A method and system for determining optimal selective felling intensity based on single tree carbon fixation model

Abstract

The present invention belongs to the technical field of forest ecology, and specifically provides a method and system for determining the optimal selective felling intensity based on a single tree carbon fixation model. The system includes a data input module, which is configured to obtain forest survey data; a data analysis module, which is configured to output the maximum selective felling intensity according to the forest survey data; a data output module, which is configured to set a selective felling intensity range, output felling information according to the selected selective felling intensity range, and is also configured to output predicted carbon sequestration changes. The present invention can be used to quantitatively select trees for selective felling in the direction of multi-layer and uneven age according to the forest carbon fixation potential and forest stand structure, solving the technical problems that traditional selective felling methods require field observation by staff and require high professional knowledge of staff, and is fast, effective, convenient and practical.

Description

Technical Field

[0001] The present invention relates to the technical field of forest ecology, and more particularly to a method and system for determining optimal selective felling intensity based on a single-tree carbon fixation model. Background Art

[0002] Forest ecosystems are the largest carbon pool in terrestrial ecosystems, and forests have huge carbon storage capacity. Improving forest quality is the key to improving the carbon sequestration capacity of forests. Forest felling is the beginning of forest regeneration operations. Compared with clear-cutting, selective felling is the best forest management strategy. Selective felling with appropriate intensity in a small area will effectively improve the light conditions of the forest stand, promote the optimization of forest structure, and have a certain beneficial effect on the carbon sequestration capacity of the forest. Selective felling should control the felling intensity, and determine the selective felling method according to local conditions. Precious tree species and immature trees should not be felled. Selective felling operations should be carried out in accordance with the principle of "cutting the big and leaving the small, cutting the dense and leaving the sparse, cutting the bad and leaving the good, cutting the old and leaving the strong", creating conditions for site renewal and soil and water conservation.

[0003] The prior art has the following technical defects:

[0004] (1) Traditional selective felling methods require field observation by staff, which consumes manpower and material resources and takes a long time to work;

[0005] (2) The traditional selective felling method requires high professional knowledge from the staff, and the selection and intensity of the selective felling trees are greatly influenced by human subjective factors.

[0006] Therefore, the current selective felling method has certain inaccuracies and limitations, and the efficiency of selective felling is very low, making it difficult for staff to carry out selective felling work. Summary of the invention

[0007] To this end, the present invention provides a method and system for determining the optimal selective felling intensity based on a single tree carbon fixation model.

[0008] The first aspect of the present invention provides a method comprising the following steps:

[0009] S1. Obtain forest survey data of a first region, and determine the biomass and tree species types in a plurality of survey batches from the forest survey data;

[0010] S2. Determine whether the tree species is a reserved tree;

[0011] S3, calculating the maximum selective felling intensity, wherein the maximum selective felling intensity is calculated using the biomass in adjacent survey batches and survey time as variables;

[0012] S3, determining selective felling trees and removing the selective felling trees from the first area and its forest survey data;

[0013] S4. Calculate the biomass growth of a single tree according to the single tree carbon fixation model, and calculate the total carbon fixation amount at the same time, wherein the total carbon fixation amount is equal to the sum of the biomass growth of a single tree of all trees in the first area;

[0014] S6, calculating the change in total carbon sequestration in the first area within a preset period of time after the selective felling is removed;

[0015] S7. Determine the optimal selective felling intensity according to the change in the total carbon fixation amount.

[0016] Furthermore, if the organism meets any of the retention conditions, it will be used as a retained tree;

[0017] The retention conditions of the retained wood include:

[0018] The first reservation condition is to reserve trees of designated species as reserved trees;

[0019] The second retention condition is to reserve tree species with biophysical and chemical parameters above the preset values;

[0020] The third retention condition is to reserve tree species whose total number of biological individuals is lower than the preset value.

[0021] Further, the maximum selective felling intensity is calculated by the following formula:

[0022]

[0023] Among them, ΔB is the total biomass B of the second survey 2 Compared with the total biomass B in the first survey 1 The difference between the two surveys, M is the time interval between the two surveys, ∑B i is the biomass B of the second survey 2 sum.

[0024] Furthermore, the decision step of selective felling is specifically set as follows:

[0025] S31, determining all neighboring trees that intersect each retained tree with its crown in the first area

[0026] S32, determining a neighboring tree whose biomass is smaller than that of the currently retained tree;

[0027] S32, determining neighboring trees whose preset biophysical and chemical parameters are smaller than those of the retained trees;

[0028] S33, judging whether S32 and the adjacent trees determined in S32 meet the selective felling conditions,

[0029] If so, harvesting is carried out.

[0030] Otherwise keep it.

[0031] Further, the selective felling conditions are specifically set as:

[0032] S310, obtaining statistics on the number of trees adjacent to all the retained trees,

[0033] S320, determining the largest biomass among the retained trees with the largest number of plants as the largest retained tree;

[0034] S330, if the biomass of the neighboring trees of the largest retained tree is greater than that of the largest retained tree, then the tree will not be felled; if there is a non-reserved tree with a smaller biomass than the retained tree among the neighboring trees, then the non-reserved tree with the smallest biomass among the neighboring trees will be marked as a selective felling tree for the first time;

[0035] S340, after executing S3's removal, execute S310-S330 cyclically until the preset felling intensity is reached.

[0036] Furthermore, the biomass growth of a single tree is calculated based on the single tree carbon fixation model, specifically:

[0037]

[0038] Among them, A represents the crown area of ​​the tree, A no is the area where the target tree and the neighbor tree do not overlap, A o,k is the area where the target tree i overlaps with the neighbor tree j, B i is the biomass of the target tree, B j is the biomass of the neighboring tree, B max,i is the maximum potential biomass of the tree species;

[0039] The radius R of the tree crown A is calculated as follows:

[0040] R = αln(B i +1)+β

[0041] where α and β are region-specific conversion coefficients for biomass and crown area.

[0042] Furthermore, if the biomass growth g of a tree is 0 for five consecutive years, the tree is considered dead and no longer participates in the calculation of the single tree carbon fixation rate.

[0043] A second aspect of the present invention provides a system suitable for implementing the method of the first aspect, comprising:

[0044] a data input module configured to obtain forest inventory data;

[0045] A data analysis module is configured to output a maximum selective felling intensity according to the forest survey data;

[0046] The data output module is configured to set a selective felling intensity range, output felling information according to the selected selective felling intensity range, and is also configured to output predicted carbon sequestration changes.

[0047] The above technical solution of the present invention has the following advantages compared with the prior art:

[0048] The present invention develops a new method for determining selective felling based on the relationship between trees and their neighbors. It can be used to quantitatively select selective felling trees based on the forest carbon sequestration potential. It solves the technical problems that the traditional selective felling method requires field observation by staff and requires high professional knowledge of staff. It is fast, effective, convenient and practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A schematic diagram of the process provided by the present invention;

[0050] Figure 2 A structural block diagram of the system provided by the present invention;

[0051] Figure 3 A schematic diagram of the initial tree size and distribution of the forest stand provided by the present invention;

[0052] Figure 4 Schematic diagram of the first selective felling intensity selection provided by the present invention Figure 1 ;

[0053] Figure 5 The second selective felling intensity selection provided by the present invention is shown in FIG. Figure 2 ;

[0054] Figure 6 A schematic diagram of carbon sequestration levels in the next 20 years under the first selective felling intensity provided by the present invention;

[0055] Figure 7 A schematic diagram of the carbon sequestration level in the next 20 years under the second selective felling intensity provided by the present invention. DETAILED DESCRIPTION

[0056] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0057] Embodiment 1

[0058] In one aspect of the present invention, a system is provided. Figure 2 As shown, including:

[0059] a data input module configured to obtain forest inventory data;

[0060] A data analysis module is configured to output a maximum selective felling intensity according to the forest survey data;

[0061] The data output module is configured to set a selective felling intensity range, output felling information according to the selected selective felling intensity range, and is also configured to output predicted carbon sequestration changes.

[0062] In a second aspect of the present invention, a method is provided, such as Figure 1 As shown, it is suitable for implementing the system as the first aspect of the present invention, comprising the following steps:

[0063] S1. Obtain forest survey data of a first region, and determine the biomass and tree species types in a plurality of survey batches from the forest survey data;

[0064] S2. Determine whether the tree species is a reserved tree;

[0065] S3, calculating the maximum selective felling intensity, wherein the maximum selective felling intensity is calculated using the biomass in adjacent survey batches and survey time as variables;

[0066] S3, determining selective felling trees and removing the selective felling trees from the first area and its forest survey data;

[0067] S4. Calculate the biomass growth of a single tree according to the single tree carbon sequestration model, and calculate the total carbon sequestration amount at the same time, wherein the total carbon sequestration amount is equal to the sum of the biomass growth of a single tree of all trees in the first region;

[0068] S6, calculating the change in total carbon sequestration in the first area within a preset time after the selective felling is removed;

[0069] S7. Determine the optimal selective felling intensity according to the change in the total carbon fixation amount.

[0070] Furthermore, if the organism meets any of the retention conditions, it will be used as a retained tree;

[0071] The retention conditions of the retained wood include:

[0072] The first reservation condition is to reserve trees of designated species as reserved trees;

[0073] The second retention condition is to reserve tree species with biophysical and chemical parameters above the preset values;

[0074] The third retention condition is to reserve tree species whose total number of biological individuals is lower than the preset value.

[0075] Further, the maximum selective felling intensity is calculated by the following formula:

[0076]

[0077] Among them, ΔB is the total biomass B of the second survey 2 Compared with the total biomass B in the first survey 1 The difference between the two surveys, M is the time interval between the two surveys, ∑B i is the biomass B of the second survey 2 sum.

[0078] Furthermore, the decision step of selective felling is specifically set as follows:

[0079] S31, determining all neighboring trees that intersect each retained tree with its crown in the first area

[0080] S32, determining a neighboring tree whose biomass is smaller than that of the currently retained tree;

[0081] S32, determining neighboring trees whose preset biophysical and chemical parameters are smaller than those of the retained trees;

[0082] S33, judging whether S32 and the adjacent trees determined in S32 meet the selective felling conditions,

[0083] If so, harvesting is carried out.

[0084] Otherwise keep it.

[0085] Further, the selective felling conditions are specifically set as:

[0086] S310, obtaining statistics on the number of trees adjacent to all the retained trees,

[0087] S320, determining the largest biomass among the retained trees with the largest number of plants as the largest retained tree;

[0088] S330, if the biomass of the neighboring trees of the largest retained tree is greater than that of the largest retained tree, then the tree will not be felled; if there is a non-reserved tree with a smaller biomass than the retained tree among the neighboring trees, then the non-reserved tree with the smallest biomass among the neighboring trees will be marked as a selective felling tree for the first time;

[0089] S340, after executing S3's removal, execute S310-S330 cyclically until the preset felling intensity is reached.

[0090] Furthermore, the biomass growth of a single tree is calculated based on the single tree carbon fixation model, specifically:

[0091]

[0092] Among them, A represents the crown area of ​​the tree, A no is the area where the target tree and the neighbor tree do not overlap, A o,k is the area where the target tree i overlaps with the neighbor tree j, Bi is the biomass of the target tree, B j is the biomass of the neighboring tree, B max,i is the maximum potential biomass of the tree species;

[0093] The radius R of the tree crown A is calculated as follows:

[0094] R = αln(B i +1)+β

[0095] where α and β are region-specific conversion coefficients for biomass and crown area.

[0096] Furthermore, if the biomass growth g of a tree is 0 for five consecutive years, the tree is considered dead and no longer participates in the calculation of the single tree carbon fixation rate.

[0097] Embodiment 2

[0098] This embodiment uses a specific research site as the first area and carries out the method as in the first embodiment.

[0099] The study plot is located in the Jiaohe Experimental Area Management Bureau, Jiaohe City, Jilin Province (43°58′N, 127°45′E). The plot covers an area of ​​1 hectare (100 m × 100 m) and was established in the summer of 2010 according to the standards of the Center for Tropical Forest Science (CTFS). The main characteristics of the forest in this plot are temperate coniferous and broad-leaved mixed forests. The climate in the study area is temperate continental, affected by the temperate monsoon, with an average annual temperature of 3.7°C. Based on the forest survey results of the plot in 2018 and 2021, the format of the demonstration data input is shown in Table 1:

[0100] Table 1

[0101]

[0102] After importing the data, click the data input button on the Netlogo interface, and the interface will display the initial tree size and distribution of the forest stand. Figure 3 .

[0103] Set the selective felling intensity. When performing selective felling operations on forest stands, the amount of selective felling must be determined based on the growth volume, that is, the annual felling volume must not be higher than the accumulated growth volume of the forest stand. The maximum selective felling intensity L is calculated based on the information in the data input module as shown in formula a:

[0104]

[0105] Among them, ΔB is the total biomass B in the second survey 2 Compared with the total biomass B in the first survey 1 The difference between the two surveys, M is the time interval between the two surveys, ∑B iis the biomass B of the second survey 2 sum.

[0106] In the Netlogo interface, set the selective felling intensity slider from 0% to 2% with an interval of 0.1%. When the selective felling intensity set by the user is greater than L, the interface will prompt "The selective felling intensity is too high, it is recommended to reduce the selective felling intensity."

[0107] Determine the trees for selective felling and fell the non-reserved trees among the multiple trees growing together. Compare the biomass of all neighboring trees that intersect with the crowns of each retained tree in the forest stand transformation area and determine the number of neighboring trees with biomass less than that of the retained tree; based on the number of neighboring trees around the retained tree and the number of neighboring trees with a breast diameter less than that of the retained tree, judge and determine whether the neighboring trees meet the selective felling conditions according to the selective felling standards. If they meet the selective felling conditions, the neighboring trees are marked as fellable trees and felled; if they meet the non-falling conditions, they are retained and not felled;

[0108] In particular, the selective felling criteria are as follows:

[0109] First, compare the number of neighboring trees of all the reserved trees, and select the reserved tree with the most neighboring trees. If there are multiple reserved trees with the most neighboring trees, then select the reserved tree with the largest biomass;

[0110] If the biomass of the neighboring trees of the largest retained tree is larger than that of the retained tree, it will not be cut down. If there is a non-reserved tree with a smaller biomass than the retained tree among the neighboring trees, the non-reserved tree with the smallest biomass among the neighboring trees will be marked as the selective felling tree for the first time.

[0111] Individual trees marked for felling in the first felling will not participate in the selection process for the second felling, and will be highlighted in yellow for felling;

[0112] The process of selecting felling trees for the Nth time is the same as the process of selecting felling trees for the first time, and the felling selection process is executed until the set felling intensity is reached.

[0113] In Netlogo, set M to 3, set the selective felling intensity to 1% and 2% respectively, and click the selective felling selection button. The results are shown in Figure 4 (selective felling intensity L-threshold = 1%) and Figure 5 (Selective felling intensity L-threshold = 2%).

[0114] Click the data export button in the Netlogo interface to export all selective felling information as a csv document. See Table 2 for the format of exporting selective felling information.

[0115] Table 2

[0116]

[0117]

[0118] Remove selective felled trees and predict the change in forest carbon sequestration within 20 years after removing felled trees. The carbon sequestration of a single tree each year is fB+fg, where f is the carbon conversion rate of biomass, which is set to 0.5 here;

[0119] Construct a single tree biomass growth model: Calculate the annual average biomass growth rate g of a single tree as shown in formula b;

[0120]

[0121] Among them, A represents the crown area of ​​the tree, A no is the area where the target tree and the neighbor tree do not overlap, A o,k is the area where the target tree i overlaps with the neighbor tree j, B i is the biomass of the target tree, B j is the biomass of the neighboring tree, B max,i is the maximum potential biomass of the tree species.

[0122] The calculation formula of the radius R of the tree crown A is as follows:

[0123] R = αln(B i +1)+β formula c;

[0124] Among them, α and β are the conversion coefficients of region-specific biomass and crown area, which are set here as 0.8 for α and 1.6 for β.

[0125] If a tree's g is 0 for five consecutive years, the tree is considered dead, its color is set to yellow, and it is no longer included in the calculation of the single-tree carbon fixation rate;

[0126] The carbon sequestration of a forest stand in each year is the sum of the carbon sequestration of all individual trees in that year;

[0127] The relationship between the year and the amount of carbon sequestered in the forest is shown in a curve graph, including the amount of carbon sequestered in the forest before felling, the amount of carbon sequestered in the year of felling, and the amount of carbon sequestered in the next 20 years. Figure 6 (selective felling intensity L-threshold = 1%) and Figure 7 (Selective felling intensity L-threshold = 2%).

[0128] The flowchart and block diagram in the accompanying drawings show the possible architecture, role and operation of the device, method and computer program product according to the embodiment of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of the code, and the module, the program segment or a part of the code contains one or more executable instructions for realizing the specified logical role. In some alternative implementations, the role marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed in parallel, and they can sometimes be executed in the opposite order, which can depend on the role involved. In the description corresponding to the flowchart and the block diagram in the accompanying drawings, the operations or steps corresponding to different boxes can also occur in a different order from the order disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps can actually be executed in parallel, and they can sometimes be executed in the opposite order, which can depend on the role involved. Each block in the block diagram and / or flowchart, and combinations of blocks in the block diagram and / or flowchart, may be implemented by a dedicated hardware-based device that performs the specified role or action, or may be implemented by a combination of dedicated hardware and computer instructions.

Claims

1. A method for determining the optimal selective felling intensity based on a single tree carbon fixation model, characterized in that: The steps include: S1. Obtain forest survey data of a first region, and determine the biomass and tree species types in a plurality of survey batches from the forest survey data; S2. Determine whether the tree species is a reserved tree; S3, calculating the maximum selective felling intensity, wherein the maximum selective felling intensity is calculated using the biomass in adjacent survey batches and survey time as variables; The maximum selective felling intensity is calculated by the following formula: Among them, ΔB is the difference between the total biomass B2 of the second survey and the total biomass B1 of the first survey, M is the time interval between the two surveys, ∑B i It is the sum of the biomass B2 in the second survey; S3, determining selective felling trees and removing the selective felling trees from the first area and its forest survey data; S4. Calculate the biomass growth of a single tree according to the single tree carbon sequestration model, and calculate the total carbon sequestration amount at the same time, wherein the total carbon sequestration amount is equal to the sum of the biomass growth of a single tree of all trees in the first region; The growth of single tree biomass is calculated according to the single tree carbon fixation model, specifically: Among them, A represents the crown area of ​​the tree, A no is the area where the target tree and the neighbor tree do not overlap, A o,k is the area where the target tree i overlaps with the neighbor tree j, B i is the biomass of the target tree, B j is the biomass of the neighboring tree, B max,i is the maximum potential biomass of the tree species; The radius R of the tree crown A is calculated as follows: R=αln(B i +1)+b Among them, α and β are the conversion coefficients of region-specific biomass and crown area; S6, calculating the change in total carbon sequestration in the first area within a preset time after the selective felling is removed; S7. Determine the optimal selective felling intensity according to the change in the total carbon fixation amount.

2. The method according to claim 1, characterized in that In S2, if the organism meets any of the retention conditions, it will be regarded as a retained tree; The retention conditions of the retained wood include: The first reservation condition is to reserve trees of designated species as reserved trees; The second retention condition is to reserve tree species with biophysical and chemical parameters above the preset values; The third retention condition is to reserve tree species whose total number of biological individuals is lower than the preset value.

3. The method according to claim 2, characterized in that The determination step of selective felling is specifically set as follows: S31, determining all neighboring trees that intersect each retained tree with its crown in the first area S32, determining a neighboring tree whose biomass is smaller than that of the currently retained tree; S32, determining neighboring trees whose preset biophysical and chemical parameters are smaller than those of the retained trees; S33, judging whether S32 and the adjacent trees determined in S32 meet the selective felling conditions, If so, proceed with felling. Otherwise keep it.

4. The method according to claim 3, characterized in that The selective felling conditions are specifically set as: S310, obtaining statistics on the number of trees adjacent to all the retained trees, S320, determining the largest biomass among the retained trees with the largest number of plants as the largest retained tree; S330, if the biomass of the neighboring trees of the largest retained tree is greater than that of the largest retained tree, then the tree will not be felled; if there is a non-reserved tree with a smaller biomass than the retained tree among the neighboring trees, then the non-reserved tree with the smallest biomass among the neighboring trees will be marked as a selective felling tree for the first time; S340, after executing S3's removal, execute S310-S330 cyclically until the preset felling intensity is reached.

5. The method according to claim 4, characterized in that If the biomass growth g of a tree is 0 for five consecutive years, the tree is considered dead and no longer participates in the calculation of the single tree carbon fixation rate.

6. A system for determining the optimal selective felling intensity based on a single tree carbon fixation model, suitable for implementing the method according to any one of claims 1 to 5, characterized in that: include: a data input module configured to obtain forest inventory data; A data analysis module is configured to output a maximum selective felling intensity according to the forest survey data; The data output module is configured to set a selective felling intensity range, output felling information according to the selected selective felling intensity range, and is also configured to output predicted carbon sequestration changes.

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