A method for quantifying the impact of the ecological barrier function of black soil farmland on grain yield

Abstract

This invention provides a method for quantifying the impact of the ecological barrier function of black soil farmland on grain yield, relating to the field of grain yield impact assessment technology. The method includes: acquiring geospatial data on climate, soil, hydrology, and land use of the target ecological region; determining the extent of the black soil farmland ecological barrier and calculating its five ecosystem service function values ​​(habitat quality, water conservation, soil retention, water purification, and carbon sequestration); generating an ecological barrier function comprehensive value (ESI) through normalization and equal-weighted overlay; calculating and normalizing the grain yield of black soil farmland using remote sensing data and the harvest index method; fitting the nonlinear relationship between ESI and grain yield based on multi-scale window random sampling; and determining the optimal ratio of ecological barrier grids, the minimum threshold for ecological function, and the saturation threshold for farmland ecological function through derivative analysis. This invention overcomes the challenge of quantification at the landscape or regional scale, providing precise evidence for black soil ecological restoration and food security decision-making.

Description

Technical Field

[0001] This invention relates to the field of grain yield impact assessment technology, and in particular to a method for quantifying the impact of the ecological barrier function of black soil farmland on grain yield. Background Technology

[0002] The ecological barrier function of arable land refers to the ecological services provided by the ecosystem surrounding arable land. It can effectively protect the ecological environment of arable land, reduce the negative impacts of natural disasters and human activities on arable land, and thus ensure the sustainability of agricultural production and ecological security.

[0003] In recent years, large-scale land reclamation activities have led to a significant decline in the proportion of natural ecosystems such as forests, grasslands, and wetlands. Coupled with climate change and rapid urbanization, this has severely damaged the ecological barrier function of black soil farmland, thereby threatening food security. Therefore, restoring and strengthening the ecological barrier function of black soil farmland can effectively improve the stability and sustainability of grain production in black soil regions.

[0004] Currently, many scholars both domestically and internationally have studied the impact of certain single functions of cultivated land ecological barriers on grain yield at local scales through field observations of sample plots. However, these methods are difficult to generalize and quantify at larger scales, especially at landscape or regional scales, where groundbreaking research results are still lacking. This leaves the protection and restoration of black soil cultivated land ecological barriers without a reliable theoretical basis. Therefore, the main problem currently facing technology is that an effective method has not yet been invented to accurately quantify the impact of black soil cultivated land ecological barrier functions on grain yield at landscape or regional scales. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a method for quantifying the impact of the ecological barrier function of black soil farmland on grain yield, and to solve the technical problem that the prior art cannot accurately quantify the impact of the ecological barrier function of black soil farmland on grain yield at the landscape or regional scale.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] A method for quantifying the impact of the ecological barrier function of black soil farmland on grain yield includes:

[0008] Acquire various geospatial data of the target ecological region;

[0009] The extent of the black soil farmland ecological barrier in the target ecological region is determined, and ecosystem service function values ​​are obtained based on various geospatial data of the farmland ecological barrier; the ecosystem service function values ​​include habitat quality, water conservation, soil retention, water purification, and carbon sequestration.

[0010] The values ​​of the five categories of ecosystem service functions were normalized and then combined with equal weights to obtain the comprehensive value of the ecological barrier function of black soil farmland.

[0011] The extent of black soil farmland in the target ecological region is determined, and the grain yield of black soil farmland in the target ecological region is obtained based on various geospatial data of black soil farmland, and the grain yield is normalized.

[0012] By using multi-scale window random sampling, the quantitative relationship between the comprehensive value of the ecological barrier function and the normalized grain yield is fitted, and the threshold of the impact of the ecological barrier function on grain yield is determined based on derivative analysis, so as to complete the quantification of the impact on grain yield.

[0013] Preferably, the geospatial data includes climate, soil, hydrology, land use, and remote sensing imagery data at the same spatiotemporal scale.

[0014] Preferably, the extent of the black soil farmland ecological barrier in the target ecological region is determined, and ecosystem service function values ​​are obtained based on various geospatial data of the farmland ecological barrier, including:

[0015] After removing cultivated land and built-up land from the target ecological area, the extent of the black soil cultivated land ecological barrier is obtained. Ecosystem service functions are then calculated based on various geospatial data within this extent. The calculation steps for the ecosystem service functions are as follows:

[0016] The habitat quality is calculated by combining the suitability of the habitat, the intensity of external threats, and sensitivity. The formula for calculating habitat quality is as follows: In the formula, Q xj H represents the habitat quality of cell x on type j land cover; j Habitat suitability for J-type land cover; The stress level of each land use type; k is the half-saturation constant; Z is the normalization constant, usually taken as 2.5; the water conservation is obtained by subtracting the annual runoff from the water yield; the formula for calculating the water yield is: Among them, Y xj Annual water yield of grid cell x on land use type j; AET xj P represents the annual average evapotranspiration of grid cell x on land use type j. x The annual precipitation for grid cell x; AET xj / P x The Zhang coefficient is used to calculate the total annual runoff. The total annual runoff is estimated by assigning an average runoff coefficient value to each land use type and multiplying it by the annual precipitation of each pixel. The formula for calculating the total annual runoff is Runoff.ij =P ij ×C j The formula for calculating water conservation is: WR ij =Y xj -Runoff ij ;In the formula, WR ij It is LUCC j The water conservation values ​​of each pixel in that year, Runoff ij Total annual runoff, P ij Indicates LUCC j The annual precipitation of each pixel in that year, C j Indicates the j-th land use type; LUCC j This represents the type of land use and land cover, i.e., the j-th category.

[0017] Estimate the erosion reduction and sediment retention, and calculate the soil conservation by subtracting the sediment retention from the soil loss; the formula for calculating soil conservation is: SEDRET = PKLS x -USLE x ;In the formula, SEDRET x This represents the soil retention value of raster x in a certain land use type; PKLS x USLEx represents the potential soil loss of grid x in a certain land use type, while USLEx represents the actual erosion of grid x in a certain land use type, i.e., the soil erosion under vegetation cover and soil and water conservation measures.

[0018] The nitrogen and phosphorus output of each land use type was estimated to obtain the water purification results; whereby, ALV x =HSS x ×POL x ; λ x =log(∑ U Y U In the formula, ALV x The load value adjusted at grid cell x; POL x The output coefficient of grid cell x; HSS x This represents the hydrological sensitivity value at grid cell x. λ is the average runoff index of the catchment area. x is the runoff index at grid cell x, used to express the sum of water production of all grid cells in the catchment area;

[0019] Based on different land use types within a grid cell, the total carbon storage in the grid cell is calculated by multiplying the average carbon density of the four carbon pools (above-ground carbon, below-ground carbon, litter carbon, and soil carbon) in different ecosystems or vegetation types by their respective areas; where B = ∑BEF·X i ·A i C -tot =C -above +C -below +C -soil +C -dead In the formula: B is the total biomass; BEF is the biomass conversion factor, X i and A i These represent the unit volume and distribution area of ​​a certain type i land use; C_tot represents the total carbon storage, i.e., carbon sequestration; C_above represents the carbon storage above ground; C_below represents the carbon storage below ground; C_soil represents the soil carbon storage; and C_dead represents the carbon storage of litter.

[0020] Preferably, the formula for calculating the comprehensive value of the ecological barrier function is as follows:

[0021] ESI=NorHQ(i,t)+NorWY(i,t)+NorSR(i,t)+NorNDR(i,t)+NorCS(i,t)

[0022] In the formula: ESI is the comprehensive value of the ecological barrier function, and NorHQ(i,t), NorWY(i,t), NorSR(i,t), NorNDR(i,t), and NorCS(i,t) are the normalized values ​​of habitat quality, water conservation, soil retention, water purification, and carbon sequestration of grid i in year t, respectively.

[0023] Preferably, the extent of black soil cultivated land in the target ecological region is determined, and the grain yield of the black soil cultivated land in the target ecological region is obtained based on various geospatial data of the black soil cultivated land. The grain yield is then normalized, including:

[0024] Extract all cultivated land within the target ecological area as the black soil cultivated land range;

[0025] Based on remote sensing technology, the harvest index method is used to estimate the grain yield of cultivated land in black soil areas; the formula for calculating the grain yield is: Yield = GPP yearly ×2×0.9×HI; where Yield is grain yield; GPP yearly 1 represents annual biomass; 2 represents the conversion coefficient; 0.9 represents the proportion of aboveground productivity; hI represents the harvest index;

[0026] The grain yield is normalized so that the grain yield value of the black soil farmland in the target ecological region is in the range of 0-1.

[0027] Preferably, the calculation steps for the annual biomass include:

[0028] Acquire MOD17A2H data; the MOD17A2H data is a MODISGPP product with a spatial resolution of 500m and a temporal resolution of 8d;

[0029] The MOD17A2H data was processed in batches using MRT software, specifically as follows:

[0030] Five images from eight days were stitched together to form a temporary HDF file;

[0031] Convert the original sinusoidal projection of the HDF temporary file to WGS84 projection and export it in TIFF format;

[0032] Import the exported TIFF file into ArcGIS software to calculate the annual biomass, and then clip it based on the vector area of ​​the black soil cultivated land in the target ecological region.

[0033] Preferably, by using multi-scale window random sampling, the quantitative relationship between the comprehensive value of the ecological barrier function and the normalized grain yield is fitted, and the threshold of the impact of the ecological barrier function on grain yield is determined based on derivative analysis, so as to complete the quantification of the impact on grain yield, including:

[0034] Multiple spatial scale windows are set up, and the comprehensive value of ecological barrier function and normalized grain yield of black soil farmland in the target ecological area are randomly sampled to obtain the sampling dataset under each scale window; the sampling dataset includes: ecological barrier grid ratio, average ecological barrier function value, average farmland grid ecological barrier function value and corresponding average grain yield value.

[0035] Based on the sampled dataset, various relational models were fitted respectively; the relational models include: a polynomial relational equation between the proportion of ecological barrier grids and average grain yield, a polynomial relational equation between the average ecological barrier function value and average grain yield, and a logarithmic relational equation between the average cultivated land grid ecological barrier function value and average grain yield.

[0036] For each relational model, derivative analysis is performed to determine the threshold affecting grain yield;

[0037] The average values ​​of each threshold under different scale windows were statistically analyzed to generate a quantitative impact of the ecological barrier function of black soil farmland on grain yield.

[0038] Preferably, the polynomial equation relating the proportion of the ecological barrier grid to the average grain yield is: y = a n x n +a n-1 x n-1 +…+a1x+a0; where y is the average grain yield; x is the proportion of the ecological barrier grid; a n ,a n-1 a1, a0 are polynomial coefficients; the polynomial equation relating the average ecological barrier function value to the average grain yield is: y = a n x' n +a n-1 x' n-1 +…+a1x'+a0; where x' is the average ecological barrier function value; the logarithmic relationship equation between the average cultivated land grid ecological barrier function value and the average grain yield is: y=aln(x”)+b; where x” is the average cultivated land grid ecological barrier function value, and a and b are the fitted coefficients.

[0039] Preferably, derivative analysis is performed on each relational model to determine the threshold affecting grain yield, including:

[0040] By solving the first derivative of the polynomial equation relating the proportion of ecological barrier grids to average grain yield... The threshold for obtaining the optimal proportion of ecological barrier grids;

[0041] By verifying the second derivative Determine the minimum threshold for promoting the average ecological barrier function value;

[0042] By setting the relative rate of change condition Determine the saturation threshold for the ecological barrier function of average cultivated land grid.

[0043] Preferably, the spatial scale window includes 10km, 25km, and 50km.

[0044] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0045] This invention provides a method for quantifying the impact of the ecological barrier function of black soil cultivated land on grain yield, comprising: acquiring various geospatial data of a target ecological region; determining the extent of the black soil cultivated land ecological barrier in the target ecological region, and obtaining ecosystem service function values ​​based on the various geospatial data of the cultivated land ecological barrier; the ecosystem service function values ​​include habitat quality, water conservation, soil retention, water purification, and carbon sequestration; normalizing the five types of ecosystem service function values ​​respectively, and obtaining a comprehensive value of the ecological barrier function of black soil cultivated land through equal-weighted superposition; determining the extent of the black soil cultivated land in the target ecological region, obtaining the grain yield of the black soil cultivated land in the target ecological region based on the various geospatial data of the black soil cultivated land, and normalizing the grain yield; fitting the quantitative relationship between the comprehensive value of the ecological barrier function and the normalized grain yield through multi-scale window random sampling, and determining the threshold of the impact of the ecological barrier function on grain yield based on derivative analysis, thereby completing the quantification of the impact on grain yield. This invention can accurately quantify the impact of the ecological barrier function of black soil cultivated land on grain yield at the landscape or regional scale. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 A flowchart of the method provided in an embodiment of the present invention;

[0048] Figure 2 This is a schematic diagram of the overall process of the method for quantifying the impact of the ecological barrier function of black soil farmland on grain yield provided in an embodiment of the present invention.

[0049] Figure 3 This is a functional map of the ecological barrier of cultivated land in the black soil of the Sanjiang Plain provided in an embodiment of the present invention; the functional value of cultivated land ecological barrier has been standardized and ranges from 0 to 1.

[0050] Figure 4 This is a map showing the grain yield of cultivated land in the black soil region of the Sanjiang Plain, provided as an embodiment of the present invention. The grain yield has been standardized and ranges from 0 to 1.

[0051] Figure 5 This is a graph showing the fitting relationship between the proportion of ecological barrier grids and average grain yield under different scale windows provided in this embodiment of the invention.

[0052] Figure 6This is a graph showing the fitting relationship between the average ecological barrier function value and the average grain yield under different scale windows provided in the embodiments of the present invention;

[0053] Figure 7 This is a graph showing the fitting relationship between the average cultivated land grid ecological barrier function and average grain yield under different scale windows provided in this embodiment of the invention. Detailed Implementation

[0054] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] The purpose of this invention is to provide a method for quantifying the impact of the ecological barrier function of black soil farmland on grain yield, which can accurately quantify the impact of the ecological barrier function of black soil farmland on grain yield at the landscape or regional scale.

[0056] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0057] Figure 1 The method flowchart provided in the embodiments of the present invention is as follows: Figure 1 As shown, this invention provides a method for quantifying the impact of the ecological barrier function of black soil farmland on grain yield, comprising:

[0058] Step 100: Obtain various geospatial data of the target ecological region;

[0059] Step 200: Determine the extent of the black soil farmland ecological barrier in the target ecological region, and obtain the ecosystem service function value based on various geospatial data of the farmland ecological barrier; the ecosystem service function value includes habitat quality, water conservation, soil retention, water purification and carbon sequestration.

[0060] Step 300: Normalize the values ​​of the five types of ecosystem service functions respectively, and obtain the comprehensive value of the ecological barrier function of black soil farmland by equal weight superposition;

[0061] Step 400: Determine the extent of black soil farmland in the target ecological region, obtain the grain yield of black soil farmland in the target ecological region based on various geospatial data of black soil farmland, and normalize the grain yield.

[0062] Step 500: Through multi-scale window random sampling, fit the quantitative relationship between the comprehensive value of ecological barrier function and the normalized grain yield, and determine the threshold of the impact of ecological barrier function on grain yield based on derivative analysis, so as to complete the quantification of the impact on grain yield.

[0063] Specifically, such as Figure 2 As shown, the method for quantifying the impact of the ecological barrier function of black soil farmland on grain yield is as follows:

[0064] S1. Obtain various geospatial data of the ecological region;

[0065] S2. Determine the scope of the black soil farmland ecological barrier in the ecological region, and obtain the ecosystem service functions of the ecological barrier in the region, such as habitat quality, water conservation, soil retention, water purification and carbon sequestration, based on various geospatial data of the farmland ecological barrier.

[0066] S3. Based on the various ecosystem service functions of the black soil farmland ecological barrier, the functions of the black soil farmland ecological barrier are obtained by equal weighting and superimposing.

[0067] S4. Determine the extent of the black soil farmland in the ecological region, and obtain the grain yield of the black soil farmland in the ecological region based on various geospatial data of the farmland;

[0068] S5. For the aforementioned region, quantify the impact of the ecological barrier function of black soil farmland on grain yield.

[0069] Optionally, the geospatial data mentioned in step S1 includes climate, soil, hydrology, land use and remote sensing image data with the same spatiotemporal scale;

[0070] Further, step S2 determines the scope of the black soil farmland ecological barrier in the ecological region, and obtains the habitat quality, water conservation, soil retention, water purification and carbon sequestration ecological service functions of the ecological barrier based on various geospatial data of the farmland ecological barrier.

[0071] The scope of the black soil farmland ecological barrier is obtained by removing farmland and building land in the ecological area, and its ecological service function is calculated based on various geospatial data within the scope.

[0072] (1) Habitat quality (HQ): Based on Formula 1, habitat quality is calculated by combining habitat suitability, the intensity of external threats, and sensitivity. The calculation formula is as follows:

[0073]

[0074] In the formula: Q xj H represents the habitat quality of cell x on type j land cover; j Habitat suitability for J-type land cover; The stress level of each land use type; k is the half-saturation constant; Z is the normalization constant, usually taken as 2.5; (2) Water conservation (WY): Water conservation is obtained by subtracting the total annual runoff from the water production. The water production is estimated based on Formula 2; by assigning the average runoff coefficient value to each land use type and multiplying it by the annual precipitation of each pixel, the total annual runoff is estimated;

[0075]

[0076] In the formula: Y xj The annual water yield m of grid cell x on land use type j 3 AET xj P represents the annual average evapotranspiration of grid cell x on land use type j. x The annual precipitation for grid cell x; AET xj / P x The Zhang coefficient is an algorithm based on the Budyko equation combined with actual conditions.

[0077] Runoff ij =P ij ×C j (3)

[0078] WR ij =Y xj -Runoff ij (4)

[0079] In the formula, WR ij It is LUCC j The water conservation capacity of each pixel in that year, Y xj It is LUCC j The annual water output of each pixel, in mm, Runoff ij It is LUCC j Annual runoff volume of the Earth's surface in each pixel, in mm / a, P ij Indicates LUCC j The annual precipitation for each pixel in that year, in mm and C. j This represents the type j of land use.

[0080] (3) Soil retention (SR): Erosion reduction and sediment retention are estimated using Formula 5. Finally, soil retention is obtained by subtracting sediment retention from soil loss.

[0081] SEDRET = PKLS x -USLE x (5)

[0082] In the formula: SEDRET xRepresents the soil retention capacity of grid x for a certain land use type; PKLS x USLEx represents the potential soil loss of grid x in a certain land use type, while USLEx represents the actual erosion of grid x in a certain land use type, i.e., the soil erosion under vegetation cover and soil and water conservation measures.

[0083] (4) Water purification (NDR): The nitrogen and phosphorus output of each land use type is estimated based on formulas 7, 8 and 9;

[0084] ALV x =HSS x ×POL x (7)

[0085]

[0086] λ x =log(∑ U Y U (9)

[0087] In the formula, ALV x The load value adjusted at grid cell x; POL x The output coefficient of grid cell x; HSS x This represents the hydrological sensitivity value at grid cell x. λ is the average runoff index of the catchment area. x is the runoff index at grid cell x, used to express the sum of water production of all grid cells in the catchment area;

[0088] As an example, the load value adjusted at the grid unit in this embodiment is "nitrogen and phosphorus output", which refers to the water purification function.

[0089] (5) Carbon sequestration (CS): Based on formulas 10 and 11, the carbon sequestration amount is estimated. Based on different land use types on the grid cell, the average carbon density of the four carbon pools of aboveground carbon, underground carbon, litter carbon and soil carbon in different ecosystems or vegetation types on the grid cell is multiplied by their respective areas to calculate the total carbon storage on the grid cell.

[0090] B = ∑BEF·X i ·A i (10)

[0091] C -tot =C -above +C -below +C -soil +C -dead (11)

[0092] In the formula: B is the total biomass; BEF is the biomass conversion factor; Xi and Ai are the unit volume and distribution area of ​​a certain type i land use, respectively; C_tot represents the total carbon storage; C_above represents the carbon storage of the aboveground part; C_below represents the carbon storage of the underground part; C_soil represents the soil carbon storage; and C_dead represents the carbon storage of litter.

[0093] Furthermore, such as Figure 3 As shown, step S3 obtains the ecological barrier function of black soil farmland by equally weighting the various ecosystem service functions of the black soil farmland ecological barrier.

[0094] The five types of ecosystem services contribute equally to the ecological barrier function of arable land. Therefore, the values ​​for habitat quality, water conservation, soil retention, water purification, and carbon sequestration are normalized. The ecological barrier function value of each grid is the sum of the normalized values ​​of the five types of ecosystem services, as shown in the formula:

[0095] ESI=NorHQ(i,t)+NorWY(i,t)+NorSR(i,t)+NorNDR(i,t)+

[0096] NorCS(i,t)(12)

[0097] In the formula: ESI is the ecological barrier function of black soil farmland, and NorHQ(i,t), NorWY(i,t), NorSR(i,t), NorNDR(i,t), and NorCS(i,t) are the normalized values ​​of habitat quality, water conservation, soil retention, water purification, and carbon sequestration of grid i in year t, respectively.

[0098] Furthermore, such as Figure 4 As shown, step S4 determines the extent of the black soil farmland in the ecological region and obtains the grain yield of the black soil farmland in the ecological region based on various geospatial data of the farmland.

[0099] All arable land within the ecological area is defined as the black soil arable land area. The grain yield of the black soil arable land is calculated based on this area.

[0100] Based on remote sensing technology, the harvest index (HI) method was used to estimate crop yield in black soil cultivated land areas. HI is the ratio of economic yield to biological yield at harvest, also known as the economic coefficient, which essentially represents the distribution ratio of crop assimilates between grains and vegetative organs. The calculation formula is as follows:

[0101] Yield = GPP yearly ×2×0.9×HI(13)

[0102] In the formula, Yield is the crop yield (kg / hm); GPP yearly 1 represents annual biomass (kg / hm); 2 represents the conversion coefficient; 0.9 represents the proportion of aboveground productivity; and HI represents the harvest index.

[0103] (1) GPP yearly (Annual Biomass) Calculation: MOD17A2H data was used, which is a MODISGPP (Gross Primary Productivity) product with a spatial resolution of 500m and a temporal resolution of 8 days. MRT software was used for batch processing of the MOD17A2H imagery. First, five images from each of the eight days were stitched together to form a temporary HDF file. Then, the original SIN (sine) projection was converted to WGS84 (geocentric coordinate system) projection. Next, the required GPP dataset was extracted and then converted to a TIFE format file, which is easily analyzed and processed on multiple platforms. Finally, ArcGIS software was used to calculate the annual GPP data, and the data was cropped according to the vector region of the study area.

[0104] The exemplary vector region refers to the vector region of black soil arable land. The purpose of cropping is to calculate the grain yield of arable land based on the GPP of black soil arable land.

[0105] (2) HI (harvest index) calculation: Based on the grain output statistics of each county and city in the ecological area, combined with MODISGPP remote sensing data, the HI value is obtained by comparison through formula (13).

[0106] (3) By normalizing Yield (crop yield), the grain yield of black soil farmland in the ecological region is in the range of 0-1.

[0107] As an optional implementation, step S5 quantifies the impact of the ecological barrier function of black soil farmland on grain yield in the region.

[0108] First, by setting windows at different scales (e.g., 10km, 25km, 50km), the ecological barrier function and grain yield within the specified area are randomly sampled to obtain datasets of ecological barrier grid proportion, average ecological barrier function value, average cultivated land grid ecological barrier function, and average grain yield at each scale window. Then, the relationships between ecological barrier grid proportion and average grain yield, average ecological barrier function value and average grain yield, and average cultivated land grid ecological barrier function and average grain yield are fitted. Next, at different scale windows, the thresholds for the impact of ecological barrier grid proportion, average ecological barrier function value, and average cultivated land grid ecological barrier function value on grain yield are identified. Finally, the average value of each threshold at different scale windows is calculated to quantify the impact of the black soil cultivated land ecological barrier function on grain yield.

[0109] (1) The impact of the proportion of ecological barrier grids on average grain yield

[0110] The proportion of ecological barrier grids and average grain yield under different scale windows were obtained by random sampling, and the fitting equation is as follows:

[0111] y = a n x n +a n-1 x n-1 +…+a1x+a0 (14)

[0112] Where: y is the average grain yield; x is the percentage of ecological barrier grids; a n ,a n-1 ,…,a1,a0 are the polynomial coefficients.

[0113] The optimal ratio of ecological barrier grids is identified by fitting the equation. Since a larger ecological barrier grid ratio does not necessarily lead to higher average food yield, a threshold for x needs to be found. This threshold can be obtained by taking the first derivative of y with respect to x and setting the derivative to zero.

[0114]

[0115] Solving this equation yields the value of x, which represents the optimal proportion of the ecological barrier grid.

[0116] (2) Impact of average ecological barrier function value on average grain yield

[0117] The average ecological barrier function value and average grain yield were obtained through random sampling at different scale windows. The fitted equation formula is as follows:

[0118] y = a n x n +a n-1 x n-1 +…+a1x+a0(16)

[0119] Where: y is the average grain yield; x is the average ecological barrier function value; a n ,a n-1 A0, ..., a1 are polynomial coefficients. This equation can be used to identify the minimum threshold for the average ecological barrier function value; only when this threshold is exceeded does the ecological barrier promote food production. The solution is obtained by setting the first derivative to zero, and then verified by calculating the second derivative.

[0120] Extreme points can be found by differentiating y with respect to x and setting the derivative to zero:

[0121]

[0122] Solving this equation yields the value of x, which is the minimum threshold for the average ecological barrier function value.

[0123] Verify the extremum property using the second derivative:

[0124]

[0125] if Then x is the minimum point, which is the minimum threshold of the average ecological barrier function value that promotes grain yield.

[0126] (3) The impact of the ecological barrier function of average cultivated land grid on average grain yield

[0127] The average ecological barrier function of cultivated land grids and average grain yield were obtained under different scale windows through random sampling. The relationship between the two was fitted using a ln function. The fitting equation is as follows:

[0128] y = alan(x) + b(19)

[0129] Where y is the average grain yield, x is the average ecological barrier function value of cultivated land grid, and a and b are the coefficients obtained from the fitting.

[0130] By fitting an equation, a threshold for the ecological barrier function of average cultivated land grids can be identified. Beyond this threshold, the increase in grain yield slows down, and even further improvements in the ecological barrier function will not significantly increase grain yield. For example, if the threshold condition is set as follows: an increase of 1 unit in x will result in an increase in y of less than 2% when x is present. If a rapid increase in grain yield is needed, a window with low average cultivated land grid ecological barrier function can be identified, and its ecological barrier function can be improved to quickly reach this threshold.

[0131] 1. To analyze the rate of change of y with respect to x, substitute x+1 into the fitting formula;

[0132] y(x+1)=aln(x+1)+b(20)

[0133] 2. Calculate the relative change of the difference and define it as:

[0134]

[0135] Substitute y(x+1) and y(x) into the equation;

[0136]

[0137] Further simplification;

[0138]

[0139] 3. Set a threshold condition. Suppose we want to find x values ​​that satisfy the condition that the relative change is less than a certain threshold ∈ (e.g., ∈ = 0.02), i.e.;

[0140]

[0141] Specifically, this embodiment provides several examples for reference:

[0142] Case 1

[0143] By fitting equations relating the proportion of ecological barrier grids to average grain yield under different scale windows, and obtaining extreme points by setting the first derivative to zero, the following method was used. Figure 5 As shown, it was found that as the proportion of ecological barrier grids increases, when the proportion of ecological barrier grids is greater than 0.84 (10km), 0.78 (25km), and 0.60 (50km), the average grain yield begins to decline, indicating that a larger proportion of ecological barrier grids is not necessarily better.

[0144] Case 2

[0145] like Figure 6 As shown, by fitting the equations of average ecological barrier function value and average grain yield under different scale windows, and solving for the extreme points by setting the first derivative to zero, it was found that as the average ecological barrier function value increases, the average grain yield only begins to increase when the average ecological barrier function value is greater than 0.50 (10km), 0.21 (25km), and 0.17 (50km).

[0146] Case 3

[0147] like Figure 7 As shown, the equations for average cultivated land grid ecological barrier function and average grain yield under different scale windows were fitted using the ln function. It was found that as the average cultivated land grid ecological barrier function increases, when the average cultivated land grid ecological barrier function value is greater than 1.72 (10km), 1.65 (25km), and 1.59 (50km), the increase in average grain yield for each unit increase in average cultivated land grid ecological barrier function will be less than 2% of the increase in average cultivated land grid ecological barrier function.

[0148] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0149] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for quantifying the impact of the ecological barrier function of black soil arable land on grain yield, characterized in that, The method comprises the following steps: acquiring various types of geographic spatial data of a target ecological region; determining the range of black land farmland ecological barriers in the target ecological region, and obtaining ecological system service function values according to various types of geographic spatial data of the farmland ecological barriers; the ecological system service function values include habitat quality, water conservation, soil conservation, water purification and carbon storage; normalizing the five types of ecological system service function values respectively, and obtaining a comprehensive value of the black land farmland ecological barrier function through equal-weight superposition; determining the range of black land farmland in the target ecological region, and obtaining the grain yield of the black land farmland in the target ecological region according to various types of geographic spatial data of the black land farmland, and normalizing the grain yield; fitting the quantitative relationship between the comprehensive value of the ecological barrier function and the normalized grain yield through multi-scale window random sampling, and determining the threshold value of the influence of the ecological barrier function on the grain yield based on derivative analysis to complete the quantification of the influence on the grain yield; determining the range of black land farmland ecological barriers in the target ecological region, and obtaining ecological system service function values according to various types of geographic spatial data of the farmland ecological barriers, including: removing farmland and building land in the target ecological region to obtain the range of the black land farmland ecological barrier, and calculating ecological service functions according to various types of geographic spatial data in the range; the calculation steps of the ecological service functions are as follows: The habitat quality is calculated according to the habitat suitability, the intensity of external threat source and the sensitivity, and the calculation formula of the habitat quality is: In the formula, Q xj represents the habitat quality of the x pixel on the j type land cover; H j is the habitat suitability of the j type land cover; is the stress level of each land use type; k is a half-saturation constant; and Z is a normalization constant, and the value is 2.

5. The water source conservation is obtained by subtracting the total annual runoff from the water yield; the calculation formula of the water yield is: Yjx= AETjx- Pjx xj xj x xj x Z is the Zhang coefficient; the total annual runoff is estimated by assigning the average runoff coefficient value to each land use type, multiplying the annual precipitation of each pixel in the year, and then estimating; the calculation formula of the total annual runoff is Runoff ij = P ij × C j ; the calculation formula of the water source conservation is WR ij = Y xj - Runoff ij ; in the formula, WR ij is the value of the water source conservation of each pixel in the year of LUCC j , Runoff ij is the total annual runoff, P ij represents the annual precipitation of each pixel in the year of LUCC j , C j represents the jth land use mode; LUCC j represents the jth land use and land cover type;​​​​ The soil conservation is calculated by subtracting the sediment interception from the soil loss amount, and the formula is SEDRET=PKLS x -USLE x ; wherein SEDRET x represents the soil conservation value of grid x on a certain type of land use; PKLS x represents the potential soil loss amount of grid x on a certain type of land use, and USLE x respectively represents the actual erosion amount of grid x on a certain type of land use, i.e. the soil erosion amount under vegetation coverage and soil and water conservation measures; The nitrogen and phosphorus output of each land use type is estimated to obtain the water quality purification; wherein, ALV x = HSS x × POL x ; λ x = log(∑ U Y U ); in the formula, ALV x is the adjusted load value at the grid unit x; POL x is the output coefficient of the grid unit x; HSS x is the hydrological sensitivity value at the grid unit x, is the average runoff index of the catchment area; λ x is the runoff index at the grid unit x, used to express the sum of water yields of all grids of the catchment area; Based on different land use types on the grid cell, the average carbon density of four carbon pools of aboveground carbon, belowground carbon, litter carbon and soil carbon in different ecosystems or vegetation types on the grid cell is multiplied by the corresponding area to calculate the total carbon storage on the grid cell, and the carbon storage is obtained; wherein B =∑BEF·X i ·A i ; C -tot = C -above + C -below + C -soil + C -dead ; in the formula: B is the total biomass; BEF is the biomass conversion factor, X i and A i are the unit storage and distribution area of a certain i type of land use type; C_tot represents the total carbon storage, that is, the carbon storage, C_above represents the carbon storage of the aboveground part, C_below represents the carbon storage of the underground part, C_soil represents the soil carbon storage, and C_dead represents the litter carbon storage; fitting the quantitative relationship between the comprehensive value of the ecological barrier function and the normalized grain yield through multi-scale window random sampling, and determining the threshold value of the influence of the ecological barrier function on the grain yield based on derivative analysis to complete the quantification of the influence on the grain yield, including: setting a plurality of spatial scale windows, and randomly sampling the comprehensive value of the ecological barrier function of the black land farmland and the normalized grain yield in the target ecological region to obtain a sampling data set under each scale window; the sampling data set includes: ecological barrier grid proportion, average ecological barrier function value, average farmland grid ecological barrier function value and corresponding average grain yield value; fitting each relationship model based on the sampling data set; the relationship model includes: a polynomial relationship equation between the ecological barrier grid proportion and the average grain yield, a polynomial relationship equation between the average ecological barrier function value and the average grain yield, and a logarithmic relationship equation between the average farmland grid ecological barrier function value and the average grain yield; derivative analysis is performed on each relationship model to determine the threshold value affecting the grain yield; statistically averaging the threshold values under different scale windows to generate the quantified influence result of the black land farmland ecological barrier function on the grain yield; The polynomial relationship equation between the ecological barrier grid proportion and the average grain yield is y=a n x n +a n-1 x n-1 +…+a1x+a0; wherein y is the average grain yield; x is the ecological barrier grid proportion; a n ,a n-1 ,…,a1,a0 are polynomial coefficients; the polynomial relationship equation between the average ecological barrier function value and the average grain yield is y=a n x' n +a n-1 x' n-1 +…+a1x'+a0; wherein x' is the average ecological barrier function value; the logarithmic relationship equation between the average cultivated land grid ecological barrier function value and the average grain yield is y=aln(x")+b; wherein x" is the average cultivated land grid ecological barrier function value, and a and b are fitted coefficients; derivative analysis is performed on each relationship model to determine the threshold value affecting the grain yield, including: by solving the first derivative of a polynomial relationship equation of the ecological barrier grid proportion and the average grain yield obtain a threshold of the optimal proportion of the ecological barrier grid proportion by verifying the second derivative determining a threshold of minimum facilitation of the average ecological barrier function value; By setting a relative change rate condition A threshold value is determined for saturation of the average farmland grid ecological barrier function. 2.The method of quantifying the impact of the ecological barrier function of black soil arable land on grain yield according to claim 1, characterized in that, The geographic spatial data includes climate, soil, hydrology, land use and remote sensing image data with the same time and space scale. 3.The method of quantifying the impact of the ecological barrier function of black soil arable land on grain yield according to claim 1, characterized in that, The calculation formula of the comprehensive value of the ecological barrier function is: ESI = NorHQ(i, t) + NorWY(i, t) + NorSR(i, t) + NorNDR(i, t) + NorCS(i, t) In the formula, ESI is the ecological barrier function comprehensive value, NorHQ(i, t), NorWY(i, t), NorSR(i, t), NorNDR(i, t) and NorCS(i, t) are normalized values of habitat quality, water conservation, soil conservation, water purification and carbon storage of grid i in year t respectively. 4.The method of quantifying the impact of the ecological barrier function of black soil arable land on grain yield according to claim 1, characterized in that, The range of black land farmland in the target ecological region is determined, and the grain yield of the black land farmland in the target ecological region is obtained according to various types of geographic spatial data of the black land farmland, and the grain yield is normalized, including: Extracting all farmland in the target ecological region as the range of black land farmland; On the basis of remote sensing technology, the grain yield of the black soil cultivated land is estimated by using the harvest index method; the calculation formula of the grain yield is: Yield=GPP yearly ×2×0.9×HI; in the formula, Yield is the grain yield; GPP yearly is the annual biomass; 2 is the conversion coefficient; 0.9 is the proportion of aboveground productivity; and HI is the harvest index. The grain yield is normalized so that the grain yield value of the black land farmland in the target ecological region ranges from 0 to 1. 5.The method for quantifying the impact of the ecological barrier function of black soil arable land on grain yield according to claim 4, characterized in that, The annual biomass calculation step includes: Obtaining MOD17A2H data; the MOD17A2H data is MODIS GPP product, with a spatial resolution of 500 m and a time resolution of 8 d; Using MRT software to batch process the MOD17A2H data, specifically: Splicing 5 8-day images to form an HDF temporary file; Converting the original sinusoidal projection of the HDF temporary file to WGS84 projection and exporting in TIFF format; Importing the exported TIFF format file into ArcGIS software to calculate the annual biomass, and clipping according to the vector region of the black land farmland in the target ecological region. 6.The method of quantifying the impact of the ecological barrier function of black soil arable land on grain yield according to claim 1, characterized in that, The spatial scale window includes 10 km, 25 km and 50 km.

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