystem quality of all pixels in each target area with a normal distribution function respectively to obtain fitting parameters; S5, extracting qualified pixels and performing spatial aggregation, and the aggregation result is the reference ecosystem.

2. The method for identifying a reference ecosystem in an open-pit mine area based on a normal distribution function according to claim 1, characterized in that, Based on the consideration of the succession law of the ecosystem, the spatial position of the dump, and the direction of ecological restoration, the protection and restoration area corresponds to two types of reference ecosystems: herbaceous reference ecosystem and woody reference ecosystem. Based on the boundary of the target mining area, the area where the herbaceous plants are located within a range of 10 km around the target mining area is extracted as the target area for identifying the herbaceous reference ecosystem, and the area where the woody plants are located is extracted as the target area for identifying the woody reference ecosystem. Based on the remote sensing image, the dump area in the open-pit coal mine is circled out by using the visual interpretation method, which is the ecological reconstruction area of the open-pit coal mine.

3. The method for identifying a reference ecosystem in an open pit mine area based on a normal distribution function according to claim 2, characterized in that, The ecological reconstruction area corresponds to three types of reference ecosystems: platform grassland reference ecosystem, platform forest land reference ecosystem, and slope reference ecosystem. The target mining area and N mining areas closest to the target mining area and having carried out ecological restoration projects five years ago are selected, N≥3. The specific area D that has carried out ecological restoration five years ago is extracted from the dump of the above mining areas by using the historical remote sensing image and the visual interpretation method, and the area D is divided into platform area D-1 and slope area D-2. The area where the grassland is located in the platform area D-1 is extracted as the target area D-1-1 for identifying the platform grassland reference ecosystem, and the area where the forest land is located in the platform area D-1 is extracted as the target area D-1-2 for identifying the platform forest land reference ecosystem. The slope area D-2 is used as the target area for identifying the slope reference ecosystem.

4. The method for identifying a reference ecosystem in an open-pit mine area based on a normal distribution function according to claim 3, characterized in that, The target areas of each type of reference ecosystem: the target area of the herbaceous reference ecosystem, the target area of the woody reference ecosystem, the target area of the platform grassland reference ecosystem, the target area of the platform forest land reference ecosystem, and the target area of the slope reference ecosystem, a total of five target areas. Based on the remote sensing technology, the ecological parameters of the above five target areas in the current year or in August of the previous year are calculated: vegetation coverage, leaf area index, biomass, chlorophyll content, and soil moisture. After the calculation results of the ecological parameters of each target area are normalized, they are added according to the weight of 3:2:2:1:2 to obtain the ecosystem quality Q of all pixels in each target area, and the ecosystem quality Q of all pixels in the above five target areas is normalized respectively.

5. The method for identifying a reference ecosystem in an open pit mine area based on a normal distribution function according to claim 4, characterized in that, The ecosystem quality Q of all pixels in each target area is normalized to 0-1 by using the min-max method: ， In the formula, FVC refers to vegetation coverage, LAI refers to leaf area index, Biomass refers to biomass, C refers to chlorophyll content, and SMC refers to soil moisture.

6. The method for identifying a reference ecosystem in an open pit mine area based on a normal distribution function according to claim 5, characterized in that, The ecosystem quality Q of all pixels in each target area is extracted, and the extraction results of each target area are fitted with a normal distribution function to obtain the mean μ of the normal distribution function and the standard deviation σ of the normal distribution function.

7. The method for identifying a reference ecosystem in an open pit mine area based on a normal distribution function according to claim 6, characterized in that, The normal distribution function fitting process is: the ecosystem quality of all pixels in each target area should be extracted first, and a frequency distribution histogram is drawn, wherein the horizontal coordinate is the ecosystem quality Q, and the vertical coordinate is the number of pixels; then the normal distribution function f(x) of the frequency distribution histogram of each target area is calculated by using the following formula: 。 8. The method for identifying a reference ecosystem in an open-pit mine area based on a normal distribution function according to claim 7, characterized in that, The pixels of each target area whose ecosystem quality is located in [μ+σ-z, μ+σ+z] are extracted, the value of z is 0.005, and the extracted pixels are spatially aggregated, and the aggregation result is the reference ecosystem of each target area.

9. The method for identifying a reference ecosystem in an open pit mine area based on a normal distribution function according to claim 8, characterized in that, The spatial aggregation process of the extracted pixels is as follows: the distance parameter is set to 10 m by using the surface aggregation tool of ArcGIS software; the generated patches after aggregation are sorted according to the area from large to small, and the top 5 patches in each target area are extracted; it is judged whether the areas of the extracted patches are all greater than or equal to 400 m 2 , if yes, the current patch is the reference ecosystem of each target area, if no, the z value in the range [μ+σ-z, μ+σ+z] is increased by 0.001, and the steps in this paragraph are repeated until the judgment result is yes.

10. A computer device, comprising: The system comprises a processor and a memory, the processor is electrically connected with the memory, the memory is used for storing instructions and data, and the processor is used for executing the method for identifying the reference ecosystem of the open-pit mine area based on the normal distribution function according to any one of claims 1-9.

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