Method and system for estimating overground and underground net primary productivity of terrestrial ecosystem

Abstract

The invention provides a terrestrial ecosystem overground and underground net primary productivity estimation method and system. The method comprises the following steps: acquiring vegetation overground and underground net primary productivity observation data and resource availability data; calibrating a comprehensive rate frame parameter according to the overground net primary productivity observation data, and estimating an overground net primary productivity simulation value based on the comprehensive rate frame parameter; estimating an overground and underground net primary productivity distribution proportion based on overground and underground net primary productivity observation data of vegetation; and estimating an underground net primary productivity simulation value based on an above-ground net primary productivity simulation value obtained based on the above-ground and underground net primary productivity distribution proportion. The method has good applicability; the method can be used for simulating the spatial and temporal distribution rule of vegetation productivity and steadily evaluating the evolution dynamic state of the vegetation net primary productivity, is beneficial to evaluating a global carbon model, further accurately evaluating the regional carbon income and expenditure level and deepening the understanding of the global carbon balance complex dynamic state under the constantly changing climate condition.

Description

Technical Field

[0001] The invention belongs to the technical field of ecology, and in particular relates to a method and system for estimating above-ground and underground net primary productivity of a terrestrial ecosystem. Background Art

[0002] The net primary productivity (NPP) of vegetation in terrestrial ecosystems refers to the net total amount of organic matter accumulated by vegetation through photosynthesis, and is an important component of the global terrestrial carbon cycle. A deep understanding of the dynamic evolution of vegetation net primary productivity can provide a scientific basis and effective support for monitoring regional carbon budgets, evaluating ecosystem functions, and formulating carbon management strategies. As an important part of the terrestrial carbon cycle, accurately estimating the vegetation productivity process is the key to predicting the carbon peak and carbon neutrality levels under climate change conditions. It is also the premise and basis for a reasonable evaluation of regional carbon balances, and is a major focus of current carbon cycle research.

[0003] In recent decades, the emergence of statistical models, remote sensing technology and terrestrial ecosystem models has driven significant progress in the quantification of global NPP. These methods mainly rely on empirical relationships between NPP and predictor variables, or theoretical assumptions about the photosynthesis process. However, there are large differences in the NPP estimated by these models, with considerable uncertainty. In addition, the belowground part of net productivity (BNPP) is the most uncertain part of the global carbon cycle, but it is still under-explored due to the limitations of observation difficulties and high costs.

[0004] In view of this, how to propose a method to estimate the above-ground and underground net primary productivity of terrestrial ecosystems, which can estimate the spatial patterns of NPP and its components in a robust and concise manner, has become a technical problem that needs to be solved at present. Summary of the invention

[0005] In response to the shortcomings in the prior art, the present invention is based on the measured data of the net primary productivity of ecosystem vegetation, according to the response relationship of the aboveground part of the net productivity to the availability of different resources (water availability, light availability), and combined with the aboveground and underground carbon distribution relationship of the net primary productivity of vegetation, a method for estimating the above-ground and underground net primary productivity of terrestrial ecosystems is proposed.

[0006] In order to solve the above problems, the present invention adopts the following technical solutions:

[0007] A method for estimating above-ground and below-ground net primary productivity of terrestrial ecosystems comprises the following steps:

[0008] Step 1, obtaining the above-ground and underground net primary productivity observation data of vegetation and resource availability data, and dividing the above-ground net primary productivity observation data obtained into a calibration data set and a test data set;

[0009] Step 2: calibrate the comprehensive rate framework parameters according to the aboveground net primary productivity observation data in the calibration data set, and construct an aboveground net primary productivity estimation model based on the comprehensive rate framework parameters to estimate the aboveground net primary productivity simulation value;

[0010] Step 3: Based on the observation data of net primary productivity above and below ground, the distribution ratio of net primary productivity above and below ground is estimated according to the functional balance theory;

[0011] Step 4: Estimate the simulated value of underground net primary productivity based on the distribution ratio of above-ground and underground net primary productivity and the simulated value of above-ground net primary productivity obtained in step 2.

[0012] Furthermore, the method also includes step 5: verifying the simulation accuracy of the simulated values ​​of above-ground net primary productivity and the simulated values ​​of underground net primary productivity.

[0013] Furthermore, the comprehensive rate framework parameters in step 2 are:

[0014]

[0015] Where r is the comprehensive resource-limited rate of vegetation photosynthesis, ω i is the sensitivity of vegetation to the availability of different resources, x i is the normalized resource availability, where i represents different resource types, x1 is the normalized energy availability, and n is the total number of resource types.

[0016] Furthermore, the

[0017] Furthermore, the distribution ratio R of above-ground and underground net primary productivity in step 3 is:

[0018] Among them, BNPP is the observed data of underground net primary productivity, ANPP is the observed data of above-ground net primary productivity; f(ANPP) is the function of the observed data of above-ground net primary productivity.

[0019] Furthermore, the simulated value of underground net primary productivity BNPP' in step 4 is:

[0020] BNPP'=ANPP'×R.

[0021] Furthermore, in step 5, the Nash efficiency coefficient is selected to verify the simulation accuracy of the above-ground net primary productivity simulation value and the underground net primary productivity simulation value.

[0022] In another aspect, the present invention provides a system for estimating above-ground and below-ground net primary productivity of a terrestrial ecosystem, comprising:

[0023] An observation data acquisition module is used to acquire the above-ground and underground net primary productivity observation data of vegetation and resource availability data, and divide the acquired above-ground net primary productivity observation data into a calibration data set and a test data set;

[0024] The first estimation module is used to calibrate the comprehensive rate framework parameters according to the aboveground net primary productivity observation data in the calibration data set, and to construct an aboveground net primary productivity estimation model based on the comprehensive rate framework parameters to estimate the aboveground net primary productivity simulation value;

[0025] A distribution ratio estimation module is used to estimate the distribution ratio of above-ground and underground net primary productivity based on the observation data of above-ground and underground net primary productivity of vegetation according to the functional balance theory;

[0026] A second estimation module is used to estimate the simulated value of underground net primary productivity based on the distribution ratio of above-ground and underground net primary productivity and the obtained simulated value of above-ground net primary productivity;

[0027] The verification module is used to verify the simulation accuracy of the above-ground net primary productivity simulation value and the underground net primary productivity simulation value.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] Based on the actual observation data of vegetation net primary productivity, an explicit model for estimating aboveground and underground net primary productivity is proposed. The present invention has the characteristics of few parameters, simple and transparent structure, and therefore has good applicability. The present invention is simple and practical, and can be used to simulate the temporal and spatial distribution of vegetation productivity and robustly evaluate the evolution dynamics of vegetation net primary productivity. It is helpful to evaluate the global carbon model, further accurately evaluate the regional carbon balance level, and deepen the understanding of the complex dynamics of global carbon balance under changing climate conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 This is a flow chart of a method according to an embodiment of the present invention;

[0032] Figure 2 This is a model simulation effect test diagram of an embodiment of the present invention;

[0033] Figure 3 This is an application diagram of the spatial distribution estimation of global ecosystem net primary productivity according to an embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] It should be noted that, in the description of the embodiments of the present invention, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "include one..." do not exclude the existence of other identical elements in the process, method, article or device including the elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0036] The terms "first", "second", etc. in this application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0037] Example 1

[0038] The embodiment provides a method for estimating above-ground and below-ground net primary productivity of a terrestrial ecosystem, evaluating the model performance and applying it, including the following steps:

[0039] Step 1, obtaining the above-ground and underground net primary productivity observation data of vegetation and resource availability data, and dividing the above-ground net primary productivity observation data obtained into a calibration data set and a test data set;

[0040] This example selects 688 ANPP sample point measured data compiled as research examples, of which 297 sample points have paired BNPP observation data (https: / / doi.org / 10.6084 / m9.figshare.27237795.v1). The meteorological data of the corresponding location is extracted according to the latitude and longitude of the sample point.

[0041] The resource availability water and energy considered in this embodiment, the multi-year average absorbed light and effective radiation (APAR) and multi-year average precipitation (MAP) are used to characterize energy availability and water availability, respectively, and the obtained aboveground net primary productivity (ANPP) observation data set is divided into 481 calibration points and 207 test points;

[0042] Step 2: calibrate the comprehensive rate framework parameters according to the aboveground net primary productivity observation data in the calibration data set, and construct an aboveground net primary productivity estimation model based on the comprehensive rate framework parameters to estimate the aboveground net primary productivity simulation value;

[0043] According to the ANPP at the rate period and the normalized resource availability data, the integrated rate framework parameters are determined, and the expression is:

[0044]

[0045] Where x1 is the normalized energy availability and x2 is the normalized water availability.

[0046] The aboveground net primary productivity estimation model is:

[0047]

[0048] Among them, A max is the maximum aboveground net primary productivity, and ANPP' is the simulated value of aboveground net primary productivity.

[0049] Step 3: Based on the observation data of net primary productivity above and below ground, the distribution ratio of net primary productivity above and below ground is estimated according to the functional balance theory;

[0050] The distribution ratio of net primary productivity above and below ground is established based on measured data as follows:

[0051]

[0052] Step 4: Estimate the simulated value of underground net primary productivity based on the distribution ratio of above-ground and underground net primary productivity and the simulated value of above-ground net primary productivity obtained in step 2.

[0053] Step 5: Verify the simulation accuracy of the aboveground net primary productivity simulation values ​​and the underground net primary productivity simulation values.

[0054] The evaluation index is the Nash efficiency coefficient NSE, and the formula is as follows:

[0055]

[0056] In the formula, O i and P i are the observed and simulated values. Yes i The average value, YesP i The average value of (i=1,2,...,m);

[0057] The results show that the simulation of aboveground net primary productivity (ANPP) of vegetation is 0.71 in the rate period and 0.66 in the test period ( Figure 2 a). For the simulation of the aboveground and underground distribution ratio (BNPP:ANPP), the established model accuracy can reach 0.86 ( Figure 2 b). Further, by multiplying the estimated ANPP with the above-ground and underground distribution ratio, the BNPP accuracy indirectly estimated reached 0.93, proving that this method has a high degree of closure.

[0058] Figure 3 For the extended application of the present invention, the spatial variation characteristics of aboveground and underground productivity and their distribution ratios are estimated. The global ANPP, BNPP and fBNPP (BNPP / , respectively) are Figure 3 As shown in (a), 3(b), and 3(c).

[0059] It can be seen that the method for estimating the above-ground and underground net primary productivity of terrestrial ecosystems proposed in the present invention can effectively simulate the above-ground and underground net primary productivity of vegetation and robustly capture its spatial distribution characteristics.

[0060] Example 2

[0061] This embodiment provides a system for estimating above-ground and underground net primary productivity of a terrestrial ecosystem, comprising:

[0062] An observation data acquisition module is used to acquire the above-ground and underground net primary productivity observation data of vegetation and resource availability data, and divide the acquired above-ground net primary productivity observation data into a calibration data set and a test data set;

[0063] The first estimation module is used to calibrate the comprehensive rate framework parameters according to the aboveground net primary productivity observation data in the calibration data set, and to construct an aboveground net primary productivity estimation model based on the comprehensive rate framework parameters to estimate the aboveground net primary productivity simulation value;

[0064] A distribution ratio estimation module is used to estimate the distribution ratio of above-ground and underground net primary productivity based on the observation data of above-ground and underground net primary productivity of vegetation according to the functional balance theory;

[0065] A second estimation module is used to estimate the simulated value of underground net primary productivity based on the distribution ratio of above-ground and underground net primary productivity and the obtained simulated value of above-ground net primary productivity;

[0066] The verification module is used to verify the simulation accuracy of the above-ground net primary productivity simulation value and the underground net primary productivity simulation value.

[0067] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for estimating above-ground and underground net primary productivity of terrestrial ecosystems, characterized in that: The following steps are involved: Step 1, obtaining the above-ground and underground net primary productivity observation data of vegetation and resource availability data, and dividing the above-ground net primary productivity observation data obtained into a calibration data set and a test data set; Step 2: calibrate the comprehensive rate framework parameters according to the aboveground net primary productivity observation data in the calibration data set, and construct an aboveground net primary productivity estimation model based on the comprehensive rate framework parameters to estimate the aboveground net primary productivity simulation value; Step 3: Based on the observation data of net primary productivity above and below ground, the distribution ratio of net primary productivity above and below ground is estimated according to the functional balance theory; Step 4: Estimate the simulated value of underground net primary productivity based on the distribution ratio of above-ground and underground net primary productivity and the simulated value of above-ground net primary productivity obtained in step 2.

2. The method for estimating above-ground and underground net primary productivity of terrestrial ecosystems according to claim 1, characterized in that: It also includes step 5: verifying the simulation accuracy of the simulated values ​​of above-ground net primary productivity and below-ground net primary productivity.

3. The method for estimating above-ground and underground net primary productivity of a terrestrial ecosystem according to claim 1, characterized in that: The comprehensive rate framework parameters in step 2 are: Where r is the comprehensive resource-limited rate of vegetation photosynthesis, ω i is the sensitivity of vegetation to the availability of different resources, x i is the normalized resource availability, where i represents different resource types, x1 is the normalized energy availability, and n is the total number of resource types.

4. The method for estimating above-ground and underground net primary productivity of a terrestrial ecosystem according to claim 3, characterized in that: The aboveground net primary productivity estimation model is: ANPP'=A max ×r Among them, A max is the maximum aboveground net primary productivity, and ANPP' is the simulated value of aboveground net primary productivity.

5. The method for estimating above-ground and underground net primary productivity of a terrestrial ecosystem according to claim 1, characterized in that: The above-ground and underground net primary productivity distribution ratio R in step 3 is: Among them, BNPP is the observed data of underground net primary productivity, ANPP is the observed data of above-ground net primary productivity; f(ANPP) is the function of the observed data of above-ground net primary productivity.

6. The method for estimating above-ground and underground net primary productivity of terrestrial ecosystems according to claim 5, characterized in that: The simulated value of underground net primary productivity BNPP' in step 4 is: BNPP'=ANPP'×R.

7. The method for estimating above-ground and underground net primary productivity of terrestrial ecosystems according to claim 2, characterized in that: In step 5, the Nash efficiency coefficient is selected to verify the simulation accuracy of the above-ground net primary productivity simulation value and the underground net primary productivity simulation value.

8. A system for estimating above-ground and underground net primary productivity of terrestrial ecosystems, characterized in that: include: An observation data acquisition module is used to acquire the above-ground and underground net primary productivity observation data of vegetation and resource availability data, and divide the acquired above-ground net primary productivity observation data into a calibration data set and a test data set; The first estimation module is used to calibrate the comprehensive rate framework parameters according to the aboveground net primary productivity observation data in the calibration data set, and to construct an aboveground net primary productivity estimation model based on the comprehensive rate framework parameters to estimate the aboveground net primary productivity simulation value; A distribution ratio estimation module is used to estimate the distribution ratio of above-ground and underground net primary productivity based on the observation data of above-ground and underground net primary productivity of vegetation according to the functional balance theory; A second estimation module is used to estimate the simulated value of underground net primary productivity based on the distribution ratio of above-ground and underground net primary productivity and the obtained simulated value of above-ground net primary productivity; A verification module, which is used to verify the simulation accuracy of the aboveground net primary productivity simulation value and the underground net primary productivity simulation value; The system for estimating above-ground and underground net primary productivity of terrestrial ecosystems is used to execute the steps in the method for estimating above-ground and underground net primary productivity of terrestrial ecosystems described in any one of claims 1-7.

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