Method for screening regional high-carbon-sequestration tree species

Abstract

The invention belongs to the field of ecology and forest cultivation, and particularly relates to a method for screening regional high-carbon-sequestration tree species. The method comprises the following steps: firstly, establishing a regional suitable tree species directory, obtaining carbon sequestration rates of different tree species in the regional suitable tree species directory through a carbon sequestration rate model, and screening out regional high-carbon sequestration tree species by comparing the carbon sequestration rates of the tree species; compared with a method for screening the high-carbon-sequestration tree species and varieties only according to the growth speed of forest trees, the method for screening the regional high-carbon-sequestration tree species is higher in scientificity and accuracy. According to the method, all ways of forest carbon sequestration and carbon loss are fully considered, and a solid theoretical basis is achieved. However, a high-carbon-sequestration tree species selection method which is generally adopted at present only depends on the growth amount of trees, does not consider carbon loss, is weak in theoretical basis and cannot accurately evaluate the carbon sequestration capacity of the trees. Therefore, the method disclosed by the invention is higher in scientificity, and the high-carbon sequestration tree species can be more accurately screened out.

Description

Technical Field

[0001] The present invention belongs to the fields of ecology and forest cultivation, and particularly relates to a method for screening high carbon sequestration tree species in a region. Background Art

[0002] Forests are the largest carbon sinks in terrestrial ecosystems. Giving full play to the carbon sequestration function of forests and increasing the increment of forest carbon sinks are effective ways to boost the country's "dual carbon" goals to be achieved as scheduled. Under the policy background of comprehensive protection of natural forests, the key to enhancing China's forest carbon sink capacity lies in constructing and managing artificial forests with high carbon sequestration efficiency. Suitable tree species and excellent varieties are the basis for establishing carbon sequestration forests. However, for a long time, the goals of artificial forest construction have mainly been for purposes such as timber forests, shelter forests, and fuelwood forests, without considering the carbon sequestration function of forest stands. Since the country's "dual carbon" goals were proposed in 2020, carbon sequestration and increment have been regarded as one of the important goals of artificial forest management. The establishment of carbon sequestration forests with carbon sequestration as the main forestry goal has begun to be taken seriously.

[0003] Trees absorb carbon dioxide through photosynthesis and fix carbon in their bodies. At the same time, a part of the carbon is lost through their own respiration. The net primary productivity formed by subtracting respiration from photosynthesis is the carbon fixed by plants. However, the carbon fixed by the net primary production of forest trees cannot all be preserved. The main biomass of forest trees is concentrated in the leaves, and a large amount of carbon is released into the atmosphere every year after the leaves of forest trees wither and decompose. Therefore, the withering and decomposition of forest tree leaves are important ways of their carbon loss. At present, due to the limitations of methods and the lack of theoretical knowledge, the carbon loss from the decomposition of withered leaves is often ignored in the accounting and assessment of forest carbon sequestration. The amount of leaf withering per year is different for different tree species, and the decomposition rate of withered leaves also varies greatly. Therefore, the amount of carbon loss from the withering and decomposition of leaves per year is very different for different tree species.

[0004] How to select suitable tree species and excellent varieties is the primary problem faced in scientifically establishing carbon sequestration forests. At present, the screening of carbon sequestration tree species and varieties is based on tree species suitable for local climate and soil conditions, and high carbon sequestration tree species are selected according to growth rate. That is, it is considered that tree species and varieties with fast growth have strong carbon sequestration ability. However, evaluating the carbon sequestration ability of trees based on growth rate does not consider the carbon loss from the withering and decomposition of leaves and cannot accurately evaluate the carbon sequestration ability of trees. Therefore, there is an urgent need to develop a simple and feasible screening method for high carbon sequestration tree species that fully considers the carbon loss of leaves, improve the scientificity and accuracy of the screening of carbon sequestration tree species, and lay a foundation for the establishment of carbon sequestration forests. Summary of the Invention

[0005] The purpose of the present invention is to provide a screening method for high carbon sequestration tree species that comprehensively considers the two fluxes of carbon fixation and carbon loss of forest trees. It is applicable to the selection of high carbon sequestration tree species in the process of establishing carbon sequestration forests in the disciplines of ecology and forest cultivation.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A screening method for high carbon sequestration tree species in a region, first establishing a list of suitable tree species in the region, obtaining the carbon sequestration rates of different tree species in the list of suitable tree species in the region through a carbon sequestration rate model, and screening out high carbon sequestration tree species in the region by comparing the carbon sequestration rates of each tree species.

[0008] Furthermore,

[0009] Establishing a list of suitable tree species in the region is to select suitable tree species in the region according to the climate and soil characteristics of the carbon sequestration forest construction area, referring to the adaptability of existing afforestation tree species in the region, and the list of native tree species, and establishing a list.

[0010] Taking the average annual increment of forest biomass during the rotation period, the average annual leaf litter amount of forest trees during the rotation period, and the decomposition rate of forest tree litter leaves as independent variables, and the carbon sequestration rate of a single forest tree during the rotation period as the dependent variable, to establish a carbon sequestration rate model.

[0011] The carbon sequestration rate model is Cn = (P - L×M)×0.5;

[0012] Wherein, P is the average annual increment of forest biomass during the rotation period, with the unit of kg.ha -1 year -1 , L is the average annual leaf litter amount of forest trees during the rotation period, with the unit of kg.ha -1 year -1 , M is the decomposition rate of forest tree litter leaves; 0.5 is the average carbon content rate of plants.

[0013] The above-mentioned average annual increment of forest biomass P during the rotation period = P r / r; wherein, P r is the biomass of forest trees in the harvesting year, and r is the rotation period age. Calculate the diameter at breast height D of forest trees in the harvesting year according to the growth model of tree species r , and then substitute D r into the biomass model to calculate the biomass P of forest trees in the harvesting year r . The growth model of tree species, the biomass model, and the rotation period age r are all obtained by referring to literature materials.

[0014] The above-mentioned average annual leaf litter amount L of forest trees during the rotation period = P L / leaf life; wherein P L is the average annual leaf biomass during the rotation period. P L is the average annual leaf biomass during the rotation period; wherein calculate the average annual leaf biomass during the rotation period according to the growth model

[0015] ˉˉ

[0016] The average diameter at breast height D of the trees is measured, and then D is substituted into the leaf biomass equation to calculate the average annual leaf biomass P during the rotation period. L The growth model, leaf biomass equation, and leaf lifespan are all obtained by referring to the literature.

[0017] Sort the carbon sequestration rates of each tree species. Those with a carbon sequestration rate greater than the average of the region's suitable tree species are high-carbon sequestration tree species.

[0018] The advantages of the present invention are as follows:

[0019] (1) Compared with the method of screening high-carbon sequestration tree species and varieties only based on the growth rate of forest trees, the screening method of regional high-carbon sequestration tree species in the present invention is more scientific and accurate. The method of the present invention fully considers all aspects of forest carbon sequestration and carbon loss, and has a solid theoretical basis. Currently, the commonly used method for selecting high-carbon sequestration tree species only relies on the growth of trees and does not consider carbon loss, with a weak theoretical basis and unable to accurately evaluate the carbon sequestration ability of forest trees. Therefore, the method of the present invention is more scientific and can more accurately screen out high-carbon sequestration tree species.

[0020] (2) The screening method of regional high-carbon sequestration tree species in the present invention quantifies the carbon sequestration ability of forest trees. This method uses the method of establishing a mathematical model and database for the average annual theoretical carbon sequestration amount (carbon sequestration rate) of a single forest tree during the rotation period, and uses this quantitative index of carbon sequestration rate to indicate the carbon sequestration ability of forest trees. Currently, using the growth rate of trees to indicate the carbon sequestration ability of forest trees cannot quantify the carbon sequestration ability of forest trees, nor can it compare the carbon sequestration abilities of tree species and varieties with similar growth rates. Therefore, this quantitative method also makes the screening of carbon sequestration tree species more accurate.

[0021] (3) It has strong popularization and operability. Based on the database of the carbon sequestration rates of suitable tree species in the region according to the method of the present invention, it can be used as a basis for forestry department staff at all levels to screen high-carbon sequestration tree species. Especially for grass-roots forestry department staff with relatively limited theoretical knowledge, it is very easy to screen out high-carbon sequestration tree species according to the ranking of the carbon sequestration rates of each tree species, providing practical guidance for them. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the screening method of regional high-carbon sequestration tree species in an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] The following further describes the present invention in combination with the implementation example - the establishment of the carbon sequestration model of the main afforestation tree species in the southern mountainous area of Anhui and the screening of high-carbon sequestration tree species.

[0024] The steps of the screening method for high-carbon sequestration tree species in the southern mountainous area of Anhui are as follows:

[0025] (1) Establishment of a list of suitable afforestation tree species in the southern mountainous area of Anhui

[0026] According to the climate and soil characteristics of the carbon sequestration forest construction area, referring to the adaptability of existing afforestation tree species in the area and the list of native tree species, suitable tree species for the area were selected to establish a list of suitable afforestation tree species in the southern mountainous area of Anhui Province, as shown in Table 1.

[0027] Table 1 List of main suitable afforestation tree species in the southern mountainous area of Anhui Province

[0028]

[0029]

[0030] (2) Construct a carbon sequestration rate model for suitable tree species

[0031] Taking the average annual increment of forest biomass P during the rotation period, the average annual leaf litter fall L of forest trees during the rotation period, and the decomposition rate M of forest litter leaves as independent variables, and the carbon sequestration rate Cn of a single forest tree during the rotation period as the dependent variable, a carbon sequestration rate model was established.

[0032] The carbon sequestration rate model is Cn = (P - L×M)×0.5;

[0033] Among them, P is the average annual increment of forest biomass during the rotation period, with the unit of kg.ha -1 year -1 ; L is the average annual leaf litter fall of forest trees during the rotation period, with the unit of kg.ha -1 year -1 ; M is the decomposition rate of forest litter leaves; 0.5 is the average carbon content rate of plants.

[0034] The above-mentioned average annual increment of forest biomass P during the rotation period = P r / r; among them, P r is the biomass of forest trees in the harvesting year, and r is the rotation period age; among them, the diameter at breast height D of forest trees in the harvesting year is calculated according to the growth model of tree species r (see Table 2), and then D r is substituted into the biomass model to calculate the biomass P of forest trees in the harvesting year r (see Table 3). The growth model, biomass model, and rotation period age r of tree species are all obtained by consulting literature materials ((LY / T 2908―2017 "Classification of Age Classes and Age Groups of Main Tree Species"; Luo Yunjian et al., "Handbook of Biomass Models of Main Forest Trees in China", 2015).

[0035] The above-mentioned average annual leaf litter fall L of forest trees during the rotation period = P L / leaf life; among them, P L is the average annual leaf biomass during the rotation period; among them, the average diameter at breast height of trees during the rotation period is calculated according to the growth model (see Table 4), and then Substitute into the leaf biomass equation to calculate the average annual leaf biomass P within the rotation period L , as shown in Table 4. The growth model, leaf biomass equation, and leaf lifespan were all obtained by referring to literature (Ding Zengfa, Biomass Models and Growth Equations of Four Dominant Tree Species such as Castanopsis eyrei in Anhui Subtropical Evergreen Broad-leaved Forest, 2014; Luo Yunjian et al., Handbook of Biomass Models of Main Forest Trees in China, 2015).

[0036] The decomposition rate M of the above forest tree litter was obtained by referring to literature (Sun Zhaolin's doctoral dissertation, Forest Litter Decomposition and Its Response to Simulated Nitrogen Deposition, 2021).

[0037] Table 2 Rotation Periods, Growth Models, and DBH of Forest Trees in the Harvest Year of Each Tree Species in the Southern Anhui Mountain Area (D r )

[0038]

[0039] Table 3 Total Biomass Equations, Biomass (P r ) of Forest Trees in the Harvest Year, and Annual Average Growth (P) of Each Tree Species in the Southern Anhui Mountain Area

[0040]

[0041]

[0042] Table 4 Leaf Lifespan, Leaf Biomass Equation, and P L Calculated Value

[0043]

[0044] Table 4 Carbon Sequestration Rates and Main Parameters of Each Tree Species in the Southern Anhui Mountain Area

[0045]

[0046]

[0047] (3) Select tree species with high carbon sequestration

[0048] As can be seen from Table 2, the carbon sequestration rates of 11 common suitable afforestation tree species in the southern Anhui mountain area vary greatly, ranging from 0.50 to 6.33 kg C / tree / year. The average value of the carbon sequestration rates of the 11 suitable tree species is 3.03 kg C / tree / year. The tree species with carbon sequestration rates higher than the average are Liquidambar formosana, Cinnamomum camphora, Sassafras tzumu, Pinus elliottii, and Schima superba. Therefore, Liquidambar formosana, Cinnamomum camphora, Sassafras tzumu, Pinus elliottii, and Schima superba can be identified as high-carbon-sequestration tree species in the southern Anhui mountain area, and these five tree species can be preferentially selected for the construction of carbon sequestration forests.

[0049] The screening method for regional high carbon sequestration tree species of the present invention quantifies the carbon sequestration capacity of forest trees. By using the method of establishing a mathematical model and database for the annual average theoretical carbon sequestration amount (carbon sequestration rate) of a single forest tree within the rotation period, the carbon sequestration capacity of forest trees is indicated by this quantitative index of carbon sequestration rate. This quantitative method also makes the screening of carbon sequestration tree species more accurate. The database of carbon sequestration rates of regional suitable tree species of the method of the present invention can be used as a basis for forestry department staff at all levels to screen high carbon sequestration tree species. Especially for the grass-roots forestry department staff with relatively scarce theoretical knowledge, it is very easy to screen out high carbon sequestration tree species according to the ranking of carbon sequestration rates of each tree species, providing practical guidance for them.

Claims

1. A method for screening regional high carbon fixation tree species, characterized by: First, a list of regional suitable tree species is established. The carbon fixation rate of different tree species in the regional suitable tree species list is obtained through the carbon fixation rate model. By comparing the carbon fixation rates of each tree species, regional high carbon fixation tree species are screened out.

2. The method for screening regional high carbon fixation tree species according to claim 1, characterized in that: A carbon fixation rate model was established with the average annual growth of tree biomass during the rotation period, the average annual leaf litter during the rotation period, and the decomposition rate of fallen leaves as independent variables, and the carbon fixation rate of individual trees during the rotation period as the dependent variable.

3. The method for screening regional high carbon fixation tree species according to claim 2, characterized in that: The carbon fixation rate model is Cn = (PL × M) × 0.5; Among them, Cn is the carbon fixation rate; P is the average annual growth of forest biomass during the rotation period, in kg.ha -1 year -1 ; L is the average annual leaf litter of trees during the rotation period, in kg.ha -1 year -1 ; M is the decomposition rate of fallen leaves of trees.

4. The method for screening regional high carbon fixation tree species according to claim 3, characterized in that: The average annual increase in tree biomass during the rotation period is P = P r / r; where P r is the biomass of trees in the year of felling, and r is the age of the rotation period.

5. The method for screening regional high carbon fixation tree species according to claim 3, characterized in that: The average annual leaf litter of trees during the rotation period is L = P L / blade life; where P L is the average annual leaf biomass during the rotation period.

6. The method for screening regional high carbon fixation tree species according to claim 1, characterized in that: The establishment of a regional list of suitable tree species is based on the climate and soil characteristics of the carbon sequestration forest construction area, with reference to the adaptability of existing afforestation tree species in the region and the list of native tree species, to select regional suitable tree species and establish a list.

7. The method for screening regional high carbon fixation tree species according to claim 1, characterized in that: The carbon fixation rates of various tree species are ranked, and those with a carbon fixation rate greater than the average of regional suitable tree species are high carbon fixation tree species.

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