Emergent vegetation management method for increasing biological carbon sequestration function

Abstract

The invention discloses an emergent vegetation management method for increasing a biological carbon sequestration function, and belongs to the technical field of ecological system management and restoration, and the method comprises the following steps: in the stable growth period of emergent vegetation, discharging part of wetland moisture, and carrying out first mowing on overground parts of plants above the water surface; after the emergent vegetation further grows, the water level is restored to the end of the growth season, finally water is drained, secondary mowing is carried out, and all the emergent vegetation on the ground is harvested. According to the method, the overground biomass is increased through the plant photosynthetic carbon sequestration function by adjusting the appropriate harvesting time and mode of the wetland emergent vegetation, and therefore the biological carbon sequestration amount is increased. Compared with a traditional method for harvesting wetland vegetation at a time, the method has the advantages that the plant growth rate is remarkably increased, the overground biomass of the plants and the accumulation of organic carbon in surface soil are promoted, and the improvement of the wetland carbon sequestration function is facilitated.

Description

Technical Field

[0001] This invention belongs to the field of ecosystem management and restoration technology, and in particular relates to a method for managing emergent vegetation to enhance its biological carbon sequestration function. Background Technology

[0002] Wetlands, as important carbon sink ecosystems, use vegetation to fix atmospheric carbon dioxide through photosynthesis and store carbon in plants and soil. Currently, the management of wetland emergent vegetation mostly adopts a one-time harvesting method, that is, harvesting the above-ground parts all at the end of the growing season. Although this method can obtain biomass, it fails to fully utilize the regenerative capacity of plants during their growth process, limiting the vegetation's carbon sequestration potential and carbon accumulation efficiency.

[0003] Current technologies lack periodic harvesting management methods that combine the growth characteristics and carbon sequestration mechanisms of emergent vegetation, resulting in the underutilization of wetland carbon sequestration functions. Therefore, it is necessary to develop a scientific and rational management method for emergent vegetation to enhance the carbon sequestration capacity and resource utilization of wetland ecosystems. Summary of the Invention

[0004] To enhance the carbon sequestration function of wetland plants and optimize the utilization of large emergent vegetation resources in wetlands, this invention proposes a management method for emergent vegetation that increases biological carbon sequestration function. This method enhances the biological carbon sequestration function of emergent vegetation by adjusting the harvest time and method. It has advantages such as simple operation and significant carbon sequestration effect, providing a basis for the scientific management of wetlands and the rational utilization of vegetation resources.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: This invention provides a method for managing emergent vegetation to enhance its biological carbon sequestration function, comprising the following steps: during the stable growth period of emergent vegetation, draining some of the wetland water and first mowing the above-ground parts of the plants above the water surface; after the emergent vegetation has grown further, restoring the water level to the end of the growing season, finally draining the water, and then mowing a second time to harvest all the above-ground emergent vegetation.

[0006] Furthermore, the initial harvesting involves manually or mechanically harvesting the above-ground parts of the plants that are above the water surface to prevent water from entering the plants and affecting their growth.

[0007] Furthermore, the emergent vegetation includes one or more of reeds, cattails, and wild rice.

[0008] Furthermore, the emergent vegetation is selected from cattails.

[0009] Furthermore, the stable growth period refers to the later stage of emergent vegetation growth, which is August to September.

[0010] Furthermore, the drainage of some wetland water is to ensure that the wetland water level does not exceed 20cm.

[0011] Furthermore, the vegetation further grows to the point that the vegetation stubble after the first mowing grows to more than 50 cm.

[0012] Furthermore, the restored water level is an increase of 50-80cm.

[0013] Compared with the prior art, the present invention has the following advantages and technical effects: This invention aims to increase aboveground biomass by adjusting the appropriate harvesting time and method of emergent vegetation in wetlands, thereby increasing biological carbon sequestration through the photosynthetic carbon sequestration function of plants. Compared with the traditional method of harvesting wetland vegetation all at once, this method significantly improves plant growth rate, promotes aboveground biomass and the accumulation of organic carbon in the topsoil, and contributes to enhancing the carbon sequestration function of wetlands. Detailed Implementation

[0014] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0015] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0016] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0017] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0018] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0019] The following embodiments of the present invention provide a method for managing emergent vegetation to enhance its biological carbon sequestration function. The specific steps are as follows: Select a wetland emergent vegetation distribution area, drain the wetland water to a suitable water level during its stable growth period; perform the first harvesting of the above-ground parts of the plants above the water surface, i.e., harvest the above-ground parts of the plants manually or mechanically; as the vegetation further grows, restore the water level to the end of the growing season, drain the water, and perform a second harvesting to collect all the above-ground biomass; calculate the carbon sequestration of the plants and the carbon sequestration of the soil.

[0020] In a preferred embodiment, the emergent vegetation includes one or more of reeds, cattails, and wild rice.

[0021] In a preferred embodiment, the stable growth period is the later stage of emergent vegetation growth, which is August to September.

[0022] In a preferred embodiment, draining some of the wetland water means keeping the wetland water level no higher than 20cm.

[0023] In a preferred embodiment, the vegetation is further grown until the vegetation stubble after the first mowing grows to more than 50 cm.

[0024] In a preferred embodiment, the restored water level is raised by 50-80cm.

[0025] Example 1 In 2022, in the Niuxintao wetland area of ​​the western Songnen Plain, a cattail population with relatively uniform growth was selected and divided into four plots, each approximately 4 m × 4 m in size. Four different secondary harvesting management methods were implemented, namely, harvesting at different times: late June / late October, late July / late October, late August / late October, and late September / late October. Specifically, in late June, late July, late August, and late September, the water level was lowered to below or equal to 20 cm, and the above-ground parts of the plants were harvested manually to avoid water entering the plants and affecting their growth. After the vegetation residue from the first harvest had grown to 50 cm, the water level was raised by 50-80 cm until October. Finally, the water was drained, and a second harvest was carried out to harvest all the above-ground cattails. Meanwhile, in early June, three 1m×1m fixed quadrats were set up in each of the above-mentioned plots, with the water level not exceeding 20cm. Starting from June, the density and population height in the fixed quadrats were recorded every month. The aboveground parts of the cattails above the water surface were dried and weighed according to the mowing treatment. At the end of the growing season, aboveground (second mowing) and underground biomass were collected from all fixed quadrats, and topsoil and subsurface soil (0-40cm) were collected to analyze the organic carbon content of plants and rhizosphere soil.

[0026] Comparative Example 1 In the same year, in the Niuxintao wetland area in the western Songnen Plain, a cattail population with relatively uniform growth was selected and managed under a single-harvest system in another plot (approximately 4 m × 4 m), meaning harvesting was only carried out in October. Simultaneously, in early June, three 1 m × 1 m fixed quadrats were established within this plot, with water levels not exceeding 20 cm. From June onwards, the density and population height within the fixed quadrats were recorded monthly. The above-ground parts of the cattails above the water surface were dried and weighed. At the end of the growing season, aboveground and belowground biomass were collected from all fixed quadrats, and topsoil and subsurface soil (0-40 cm) were collected to analyze the organic carbon content of the plants and rhizosphere soil.

[0027] Table 1 shows the changes in cattail plant height growth rate at different harvest times in the planting areas of Example 1 and Comparative Example 1; Table 2 shows the cumulative plant height and biomass in Example 1 and Comparative Example 1; Table 3 shows the rhizosphere soil organic carbon content in Example 1 and Comparative Example 1; and Table 4 shows the plant and soil carbon increments at different harvest times in Example 1 and Comparative Example 1. The cumulative aboveground biomass and cumulative belowground biomass are calculated as the sum of aboveground biomass at the first and second harvests, respectively, while the accumulated aboveground biomass is the total biomass at the second harvest. The units are g / m³. 2 The rhizosphere soil organic carbon content was measured using the potassium dichromate oxidation-external heating method, according to "Determination of Organic Matter and Calculation of Carbon-Nitrogen Ratio in Forest Soils (LY / T1237-1999)". The unit is g / kg. The plant carbon increment was calculated as: [(Aboveground biomass of the example - Aboveground biomass of the comparative example) + (Belowground biomass of the example - Belowground biomass of the comparative example)] × 43%, in g / m³. 2 Soil carbon increment calculation method: The sum of the four layers (soil organic carbon in the example - soil organic carbon in the comparative example) is divided by 4, and the unit is g / kg; The total carbon increment of plants and soil is calculated as: soil carbon increment + plant carbon increment / aboveground biomass and belowground biomass of plants per unit area, and the unit is g / kg.

[0028] Table 1. Changes in the growth rate of cattail plant height at different harvest times. Note: JE, JY, AT, and SR represent two harvesting treatments in Example 1 (late June / late October, late July / late October, late August / late October, and late September / late October), respectively; OR represents a single harvesting treatment in Comparative Example 1, and so on. Lowercase letters indicate significant differences between different treatments in the same column. P <0.05), the same applies below.

[0029] Table 2 Cumulative plant height and biomass Table 3. Rhizosphere soil organic carbon content Table 4. Plant and soil carbon increments at different harvest times Table 1 shows that in Comparative Example 1, the rapid growth period of OR cattail was June-July, with an average daily growth of 3.17 cm, while the stable growth period was from August to October, with an average daily growth of 0.5 cm. Cutting during either the rapid or stable growth period stimulated rapid regrowth of the cattail. Cutting during the stable growth period in August and September significantly increased the regrowth rate to 2-4 cm per day. In Example 1, the early-cut (JE, JY) cattails showed a significantly increased growth rate in the following two months, reaching 5.41 and 5.76 cm per day in the first month after the first cut, and 2.30 and 4.05 cm per day in the second month; while in Example 1, the late-cut (AT, SR) cattails reached 4.14 and 2.03 cm per day in the first month after the first cut.

[0030] Table 2 shows that early-harvested cattails (JE, JY) could still grow to over 2 meters tall when harvested a second time at the end of October. However, compared to Comparative Example 1, both showed a decrease in overall aboveground biomass and an increase in underground biomass. Specifically, cattails harvested for the first time in late June showed a decrease of 272g in aboveground dry weight per square meter and an increase of 175g in underground dry weight per square meter, resulting in an overall decrease of 97g. Cattails harvested for the first time in late July showed a decrease of 275g in aboveground dry weight per square meter and an increase of 62g in underground dry weight per square meter, resulting in an overall decrease. The weight increase was 213g less. The increase in weight per square meter of above-ground and underground parts of cattails was 62g and 203g respectively, with an overall increase of 265g. The increase in weight per square meter of above-ground and underground parts of cattails was 422g and 176g respectively, with an overall increase of 598g. Because the first cut of cattails in late-cut (AT, SR) was later, the above-ground parts of the cattails stopped growing after the first cut, resulting in a lower cumulative plant height than that of cattails in early-cut (JE, JY).

[0031] Combining Tables 2 and 4, and converting the carbon content of cattail plants to 43% to calculate plant carbon sequestration, under the two-harvest management method, JE, JY, AT, and SR plants increased carbon per square meter by -41.71, -91.59, 113.95, and 257.14 g respectively compared to OR. Converted to g / kg, this translates to increases of -23.07, -54.13, 52.51, and 102.73 g respectively, divided by the plant mass per square meter. From the perspective of plant carbon sequestration, the highest biomass was observed during harvests in August and September. This is related to the rains in August and September and the decrease in biomass due to plant withering and leaf drop in October. Correspondingly, JE, JY, AT, and SR plants increased carbon per kilogram of soil by 1.42 g, 1.40 g, -0.33 g, and 0.31 g respectively compared to OR.

[0032] As shown in Table 3, early mowing (JE) increases soil organic carbon content in the 0-20cm soil layer, while early mowing (JY) increases soil organic carbon content in the 0-40cm soil layer. In other words, from the perspective of soil carbon pool, early mowing (JE, JY) can promote the increase of soil organic carbon, while late mowing (AT, SR) has no significant effect on increasing soil organic carbon content, and is even lower than OR.

[0033] The carbon sequestration by plants (increase in aboveground and belowground levels) and soil carbon sequestration (increase in soil carbon per unit mass) in Table 4 were comprehensively quantified. The total carbon sequestration was ranked as follows: SR (103.04g) > AT (52.18g) > OR (0g) > JE (-21.65g) > JY (-52.73g). It can be seen that the SR and AT treatments achieved an increase in total carbon sequestration, balancing a longer early growth period (accumulating sufficient basal biomass), moderate regeneration stimulation, and minimal negative impact on the soil carbon pool. The JE and JY treatments (first harvest in June and July) showed negative total carbon sequestration values, indicating that their overall carbon sequestration effect was not as good as that of traditional single harvesting. Although they effectively increased the carbon content of deep soil, this soil carbon gain was insufficient to compensate for the significant loss of aboveground biomass. Considering both plant and soil carbon sequestration effects, the carbon increase effect was best with double harvesting of cattails in late August / late October and late September / late October.

[0034] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A management method of emergent vegetation for increasing a biological carbon fixation function, characterized by, The method comprises the following steps: During the stable growth period of the emergent vegetation, part of the water in the wetland is drained, and the above-ground part of the vegetation above the water surface is cut for the first time; after the emergent vegetation grows further, the water level is restored to the end of the growth season, the water is finally drained, and the emergent vegetation above the ground is cut for the second time.

2. The management method of emergent vegetation for increasing the function of carbon sequestration according to claim 1, characterized by, The emergent vegetation comprises one or more of reed, cattail and rice.

3. The method for managing the emergent vegetation with the function of increasing the biological carbon fixation according to claim 1, wherein The emergent vegetation is selected from cattail.

4. The method for managing an emergent vegetation with a function of carbon sequestration according to claim 1, wherein The stable growth period is the late growth period of the emergent vegetation, and the late growth period of the emergent vegetation is August to September.

5. The method for managing an emergent vegetation with a function of carbon sequestration according to claim 1, wherein The part of the water in the wetland is drained to a water level of not higher than 20 cm.

6. The method for managing an emergent vegetation with a function of carbon sequestration according to claim 1, wherein The further growth of the vegetation is that the stubble after the first cutting grows by more than 50 cm.

7. The method for managing an emergent vegetation with a function of carbon sequestration according to claim 1, wherein The water level is restored to an increase of 50-80 cm.

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