Degenerated river wetland vegetation recovery method

Abstract

The invention discloses a degraded river wetland vegetation restoration method, and relates to the technical field of ecological restoration. Comprising the following steps: (1) investigating background conditions of a target wetland area, detecting and analyzing water quality and soil, and recording pollution conditions and distribution conditions of existing vegetation; (2) planting fast-growing herbaceous plants, physically removing the fast-growing herbaceous plants before autumn every year, and detecting and analyzing water quality and soil; and (3) planting arbor plants, shrub plants and herbaceous plants of wetland dominant species according to the wetland vegetation distribution condition. Through scientific dominance survey, dominant plant varieties adapting to the local environment are accurately screened and planted in a matched mode. The plants have a synergistic effect, and a mature ecological system which is reasonable in structure and complete in function is constructed.

Description

Technical Field

[0001] This invention relates to the field of ecological restoration technology, and more specifically to a method for restoring vegetation in degraded river wetlands. Background Technology

[0002] With accelerated industrialization, pollution loads in major river basins in my country continue to exceed standards. Nationwide, 31.2% of river sections have COD concentrations ≥20 mg / L, exceeding Class III water quality standards. Heavy metal pollution is particularly prominent in densely industrialized areas, with average Cd concentrations in some regions reaching 0.25-1.8 mg / kg, exceeding background levels by 3-10 times. Pollutants accumulate in wetland sediments through dynamic processes of adsorption and desorption, forming secondary pollution sources.

[0003] The riparian zone is a semi-terrestrial ecosystem situated between rivers and land. It is a transitional zone with a buffering effect, directly or indirectly influenced by river level fluctuations. It typically connects terrestrial and aquatic systems through hydrological processes such as surface runoff and subsurface flow. While the riparian zone constitutes a small area within the watershed ecosystem, it plays an irreplaceable role in the inflow of water and nutrients into rivers, playing a crucial role in intercepting non-point source pollution, constructing river habitats, and promoting connectivity between rivers and their surrounding environment.

[0004] Traditional river flushing and purification methods are insufficient to eradicate secondary pollution in river wetlands. Due to the hydraulic retention effect, in river sections with a meander angle greater than 1.5, pollutant migration time is extended to 2.3 times that of straight river sections. The self-purification capacity of water bodies decreases to 38% of that during the wet season. Sedimentary heavy metals can be converted to dissolved forms under anaerobic conditions, with an annual release rate of 12-15%. This type of pollution leads to the collapse of river wetland ecosystem functions, manifested primarily by the death of submerged plants, degradation of riparian vegetation, and a sharp decline in benthic biodiversity.

[0005] Wetland restoration refers to the repair or reconstruction of degraded or disappeared wetlands through ecological technologies or ecological engineering, to reproduce their pre-disturbance structure and function, as well as their related physical, chemical and biological characteristics; or to reconstruct them into characteristics that are not entirely the same as before the disturbance, so that they can perform corresponding ecological functions and provide various service values, based on existing conditions and objectives.

[0006] In current wetland vegetation restoration practices, the selected plant species are often too homogeneous. While this artificially chosen, simplified community structure may have some advantages in terms of initial recovery speed, its deeper ecological risks cannot be ignored. The homogeneity of plant species directly leads to a lack of biodiversity in wetland ecosystems. The absence of a multi-layered and multi-type mix of trees, shrubs, grasses, wetland plants, and aquatic plants prevents wetlands from forming complex and functionally complementary plant communities.

[0007] Therefore, providing a method for restoring degraded river wetland vegetation that can reduce river wetland pollution is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0008] In view of this, the present invention provides a method for restoring vegetation in degraded river wetlands.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A method for restoring vegetation in degraded river wetlands includes the following steps:

[0011] (1) Conduct a baseline survey of the target wetland area, test and analyze the water quality and soil, and record the pollution status and the distribution of existing vegetation;

[0012] (2) Plant fast-growing herbaceous plants, physically remove them before autumn each year, and test and analyze the water and soil quality;

[0013] (3) Plant dominant wetland species of trees, shrubs and herbaceous plants according to the distribution of wetland vegetation.

[0014] Furthermore, the fast-growing herbaceous plant mentioned in step (2) is reed.

[0015] Furthermore, if the pollutant exceeds the standard in step (2), repeat this step; if the pollutant meets the standard in step (2), proceed to the next step.

[0016] Furthermore, the tree plant is one or more combinations of black locust and white poplar.

[0017] Furthermore, the shrub is one or more of Forsythia suspensa and Lonicera japonica.

[0018] Furthermore, the herbaceous plants are divided into riparian zones and shallow water areas;

[0019] The riverbank zone is planted with one or more of the following: reeds, cattails, water onions, and sedges.

[0020] The shallow water area is planted with one or more of the following: lotus, cattail, and reed.

[0021] Furthermore, it also includes a restoration confirmation process, in which the surface vegetation of the degraded wetland is investigated in the summer and autumn of the same year after the degraded wetland has been treated in step (3).

[0022] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] This invention utilizes reeds for planting and regular harvesting to directly and physically remove pollutants from degraded river wetlands, effectively reducing the environmental burden of mild pollution. This continuous harvesting process acts like "detoxifying" the wetlands, significantly improving soil and water conditions and resulting in a marked increase in the survival rate of other herbaceous plants cultivated in polluted areas, such as sedges, cattails, and lotus.

[0024] Through scientific dominance surveys, this invention precisely selects and plants advantageous plant species adapted to the local environment. These plants work synergistically to construct a well-structured and fully functional mature ecosystem. This system not only enhances the wetland's own purification capacity but also promotes the restoration of ecological balance, achieving the long-term maintenance of environmental health. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1

[0027] From autumn 2021 to autumn 2024, a study was conducted in the target degraded river wetlands to investigate the distribution of resources such as the main wetland plant species, abundance, cover, height, growth status, and habitat conditions within the park.

[0028] The main aquatic plants in different areas were investigated using a random sampling method, with quadrats randomly and evenly set up within each degraded river wetland. The main quadrats for trees and large shrubs were 100 m² in size. 2 (10×10m), the main sample plot area for shrubs and tall herbaceous plants is 25m². 2 (5×5m); the main quadrat area for herbaceous plants is 1m². 2 (1×1m). Each tree in the main quadrat of the forest tree community was investigated; four 5×5m shrub quadrats were set up diagonally opposite the tree quadrats, and each shrub was investigated, recording species name, average height, abundance, and canopy; five 1×1m herb quadrats were set up at the four corners and the center of each shrub quadrat, and the species name, abundance, canopy, and height of the herbaceous plants in the quadrats were recorded; the location of the quadrats was determined using GPS, and the geographical coordinates, altitude, slope, and other habitat indicators of the quadrats were recorded.

[0029] Based on the survey results, the number of families, genera and species of plant resources in each degraded river wetland was counted, plant communities with good growth were selected, species importance values ​​were calculated based on the survey results, dominant species and associated species were selected, and a suitable aquatic plant combination pattern for the local environment was selected.

[0030] Species Importance Calculation

[0031] Dominant species of trees, shrubs, and herbaceous plants (IV>1) are determined based on importance value (IV).

[0032] Importance value of tree species = (relative abundance + relative frequency + relative significance) / 3

[0033] Relative abundance = (Number of individuals of a certain plant / Total number of individuals of all plants) × 100%

[0034] Relative frequency = (Frequency of this species / Sum of frequencies of all species) × 100%

[0035] Relative significance (dominance) = (sum of chest area of ​​this species in the quadrat / sum of chest area of ​​all individuals in the quadrat) × 100%

[0036] Importance value of shrubs and herbs = (relative abundance + relative frequency + relative cover) / 3

[0037] Relative abundance = (Number of individuals of each species / Total number of individuals of all species) × 100%

[0038] Relative frequency = (Frequency of this species / Sum of frequencies of all species) × 100%

[0039] Relative cover (dominance) = (coverage of a species / sum of all covers) × 100%

[0040] Dominant species and common communities in degraded river wetlands

[0041] Table 1. Main dominant species in the target degraded river wetlands

[0042]

[0043] Within the target degraded river wetlands, reed communities are the most widespread and largest vegetation type, commonly accompanied by cattails, water onions, burdock, and sedges. Cattail communities commonly include reeds, burdock, water sedge, and water plantain. Sedge communities commonly include reeds. Lotus communities are the most aesthetically pleasing plant communities, with water depths not exceeding 1.7 meters. Common companion species include cattails, reeds, and some algae, such as hornwort and hydrangea. Water onion communities commonly include sedge, reeds, and water plantain.

[0044] Because reeds have the widest distribution and the highest survival rate, they are used as a fast-growing herbaceous plant for pollution control.

[0045] In late autumn of 2021, mature, drooping reed spikes were harvested from the wetlands, dried in the sun, and then placed in ventilated woven bags. The bags containing the reed spikes were then stored in a well-ventilated and dry environment at a temperature of 4°C until sowing in the spring of 2022.

[0046] Before sowing, the wetland pollution was tested, and the results are shown in Table 1. The wetland pollution index exceeded the environmental protection standard and was classified as slightly polluted.

[0047] For reed seeds that do not sink after soaking in potassium nitrate solution for 8 hours, remove the seeds that sink to the bottom of the solution and rinse them five times with clean water to obtain reed seeds for sowing.

[0048] When the outdoor temperature stabilizes at 10℃ in the spring of 2022, sow 10 reed seeds per group; the spacing between each group should be 50cm.

[0049] Before the fall of 2022, the reeds will be physically harvested and disposed of in a harmless manner, repeating the steps from last year.

[0050] Before sowing in the spring of 2023, the pollution level of the wetlands was tested, and some indicators exceeded the national standards, so the same steps were repeated as last year.

[0051] Before sowing in the spring of 2024, the wetland pollution level was tested and found to be in compliance with national standards.

[0052] Table 2. Status of Pollution Remediation of Targeted Degraded Rivers and Wetlands

[0053] Testing items Environmental standards 2022 2023 2024 Total removal rate Total phosphorus (in p) ≤ 0.4 0.75 0.49 0.21 72％ Total nitrogen (in p) ≤ 2.0 4.21 2.83 1.85 56.1％ COD (denoted by p) ≦ 40 68.15 45.59 27.16 60.1％ Ammonia nitrogen (denoted by p) ≤ 2.0 4.34 1.67 0.91 79％ Sulfides (denoted by p) ≦ 1.0 0.66 0.48 0.25 62％ Sediment Cd (mg / kg) ≦ 0.6 0.85 0.51 0.35 58.8％ Sediment Hg (mg / kg) ≦ 0.5 0.73 0.60 0.46 37％

[0054] In the spring of 2024, based on the distribution of wetland vegetation, dominant species and associated species communities were selected and wetland community plants were planted in the treated pollution areas and adjacent untreated areas. The survival rate was counted in the autumn of that year.

[0055] Trees: Black locust, white poplar.

[0056] Shrubs: Forsythia, Honeysuckle.

[0057] Riverbank herbaceous plants: reeds, cattails, water onions, sedges;

[0058] Herbaceous plants in shallow water areas: lotus, cattail, reed.

[0059] Table 3 Survival rate of planted plants in target degraded river wetlands

[0060]

[0061] Table 3 shows that the pollution control system constructed using the fast-growing herbaceous plant reed (Phragmites australis) in this invention efficiently adsorbs heavy metals and organic pollutants through its extensive root network. The reed stalks are then physically harvested and treated harmlessly to remove pollution, significantly improving the soil and water environment of degraded river wetlands. Compared to untreated areas, the survival rate in the treated area achieved a breakthrough improvement, with the average survival rate of herbaceous communities increasing from 28.6% in the untreated area to 66.4% in the treated area. The survival rates of shrubs and trees also improved to some extent. The pollutant interception and transformation function of reeds effectively reduced wetland pollution and created healthier ecological niches for other plants, especially restoring associated species such as wetland sedges, cattails, and lotus into stable communities.

[0062] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for restoring vegetation in degraded river wetlands, characterized in that, Includes the following steps: (1) Conduct a baseline survey of the target wetland area, test and analyze the water quality and soil, and record the pollution status and the distribution of existing vegetation; (2) Plant fast-growing herbaceous plants, physically remove them before autumn each year, and test and analyze the water and soil quality; (3) Plant dominant wetland species of trees, shrubs and herbaceous plants according to the distribution of wetland vegetation.

2. The method for restoring vegetation in degraded river wetlands according to claim 1, characterized in that, The fast-growing herbaceous plant mentioned in step (2) is reed.

3. The method for restoring vegetation in degraded river wetlands according to claim 1, characterized in that, If the pollutant exceeds the standard in step (2), repeat this step; if the pollutant meets the standard in step (2), proceed to the next step.

4. The method for restoring vegetation in degraded river wetlands according to claim 1, characterized in that, The tree species mentioned are one or more combinations of black locust and white poplar.

5. The method for restoring vegetation in degraded river wetlands according to claim 1, characterized in that, The shrubs are one or more of Forsythia suspensa and Lonicera japonica.

6. The method for restoring vegetation in degraded river wetlands according to claim 1, characterized in that, The herbaceous plants are divided into riparian zones and shallow water areas; The riverbank zone is planted with one or more of the following: reeds, cattails, water onions, and sedges. The shallow water area is planted with one or more of the following: lotus, cattail, and reed.

7. The method for restoring vegetation in degraded river wetlands according to claim 1, characterized in that, It also includes a restoration confirmation process, in which the surface vegetation of the degraded wetland is investigated in the summer and autumn of the same year after the degraded wetland has been treated in step (3).

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