An ecological model of carbon loss and gain of a grazing grassland ecosystem

Abstract

The utility model discloses an ecological model of carbon loss and gain of grazing grassland ecosystem, which couples carbon loss caused by grazing, increase of soil organic carbon pool caused by animal excrement and carbon loss caused by animal trampling plant by establishing grazing carbon balance model and animal trampling carbon loss model, so as to obtain actual carbon loss and gain of grassland ecosystem. In the application, the utility model fully considers the factors of animal grazing, animal excretion and animal trampling in the whole grazing process, perfects the influence of disturbance factors of whole grassland ecosystem on vegetation, reduces the uncertainty of regional grassland carbon cycle simulation and improves the accuracy of results. Therefore, the utility model has high accuracy.

Description

TECHNICAL FIELD

[0001] The present application relates to an ecological model, belonging to the field of carbon cycle, and particularly relates to an ecological model for carbon loss and gain of a grazing grassland ecosystem. BACKGROUND

[0002] Grazing is the main production mode of herdsmen in grassland areas, but with the increase in population, human disturbance to grassland production is increasing, a large number of natural grasslands are reclaimed into farmland and operational pastures, the grazing intensity of grassland is increasing year by year, and the increasing grazing activities change the structure and function of the grassland ecosystem, and also exacerbate the impact of climate change on the grassland in arid areas; according to statistics, the area of grassland desertification is increasing at a rate of 0.5%-0.7% per year, and overgrazing is the main cause of grassland degradation and desertification, and climate change accelerates this process; at the same time, grassland desertification also affects the climate system by changing the surface energy balance; therefore, the ecological model needs to more accurately simulate the carbon cycle process of the grassland ecosystem, and grazing is an important part of it, and perfecting the description of grazing behavior in the existing model will help better assess the carbon and water cycle and the surface energy balance of the grassland ecosystem.

[0003] Previous studies have explored the impact of grazing on grassland carbon cycle, grazing changes the vegetation structure, biomass and nutrient redistribution, thereby indirectly affecting the vegetation and soil carbon pool, but the impact of grazing on the soil carbon pool is related to grazing intensity, climate conditions, etc., and the conclusions still have great differences; moderate grazing intensity helps to maintain or enhance the diversity of species in the grassland ecosystem, while lower or higher intensity of grazing will lead to a decrease in species diversity, but how to integrate the rules shown by the site experiments, describe the impact of grazing process on the grassland carbon cycle and perfect the existing model, there are still great difficulties.

[0004] In recent years, some ecological models have begun to consider the impact of grazing behavior on the grassland ecosystem to improve the simulation capability of carbon cycle; for example, the Biome-BGC model is an early developed model that couples grazing and vegetation carbon cycle, which considers the impact of animal grazing on vegetation leaf carbon, but Biome-BGC does not consider the maximum boundary of animal consumption existing in grazing behavior, which is easy to cause the simulation results to have "penetration" alarm, and also does not consider the impact of animal trampling behavior on the structure of grassland, which leads to the simulation results to underestimate the damage of grazing behavior, and it is difficult to achieve accurate simulation of regional ecosystem carbon cycle, therefore, there is an urgent need for a model that can reflect the special physiological and ecological structure characteristics of the grassland ecosystem and the complete grazing process (including animal feeding-animal excretion-animal trampling), reduce the uncertainty of regional grassland carbon cycle simulation caused by inaccurate description of grazing, and improve the accuracy of grassland carbon cycle simulation.

[0005] The information disclosed in this Background section is only for the purpose of increasing an understanding of the general background of the application and does not necessarily constitute an acknowledgement or any form of suggestion that this information forms part of the prior art already known to a person of ordinary skill in the art. SUMMARY

[0006] The purpose of the present application is to overcome the defects and problems of low accuracy in the prior art, and to provide an ecological model of carbon loss and gain of a grazing grassland ecosystem with high accuracy.

[0007] To achieve the above purpose, the technical solution of the present application is: an ecological model of carbon loss and gain of a grazing grassland ecosystem, comprising a grazing carbon balance model and an animal trampling carbon loss model.

[0008] The grazing carbon balance model comprises the amount of leaf carbon consumed by animals ΔC leaf and the amount of leaf carbon flowing to animals C graze ; the amount of leaf carbon flowing to animals C graze is used to obtain the amount of carbon loss C loss，graze caused by grazing, and the increase ΔSOC of soil organic carbon pool caused by animal excrement;

[0009] The animal trampling carbon loss model is used to obtain the carbon loss (C_loss_TI) caused by animal trampling plants;

[0010] In the ecological model, the amount of carbon loss C loss，graze caused by grazing, the increase ΔSOC of soil organic carbon pool caused by animal excrement, and the carbon loss (C_loss_TI) caused by animal trampling plants are coupled and calculated to obtain the actual carbon loss and gain C real of the grazing grassland ecosystem.

[0011] The actual carbon loss and gain C real of the grazing grassland ecosystem is expressed as follows:

[0012] C real =C raw -C_loss_TI-C loss，graze +ΔSOC;

[0013] Wherein: C raw is the initial value of leaf carbon.

[0014] The grazing carbon balance model is expressed by the following formula:

[0015] ΔC leaf =-C graze ;

[0016] Wherein: ΔC leaf is the amount of leaf carbon consumed by animal grazing; C grazeCleaf is the amount of carbon in the leaves consumed by the animals, which is equal to the amount of carbon in the dry matter.

[0017] The increase of soil organic carbon pool ΔSOC caused by the animal excrements is expressed as the following formula:

[0018] ΔSOC = C faeces +C urine = f faeces × C graze +f urine × C graze ;

[0019] Wherein: C faeces is the carbon in the animal feces; C urine is the carbon in the animal urine; f faeces and f urine respectively represent the proportion of grassland carbon consumed by grazing that is converted into carbon in feces and urine.

[0020] The amount of carbon loss C loss，graze caused by grazing is expressed as the following formula:

[0021] C loss，graze = R c + CH4+ C meat = f Rc × C graze +f CH4 × C graze +f meat × C graze ;

[0022] f meat = 100% - f Rc -f CH4 -f faeces -f urine ;

[0023] Wherein: R c is the carbon loss caused by respiration consumption of livestock; CH4 is the amount of carbon loss caused by livestock releasing methane into the atmosphere in the form of methane; C meat is the amount of carbon loss caused by livestock as meat and dairy exports; f Rc is the proportion of carbon consumed by respiration of livestock; f CH4 is the proportion of carbon consumed by methane production; f meat is the proportion of carbon in meat production.

[0024] The proportion f urine of grassland carbon consumed by grazing that is converted into carbon in urine is expressed as the following formula:

[0025]

[0026] CN urine = 12 / 28;

[0027] wherein: CN urine = 12 / 28 is the ratio of carbon to nitrogen in urea; N urine is the nitrogen content in urine;

[0028] The nitrogen content N urine in the urine is expressed by the following formula:

[0029] N urine = f excreta_N，urine × N excreta = f excreta_N，urine × f N，excreta × N graze ;

[0030] N excreta = f N，excreta × N graze ;

[0031] wherein: f excreta_N，urine is the proportion of nitrogen in urine; f N，excreta is the proportion of nitrogen in excrement; N graze is the nitrogen consumed by grazing livestock; N excreta is the nitrogen content in feces.

[0032] The proportion f urine of grassland carbon consumed by grazing converted into carbon in urine is calculated by the following formula:

[0033]

[0034] wherein: CN leaf is the ratio of carbon to nitrogen in plant leaves.

[0035] The amount of leaf carbon C graze flowing to animals is determined by grazing demand C demand and pasture supply C supply , expressed by the following formula:

[0036] C graze = min(C demand , C supply );

[0037] The grazing demand C demand is determined by grazing intensity G l and satiation consumption rate D X , expressed by the following formula:

[0038] C demand = G l × D X ;

[0039] The satiation consumption rate D X , expressed as the following formula:

[0040] D X = 2.0-2.4 kg / day / standard sheep.

[0041] The supply amount C of the pasture supply is determined by the grassland grazing area Area per day graze and the leaf carbon amount C of the grassland available to the livestock per unit area leaf，av , expressed as the following formula:

[0042] C supply = Area graze × C leaf，av ;

[0043] Area graze = G e × G l ;

[0044] C leaf，av = C leaf - C leaf，r ;

[0045] wherein: G e is the average land area covered by each sheep per day; C leaf is the total leaf carbon amount of the grassland; and C leaf，r is the remaining leaf carbon amount that cannot be eaten and utilized by the livestock.

[0046] The animal trampling carbon loss model, expressed as the following formula:

[0047] C_loss_TI = 0.8% × C supply ;

[0048] wherein: (C_loss_TI) is the carbon loss caused by the animals trampling the plants, i.e. the trampled vegetation leaf carbon amount.

[0049] Compared with the prior art, the present application has the following beneficial effects:

[0050] 1. This invention provides an ecological model for carbon gain and loss in a grazing grassland ecosystem. By establishing a grazing carbon balance model and an animal trampling carbon loss model, and coupling the carbon loss caused by grazing, the increase in soil organic carbon pool due to animal excrement, and the carbon loss caused by animal trampling on vegetation in the ecological model, the actual carbon gain and loss of the grassland ecosystem can be obtained. In application, this design fully considers the factors of animal grazing, animal excrement, and animal trampling throughout the entire grazing process, improving the impact of disturbance factors on vegetation in the entire grassland ecosystem, reducing the uncertainty in regional grassland carbon cycle simulation, and improving the accuracy of the results. Therefore, this invention has high precision.

[0051] 2. In the ecological model for carbon gain and loss in a grazing grassland ecosystem proposed in this invention, not only is the carbon loss caused by animals grazing and trampling during grazing considered, but the fertilizing effect of animal excrement on grassland growth is also fully taken into account. Based on this, the carbon content is calculated, and the final carbon gain and loss result is relatively accurate. Therefore, this invention has high precision.

[0052] 3. In the ecological model of carbon gain and loss in a grazing grassland ecosystem proposed in this invention, the optimized ecological model fully considers that not all the carbon consumed by grazing will return to the soil in the form of excrement, but a portion will be consumed in the form of carbon dioxide, methane, and meat production. This further reduces the incompleteness in the ecological model and improves the accuracy of the simulation results. Therefore, this invention has high accuracy. Attached Figure Description

[0053] Figure 1 This is a schematic diagram of the ecological model of the present invention.

[0054] Figure 2 This is a schematic diagram of the coupling model between the original AEM model and the ecological model in Embodiment 2 of this invention.

[0055] Figure 3 This is a simulation result of the grazing process coupled at the site scale in Embodiment 2 of the present invention.

[0056] Figure 4 This is a point-to-point comparison of the simulation results of the regional-scale coupling of the grazing process in Embodiment 2 of this invention. Detailed Implementation

[0057] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0058] See Figure 1 An ecological model of carbon gain and loss in a grazing grassland ecosystem, the ecological model comprising a grazing carbon balance model and an animal trampling carbon loss model;

[0059] The grazing carbon balance model includes the amount of leaf carbon consumed by animals ΔC leaf The amount of leaf carbon flowing to animals C graze The amount of leaf carbon flowing to animals C graze The amount of carbon loss caused by grazing C loss，graze And the increase of soil organic carbon pool ΔSOC caused by animal excrement;

[0060] The animal trampling carbon loss model is used to obtain the carbon loss caused by animal trampling plants (C_loss_TI) ;

[0061] In the ecological model, the amount of carbon loss caused by grazing C loss，graze The increase of soil organic carbon pool ΔSOC caused by animal excrement and the carbon loss caused by animal trampling plants (C_loss_TI) are coupled and calculated to obtain the actual carbon gain and loss C real of the grazing grassland ecosystem.

[0062] The actual carbon gain and loss C real of the grazing grassland ecosystem is expressed as follows:

[0063] C real =C rａw -C_loss_TI-C loss，graze +ΔSOC;

[0064] Wherein: C raw is the initial value of leaf carbon, which is obtained by estimating the grazing area;

[0065] The grazing carbon balance model is expressed by the following formula:

[0066] ΔC leaf =-C graze ;

[0067] Wherein: ΔC leaf is the amount of leaf carbon consumed by animals; C graze is the amount of leaf carbon flowing to animals, i.e. the carbon consumed by animals, which is equal to the carbon content in dry matter.

[0068] The increase of soil organic carbon pool ΔSOC caused by animal excrement is expressed by the following formula:

[0069] ΔSOC=C faeces +C urine =C faeces ×C graze +C urine ×C graze ;

[0070] Wherein: C faeces is the carbon in animal feces; C urineCarbon in animal urine; f faeces With f urine Respectively represent the proportion of grassland carbon consumed by grazing converted into carbon in feces and urine.

[0071] The amount of carbon loss caused by grazing C loss，graze , expressed as the following formula:

[0072] C lass，graze = R c + CH4+ C meat = f Rc × C graze + f CH4 × C graze + f meat × C graze ;

[0073] f meat = 100%- f Rc - f CH4 - f faeces - f urine ;

[0074] Wherein: R c is the carbon loss caused by respiration consumption of livestock; CH4is the amount of carbon loss caused by livestock releasing methane into the atmosphere in the form of methane; C meat is the amount of carbon loss caused by livestock as meat and dairy products exported; f Rc is the proportion of carbon consumed by respiration of livestock; f CH4 is the proportion of carbon consumed by methane production; f meat is the proportion of carbon in meat production.

[0075] The proportion f urine of grassland carbon consumed by grazing converted into carbon in urine, expressed as the following formula:

[0076]

[0077] CN urine = 12 / 28;

[0078] Wherein: CN urine = 12 / 28 is the ratio of carbon to nitrogen in urea; N urine is the content of nitrogen in urine;

[0079] The content of nitrogen N urine in urine, expressed as the following formula:

[0080] N urine = f excreta_N，urine × N excreta = f excreta_N，urine × f N，excreta × Ngraze

[0081] N excreta = f N，excreta × N graze ;

[0082] wherein: f excreta_N，urine is the proportion of nitrogen in urine; f N，excreta is the proportion of nitrogen in excrement; N graze is the nitrogen consumed by livestock grazing; N excreta is the nitrogen content in feces.

[0083] The proportion f urine of grassland carbon consumed by grazing converted into carbon in urine is calculated by the following formula:

[0084]

[0085] wherein: CN leaf is the ratio of carbon to nitrogen in plant leaves.

[0086] The amount of leaf carbon C graze flowing to animals is determined by grazing demand C demand and grass supply C supply , which is expressed by the following formula:

[0087] C graze = min(C demand , C supply );

[0088] The grazing demand C demand is determined by grazing intensity G l and satiation consumption rate D X , which is expressed by the following formula:

[0089] C demand = G l × D X ;

[0090] The satiation consumption rate D X , which represents the grass consumption of each standard sheep per day, is expressed by the following formula:

[0091] D X = 2.0-2.4 kg / day / standard sheep.

[0092] The grass supply C supply is determined by the grassland grazing area Area graze per day and the leaf carbon amount C leaf，av available to livestock per unit area of grassland, which is expressed by the following formula:

[0093] Csupply = Area graze × C leaf，av ;

[0094] Area graze = G e × G l ;

[0095] C leaf，av = C leaf - C leaf，r ;

[0096] Wherein: G e is the average land area that each sheep can cover per day; C leaf is the total leaf carbon content of the grassland; C leaf，r is the residual part of the leaf carbon content that cannot be eaten and utilized by livestock.

[0097] The animal trampling carbon loss model is expressed as the following formula:

[0098] C_loss_TI = 0.8% × C supply ;

[0099] Wherein: (C_loss_TI) is the carbon loss caused by the animals trampling the plants, that is, the trampled vegetation leaf carbon content.

[0100] The principle of the present application is described as follows:

[0101] The existing grassland ecological model in arid areas does not consider the influence of grazing on the carbon dynamics of the grassland when simulating the carbon cycle process of the grassland, but during the grazing process, the animals often eat the leaf carbon of the grassland, trample the vegetation of the grassland, and cause the loss of the carbon pool, and the excrement of the animals has the effect of fertilization and helps the growth of the grassland, which causes the increase of the carbon pool of the grassland; the present application describes the process of the influence of the animals on the carbon pool of the grassland, fully considers the influence of the grazing process of the animals on the structure and function of the grassland ecosystem, and the existing model only considers the process of generating the initial carbon pool of the grassland based on photosynthesis, and through increasing the influence of the grazing process on the carbon loss and gain of the initial carbon pool of the grassland, the complete ecological chain can be accurately evaluated.

[0102] Embodiment 1:

[0103] Referring to Figure 1 , an ecological model of grazing grassland ecosystem carbon loss and gain; the ecological model comprises a grazing carbon balance model and an animal trampling carbon loss model;

[0104] The grazing carbon balance model, the leaf carbon content ΔC leaf consumed by the animals and the leaf carbon content C graze flowing to the animals are balanced and equal, which is expressed as the following formula:

[0105] AC leaf = -C graze ;

[0106] wherein: AC leaf is the amount of leaf carbon consumed by the animal; C graze is the amount of leaf carbon flowing to the animal, i.e. the carbon consumed by the animal in grazing, which is equal to the carbon content in dry matter, and is taken as 0.4-0.6;

[0107] First, according to the grazing requirement C demand and the supply amount of pasture C supply , the amount of leaf carbon flowing to the animal C graze is obtained, which is expressed as the following formula:

[0108] C graze = min(C demand , C supply );

[0109] The grazing requirement C demand is determined by the grazing intensity G l and the satiation consumption rate D X , which is expressed as the following formula:

[0110] C demand = G l × D X ;

[0111] The satiation consumption rate D X is expressed as the following formula:

[0112] D X = 2.0-2.4 kg / day / standard sheep;

[0113] The supply amount of pasture C supply is determined by the grassland grazing area Area graze per day and the leaf carbon amount C leaf，av of grassland available to livestock per unit area, which is expressed as the following formula:

[0114] C supply = Area graze × C leaf，av ;

[0115] Area graze = G e × G l ;

[0116] C leaf，av = C leaf - C leaf，r ;

[0117] wherein: Ge the average land area covered by each sheep per day; C leaf the total leaf carbon of the grassland; C leaf，r the remaining part of the leaf carbon that cannot be eaten and utilized by the livestock;

[0118] Then, according to the leaf carbon C graze flowing to the animals, the carbon loss C loss，graze caused by grazing and the increase of soil organic carbon pool ΔSOC caused by animal excrement are obtained.

[0119] The carbon loss C loss，graze caused by grazing is expressed as the following formula:

[0120] C loss，graze = R c + CH4+ C meat = f Rc × C graze + f CH4 × C graze + f meat × C graze ;

[0121] f meat = 100%- f Rc - f CH4 - f faeces - f urine ;

[0122] Wherein: R c is the carbon loss caused by respiration consumption of the livestock; CH4 is the carbon loss caused by the livestock releasing methane into the atmosphere in the form of methane; C meat is the carbon loss caused by the livestock exporting as meat and dairy products; f Rc is the carbon proportion of respiration consumption of the livestock, with a value of 0.4-0.6; f CH4 is the carbon proportion of methane production and consumption, with a value of 0.02-0.04; f meat is the proportion of carbon in meat production.

[0123] The increase of soil organic carbon pool ΔSOC caused by animal excrement is expressed as the following formula:

[0124] ΔSOC = C faeces + C urine = f faeces × C graze + f urine × C graze ;

[0125] Wherein: C faeces is the carbon in animal feces; C urine is the carbon in animal urine; ffaeces f urine respectively represent the proportion of grassland carbon consumed by grazing converted into carbon in feces and urine, and the value is 0.2-0.4;

[0126] The proportion of grassland carbon consumed by grazing converted into carbon in urine is f urine , which is expressed by the following formula:

[0127]

[0128] CN urine = 12 / 28;

[0129] Wherein: CN urine = 12 / 28 is the ratio of carbon to nitrogen in urea; N urine is the nitrogen content in urine;

[0130] The nitrogen content N urine in urine is expressed by the following formula:

[0131] N urine = f excreta_N，urine × N excreta = f excreta_N，urine × f N，excreta × N graze ;

[0132] N excreta = f N，excreta × N graze ;

[0133] Wherein: f excreta_N，urine is the proportion of nitrogen in urine, the proportion is 50%-70%; f N，excreta is the proportion of nitrogen in excrement, the proportion is 70%-90%; N graze is the nitrogen consumed by grazing; N excreta is the nitrogen content in feces;

[0134] The proportion of grassland carbon consumed by grazing converted into carbon in urine is f urine , which is calculated by the following formula:

[0135]

[0136] Wherein: CN leaf is the ratio of carbon to nitrogen in plant leaves;

[0137] And the trampling intensity of the animal is obtained based on the forage supply amount C supply , which is expressed by the following formula:

[0138] C_loss-TI = 0.8% × C supply ;

[0139] Where: (C_loss_TI) represents the carbon loss caused by animal trampling of plants, that is, the amount of leaf carbon lost due to trampling; 0.8% is obtained based on actual measurement data, indicating that approximately 0.8% of leaf carbon is removed every day;

[0140] Finally, the carbon loss C caused by grazing was... loss，graze By coupling the increase in soil organic carbon pool by animal excrement (ΔSOC) with the carbon loss caused by animal trampling on vegetation (C_loss_TI), the actual carbon gain / loss C of the grazing grassland ecosystem can be obtained. real It is represented as follows:

[0141] C real =C rａw -C_loss_TI-C loss，graze +ΔSOC;

[0142] Where: C raw The initial value of leaf carbon is estimated based on the required simulation area.

[0143] Example 2:

[0144] The basic content is the same as in Example 1, except that:

[0145] See Figure 2 In this embodiment, the original AEM-Grazing model (Arid Ecosystem Model) is coupled with an ecological model of carbon gain and loss in grazing grassland ecosystems. The leaf carbon in the vegetation carbon pool is divided into two parts: one part is mainly underground biomass that cannot be consumed by animals, which flows to the litter carbon pool according to the original process; the other part uses this ecological model to evaluate the actual carbon gain and loss of vegetation leaf carbon. After removing the consumption caused by animal grazing and trampling and adding the feedback from animal excrement, it is then merged with the litter carbon pool in the first part and finally flows to the soil organic carbon pool to obtain the final carbon gain and loss of grassland ecology in this area.

[0146] In order to evaluate the simulation effect of site-scale grazing on the carbon loss and gain of grassland ecosystem, the ecological model is coupled with the original AEM model to simulate site flux results, and then the model results are verified by using flux observation data of the eddy correlation system located in the observation site of Xinyuan Qiuzhutai in Xinjiang Uygur Autonomous Region; the site is located in the meadow grassland of the cutting field, and the grassland is a typical weed meadow, and the dominant grass species are Geranium sp., Potentilla sp., Poa sp. and Codonopsis clematidea (Schrenk) C.B.Clarke; the annual average precipitation is 442.3 mm, and the annual average temperature is 3.2℃; the GPP flux data observation time for model verification is from May 29, 2017 to May 31, 2019, and the comparison and verification of the simulation results and the observation results are seen in Figure 3 .

[0147] In order to evaluate the simulation effect of the ecological model at the regional scale, the AEM model coupled with the ecological model is used to simulate the regional grassland net primary productivity NPP (Net Primary Productivity), and the simulation results are compared and verified with the remote sensing data point by point, all the data are unified to the same spatial resolution, and the regional scale carbon cycle data simulated by the model are further evaluated by using the remote sensing data, and the point-to-point comparison and evaluation results are seen in Figure 4 (the remote sensing data sources are: AVHRR GLO-PEN NPP and MODIS NPP).

[0148] The simulation results and the evaluation results both show that the simulation results of the carbon loss and gain of grassland ecosystem caused by grazing behavior at site scale, regional scale and even global scale can be obtained by using the present application, the important role of grazing process in grassland carbon cycle is improved, and the monitoring ability of grassland ecosystem carbon cycle is improved.

[0149] The above only describes the preferred embodiments of the present application, and the protection scope of the present application is not limited to the above embodiments, but any equivalent modifications or changes made by those skilled in the art according to the disclosed content of the present application shall be included in the protection scope recited in the claims.

Claims

1. A method for constructing a carbon gain / loss ecological model for a grazing grassland ecosystem, characterized in that: The ecological model includes a grazing carbon balance model and an animal trampling carbon loss model; The grazing carbon balance model includes the amount of leaf carbon consumed by the animals. Leaf carbon content flowing to animals The amount of leaf carbon flowing to animals Used to obtain carbon loss due to grazing and the increase in soil organic carbon pool due to animal excrement ; The animal trampling carbon loss model is used to obtain the carbon loss caused by animals trampling vegetation. ; In the aforementioned ecological model, the carbon loss caused by grazing is considered. The increase in soil organic carbon pool due to animal excrement Carbon loss caused by animals trampling plants Coupled calculations were performed to obtain the actual carbon gain and loss of the grazing grassland ecosystem. ; The actual carbon gain / loss of the grazing grassland ecosystem It is represented as follows: ； in: This represents the initial value of leaf carbon. The carbon loss model caused by animal trampling is expressed by the following formula: ； in: Carbon loss caused by animals trampling on plants, This indicates that 0.8% of the leaf carbon is removed daily. For the supply of pasture.

2. The method for constructing a carbon gain / loss ecological model for a grazing grassland ecosystem according to claim 1, characterized in that: The grazing carbon balance model is expressed by the following formula: ； in: The amount of carbon consumed by animals for grazing; The amount of carbon flowing to animals, i.e., the carbon consumed by animals, is equal to the carbon content in dry matter.

3. The method for constructing a carbon gain / loss ecological model for a grazing grassland ecosystem according to claim 2, characterized in that: The increase of animal excrement in the soil organic carbon pool It can be expressed as the following formula: ； in: Carbon in animal feces; Carbon in animal urine; and These represent the proportions of grassland carbon consumed by grazing that are converted into carbon in feces and urine, respectively.

4. The method for constructing a carbon gain / loss ecological model for a grazing grassland ecosystem according to claim 3, characterized in that: The carbon loss caused by grazing It can be expressed as the following formula: ； ； in: Carbon loss due to respiration by livestock; Carbon loss due to livestock releasing methane into the atmosphere; Carbon loss due to the export of livestock as meat and dairy products; The proportion of carbon consumed by livestock respiration; The proportion of carbon consumed in methane production; This represents the proportion of carbon in meat production.

5. The method for constructing a carbon gain / loss ecological model for a grazing grassland ecosystem according to claim 4, characterized in that: The proportion of grassland carbon consumed by grazing converted into carbon in urine It is expressed as the following formula: ； ； in: This represents the carbon to nitrogen ratio in urea. This refers to the nitrogen content in urine; The nitrogen content in the urine It is expressed as the following formula: ； ； in: This represents the percentage of nitrogen in urine. The percentage of nitrogen in excrement; Nitrogen consumed by livestock grazing; This refers to the nitrogen content in feces.

6. The method for constructing a carbon gain / loss ecological model for a grazing grassland ecosystem according to claim 5, characterized in that: The proportion of grassland carbon consumed by grazing converted into carbon in urine It is calculated using the following formula; ； in: This represents the ratio of carbon to nitrogen in plant leaves.

7. The method for constructing a carbon gain / loss ecological model for a grazing grassland ecosystem according to claim 1, characterized in that: The amount of leaf carbon flowing to animals Demand for grazing With forage supply The decision is expressed by the following formula: ； The demand for grazing Due to grazing intensity With satiety consumption rate The decision is expressed by the following formula: ； The satiety consumption rate It is expressed as the following formula: 。 8. The method for constructing a carbon gain / loss ecological model for a grazing grassland ecosystem according to claim 7, characterized in that: The amount of forage supply Based on the daily grazing area of ​​grassland Leaf carbon content of grassland per unit area available to livestock The decision is expressed by the following formula: ； ； ； in: This refers to the average land area that each sheep can cover per day. This represents the total leaf carbon content of the grassland. The remaining leaf carbon content that livestock cannot consume or utilize.

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