Method and system for evaluating the contribution of driving factors to changes in vegetation carbon sequestration

Abstract

The present invention provides a method and system for evaluating the contribution rate of driving factors to changes in vegetation carbon fixation, and relates to the field of data processing. The method comprises: calculating vegetation carbon fixation data of the area to be evaluated during the time period to be evaluated based on vegetation net primary productivity data of the area to be evaluated during the time period to be evaluated; obtaining driving factor data of the area to be evaluated during the time period to be evaluated, and calculating the change trends of multiple driving factors based on the driving factor data of the area to be evaluated during the time period to be evaluated; calculating the correlation between multiple driving factors and vegetation carbon fixation based on the vegetation carbon fixation data and driving factor data of the area to be evaluated during the time period to be evaluated; and calculating the contribution rate of multiple driving factors to the change in vegetation carbon fixation in the area to be evaluated during the time period to be evaluated based on the change trends of multiple driving factors and the correlations between multiple driving factors and vegetation carbon fixation. The method has the advantage of evaluating the contribution rates of different driving factors to the change in vegetation carbon fixation.

Description

Technical Field

[0001] The present invention relates to the field of data processing, and in particular to a method and system for evaluating the contribution rate of driving factors to changes in vegetation carbon fixation. Background Art

[0002] With the rapid development of social economy, global carbon dioxide emissions have shown a clear growth trend in recent years. Vegetation is the most basic component of terrestrial ecosystems, and vegetation carbon sequestration (VCS) has attracted widespread attention as the most direct way to reduce carbon dioxide.

[0003] At present, the research on vegetation carbon sequestration is mostly focused on the correlation analysis of temporal and spatial variation trends and influencing factors, and few scholars have proposed quantitative evaluation methods and systems for the contribution rate of influencing factors to vegetation carbon sequestration. The use of traditional correlation analysis can only explore the relationship between a single influencing factor and vegetation carbon sequestration, and the failure to exclude the influence of other meteorological factors is not conducive to extracting the impact of human activities on vegetation carbon sequestration. Some studies have used the difference method between potential vegetation net primary productivity (Net Primary Productivity, NPP) and actual vegetation net primary productivity to distinguish the contribution of human activities and meteorological factors, but this method cannot distinguish the contribution of a single influencing factor to NPP, and it is also difficult to quantitatively estimate the contribution of influencing factors.

[0004] Therefore, it is necessary to provide a method for evaluating the contribution rate of driving factors to changes in vegetation carbon sequestration, which is used to evaluate the contribution rate of different driving factors to changes in vegetation carbon sequestration. Summary of the invention

[0005] The present invention provides a method for evaluating the contribution rate of driving factors to changes in vegetation carbon fixation, comprising: obtaining vegetation net primary productivity data of an area to be evaluated during a time period to be evaluated, and calculating vegetation carbon fixation data of the area to be evaluated during the time period to be evaluated based on the vegetation net primary productivity data of the area to be evaluated during the time period to be evaluated; obtaining driving factor data of the area to be evaluated during the time period to be evaluated, and calculating change trends of multiple driving factors based on the driving factor data of the area to be evaluated during the time period to be evaluated; calculating the correlation between multiple driving factors and vegetation carbon fixation based on the vegetation carbon fixation data and driving factor data of the area to be evaluated during the time period to be evaluated; and calculating the contribution rate of multiple driving factors to the changes in vegetation carbon fixation in the area to be evaluated during the time period to be evaluated based on the change trends of the multiple driving factors and the correlations between the multiple driving factors and vegetation carbon fixation.

[0006] Furthermore, the vegetation carbon sequestration data of the area to be assessed during the period to be assessed is calculated based on the following formula according to the vegetation net primary productivity data of the area to be assessed during the period to be assessed, including: Among them, VCS(x,t) is the amount of CO2 fixed by the vegetation in the area to be evaluated per unit time t and pixel x, and NPP(x,t) is the net primary productivity of the vegetation in the area to be evaluated per unit time t and pixel x.

[0007] Furthermore, the driving factor data of the area to be evaluated during the time period to be evaluated includes meteorological data of the area to be evaluated during the time period to be evaluated; based on the driving factor data of the area to be evaluated during the time period to be evaluated, the changing trends of multiple driving factors are calculated, including: based on the meteorological data of the area to be evaluated during the time period to be evaluated, the changing trends of multiple meteorological driving factors are calculated.

[0008] Furthermore, the change trends of multiple meteorological driving factors are calculated according to the meteorological data of the area to be evaluated during the time period to be evaluated by the following formula: Among them, θ slope is the changing trend of meteorological driving factors, median() is the median value, x k is the variable at the time index k, x l is the variable at time index position l, and n is the total number of time index positions.

[0009] Furthermore, based on the vegetation carbon fixation data and driving factor data of the area to be assessed during the time period to be assessed, the correlation between multiple driving factors and vegetation carbon fixation is calculated, including: for each of the meteorological driving factors, based on the vegetation carbon fixation data and meteorological data of the area to be assessed during the time period to be assessed, calculating the correlation coefficient between each meteorological driving factor and the vegetation carbon fixation data; for any two of the meteorological driving factors, based on the meteorological data of the area to be assessed during the time period to be assessed, calculating the correlation coefficient between the two meteorological driving factors; for each of the meteorological driving factors, based on the correlation coefficient between each meteorological driving factor and the vegetation carbon fixation data and the correlation coefficient of any two meteorological driving factors, calculating the n-1 order partial correlation coefficient between the meteorological driving factor and the vegetation carbon fixation data, wherein n is the total number of driving factors.

[0010] Further, the multiple meteorological driving factors include temperature driving factors, precipitation driving factors and radiation driving factors; for each of the meteorological driving factors, the n-1 order partial correlation coefficient between the meteorological driving factor and the vegetation carbon fixation data is calculated according to the correlation coefficient between each meteorological driving factor and the vegetation carbon fixation data and the correlation coefficients of any two meteorological driving factors, including: for the temperature driving factor, according to the correlation coefficient between each meteorological driving factor and the vegetation carbon fixation data and the correlation coefficients of any two meteorological driving factors, the first-order partial correlation coefficient between the temperature driving factor and the vegetation carbon fixation data after excluding the precipitation driving factor and the first-order partial correlation coefficient between the temperature driving factor and the vegetation carbon fixation data after excluding the radiation driving factor are calculated; for the precipitation driving factor, according to the correlation coefficient between each meteorological driving factor and the vegetation carbon fixation data and the correlation coefficients of any two meteorological driving factors, the first-order partial correlation coefficient between the precipitation driving factor and the vegetation carbon fixation data after excluding the temperature driving factor and the first-order partial correlation coefficient between the precipitation driving factor and the vegetation carbon fixation data after excluding the radiation driving factor are calculated; for the radiation driving factor, according to the correlation coefficient between each meteorological driving factor and the vegetation carbon fixation data The correlation coefficient of any two meteorological driving factors is used to calculate the first-order partial correlation coefficient of the radiation driving factor and the vegetation carbon fixation data after excluding the temperature driving factor, and the first-order partial correlation coefficient of the radiation driving factor and the vegetation carbon fixation data after excluding the precipitation driving factor; according to the first-order partial correlation coefficient of the temperature driving factor and the vegetation carbon fixation data after excluding the precipitation driving factor, and the first-order partial correlation coefficient of the temperature driving factor and the vegetation carbon fixation data after excluding the radiation driving factor, and the first-order partial correlation coefficient of the precipitation driving factor and the vegetation carbon fixation data after excluding the radiation driving factor, The first-order partial correlation coefficients between the temperature driving factor and the vegetation carbon fixation data, as well as the first-order partial correlation coefficients between the radiation driving factor and the vegetation carbon fixation data after excluding the temperature driving factor, and the first-order partial correlation coefficients between the radiation driving factor and the vegetation carbon fixation data after excluding the precipitation driving factor, were calculated; the second-order partial correlation coefficients between the temperature driving factor and the vegetation carbon fixation data after excluding the precipitation driving factor and the radiation driving factor, the second-order partial correlation coefficients between the precipitation driving factor and the vegetation carbon fixation data after excluding the temperature driving factor and the radiation driving factor, and the second-order partial correlation coefficients between the radiation driving factor and the vegetation carbon fixation data after excluding the precipitation driving factor and the temperature driving factor.

[0011] Furthermore, based on the changing trends of the multiple driving factors and the correlations between the multiple driving factors and vegetation carbon sequestration, the contribution rates of the multiple driving factors to the vegetation carbon sequestration changes in the to-be-assessed area during the to-be-assessed time period are calculated, including: calculating the contribution rates of the multiple driving factors to the vegetation carbon sequestration changes in the to-be-assessed area during the to-be-assessed time period based on the changing trends of the temperature driving factors, precipitation driving factors and radiation driving factors, the second-order partial correlation coefficients between the temperature driving factors and vegetation carbon sequestration data after excluding the precipitation driving factors and radiation driving factors, and the second-order partial correlation coefficients between the radiation driving factors and vegetation carbon sequestration data after excluding the precipitation driving factors and temperature driving factors, The contribution rate of human activities to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed is calculated according to the contribution rate of temperature driving factor to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed, the contribution rate of precipitation driving factor to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed, and the contribution rate of radiation driving factor to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed; the contribution rate of human activities to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed is calculated according to the contribution rate of temperature driving factor to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed, the contribution rate of precipitation driving factor to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed, and the contribution rate of radiation driving factor to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed.

[0012] Furthermore, based on the changing trends of temperature driving factors, precipitation driving factors and radiation driving factors, the second-order partial correlation coefficients between temperature driving factors and vegetation carbon fixation data after excluding precipitation driving factors and radiation driving factors, the second-order partial correlation coefficients between precipitation driving factors and vegetation carbon fixation data after excluding temperature driving factors and radiation driving factors, and the second-order partial correlation coefficients between radiation driving factors and vegetation carbon fixation data after excluding precipitation driving factors and temperature driving factors, the contribution rate of temperature driving factors to the change of vegetation carbon fixation in the area to be assessed during the time period to be assessed, the contribution rate of precipitation driving factors to the change of vegetation carbon fixation in the area to be assessed during the time period to be assessed, and the contribution rate of radiation driving factors to the change of vegetation carbon fixation in the area to be assessed during the time period to be assessed are calculated, including: calculating the contribution rate of temperature driving factors, precipitation driving factors and radiation driving factors Contribution rate sign; based on the changing trends of temperature driving factors, precipitation driving factors and radiation driving factors, the second-order partial correlation coefficient of temperature driving factors and vegetation carbon fixation data after excluding precipitation driving factors and radiation driving factors, the second-order partial correlation coefficient of precipitation driving factors and vegetation carbon fixation data after excluding precipitation driving factors and radiation driving factors, the second-order partial correlation coefficient of radiation driving factors and vegetation carbon fixation data after excluding precipitation driving factors and temperature driving factors, and the contribution rate signs of temperature driving factors, precipitation driving factors and radiation driving factors, calculate the contribution rate of temperature driving factors to the change of vegetation carbon fixation in the area to be assessed during the time period to be assessed, the contribution rate of precipitation driving factors to the change of vegetation carbon fixation in the area to be assessed during the time period to be assessed, and the contribution rate of radiation driving factors to the change of vegetation carbon fixation in the area to be assessed during the time period to be assessed.

[0013] Furthermore, the contribution rate sign is calculated according to the following formula: Among them, Slope is the contribution rate symbol, Var i is the VCS variable, i is the time index of the variable, represents the position of the variable in the data set, positive contribution (+, indicating an increase in the impact on VCS), negative contribution (-, indicating a decrease in the impact on VCS), and n is the total number of time index positions.

[0014] The present invention provides a system for evaluating the contribution rate of driving factors to changes in vegetation carbon sequestration, which applies the above-mentioned method for evaluating the contribution rate of driving factors to changes in vegetation carbon sequestration, including: a data acquisition module, used to acquire vegetation net primary productivity data and driving factor data of an area to be evaluated during a time period to be evaluated; a data processing module, used to calculate the vegetation carbon sequestration data of the area to be evaluated during the time period to be evaluated based on the vegetation net primary productivity data of the area to be evaluated during the time period to be evaluated, and to calculate the change trends of multiple driving factors based on the driving factor data of the area to be evaluated during the time period to be evaluated, and also used to calculate the correlation between multiple driving factors and vegetation carbon sequestration based on the vegetation carbon sequestration data and driving factor data of the area to be evaluated during the time period to be evaluated; a contribution evaluation module, used to calculate the contribution rate of multiple driving factors to the change in vegetation carbon sequestration in the area to be evaluated during the time period to be evaluated based on the change trends of the multiple driving factors and the correlations between the multiple driving factors and vegetation carbon sequestration.

[0015] Compared with the prior art, the method and system for evaluating the contribution rate of driving factors to vegetation carbon fixation changes provided by the present invention have at least the following beneficial effects:

[0016] Existing technologies only focus on the spatiotemporal variation trends of VCS and the correlation of influencing factors. When studying the relationship between multiple driving factors and VCS and the relationship between multiple driving factors, traditional correlation analysis can only explore the relationship between a single driving factor and VCS, and cannot rule out the influence of other meteorological driving factors. The use of partial derivatives can effectively rule out the influence of redundant variables, thereby more accurately reflecting the relationship between a single driving factor and VCS, and is also conducive to extracting the impact of human activities on VCS. The quantitative study of the contribution of multiple factors to VCS is achieved, and the quantitative resolution is high. Combined with the complex terrain and diverse vegetation of the area to be evaluated, a localized dynamic time-effectiveness modeling method is adopted, which has a high degree of refinement and strong scalability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] This specification will be further described in the form of exemplary embodiments, which will be described in detail by the accompanying drawings. These embodiments are not restrictive, and in these embodiments, the same number represents the same structure, wherein:

[0018] Figure 1 It is a flow chart of a method for evaluating the contribution rate of driving factors to changes in vegetation carbon sequestration according to some embodiments of this specification;

[0019] Figure 2 It is a schematic diagram of modules of a system for evaluating the contribution rate of driving factors to changes in vegetation carbon sequestration according to some embodiments of this specification;

[0020] Figure 3is a schematic diagram of test analysis results shown in some embodiments of this specification;

[0021] Figure 4a is a schematic diagram of the contribution of temperature to VCS according to some embodiments of this specification;

[0022] Figure 4b is a schematic diagram of the contribution of precipitation to VCS according to some embodiments of this specification;

[0023] Figure 4c is a schematic diagram of the contribution of radiation to VCS according to some embodiments of this specification;

[0024] Figure 4d is a schematic diagram of the contribution of human activities to VCS according to some embodiments of the present specification. DETAILED DESCRIPTION

[0025] In order to more clearly illustrate the technical solutions of the embodiments of this specification, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some examples or embodiments of this specification. For ordinary technicians in this field, this specification can also be applied to other similar scenarios based on these drawings without creative work. Unless it is obvious from the language environment or otherwise explained, the same reference numerals in the figures represent the same structure or operation.

[0026] Figure 1 is a flow chart of a method for evaluating the contribution of driving factors to changes in vegetation carbon sequestration according to some embodiments of this specification, such as Figure 1 As shown, the method for assessing the contribution of driving factors to changes in vegetation carbon sequestration may include the following steps.

[0027] Step 110, obtaining the vegetation net primary productivity data of the area to be assessed during the time period to be assessed, and calculating the vegetation carbon fixation data of the area to be assessed during the time period to be assessed based on the vegetation net primary productivity data of the area to be assessed during the time period to be assessed.

[0028] The amount of CO2 fixed by vegetation in a certain period of time can be calculated by calculating the organic matter photosynthesized by vegetation in the study area during the corresponding period combined with CO2. There are differences in vegetation types in different regions, and the feedback mechanism of carbon fixation on the ecological environment is different due to the influence of geographical location, climatic conditions, etc.

[0029] The vegetation carbon sequestration data of the area to be assessed during the period to be assessed can be calculated based on the following formula according to the vegetation net primary productivity data of the area to be assessed during the period to be assessed, including:

[0030]

[0031] Among them, VCS(x,t) is the amount of CO2 fixed by the vegetation in the area to be evaluated per unit time t and pixel x, and NPP(x,t) is the net primary productivity of the vegetation in the area to be evaluated per unit time t and pixel x.

[0032] The total amount of CO2 fixed in the area to be evaluated is the product of the amount of CO2 fixed by the vegetation in the area to be evaluated per unit time t and at pixel x and the area.

[0033] Step 120 , obtaining driving factor data of the area to be evaluated in the time period to be evaluated, and calculating the change trends of multiple driving factors according to the driving factor data of the area to be evaluated in the time period to be evaluated.

[0034] Specifically, the multiple driving factors are divided into meteorological driving factors (precipitation driving factors, temperature driving factors, radiation driving factors) and human activity driving factors as shown in Table 1.

[0035] Table 1

[0036]

[0037] In some embodiments, the driving factor data of the area to be evaluated during the time period to be evaluated includes meteorological data of the area to be evaluated during the time period to be evaluated.

[0038] According to the driving factor data of the area to be evaluated during the period to be evaluated, the changing trends of multiple driving factors are calculated, including:

[0039] According to the meteorological data of the area to be evaluated during the period to be evaluated, the changing trends of multiple meteorological driving factors are calculated.

[0040] The Theil-Sen Median method was used to analyze the temporal and spatial variation trend of VCS in the evaluated area during the evaluated period, and the Mann-Kendall method was used for significance test. The Theil-Sen Median method estimates the long-term variation trend of variables by calculating the median in a long time series. This method can avoid discrete and erroneous data and reduce the impact of errors on the overall trend and judgment.

[0041] The following formula is used to calculate the changing trends of multiple meteorological driving factors based on the meteorological data of the area to be evaluated during the period to be evaluated:

[0042]

[0043] Among them, θ slope is the changing trend of meteorological driving factors, median() is the median value, x k and x lVariables representing different times, where n is the total number of time index positions. When θ slope > 0 indicates an upward trend of the variable, and vice versa for a downward trend. The larger the value of θ slope , the more obvious the increasing or decreasing trend of the meteorological driving factors in the area to be evaluated during the evaluation period. For example, taking the temperature driving factor as an example, the sample is the temperature data of a certain area from 2001 to 2020, and n is taken as 20; perform a 20-year regression calculation on the temperature, and use the data of the next year (X k ) and the data of the previous year (X l ) to calculate according to the formula, and the change trend of the temperature driving factor in these 20 years can be obtained.

[0044] The Mann-Kendall test is a non-parametric statistical method for long time series, which is used to test samples with non-normal or certain distribution characteristics. It is relatively less affected by outliers, can have missing values, and has strong quantitative analysis capabilities. Analyze the VCS of the area to be evaluated during the evaluation period at the pixel scale through Theil-Sen Median trend analysis and Mann-Kendall test, and reclassify the results of the Mann-Kendall test.

[0045] On the basis of completing the above VCS estimation and multi-year spatio-temporal change trend analysis, further apply the coefficient of variation method to evaluate the stability and persistence of the spatio-temporal change of VCS in the study area. In this case, a spatial distribution characteristic model of the stability degree of VCS in the study area during the evaluation period based on pixels is constructed according to the size of the Cv value:

[0046]

[0047] The coefficient of variation can reveal the fluctuation and stability degree of the variable during the study period, and also characterize the stability degree of the ecosystem in the corresponding time series. The larger the Cv value, the greater the fluctuation of the variable and the relatively lower the stability degree, and vice versa, the more stable the variable. When Cv ≤ 0.1, it indicates that the increasing or decreasing trend of VCS is extremely stable; 0.1 < Cv ≤ 0.2, it indicates that the increasing or decreasing trend of VCS is stable; 0.2 < Cv ≤ 0.3, it indicates that the increasing or decreasing trend of VCS is unstable; 0.3 < Cv, it indicates that the increasing or decreasing trend of VCS is extremely unstable.

[0048] According to the stability evaluation results, it is possible to determine the change trend of VCS in the study area during the study period, whether VCS maintains a stable increase or decrease throughout the year. For example, in the area where Cv ≤ 0.1 during the study period, VCS maintains an extremely stable increasing or decreasing trend, while in the area where 0.3 < Cv, the change of VCS is increasing and decreasing during the study period, showing discontinuous mutation situations.

[0049] The coefficient of variation was used to analyze the stability of the VCS in the test area to be evaluated during the test period. The test analysis results are as follows: Figure 3 As shown in the figure, the interannual fluctuation of VCS in the experimental area to be evaluated during the experimental period of evaluation is generally small, of which about 80.58% of the areas are stable (19.21% are extremely stable), and the extremely stable areas are mostly in some areas on the northwest side of the experimental area to be evaluated; while 19.42% of the areas are unstable (4.74% are extremely unstable), among which the densely populated areas in the experimental area to be evaluated have a greater impact on vegetation, and the urban centers in the experimental area to be evaluated are mostly unstable. In addition, some high-altitude areas and rivers in the experimental area to be evaluated also show obvious instability.

[0050] Step 130, calculating the correlation between multiple driving factors and vegetation carbon sequestration based on the vegetation carbon sequestration data and driving factor data of the area to be assessed during the time period to be assessed.

[0051] Specifically, correlation analysis can explore the relationship between VCS and a single driving factor, but the relationship cannot exclude the influence of other driving factors. When studying the relationship between multiple variables, the partial correlation coefficient can effectively exclude the influence of redundant variables, thereby more accurately reflecting the relationship between two variables. The partial correlation coefficient is also widely used to explore the relationship between vegetation and influencing factors. Based on the calculation of correlation and partial correlation, the second-order partial correlation coefficient is calculated to exclude the influence of other factors and explore the relationship between a single driving factor and VCS.

[0052] In some embodiments, step 130 specifically includes:

[0053] For each meteorological driving factor, the correlation coefficient between each meteorological driving factor and vegetation carbon sequestration data is calculated based on the vegetation carbon sequestration data and meteorological data of the area to be assessed during the period to be assessed;

[0054] For any two meteorological driving factors, the correlation coefficient of the two meteorological driving factors is calculated based on the meteorological data of the area to be evaluated during the period to be evaluated;

[0055] For each meteorological driving factor, the n-1 order partial correlation coefficient between the meteorological driving factor and the vegetation carbon sequestration data is calculated based on the correlation coefficient between each meteorological driving factor and the vegetation carbon sequestration data and the correlation coefficient between any two meteorological driving factors, where n is the total number of driving factors.

[0056] Multiple meteorological driving factors include temperature driving factors, precipitation driving factors and radiation driving factors.

[0057] In some embodiments, for each meteorological driving factor, the n-1 order partial correlation coefficient between the meteorological driving factor and the vegetation carbon sequestration data is calculated based on the correlation coefficient between each meteorological driving factor and the vegetation carbon sequestration data and the correlation coefficients between any two meteorological driving factors, including:

[0058] For the temperature driving factor, the first-order partial correlation coefficient between the temperature driving factor and the vegetation carbon fixation data after excluding the precipitation driving factor and the first-order partial correlation coefficient between the temperature driving factor and the vegetation carbon fixation data after excluding the radiation driving factor were calculated based on the correlation coefficient between each meteorological driving factor and the vegetation carbon fixation data and the correlation coefficient between any two meteorological driving factors.

[0059] For precipitation driving factors, based on the correlation coefficient between each meteorological driving factor and vegetation carbon fixation data and the correlation coefficient between any two meteorological driving factors, the first-order partial correlation coefficient between the precipitation driving factor and vegetation carbon fixation data after excluding the temperature driving factor and the first-order partial correlation coefficient between the precipitation driving factor and vegetation carbon fixation data after excluding the radiation driving factor were calculated;

[0060] For the radiation driving factors, the first-order partial correlation coefficients between the radiation driving factors and the vegetation carbon fixation data after excluding the temperature driving factors and the first-order partial correlation coefficients between the radiation driving factors and the vegetation carbon fixation data after excluding the precipitation driving factors were calculated based on the correlation coefficients between each meteorological driving factor and the vegetation carbon fixation data and the correlation coefficients between any two meteorological driving factors.

[0061] According to the first-order partial correlation coefficient between the temperature driving factor and the vegetation carbon fixation data after excluding the precipitation driving factor, the first-order partial correlation coefficient between the temperature driving factor and the vegetation carbon fixation data after excluding the radiation driving factor, the first-order partial correlation coefficient between the precipitation driving factor and the vegetation carbon fixation data after excluding the temperature driving factor, the first-order partial correlation coefficient between the radiation driving factor and the vegetation carbon fixation data after excluding the temperature driving factor, and the first-order partial correlation coefficient between the radiation driving factor and the vegetation carbon fixation data after excluding the precipitation driving factor, the second-order partial correlation coefficient between the temperature driving factor and the vegetation carbon fixation data after excluding the precipitation driving factor and the radiation driving factor, the second-order partial correlation coefficient between the precipitation driving factor and the vegetation carbon fixation data after excluding the temperature driving factor and the radiation driving factor, and the second-order partial correlation coefficient between the radiation driving factor and the vegetation carbon fixation data after excluding the precipitation driving factor and the temperature driving factor are calculated.

[0062] The first-order partial correlation coefficient can be calculated according to the following formula:

[0063]

[0064] Among them, R ij,k R is the partial correlation between variables i and j after excluding the influence of variable k.ij is the correlation between two variables i and j.

[0065] The second-order partial correlation coefficient can be calculated according to the following formula:

[0066]

[0067] Among them, R ij,kl In order to eliminate the partial correlation between variables i and j after the influence of variables k and l, R ij,k , R il,k , R jl,k The partial correlation coefficients of the two driving factors and VCS were calculated respectively. The relationship between VCS and meteorological driving factors and human activity driving factors was explored through the second-order partial correlation coefficient, and the t-test method was used to test the significance of the results.

[0068] Step 140, based on the change trends of the multiple driving factors and the correlation between the multiple driving factors and vegetation carbon sequestration, calculate the contribution of the multiple driving factors to the change in vegetation carbon sequestration in the area to be assessed during the time period to be assessed.

[0069] The quantitative formula that characterizes the contribution of multiple driving factors to the change of vegetation carbon sequestration in the area to be assessed during the period to be assessed is:

[0070]

[0071] In the above formula, Indicates the change amount of VCS. S c , P c 、T c and H c Respectively represent the contribution of radiation, precipitation, temperature, and human activities to the change in VCS. Each component in the right formula represents the product of the second-order partial correlation coefficient between the driving factor and VCS and the change trend of the driving factor. The contribution rate of each driving factor can be obtained by the ratio of the contribution of each driving factor to the change in VCS. For example, the contribution rate of the temperature driving factor to the change in vegetation carbon fixation can be obtained by T c and The ratio of is obtained.

[0072] In some embodiments, step 140 specifically includes:

[0073] Based on the changing trends of temperature driving factors, precipitation driving factors and radiation driving factors, the second-order partial correlation coefficients between temperature driving factors and vegetation carbon fixation data after excluding precipitation driving factors and radiation driving factors, the second-order partial correlation coefficients between precipitation driving factors and vegetation carbon fixation data after excluding temperature driving factors and radiation driving factors, and the second-order partial correlation coefficients between radiation driving factors and vegetation carbon fixation data after excluding precipitation driving factors and temperature driving factors, calculate the contribution rate of temperature driving factors to the change of vegetation carbon fixation in the area to be assessed during the time period to be assessed, the contribution rate of precipitation driving factors to the change of vegetation carbon fixation in the area to be assessed during the time period to be assessed, and the contribution rate of radiation driving factors to the change of vegetation carbon fixation in the area to be assessed during the time period to be assessed;

[0074] Based on the contribution rate of temperature driving factors to the change of vegetation carbon sequestration in the assessment area during the assessment period, the contribution rate of precipitation driving factors to the change of vegetation carbon sequestration in the assessment area during the assessment period, and the contribution rate of radiation driving factors to the change of vegetation carbon sequestration in the assessment area during the assessment period, the contribution rate of human activities to the change of vegetation carbon sequestration in the assessment area during the assessment period is calculated.

[0075] The contribution sign is calculated according to the following formula:

[0076]

[0077] Among them, Slope is the contribution rate symbol, Var i is the VCS variable, i is the time index of the variable, represents the position of the variable in the data set, positive contribution (+, indicating an increase in the impact on VCS), negative contribution (-, indicating a decrease in the impact on VCS), and n is the total number of time index positions.

[0078] The contribution rates of multiple driving factors to the experimental area to be evaluated during the experimental period to be evaluated are shown in Table 2.

[0079] Table 2

[0080]

[0081]

[0082] Depend on Figures 4a-4dIt can be seen that the impact of temperature on the VCS of the experimental area to be evaluated during the experimental period of evaluation is mainly positive contribution, with the area with positive contribution accounting for about 60.08% and the area with negative contribution accounting for 39.92%. It is relatively concentrated in the part of area A of the experimental area to be evaluated, which is manifested as positive contribution in the northern part of the part of area A of the experimental area to be evaluated and negative contribution in the plain. The spatial distribution characteristics of precipitation contribution are more obvious. It is positively contributed to most areas of the experimental area to be evaluated, accounting for 70.38% of the area, and the area with negative contribution accounts for only 28.62%. The positive contribution to the basin area is more significant, among which the basin center and its southern area have a positive contribution to VCS of more than 10g / m2 / a. The positive contribution of radiation to the VCS of the experimental area to be evaluated accounts for 57.12% of the area, and the negative contribution accounts for about 42.88%. The contribution of human activities is mainly positive, with positive contribution areas accounting for 71.90% and negative contribution accounting for only 28.10%. In the basin area and its surrounding mountainous areas, the positive contribution of human activities exceeds 30g / m2 / a, but in some area C of the experimental evaluation area, the negative contribution of human activities is more obvious. Secondly, around the two large urban centers, human activities also show obvious negative contribution.

[0083] Figure 2 is a schematic diagram of a module of a system for evaluating the contribution of driving factors to changes in vegetation carbon fixation according to some embodiments of this specification, such as Figure 2 As shown, the system for evaluating the contribution rate of driving factors to changes in vegetation carbon sequestration may include a data acquisition module, a data processing module and a contribution evaluation module.

[0084] The data acquisition module can be used to obtain the vegetation net primary productivity data and driving factor data of the area to be evaluated during the time period to be evaluated;

[0085] The data processing module can be used to calculate the vegetation carbon sequestration data of the area to be assessed during the time period to be assessed based on the vegetation net primary productivity data of the area to be assessed during the time period to be assessed, calculate the change trend of multiple driving factors based on the driving factor data of the area to be assessed during the time period to be assessed, and calculate the correlation between multiple driving factors and vegetation carbon sequestration based on the vegetation carbon sequestration data and driving factor data of the area to be assessed during the time period to be assessed;

[0086] The contribution assessment module can be used to calculate the contribution rate of multiple driving factors to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed based on the change trends of multiple driving factors and the correlation between multiple driving factors and vegetation carbon sequestration.

[0087] The system for evaluating the contribution rate of driving factors to changes in vegetation carbon sequestration can be used to execute the method for evaluating the contribution rate of driving factors to changes in vegetation carbon sequestration. For more descriptions of the system for evaluating the contribution rate of driving factors to changes in vegetation carbon sequestration, please refer to the relevant descriptions of the system for evaluating the contribution rate of driving factors to changes in vegetation carbon sequestration, which will not be repeated here.

[0088] Finally, it should be understood that the embodiments described in this specification are only used to illustrate the principles of the embodiments of this specification. Other variations may also fall within the scope of this specification. Therefore, as an example and not a limitation, alternative configurations of the embodiments of this specification may be considered consistent with the teachings of this specification. Accordingly, the embodiments of this specification are not limited to the embodiments explicitly introduced and described in this specification.

Claims

1. A method for assessing the contribution of driving factors to changes in vegetation carbon sequestration, characterized in that: include: Obtaining vegetation net primary productivity data of the area to be assessed during the time period to be assessed, and calculating vegetation carbon sequestration data of the area to be assessed during the time period to be assessed based on the vegetation net primary productivity data of the area to be assessed during the time period to be assessed; Acquire driving factor data of the area to be evaluated during the time period to be evaluated, and calculate the change trends of multiple driving factors according to the driving factor data of the area to be evaluated during the time period to be evaluated; Calculate the correlation between multiple driving factors and vegetation carbon sequestration based on the vegetation carbon sequestration data and driving factor data of the area to be assessed during the time period to be assessed, where the multiple meteorological driving factors include temperature driving factors, precipitation driving factors, and radiation driving factors; Based on the change trends of the multiple driving factors and the correlation between the multiple driving factors and vegetation carbon sequestration, the contribution rate of the multiple driving factors to the vegetation carbon sequestration change in the area to be assessed during the time period to be assessed is calculated, specifically including: Based on the changing trends of temperature driving factors, precipitation driving factors and radiation driving factors, the second-order partial correlation coefficients between temperature driving factors and vegetation carbon sequestration data after excluding precipitation driving factors and radiation driving factors, the second-order partial correlation coefficients between precipitation driving factors and vegetation carbon sequestration data after excluding temperature driving factors and radiation driving factors, and the second-order partial correlation coefficients between radiation driving factors and vegetation carbon sequestration data after excluding precipitation driving factors and temperature driving factors, calculate the contribution rate of temperature driving factors to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed, the contribution rate of precipitation driving factors to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed, and the contribution rate of radiation driving factors to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed; Based on the contribution rate of temperature driving factors to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed, the contribution rate of precipitation driving factors to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed, and the contribution rate of radiation driving factors to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed, the contribution rate of human activities to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed is calculated.

2. The method for evaluating the contribution of driving factors to changes in vegetation carbon sequestration according to claim 1, characterized in that: The vegetation carbon sequestration data of the area to be assessed during the period to be assessed is calculated based on the following formula according to the vegetation net primary productivity data of the area to be assessed during the period to be assessed, including: Among them, VCS(x,t) is the amount of CO2 fixed by the vegetation in the area to be evaluated per unit time t and pixel x, and NPP(x,t) is the net primary productivity of the vegetation in the area to be evaluated per unit time t and pixel x.

3. The method for evaluating the contribution of driving factors to vegetation carbon sequestration changes according to claim 2, characterized in that: The driving factor data of the area to be evaluated in the time period to be evaluated includes the meteorological data of the area to be evaluated in the time period to be evaluated; According to the driving factor data of the area to be evaluated in the time period to be evaluated, the changing trends of multiple driving factors are calculated, including: According to the meteorological data of the area to be evaluated during the time period to be evaluated, the changing trends of multiple meteorological driving factors are calculated.

4. The method for evaluating the contribution of driving factors to vegetation carbon sequestration changes according to claim 3, characterized in that: The change trends of multiple meteorological driving factors are calculated according to the meteorological data of the area to be evaluated during the period to be evaluated by the following formula: Among them, θ slope is the changing trend of meteorological driving factors, median() is the median value, x k is the variable at the time index k, x l is the variable at time index position l, and n is the total number of time index positions.

5. The method for evaluating the contribution of driving factors to vegetation carbon sequestration changes according to claim 3 or 4, characterized in that: According to the vegetation carbon sequestration data and driving factor data of the area to be assessed during the period to be assessed, the correlation between multiple driving factors and vegetation carbon sequestration is calculated, including: For each of the meteorological driving factors, based on the vegetation carbon sequestration data and meteorological data of the area to be assessed during the time period to be assessed, calculate the correlation coefficient between each of the meteorological driving factors and the vegetation carbon sequestration data; For any two of the meteorological driving factors, based on the meteorological data of the area to be evaluated during the time period to be evaluated, calculate the correlation coefficient of the two meteorological driving factors; For each meteorological driving factor, the n-1 order partial correlation coefficient between the meteorological driving factor and the vegetation carbon fixation data is calculated based on the correlation coefficient between each meteorological driving factor and the vegetation carbon fixation data and the correlation coefficient between any two meteorological driving factors, where n is the total number of driving factors.

6. The method for evaluating the contribution of driving factors to changes in vegetation carbon sequestration according to claim 5, characterized in that: For each of the meteorological driving factors, the n-1 order partial correlation coefficient between the meteorological driving factor and the vegetation carbon fixation data is calculated based on the correlation coefficient between each of the meteorological driving factors and the vegetation carbon fixation data and the correlation coefficients between any two of the meteorological driving factors, including: For the temperature driving factor, based on the correlation coefficient between each meteorological driving factor and the vegetation carbon fixation data and the correlation coefficient between any two meteorological driving factors, calculate the first-order partial correlation coefficient between the temperature driving factor and the vegetation carbon fixation data after excluding the precipitation driving factor and the first-order partial correlation coefficient between the temperature driving factor and the vegetation carbon fixation data after excluding the radiation driving factor; For the precipitation driving factor, based on the correlation coefficient between each meteorological driving factor and the vegetation carbon fixation data and the correlation coefficients between any two meteorological driving factors, calculate the first-order partial correlation coefficient between the precipitation driving factor and the vegetation carbon fixation data after excluding the temperature driving factor and the first-order partial correlation coefficient between the precipitation driving factor and the vegetation carbon fixation data after excluding the radiation driving factor; For the radiation driving factor, based on the correlation coefficient between each meteorological driving factor and the vegetation carbon fixation data and the correlation coefficient between any two meteorological driving factors, calculate the first-order partial correlation coefficient between the radiation driving factor and the vegetation carbon fixation data after excluding the temperature driving factor and the first-order partial correlation coefficient between the radiation driving factor and the vegetation carbon fixation data after excluding the precipitation driving factor; According to the first-order partial correlation coefficient between the temperature driving factor and the vegetation carbon fixation data after excluding the precipitation driving factor, the first-order partial correlation coefficient between the temperature driving factor and the vegetation carbon fixation data after excluding the radiation driving factor, the first-order partial correlation coefficient between the precipitation driving factor and the vegetation carbon fixation data after excluding the temperature driving factor, the first-order partial correlation coefficient between the radiation driving factor and the vegetation carbon fixation data after excluding the temperature driving factor, and the first-order partial correlation coefficient between the radiation driving factor and the vegetation carbon fixation data after excluding the precipitation driving factor, the second-order partial correlation coefficient between the temperature driving factor and the vegetation carbon fixation data after excluding the precipitation driving factor and the radiation driving factor, the second-order partial correlation coefficient between the precipitation driving factor and the vegetation carbon fixation data after excluding the temperature driving factor and the radiation driving factor, and the second-order partial correlation coefficient between the radiation driving factor and the vegetation carbon fixation data after excluding the precipitation driving factor and the temperature driving factor are calculated.

7. The method for evaluating the contribution of driving factors to changes in vegetation carbon sequestration according to claim 1, characterized in that: Based on the changing trends of temperature driving factors, precipitation driving factors and radiation driving factors, the second-order partial correlation coefficient between temperature driving factors and vegetation carbon fixation data after excluding precipitation driving factors and radiation driving factors, the second-order partial correlation coefficient between precipitation driving factors and vegetation carbon fixation data after excluding temperature driving factors and radiation driving factors, and the second-order partial correlation coefficient between radiation driving factors and vegetation carbon fixation data after excluding precipitation driving factors and temperature driving factors, the contribution rate of temperature driving factors to the change of vegetation carbon fixation in the area to be assessed during the time period to be assessed, the contribution rate of precipitation driving factors to the change of vegetation carbon fixation in the area to be assessed during the time period to be assessed, and the contribution rate of radiation driving factors to the change of vegetation carbon fixation in the area to be assessed during the time period to be assessed are calculated, including: Calculate the contribution rate signs of temperature driving factor, precipitation driving factor and radiation driving factor; Based on the changing trends of temperature driving factors, precipitation driving factors and radiation driving factors, the second-order partial correlation coefficient between temperature driving factors and vegetation carbon sequestration data after excluding precipitation driving factors and radiation driving factors, the second-order partial correlation coefficient between precipitation driving factors and vegetation carbon sequestration data after excluding precipitation driving factors and radiation driving factors, the second-order partial correlation coefficient between radiation driving factors and vegetation carbon sequestration data after excluding precipitation driving factors and temperature driving factors, and the contribution rate signs of temperature driving factors, precipitation driving factors and radiation driving factors, the contribution rate of temperature driving factors to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed, the contribution rate of precipitation driving factors to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed, and the contribution rate of radiation driving factors to the change of vegetation carbon sequestration in the area to be assessed during the time period to be assessed are calculated.

8. The method for evaluating the contribution of driving factors to changes in vegetation carbon sequestration according to claim 7, characterized in that: The contribution sign is calculated according to the following formula: Among them, Slope is the contribution rate symbol, Var i is a VCS variable, i is the year index of the variable, indicating the position of the variable in the data set, and n is the total number of time index positions.

9. A system for evaluating the contribution of driving factors to changes in vegetation carbon sequestration, characterized in that: The method for evaluating the contribution rate of driving factors to vegetation carbon sequestration changes according to any one of claims 1 to 8 comprises: A data acquisition module is used to obtain the net primary productivity data and driving factor data of the vegetation in the area to be evaluated during the time period to be evaluated; A data processing module, used to calculate the vegetation carbon sequestration data of the area to be assessed during the time period to be assessed based on the vegetation net primary productivity data of the area to be assessed during the time period to be assessed, calculate the change trend of multiple driving factors based on the driving factor data of the area to be assessed during the time period to be assessed, and also used to calculate the correlation between multiple driving factors and vegetation carbon sequestration based on the vegetation carbon sequestration data and driving factor data of the area to be assessed during the time period to be assessed; The contribution assessment module is used to calculate the contribution rate of multiple driving factors to the change of vegetation carbon fixation in the area to be assessed during the time period to be assessed based on the change trends of the multiple driving factors and the correlation between the multiple driving factors and vegetation carbon fixation.

Images