A method for directional restoration of a community of a wetland of a river beach zone with fluctuating water level

Abstract

The application provides a kind of water level fluctuation river beach zone degraded wetland Juncus effusus community directional recovery method, belongs to wetland water environment ecological management and landscape restoration technical field.The application includes the following steps: (1) the hydrological condition of river beach zone degraded wetland is investigated, and the target recovery area and the transplanting height and time of Juncus effusus are determined: the transplanting height of low-lying area is greater than or equal to 30 cm, and the transplanting is carried out in early May; the transplanting height of water level change area is greater than or equal to 25 cm, and the transplanting is carried out in early May; the transplanting height of humid area is greater than or equal to 20 cm, and the transplanting is carried out in mid-late May; (2) the degradation degree of Juncus effusus in the target recovery area is investigated, and the transplanting density of Juncus effusus is determined: the natural recovery is carried out in slight degradation area, 20-30 plants / m 2 are transplanted in moderate degradation area, and 40-60 plants / m 2 are transplanted in severe degradation area.The application can not only improve the growth adaptability of Juncus effusus, but also enhance the ecological function of wetland, and provide a new solution for ecological protection and sustainable development.

Description

Technical Field

[0001] This invention relates to the field of wetland water environment ecological management and landscape restoration technology, and in particular to a method for the targeted restoration of Lythrum salicaria communities in degraded riparian wetlands with fluctuating water levels. Background Technology

[0002] Riparian wetlands are marginal areas where aquatic and terrestrial ecosystems meet, playing vital ecological functions, including water purification, habitat creation, flood regulation, and carbon storage. However, due to urbanization, agricultural development, and inadequate water resource management, these wetlands face problems such as environmental pollution and ecological degradation. Their restoration and reconstruction have become a research hotspot and key issue in the forefront of international wetland science.

[0003] Wetland restoration encompasses four aspects: wetland matrix restoration, hydrological restoration, aquatic environment restoration, wetland biological restoration (including plants, animals, and microorganisms), and habitat restoration. Existing research has confirmed that vegetation restoration is the primary task in the restoration and reconstruction of degraded ecosystems. This is no exception for wetland ecosystems. Hydrological fluctuations have a profound impact on the ecological environment of riparian wetlands. The study of wetland plant responses to changes in water level gradients is one of the important research areas in wetland ecology. Periodic changes in water level not only affect plant growth but also determine the ecological characteristics and biodiversity of wetlands.

[0004] *Lythrum salicaria*, a perennial herb belonging to the Lythraceae family, has a stout rhizome, erect, much-branched stem that can reach up to 1 meter in height. Its inflorescence resembles a large spike, with red or pale purple flowers, and the capsule is flattened and round. Native to temperate Eurasia, it is widely found in my country along riverbanks, lakeshores, streamsides, and moist grasslands. *Lythrum salicaria* has neat and elegant clumps, delicate flower colors, and a long flowering period, making it suitable for planting in clumps along water's edge or in ponds. As an important wetland plant, *Lythrum salicaria* plays a vital role in the health and biodiversity of wetland ecosystems. It exhibits strong dispersal and adaptability, thriving under various hydrological conditions. Its well-developed root system helps stabilize soil, prevent soil erosion, effectively purify water, and improve the wetland environment. Furthermore, *Lythrum salicaria* provides habitat for various waterfowl and aquatic organisms, making it an important species for maintaining riparian biodiversity and a significant nectar source for wetlands. While Lythrum salicaria is highly adaptable and has a certain tolerance to water level changes, excessively drastic or irregular hydrological fluctuations can lead to the degradation and imbalance of Lythrum salicaria communities. Therefore, developing an effective method for Lythrum salicaria community restoration is of great significance.

[0005] Currently, methods for restoring wetland plant communities mainly focus on traditional vegetation restoration and water level management. While these methods have effectively promoted vegetation regeneration to some extent, they often face numerous challenges, particularly in effectively coping with the complex environmental changes brought about by water level fluctuations. Wetland hydrological conditions are dynamic, and frequent water level changes can lead to root immersion or drought, thus affecting plant survival and growth. For wetland plants like *Lythrum salicaria*, existing technologies have not fully utilized their advantages in plant selection, cultivation methods, and post-cultivation maintenance. Therefore, there is an urgent need to develop an innovative restoration method to improve the survival and reproductive capacity of *Lythrum salicaria* in wetlands with fluctuating water levels. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a method for the directional restoration of Lythrum salicaria communities in hydrologically fluctuating riparian zones, which can not only improve the growth adaptability of Lythrum salicaria but also enhance the ecological function of wetlands, providing a new solution for ecological protection and sustainable development.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] A method for the directional restoration of Lythrum salicaria communities in degraded riparian wetlands with fluctuating water levels includes the following steps: (1) Investigating the hydrological conditions of the degraded riparian wetlands to determine the target restoration area and the transplanting height and timing of Lythrum salicaria: transplanting height ≥30cm in low-lying areas, transplanting in early May; transplanting height ≥25cm in water level fluctuation areas, transplanting in early May; transplanting height ≥20cm in humid areas, transplanting in mid-to-late May; (2) Investigating the degree of Lythrum salicaria degradation in the target restoration area to determine the transplanting density of Lythrum salicaria: natural restoration in mildly degraded areas, transplanting 20-30 plants / m² in moderately degraded areas. 2 Transplant 40-60 plants / m² in severely degraded areas. 2 .

[0009] Preferably, the survey is conducted as follows: 3-4 transects are established within the degraded wetlands along the riverbank. Following the water level gradient, 3-6 quadrats are set up in each transect to investigate the hydrological conditions and the degree of Lythrum salicaria degradation within the transects. The transects cover areas from 50% soil moisture content to 30cm surface water level, with each transect being 8-12m wide and spaced 100-200m apart. Each quadrat has an area ≥1m². 2 .

[0010] Preferably, the low-lying area is a region where the water level is maintained at 5-10cm; the water level fluctuation area is a region where the water level is maintained at 0-30cm, and the water level rises, falls, or freezes with the seasons; the moist area is a region where the soil moisture content is ≥60%.

[0011] More preferably, it also includes a deep water area and a dry area, which are not considered as target recovery areas; the deep water area is an area where the water level is maintained at 20-50 cm, and the dry area is an area where the soil moisture content is <60%.

[0012] Preferably, the mildly degraded area is a region with a Lythrum salicaria coverage of 30%-50% and a relative density of 30%-40%; the moderately degraded area is a region with a Lythrum salicaria coverage of 10%-30% and a relative density of 10%-30%; and the severely degraded area is a region with a Lythrum salicaria coverage of <10% and a relative density of <10%.

[0013] Preferably, the loosestrife is transplanted in clumps, with 5-7 loosestrife plants per clump.

[0014] More preferably, the spacing between transplanted loosestrife clumps in moderately degraded areas is 90-110 cm; and the spacing between transplanted loosestrife clumps in severely degraded areas is 45-55 cm.

[0015] Preferably, the loosestrife is transplanted by hole planting, with the diameter of the transplanting hole being 8-10cm and the depth being 10-12cm.

[0016] More preferably, the hole planting includes: after loosening the soil, digging a transplanting hole, selecting healthy loosestrife seedlings with well-developed root systems, placing them in the transplanting hole, and filling and compacting the soil.

[0017] Preferably, the method also includes regular maintenance of the target restoration area, including: pruning or straightening the loosestrife, removing withered or weak leaves and stems; clearing weeds; and artificially replenishing water.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This invention, through targeted restoration of *Lythrum salicaria* communities, can effectively restore the function of wetland ecosystems, promoting water quality improvement and soil health. As part of the wetland plant community, the restoration of *Lythrum salicaria* helps attract various waterbirds, insects, and other organisms, enhancing wetland biodiversity. The root system of *Lythrum salicaria* effectively stabilizes the soil, reducing soil erosion and maintaining wetland stability. The growth of wetland plants absorbs carbon dioxide, helping to mitigate climate change; the restoration of *Lythrum salicaria* helps increase the carbon storage capacity of wetlands. Simultaneously, *Lythrum salicaria* is a common wetland nectar source plant with a long flowering period, producing abundant nectar and pollen during its blooming. These rich resources attract various insects, providing them with a stable plant source. Through scientific restoration methods, the sustainable use of *Lythrum salicaria* can be achieved, such as for medicinal and ornamental purposes, promoting local economic development.

[0020] The method of this invention can effectively implement precise restoration for different degradation levels and hydrological conditions, enhance the self-repair capacity of wetland ecosystems, protect biodiversity, and strengthen the ecological functions and landscape value of wetlands. Furthermore, the method is simple to operate, low in cost, easy to promote on a large scale, applicable to various wetland environments, and has minimal impact on the surrounding ecological environment during implementation. Attached Figure Description

[0021] Figure 1 This is a schematic diagram showing the restoration of the regional division in Example 1;

[0022] Figure 2 This is a diagram illustrating the cultivation of loosestrife. Detailed Implementation

[0023] This invention provides a method for the directional restoration of *Lythrum salicaria* communities in degraded riparian wetlands with fluctuating water levels. It is preferably applicable to degraded riparian wetlands with significant hydrological fluctuations, where the water level drops by 0.5-1m compared to the wet season, resulting in a reduction of more than 30% in wetland area. The method includes the following steps:

[0024] Step 1: Preliminary investigation of degraded wetlands along the riverbank

[0025] A hydrological survey of degraded wetlands along the riparian zone will be conducted. Ideally, 3-4 transects will be established within the degraded wetlands. Following a water level gradient (each gradient is 10 cm), 3-6 quadrats will be set up in each transect, with 4-5 quadrats preferred. The hydrological conditions and the degree of Lythrum salicaria degradation within the transects will be investigated. The transects will cover areas from 50% soil moisture content to 30 cm surface water level. Each transect will be 8-12 m wide, with a preferred length of 30 m and a width of 10 m. The preferred spacing between transects will be 100-200 m, with 150 m being preferred. The area of ​​each quadrat will be ≥1 m². 2 As one possible implementation method, the survey plot is a 1m × 1m plot, including but not limited to the following water level conditions:

[0026] A: From a surface dry state (soil moisture content approximately 50%) to a water level of 10cm;

[0027] B: Water level from 10cm to 20cm;

[0028] C: Water level from 20cm to 30cm.

[0029] Based on the hydrological survey results, the degraded riparian wetlands were divided into arid zones, humid zones, low-lying zones, water level fluctuation zones, and deep-water zones, as detailed below. Figure 1 As shown:

[0030] Deep water area: Maintain water level at 20-50cm;

[0031] Water level variation zone: The water level remains between 0-30cm. In summer, the water level rises due to abundant rainfall or increased upstream flow, while in winter, the water level drops or freezes due to reduced rainfall.

[0032] Low-lying areas: maintain water level at 5-10cm;

[0033] Humid areas: Soil moisture content ≥ 60%;

[0034] Arid areas: Soil moisture content < 60%.

[0035] Step 2: Determine the target recovery area

[0036] Lythrum salicaria typically grows in damp areas such as riverbanks, lakes, marshes, and wet grasslands. It is tolerant of flooding and can survive in environments with significant water level fluctuations, demonstrating strong adaptability. However, excessively high water levels will significantly inhibit its growth. Lythrum salicaria requires relatively high soil moisture content, adapting well to soils rich in organic matter and with good drainage, but it can also tolerate slightly poor soil. It usually begins to sprout in early spring (March to April), grows from late spring to early summer (May to June), flowers in summer (June to August), and fruits in autumn (August to September).

[0037] Based on the above physiological characteristics of loosestrife, the water level change area, low-lying area and humid area in step (1) are selected as the target restoration area for loosestrife population. Other areas are not suitable for the growth of loosestrife.

[0038] Step 3: Determine the degree of degradation of Lythrum salicaria in the area.

[0039] The cover and relative density of *Lythrum salicaria* in the quadrats were measured and recorded as follows:

[0040] Lythrum salicaria coverage = the percentage of the area covered by the vertical projection of the aboveground part of Lythrum salicaria to the area of ​​the sample plot;

[0041] Relative density of loosestrife = number of loosestrife / total number of plants in the quadrat × 100%.

[0042] The degree of degradation of Lythrum salicaria was determined based on statistical results, as follows:

[0043] If the coverage of Lythrum salicaria is ≥50% and the relative density is ≥40%, it is considered to be non-degraded.

[0044] The area with a loosestrife cover of 30%-50% and a relative density of 30%-40% is identified as a slightly degraded area.

[0045] The area with a loosestrife cover of 10%-30% and a relative density of 10%-30% is classified as a moderately degraded region.

[0046] If the coverage of Lythrum salicaria is less than 10% and the relative density is less than 10%, it is considered a severely degraded area.

[0047] Step 4: Development of a Recovery Plan

[0048] The selection of plant species and transplanting time should be based on different hydrological conditions, as detailed below:

[0049] Deep water areas, where the water level is too deep and the flooding time is too long, are not suitable as sites for the restoration of loosestrife communities;

[0050] In low-lying areas, select loosestrife plants with a total height of ≥30cm and transplant them in early May.

[0051] In areas with fluctuating water levels, select loosestrife plants with a total height of ≥25cm and transplant them in early May.

[0052] In humid areas, select loosestrife plants with a total height of ≥20cm and transplant them in mid-to-late May.

[0053] Dry areas with low soil moisture content are not suitable for the restoration of loosestrife communities.

[0054] The restoration and transplantation methods should be selected according to different degrees of degradation, as detailed below:

[0055] In mildly degraded areas, natural restoration is adopted without much human intervention, allowing the loosestrife to enter through natural changes in the ecological water level.

[0056] In moderately degraded areas, plant transplanting is used, with a transplanting density of 20-30 plants / m². 2 The preferred density is 25 plants / m². 2 Preferably, plants are grown in clumps, with 5-7 plants per clump, and the spacing between them is 90-110cm, with 100cm being a more preferred spacing.

[0057] In severely degraded areas, plant transplanting is used, with a transplanting density of 40-60 plants / m². 2 The preferred density is 50 plants / m². 2 Preferably, the plants are grown in clumps, with 5-7 plants per clump and a spacing of 45-55cm between clumps, and more preferably 50cm.

[0058] Step 5: Plant Transplanting

[0059] The preferred method for transplanting loosestrife is hole planting. Further optimization of the specific method is as follows:

[0060] Soil loosening: Till the soil to ensure it is loose and remove weeds so that the loosestrife can take root;

[0061] Digging planting holes: Dig holes according to the required planting density, with each hole having a diameter of 8-10cm and a depth of 10-12cm; preferably, the hole depth is 8-10cm plus at least 2cm of soil.

[0062] Obtain seedlings: Select healthy Lythrum salicaria seedlings with well-developed root systems;

[0063] Root treatment: If necessary, prune damaged roots to promote the growth of new roots;

[0064] Placing the seedlings: Gently place the seedlings into the dug holes, keeping the roots downwards and ensuring that the roots are completely buried in the soil;

[0065] Filling and compacting: Fill the hole with the original soil and compact it gently.

[0066] Step Six: Post-Grade Vegetation Monitoring and Maintenance

[0067] Ideally, during the first two years after recovery, cutting and grazing of the loosestrife must be strictly avoided. Protecting the growth environment of new plants, promoting root development and soil stability, and minimizing human interference are crucial to ensuring the loosestrife can fully establish its ecological niche.

[0068] Regular monitoring of the growth status of *Lythrum salicaria* is preferred, and further optimization includes:

[0069] Regularly conduct random sampling within the restoration area to establish quadrats and count the number of *Lythrum salicaria* plants. Record the plant density within each quadrat to analyze its growth trend. Use drones or remote sensing technology to acquire high-resolution images of the area, and quantitatively assess the distribution and quantity of *Lythrum salicaria* using image analysis software.

[0070] Observe the growth status of the loosestrife and assess its condition and health. Record changes in growth, especially under adverse conditions such as drought or water level fluctuations, paying attention to the plant's adaptability and recovery ability.

[0071] Observe the flowering and seed maturity of loosestrife, record the number of inflorescences and seed yield per plant, and assess its reproductive capacity. Monitor the natural reproduction of loosestrife and the growth of its seedlings, record the number and growth status of new plants, and assess the population's regeneration capacity.

[0072] Within the Lythrum salicaria restoration area, the species and abundance of other plant species were recorded to assess the richness and diversity of the plant community. The impact of Lythrum salicaria on the ecosystem was analyzed by comparing plant species before and after restoration. Animal species and abundance within the restoration area, including birds, insects, and other wetland organisms, were monitored to assess the impact of the Lythrum salicaria community on animal habitats. By integrating plant and animal diversity data, the ecological functions of Lythrum salicaria within the restoration area were assessed, and its contribution to wetland ecosystem stability and biodiversity was analyzed.

[0073] It is preferable that the above tests be performed once every quarter.

[0074] Regular maintenance of the loosestrife in the restoration area is preferred, and further optimization includes:

[0075] Regularly prune loosestrife to remove withered, yellowed, or weak leaves and stems, promote the growth of new branches and leaves, and improve the overall appearance and health of the plant.

[0076] Manually remove weeds from the restoration area to reduce competition and allow the loosestrife to receive more sunlight, water and nutrients;

[0077] Regularly straighten poorly growing or leaning loosestrife plants manually to ensure they grow upright and improve photosynthetic efficiency.

[0078] It is preferable to regularly monitor soil moisture and water level changes and provide appropriate artificial watering to the restored area; it is even preferable to deliver water directly to the wetland area by setting up irrigation pipes or sprinkler systems; it is even more preferable to water the area before the start of the plant growing season to promote plant germination and growth, and watering is also necessary when the soil moisture in arid areas is less than 50%.

[0079] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0080] Example 1

[0081] This embodiment selects the wetland of the 597 Management Station of the Hongxinglong Branch of the Naoli River Nature Reserve as the treatment target, with an experimental area of ​​11.24 acres. The specific steps are as follows:

[0082] Step 1: Preliminary Investigation

[0083] A field survey was conducted to investigate the distribution of plant communities, hydrological conditions, and the status of Lythrum salicaria vegetation communities in degraded wetlands. Three transects were set up in the area, and three 1.0m×1.0m quadrats were set up in each transect according to the hydrological conditions. The vegetation cover and density in the quadrats were measured and recorded. The survey results are shown in Table 1.

[0084] Table 1. Explanation of the Survey Results

[0085]

[0086]

[0087] Step 2: Select the recovery area

[0088] Based on the physiological characteristics of loosestrife, areas with water level changes, low-lying areas, and humid areas were selected as the population restoration areas for loosestrife. Other areas are not suitable for the growth of loosestrife.

[0089] Step 3: Determine the degree of degradation of Lythrum salicaria in the area.

[0090] Areas with a coverage of ≥50% and a density of ≥40% are considered undegraded; areas with a coverage of 30%-50% and a density of 30%-40% are considered slightly degraded; areas with a coverage of 10%-30% and a density ratio of 10%-30% are considered moderately degraded; and areas with a coverage of <10% and a density ratio of <10% are considered severely degraded.

[0091] Based on the preliminary investigation, four restoration areas were selected, and the area division is shown in Table 2.

[0092] Table 2 Explanation of Regional Division

[0093] Area code Degeneration of Lythrum salicaria Hydrological conditions 1 moderate Humid area 2 Severe Water level change zone 3 Severe low-lying areas 4 moderate Water level change zone

[0094] Step 4: Development of a Recovery Plan

[0095] Choose restoration and transplantation methods according to different degrees of degradation:

[0096] The restoration of mildly degraded areas adopts a natural restoration method, which does not require excessive human intervention. It allows the ecological water level to change naturally and wait for the loosestrife to grow.

[0097] Restoration of moderately degraded areas was carried out using plant transplanting, with a transplanting density of 20-30 plants / m². 2 ; ...

[0098] For restoration of severely degraded areas, plant transplanting is employed, with a transplanting density of 40-60 plants / m². 2 ; ...

[0099] Selecting plant species and transplanting time based on different hydrological conditions:

[0100] Deep water areas, where the water level is too deep and the flooding time is too long, are not suitable as sites for the restoration of loosestrife communities;

[0101] In areas with medium water levels, select loosestrife plants with a total height of ≥30cm and transplant them in mid-to-late May.

[0102] In areas with fluctuating water levels, select loosestrife plants with a total height of ≥25cm and transplant them in early May.

[0103] In humid areas, select loosestrife plants with a total height of ≥20cm and transplant them in early May.

[0104] The edges of arid zones have low soil moisture content, making them unsuitable as sites for the restoration of loosestrife communities.

[0105] Step 5: Plant Transplanting

[0106] According to the restoration plan, planting will take place in May-June 2024. The loosestrife will be transplanted using the hole planting method. See the planting method for reference. Figure 2 The regional planting situation is shown in Table 3:

[0107] Table 3 Regional Planting Situation

[0108]

[0109] Step Six: Post-Grade Vegetation Monitoring and Maintenance

[0110] Regularly monitor the growth of loosestrife, including:

[0111] Regularly conduct random sampling within the restoration area to establish quadrats and count the number of *Lythrum salicaria* plants. Record the plant density within each quadrat to analyze its growth trend. Utilize drones or remote sensing technology to acquire high-resolution images of the area, and quantitatively assess the distribution and quantity of *Lythrum salicaria* using image analysis software.

[0112] Observe the growth status of the loosestrife and assess its growth condition and health. Record changes in growth, especially under adverse conditions such as drought or water level fluctuations, paying attention to the plant's adaptability and recovery ability;

[0113] Observe the flowering and seed maturity of *Lythrum salicaria*, record the number of inflorescences and seed yield per plant, and assess its reproductive capacity. Monitor the natural reproduction of *Lythrum salicaria* and the growth of its seedlings, record the number and growth status of new plants, and assess the population's regeneration capacity.

[0114] Within the Lythrum salicaria restoration area, the species and abundance of other plant species were recorded to assess the richness and diversity of the plant community. The impact of Lythrum salicaria on the ecosystem was analyzed by comparing plant species before and after restoration. Animal species and abundance within the restoration area, including birds, insects, and other wetland organisms, were monitored to assess the impact of the Lythrum salicaria community on animal habitats. Based on the combined plant and animal diversity data, the ecological functions of Lythrum salicaria within the restoration area were assessed, and its contribution to wetland ecosystem stability and biodiversity was analyzed.

[0115] Regular maintenance of the loosestrife in the restored area includes:

[0116] Regularly prune loosestrife to remove withered, yellowed, or weak leaves and stems, promote the growth of new branches and leaves, and improve the overall appearance and health of the plant.

[0117] Manually remove weeds from the restoration area to reduce competition and allow the loosestrife to receive more sunlight, water and nutrients;

[0118] Regularly straighten poorly growing or leaning loosestrife manually to ensure upright growth and improve photosynthetic efficiency;

[0119] During the first two years after recovery, it is essential to strictly avoid mowing and grazing of the loosestrife. Protecting the growth environment of new plants, promoting root development and soil stability, and minimizing human interference are crucial to ensuring the loosestrife can fully establish its ecological niche.

[0120] Step 7: Evaluation of Results

[0121] This embodiment was demonstrated in the riparian wetlands surrounding the 597 Management Station of the Hongxinglong Branch of the Naoli River Nature Reserve. The survey of the restored area showed that the target vegetation has been rapidly established and grown significantly, and the restoration effect is good.

[0122] In moderately degraded areas, the growth of *Lythrum salicaria* showed significant improvement after using this method. With proper water management and suitable planting strategies, the plants quickly adapted to the environment and grew vigorously. The transplant survival rate of *Lythrum salicaria* was 85%. After 6 months of monitoring, and with field quadrat surveys, the average height reached 80 cm, and the leaf cover typically exceeded 65%. The planting density was approximately 30 plants / m². 2 The vegetation is evenly distributed and has formed a certain vegetation cover, gradually restoring ecological diversity.

[0123] In severely degraded areas, despite harsh environmental conditions, the growth of *Lythrum salicaria* showed positive changes after the application of the method. Initial growth was relatively slow, with a transplant survival rate of 70%. After six months of monitoring, and based on field quadrat surveys, the average height was approximately 60 cm, the average canopy cover was around 40%, and the plant density was approximately 40 plants / m². 2 It has already established a foundation for growth and has gradually improved the overall ecological environment, laying the groundwork for subsequent ecological restoration.

[0124] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for the directional restoration of *Lythrum salicaria* communities in degraded riparian wetlands with fluctuating water levels, characterized in that... Includes the following steps: (1) Investigate the hydrological conditions of the degraded wetlands along the riverbank to determine the target restoration area and the transplanting height and time of Lythrum salicaria: transplanting height ≥30cm in low-lying areas, transplanting in early May, where the low-lying areas are areas where the water level is maintained at 5-10cm; transplanting height ≥25cm in water level change areas, transplanting in early May, where the water level is maintained at 0-30cm and the water level rises, falls or freezes with the season; transplanting height ≥20cm in humid areas, transplanting in mid-to-late May, where the humid areas are areas where the soil moisture content is ≥60%; also includes deep water areas and dry areas, where the deep water areas and dry areas are not considered as target restoration areas; the deep water areas are areas where the water level is maintained at 20-50cm, and the dry areas are areas where the soil moisture content is <60%; (2) Investigate the degree of degradation of Lythrum salicaria in the target restoration area and determine the transplanting density of Lythrum salicaria: allow natural restoration in mildly degraded areas, and transplant 20-30 plants / m² in moderately degraded areas. 2 Transplant 40-60 plants / m² in severely degraded areas. 2 The mildly degraded area is the region with a Lythrum salicaria coverage of 30%-50% and a relative density of 30%-40%; the moderately degraded area is the region with a Lythrum salicaria coverage of 10%-30% and a relative density of 10%-30%; and the severely degraded area is the region with a Lythrum salicaria coverage of <10% and a relative density of <10%.

2. The method according to claim 1, characterized in that, The investigation was conducted using the following methods: Three to four transects were set up in the degraded wetlands along the riverbank. According to the water level change gradient, three to six quadrats were set up in each transect to investigate the hydrological conditions and the degree of degradation of Lythrum salicaria in the transect. The transects are areas ranging from 50% soil moisture content to 30cm water level, with each transect being 8-12m wide and spaced 100-200m apart; the area of ​​each quadrat is ≥1m². 2 .

3. The method according to claim 1, characterized in that, The loosestrife is transplanted in clumps, with 5-7 loosestrife plants per clump.

4. The method according to claim 3, characterized in that, The spacing between transplanted loosestrife clumps in moderately degraded areas is 90-110 cm; the spacing between transplanted loosestrife clumps in severely degraded areas is 45-55 cm.

5. The method according to claim 1, characterized in that, The loosestrife is transplanted using a hole planting method, with the diameter of the transplanting hole being 8-10cm and the depth being 10-12cm.

6. The method according to claim 5, characterized in that, The planting method includes: loosening the soil, digging a transplanting hole, selecting healthy loosestrife seedlings with well-developed root systems, placing them in the transplanting hole, and filling and compacting the soil.

7. The method according to claim 1, characterized in that, It also includes regular maintenance of the target restoration area, including: pruning or straightening the loosestrife, removing withered or weak leaves and stems; clearing weeds; and artificial watering.

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