A method for repairing a salt marsh wetland using meshed vegetated blocks

Abstract

The application discloses a method for repairing a salt marsh wetland by using a netted nutrient planting block, fixes Scirpus mariqueter seeds in the planting block, and fixes the planting block on a biomass fiber net framework, so that a closed water and soil environment is formed by reeds planted around the planting block, the newly planted Scirpus mariqueter is prevented from being affected by wind and waves, the germination rate and survival rate of the repairing plants are improved, the growth of the plants in the saline-alkali environment is limited, the ecological environment of the saline-alkali beach is restored, the soil quality is improved, the growth of the plants is promoted, the ecological damage problems caused by the degradation of the salt marsh wetland and the expansion of Spartina alterniflora are solved, meanwhile, environmental burdens in the ecological repairing process are avoided, and a sustainable and efficient solution is provided for long-term ecological restoration of the salt marsh wetland.

Description

Technical Field

[0001] This invention belongs to the field of tidal flat wetland ecological restoration, specifically involving a method for restoring salt marsh wetlands using net-like nutrient planting blocks. Background Technology

[0002] Salt marshes play an irreplaceable role in windbreak and sand fixation, carbon sequestration, and maintaining biodiversity. Therefore, restoring the ecological health of salt marshes not only restores their ecological functions but also has significant implications for global climate change response and regional ecological security.

[0003] Commonly used techniques for restoring salt marshes and wetlands mainly include hydrological regulation and phytoremediation.

[0004] Hydrological regulation improves the water-salt balance of wetlands by adjusting water levels, which is highly effective, but it is only suitable for small-scale restorations due to the need for long-term monitoring and high costs.

[0005] Phytoremediation holds significant potential for ecological restoration in saline wetlands, but its practical application is often limited by environmental and economic factors, especially in wetland areas subjected to strong winds and waves. Strong winds and waves cause water turbulence and soil erosion, directly impacting seed and seedling survival rates. Wetland plant seeds and seedlings are frequently washed away by strong hydrodynamic conditions after sowing or planting, failing to establish themselves. Furthermore, the highly volatile water and salinity environment of saline wetlands, with changes in salinity and water loss, makes it difficult for plant seeds and seedlings to adapt, resulting in low survival rates and further slowing down vegetation cover and ecological restoration. Phytoremediation also faces challenges such as harsh soil structure and nutrient conditions in some restoration areas, and is limited by plant adaptability and natural growth cycles, leading to a slower restoration rate.

[0006] In addition, the spread of Spartina alterniflora in coastal areas has had a significant impact on the ecosystem. First, it forms dense monocultures, crowding out native plants such as reeds. Phragmites australis ) and sea sedge (×) Bolboschoenoplectus mariqueter Biodiversity has declined significantly. Furthermore, the spread of *Spartina alterniflora* alters the ecological structure and function of wetlands, impacting habitats for birds, fish, and benthic organisms. *Spartina alterniflora* also accelerates siltation in tidal flats, obstructs natural tidal flow, damages aquaculture areas, and threatens the livelihoods of coastal residents. Currently, ecological restoration methods are being used to restore biodiversity and suppress the spread of *Spartina alterniflora* through artificial planting of native plants. However, the current method of seed sowing in tidal flats results in low seed germination rates. This is partly due to the large tidal waves and winds in the tidal flat environment, making the small seeds easily dispersed by the waves; and partly because native plant seeds have long dormancy periods, resulting in low germination rates when directly sown in the tidal flats.

[0007] Therefore, optimizing the structure of water level regulation facilities, selecting restoration plants, and improving the germination rate, survival rate, and growth rate of restoration plants are the main problems faced in the restoration of salt marsh wetlands. Summary of the Invention

[0008] The purpose of this invention is to provide a method for restoring saline wetlands using net-like nutrient planting blocks, which improves the germination rate and survival rate of restored plants, overcomes the limitations of saline-alkali environment on plant growth, restores the ecological environment of saline-alkali tidal flats, improves soil quality, promotes plant growth, solves the ecological damage problems caused by the degradation of saline wetlands and the expansion of Spartina alterniflora, and avoids the environmental burden during the ecological restoration process, providing a sustainable and efficient solution for the long-term ecological restoration of saline-alkali wetlands.

[0009] To achieve the above objectives, the technical solution of the present invention is as follows:

[0010] A method for restoring saline wetlands using mesh-like nutrient planting blocks includes the following steps:

[0011] 1) Site embankment management

[0012] Construct dikes around the treatment area, with a top width of 2-4m, a slope of 1:4-1:3, and a height of 1-1.5m; if the treatment area is larger than 50 hm². 2 Then, according to the terrain, every 30-50 hm 2 Set up a dividing dike, with the same specifications as the main dike;

[0013] 2) Planting block laying

[0014] Prepare a biomass fiber mesh framework on which several planting blocks are fixed. The planting blocks have an inner nutrient slow-release layer and an outer layer covered with a polybutylene succinate-chitosan layer. The thickness of the nutrient slow-release layer is 1-3 cm, and the thickness of the polybutylene succinate-chitosan layer is 10-20 μm.

[0015] The components of the nutrient slow-release layer, by weight percentage, include: 20-30% alginate, 20-30% modified biochar, 10-20% sea buckthorn seeds, 10-20% nano diatomaceous earth, 5-10% zeolite microspheres, 3-5% chitosan, 3-5% ammonium nitrate, 3-5% potassium dihydrogen phosphate, 3-5% phosphate rock powder, 2-4% urea, 2-4% plant protein hydrolysate, and 1-2% seaweed extract;

[0016] Then, planting trenches are dug in the treatment area according to the biomass fiber mesh framework that fixes several planting blocks, ensuring that the planting blocks are surrounded by planting trenches after the biomass fiber mesh framework is laid. Reed stems are planted in the planting trenches with their ends connected. After that, the biomass fiber mesh framework that fixes several planting blocks is laid. The reed stems and planting blocks are covered with 5-10cm of soil, and the water level inside the dike is controlled at 3-5cm. The planting trenches are 30-10cm deep.

[0017] 3) Maintenance

[0018] When the reed seedlings reach a height of 15-20cm, the water depth should be increased as the reed seedlings continue to grow, and the water level should be controlled below the heart leaves. When the reeds enter the vigorous growth period and the sea buckthorn seedlings reach a height of 20-30cm, drain and dry the field for 5-10 days, and then control the water level at 10-20cm. After 10-15 days, the water level outside the dike can be connected, and the dike can be dismantled the following year.

[0019] A method for restoring saline wetlands using mesh-like nutrient planting blocks specifically includes the following steps:

[0020] 1) Site embankment management

[0021] Before the flowering stage of Spartina alterniflora, construct dikes around the treatment area. The dikes should be 2-4m wide at the top, with a slope of 1:4-1:3 and a height of 1-1.5m, and drain all water from inside the dikes. If the treatment area is larger than 50 hm²... 2 Then, according to the terrain, every 30-50 hm 2 Set up a dividing dike, with the same specifications as the main dike;

[0022] 2) Harvesting and deep tilling of Spartina alterniflora

[0023] Harvest and shred Spartina alterniflora in the treatment area to obtain Spartina alterniflora shredded material. The length of the shredded material should be 5-10cm, and the qualified rate should be ≥90%. Add mixed microbial inoculant to the shredded material and mix well before use. Rotary tillage is carried out on the harvested treatment area to destroy the Spartina alterniflora root system. The Spartina alterniflora shredded material with mixed microbial inoculant is then rotary tilled into the soil to a depth of 30-50cm. After rotary tillage, water is released into the treatment area, and the water level is maintained at 50-70cm.

[0024] 3) Planting block laying

[0025] Within the treatment area, dig planting trenches with a longitudinal and transverse distance of 0.5-1m and a depth of 30-10cm. Plant reed stems end to end in the trenches. Lay net-like slow-release nutrient planting blocks on the treatment area, with the blocks distributed in the center of the trenches. Cover the reed stems and net-like slow-release nutrient planting blocks with 5-10cm of tidal flat soil. Control the water level inside the dike to 3-5cm.

[0026] The mesh-like slow-release planting block comprises, from the inside out, a biomass fiber mesh framework, a slow-release nutrient layer, and a polybutylene succinate-chitosan layer; the thickness of the slow-release nutrient layer is 1-3 cm, and the thickness of the polybutylene succinate-chitosan layer is 10-20 μm.

[0027] The components of the nutrient slow-release layer, by weight percentage, include: alginate 20-30%, modified biochar 20-30%, sea buckthorn seeds 10-20%, nano diatomaceous earth 10-20%, zeolite microspheres 5-10%, chitosan 3-5%, ammonium nitrate 3-5%, potassium dihydrogen phosphate 3-5%, phosphate rock powder 3-5%, urea 2-4%, plant protein hydrolysate 2-4%, and seaweed extract 1-2%.

[0028] 4) Maintenance

[0029] When the reed seedlings reach a height of 15-20cm, the water depth should be increased as the reed seedlings continue to grow, and the water level should be controlled below the heart leaves. When the reeds enter the vigorous growth period and the sea buckthorn seedlings reach a height of 20-30cm, drain and dry the field for 5-10 days, and then control the water level at 10-20cm. After 10-15 days, the water level outside the dike can be connected, and the dike can be dismantled the following year.

[0030] Preferably, the mixed microbial agent includes *Kuenenia stuttgartiensis*, *Anammoxoglobus propionicus*, *Scalindua spp.*, *Candidatus brocadia spp.*, denitrifying bacteria, and also includes sulfate-reducing bacteria *Desulfovibrio spp.* and methanogens *Methano bacterium*.

[0031] Preferably, the specific preparation steps of the biomass fiber mesh framework for fixing several planting blocks include:

[0032] ① Mix alginate and water at a mass ratio of 1:5-10, with the water temperature at 30-50 ℃, and stir until a uniform gel-like liquid is formed to obtain an alginate solution; prepare a solution of chitosan and water at a mass ratio of 1-3:100, and mix it evenly with the alginate solution to form a basic slow-release matrix; then add modified biochar, nano-diatomaceous earth, and zeolite microspheres and continue stirring and mixing; finally add ammonium nitrate, potassium dihydrogen phosphate, urea, phosphate rock powder, plant protein hydrolysate, and seaweed extract, and mix evenly to obtain a slow-release nutrient matrix;

[0033] ② Mix the seeds of *Scirpus triquetrum* evenly in a slow-release nutrient substrate, and then spray it evenly onto the biomass fiber mesh skeleton with a spray thickness of 1-3 cm;

[0034] ③ The biomass fiber mesh frame sprayed with slow-release nutrient substrate is placed in a 1-2wt% calcium chloride solution for cross-linking reaction. After the cross-linking reaction is completed, it is dried to obtain nutrient slow-release planting blocks on the biomass fiber mesh frame.

[0035] A polybutylene succinate-chitosan solution was uniformly sprayed onto the nutrient-slow-release planting blocks with a spray thickness of 10-20 μm. The blocks were then allowed to stand and vacuum-dried, and then allowed to stand for more than 12 hours to obtain a biomass fiber mesh skeleton that fixes several planting blocks.

[0036] Preferably, in step 2), the seeds of *Rubus parvifolius* undergo pretreatment. The pretreatment step involves soaking the seeds in warm water at 20-30 ℃ for 20-30 minutes, and then placing them in a cold storage at 2-5 ℃ and 40-60% humidity for 140-160 days.

[0037] Preferably, in step 3), the drying temperature is 20-40 ℃, the humidity is 30-40%, and the drying time is 12-36 h.

[0038] Preferably, in step 4), the area of ​​the planting block is 20×20 cm. 2 -40×40 cm 2 .

[0039] Preferably, in step 4), the vacuum drying vacuum degree is -0.05-0.1 MPa, the drying temperature is 20-30 ℃, and the drying time is 1-2 h.

[0040] Preferably, the biomass fiber mesh skeleton is formed from one or more of coconut shell fiber, ephedra fiber, palm fiber, polylactic acid, chitosan, polybutylene succinate, modified starch, and lignin.

[0041] In restoring salt marsh wetlands, this invention involves digging planting trenches around the planting blocks and planting reed rhizomes in the trenches. This allows a closed water and soil environment to be quickly formed around the planting blocks within 20-30 days, preventing wind and waves from affecting the newly planted sea sedge. This provides a suitable microclimate for the sea sedge, which is difficult to germinate, thus improving its survival rate.

[0042] By fixing the planting blocks to a biomass fiber mesh framework, the blocks can be secured among the reeds, mitigating the impact of wind and waves on the growth of *Scirpus triqueter* and improving its germination and survival rates. The slow-release nutrient layer within the planting block is 1-3 cm thick, and the polybutylene succinate-chitosan layer is 10-20 μm thick, providing a continuous supply of nutrients to ensure rapid growth of both *Scirpus triqueter* and the reeds.

[0043] In this slow-release nutrient matrix, alginate serves as the main colloid, forming the binding structure of the slow-release substrate and facilitating the slow release of nutrients. Modified biochar enhances nutrient adsorption and improves the soil microbial environment. Nano-diatomaceous earth strengthens the substrate's water retention and aeration, while zeolite microspheres help control the fertilizer release rate through their slow-release pore size. Chitosan has antibacterial properties, enhancing substrate stability and promoting plant root health. Ammonium nitrate and urea provide the nitrogen needed for rapid plant growth. Potassium dihydrogen phosphate and phosphate rock provide sustainable phosphorus and potassium nutrients, supporting root growth and enhancing stress resistance. Plant protein hydrolysate, rich in amino acids, promotes root growth and absorption. Seaweed extract provides trace elements and plant hormones, helping plants adapt to adversity and stimulating growth. All components work synergistically to provide nutrients, support structure, and improve water retention, thereby promoting plant growth.

[0044] The outermost layer of the mesh-like slow-release nutrient planting block is a polybutylene succinate-chitosan layer. This polybutylene succinate-chitosan composite film works synergistically to provide both slow-release and protection for the nutrient substrate. Polybutylene succinate provides strong mechanical strength and moderate water permeability, allowing the film to effectively control the slow release of nutrients in water, while its water resistance ensures the long-term stability of the substrate. The chitosan portion imparts natural antibacterial properties to the film, preventing microbial erosion of the nutrient substrate and helping to maintain substrate cleanliness and nutrient availability. In summary, the hydrophilicity of chitosan and the structural combination of polybutylene succinate allow the film to gradually release nutrients in a humid environment, extending the lifespan of the substrate block.

[0045] The design of the components in the planting block and the combination of the outer polybutylene succinate-chitosan layer enable the slow-release nutrient substrate to gradually release nutrients in a humid environment, extending the service life of the substrate block and ensuring that the plant can grow in a fixed nutrient environment for 2-3 months during the germination and growth of *Scirpus triqueter*.

[0046] Pretreatment of sea burr seeds and low-temperature stratification storage further improved the survival and germination rates of sea burr seeds.

[0047] When managing saline wetlands containing Spartina alterniflora, the Spartina alterniflora in the treatment area is harvested and crushed in advance to obtain Spartina alterniflora powder. Anaerobic ammonia-oxidizing microbial agents are then added to the Spartina alterniflora powder, followed by deep plowing into the mudflats and flooding with dikes. This method can completely kill the Spartina alterniflora. The roots and seeds, which are difficult to kill using traditional physical methods, are also eliminated. The addition of the mixed microbial agents accelerates the decomposition of plant residues, which is beneficial for nitrogen conversion and stabilization in the soil. Furthermore, the anaerobic ammonia-oxidizing microbial agents can utilize the ammonia nitrogen and nitrite released from the decomposition of Spartina alterniflora residues, converting them into nitrogen gas through anaerobic ammonia oxidation, thereby reducing nitrogen pollution in the soil and inhibiting the accumulation of harmful nitrogen. Simultaneously, the accompanying microorganisms in the agent (such as denitrifying bacteria, sulfate-reducing bacteria, and methanogens) can improve the anaerobic environment, promote denitrification and organic matter degradation, enhance the activity of anaerobic ammonia-oxidizing bacteria in the soil, and ultimately improve nitrogen conversion efficiency, supporting the ecological balance of nitrogen cycling in mudflats and water bodies.

[0048] The selected reeds and sea sedges are both native plants of China's coastal mudflats, posing no risk of ecological damage. They are adaptable to the saline-alkali environment and tidal changes of wetlands, are not easily subjected to environmental stress, and recover quickly, enabling them to rapidly occupy the ecological niches lost by Spartina alterniflora. The extensive root systems of reeds and sea sedges allow them to effectively occupy space and resources both above and below ground, forming a stable vegetation zone that limits the growth and spread of invasive Spartina alterniflora.

[0049] The raw materials used in the mesh-like slow-release nutrient matrix blocks, such as alginate, chitosan, polybutylene succinate, modified biochar, and zeolite microspheres, are all bio-based or natural materials with excellent environmental friendliness and biodegradability. Alginate and chitosan, derived from seaweed and crustaceans, can naturally degrade after use, reducing the environmental burden. Polybutylene succinate, as a biodegradable polyester, has non-toxic degradation products that can be broken down by microorganisms, making it suitable for use in soil or water bodies. Furthermore, modified biochar and zeolite microspheres not only improve soil nutrient retention capacity but also effectively reduce fertilizer loss, thereby lowering the risk of water pollution.

[0050] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0051] This invention involves planting reed stems in planting trenches and fixing sea sedge seeds within the nutrient substrate of the planting blocks. By utilizing the early growth characteristics of reeds, a suitable soil and water environment is provided for the germination of sea sedge seeds, preventing seed dispersal, improving the survival and germination rates of sea sedge seeds, restoring the ecological environment of saline-alkali tidal flats, improving soil quality, and promoting plant growth.

[0052] This invention uses reeds and sea sedges to jointly restore salt marsh wetlands. Both reeds and sea sedges have well-developed root systems, and their above-ground and underground parts can effectively occupy space and resources to form a stable vegetation zone. They can also limit the growth and spread of Spartina alterniflora, thus solving the ecological damage problems caused by the degradation of salt marsh wetlands and the expansion of Spartina alterniflora.

[0053] The present invention relates to the setting of nutrients and outer protective film in the planting block. The configuration of nutrients ensures the necessary nutrition for the germination and growth of sea sedge and reed growth. Through precise nutrient management, a slow-release substrate is used to provide the plants with the required nutrients, reducing environmental pollution caused by excessive fertilization.

[0054] The raw materials selected for the mesh-like slow-release nutrient matrix blocks of this invention, such as alginate, chitosan, polybutylene succinate, modified biochar, and zeolite microspheres, are all bio-based or natural materials. They have good environmental friendliness and biodegradability, and can naturally degrade after use, reducing the burden on the environment. While providing sufficient nutrients to the soil, they can also effectively reduce fertilizer loss, thereby reducing the risk of water pollution. Attached Figure Description

[0055] Figure 1 This is a map showing the distribution of plant plantings in the treatment area of ​​this invention. Detailed Implementation

[0056] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0057] 1. Restoration Experiment of Guangtan Salt Marsh Wetland

[0058] Four plots of 10m×10m light beach salt marsh wetland were selected. The treatment method is shown in Table 1. For three consecutive years, the accumulation of reeds and sea buckthorn was measured and statistically analyzed in November and December each year. The specific results are shown in Table 1.

[0059] The components of the slow-release layer of the nutrient planting block used, by weight percentage, include: 20% alginate, 20% modified biochar, 20% sea buckthorn seeds, 10% nano diatomaceous earth, 10% zeolite microspheres, 3% chitosan, 3% ammonium nitrate, 3% potassium dihydrogen phosphate, 3% phosphate rock powder, 3% urea, 3% plant protein hydrolysate, and 2% seaweed extract.

[0060]

[0061] As can be seen from Table 1, different restoration methods have significantly different effects on the restoration of reeds and sea sedges.

[0062] In control group 1 (no treatment), the area of ​​both Phragmites australis and Curcuma longa was 0 m² over three years. 2 It is difficult to achieve this through natural recovery alone.

[0063] In control group 2 (seed sowing), the seed survival rate was low due to factors such as wave erosion, and the area covered by reeds and sea sedges in the first year was 24.9 m². 2 and 11.6m 2 Three years later, the area only increased to 38.4m². 2 and 19.2m 2 The recovery effect is relatively limited.

[0064] Experimental group 1 (planted blocks) showed significantly better results compared to control group 2, with the area of ​​reeds and sea sedges reaching 42.1 m² in the first year. 2 and 39.6 m 2 Three years later, the area increased to 50.1 m² and 48.4 m² respectively, showing that planting blocks can significantly improve plant survival rate.

[0065] Experimental group 2 (with added microbial inoculant and planting blocks) performed best, with the area of ​​reeds and sea sedges reaching 46.1 m² in the first year. 2 and 45.7m 2 The total plant growth area exceeded 90%, far higher than other groups. This indicates that the microbial inoculant effectively improved the survival rate in the first year by improving the soil environment and promoting plant growth. After three years, the area of ​​reeds and sea sedges reached 51.4 m². 2 and 48.1m 2 The recovery effect is most significant.

[0066] In summary, the comprehensive management measures adopted in Experimental Group 2 using this patent can accelerate the restoration of the salt marsh wetland ecosystem to the greatest extent.

[0067] 2. Restoration experiment of Spartina alterniflora in salt marsh wetlands

[0068] Five plots of Spartina alterniflora with an area of ​​10m×10m were selected. The treatment methods are shown in Table 2. The area of ​​Spartina alterniflora was measured and statistically analyzed in November and December of each year for three consecutive years.

[0069] This reveals significant differences in governance effectiveness.

[0070] In control group 1, the area of ​​Spartina alterniflora remained unchanged over three years, consistently staying at 100 m². 2 This demonstrates its strong adaptability and competitive advantage.

[0071] In control group 2, physical harvesting of Spartina alterniflora significantly reduced the area of ​​Spartina alterniflora in the first year after treatment, with the area reduced to only 21.2 m². 2 However, as time went on, the area planted with Spartina alterniflora rebounded to 97.6 m² in the second and third years. 2This indicates that the method lacks persistence.

[0072] In control group 2, the treatment method of dike construction combined with deep plowing and harvesting of Spartina alterniflora reduced the area of ​​Spartina alterniflora to 1.4 m² in the first year after treatment. 2 The area planted with Spartina alterniflora increased to 38.4 m² in the second year. 2 In the third year, the area planted with Spartina alterniflora increased to 71.3 m². 2 It also failed to effectively suppress the growth of Spartina alterniflora in the long term.

[0073] In control group 3, the treatment involved dike construction, deep tilling after Spartina alterniflora harvesting, and sowing of Reed and Curcuma longa seeds. In the first year after treatment, the area affected by Spartina alterniflora decreased to 2.4 m². 2 The area planted with Spartina alterniflora increased to 18.0 m² in the second year. 2 In the third year, the area planted with Spartina alterniflora increased to 54.3 m². 2 The effect of this study on effectively inhibiting the growth of Spartina alterniflora in the long term is not significant.

[0074] See Figure 1 The plant distribution map of the treatment area using the present invention is shown, where 1 is the biomass fiber net skeleton, 2 is the planting block, 3 is the planting ditch, and 4 is reeds.

[0075] In Experiment 1, a treatment method combining dike construction, deep tillage after Spartina alterniflora harvesting, and the laying of reeds and planting blocks was adopted. In the first year after treatment, the area affected by Spartina alterniflora decreased to 1.7 m². 2 The area planted with Spartina alterniflora increased to 3.4 m² in the second year. 2 In the third year, the area covered by Spartina alterniflora was only 10.4m². 2 Using this method, the area of ​​Spartina alterniflora growth in the second and third years after treatment was significantly less than that in the control group, indicating that this method can effectively inhibit the growth of Spartina alterniflora in the long term. Furthermore, the experimental group showed a significantly larger growth area of ​​Phragmites australis and Curcuma longa in the first year compared to the control group 3, demonstrating that the method described in this invention can increase the germination rate and survival rate of Phragmites australis and Curcuma longa.

[0076] In Experiment 2, a treatment method combining dike construction, deep tilling after Spartina alterniflora harvesting, addition of mixed microbial inoculants, and the laying of reeds and planting blocks was adopted. In the first year after treatment, the area affected by Spartina alterniflora decreased to 0.4 m². 2 The area planted with Spartina alterniflora increased to 1.1 m² in the second year. 2 In the third year, the area covered by Spartina alterniflora was only 2.1m². 2Using this method, the area of ​​Spartina alterniflora growth in the second and third years after treatment was significantly less than that in the control group and also less than that in experimental group 1. This indicates that adding mixed microbial agents to Spartina alterniflora can promote the decomposition of Spartina alterniflora plant residues and promote the growth of reeds and sea sedges, thereby further inhibiting the growth of Spartina alterniflora.

[0077] Note: The amount of reed and sea sedge seeds sown in experimental groups 1 and 2 and control group 4 was the same.

[0078] Data from the control and experimental groups show that the integrated management approach combining physical, ecological, and microbial technologies of this invention is effective and helps to restore and protect the tidal flat ecosystem.

[0079]

Claims

1. A method for restoring saline wetlands using mesh-like nutrient planting blocks, characterized in that, Includes the following steps: 1) Site embankment management Construct dikes around the treatment area, with a top width of 2-4m, a slope of 1:4-1:3, and a height of 1-1.5m; if the treatment area is larger than 50 hm². 2 Then, according to the terrain, every 30-50 hm 2 Set up a dividing dike, with the same specifications as the main dike; 2) Planting block laying Prepare a biomass fiber mesh framework on which several planting blocks are fixed. The planting blocks have an inner nutrient slow-release layer and an outer layer covered with a polybutylene succinate-chitosan layer. The thickness of the nutrient slow-release layer is 1-3 cm, and the thickness of the polybutylene succinate-chitosan layer is 10-20 μm. The components of the nutrient slow-release layer, by weight percentage, include: 20-30% alginate, 20-30% modified biochar, 10-20% sea buckthorn seeds, 10-20% nano diatomaceous earth, 5-10% zeolite microspheres, 3-5% chitosan, 3-5% ammonium nitrate, 3-5% potassium dihydrogen phosphate, 3-5% phosphate rock powder, 2-4% urea, 2-4% plant protein hydrolysate, and 1-2% seaweed extract; Then, planting trenches are dug in the treatment area according to the biomass fiber mesh framework that fixes several planting blocks, ensuring that the planting blocks are surrounded by planting trenches after the biomass fiber mesh framework is laid. Reed stems are planted in the planting trenches with their ends connected. After that, the biomass fiber mesh framework that fixes several planting blocks is laid. The reed stems and planting blocks are covered with 5-10cm of soil, and the water level inside the dike is controlled at 3-5cm. The planting trenches are 30-10cm deep. 3) Maintenance When the reed seedlings reach a height of 15-20cm, the water depth should be increased as the reed seedlings continue to grow, and the water level should be controlled below the heart leaves. When the reeds enter the vigorous growth period and the sea buckthorn seedlings reach a height of 20-30cm, drain and dry the field for 5-10 days, then control the water level at 10-20cm. After 10-15 days, connect the water level outside the dike, and dismantle the dike the following year.

2. A method for restoring saline wetlands using mesh-like nutrient planting blocks, characterized in that, Specifically, the following steps are included: 1) Site embankment management Before the flowering stage of Spartina alterniflora, construct dikes around the treatment area. The dikes should be 2-4 m wide at the top, with a slope of 1:4-1:3 and a height of 1-1.5 m, and drain all water from inside the dikes. If the treatment area is larger than 50 hm²... 2 Then, according to the terrain, every 30-50 hm 2 Set up a dividing dike, with the same specifications as the main dike; 2) Harvesting and deep tilling of Spartina alterniflora Harvest and shred Spartina alterniflora in the treatment area to obtain Spartina alterniflora shredded material. The length of the shredded material should be 5-10cm, and the qualified rate should be ≥90%. Add mixed microbial inoculant to the shredded material and mix well before use. Rotary tillage is carried out on the harvested treatment area to destroy the Spartina alterniflora root system. The Spartina alterniflora shredded material with mixed microbial inoculant is then rotary tilled into the soil to a depth of 30-50cm. After rotary tillage, water is released into the treatment area, and the water level is maintained at 50-70cm. 3) Planting block laying Prepare a biomass fiber mesh framework on which several planting blocks are fixed. The planting blocks have an inner nutrient slow-release layer and an outer layer covered with a polybutylene succinate-chitosan layer. The thickness of the nutrient slow-release layer is 1-3 cm, and the thickness of the polybutylene succinate-chitosan layer is 10-20 μm. The components of the nutrient slow-release layer, by weight percentage, include: 20-30% alginate, 20-30% modified biochar, 10-20% sea buckthorn seeds, 10-20% nano-diatomaceous earth, 5-10% zeolite microspheres, 3-5% chitosan, 3-5% ammonium nitrate, 3-5% potassium dihydrogen phosphate, 3-5% phosphate rock powder, 2-4% urea, 2-4% plant protein hydrolysate, and 1-2% seaweed extract; Then, planting trenches are dug in the treatment area according to the biomass fiber mesh framework that fixes several planting blocks, ensuring that the planting blocks are surrounded by planting trenches after the biomass fiber mesh framework is laid. Reed stems are planted in the planting trenches with their ends connected. After that, the biomass fiber mesh framework that fixes several planting blocks is laid. The reed stems and planting blocks are covered with 5-10cm of soil, and the water level inside the dike is controlled at 3-5cm. The planting trenches are 30-10cm deep. 4) Maintenance When the reed seedlings reach a height of 15-20cm, the water depth should be increased as the reed seedlings continue to grow, and the water level should be controlled below the heart leaves. When the reeds enter the vigorous growth period and the sea buckthorn seedlings reach a height of 20-30cm, drain and dry the field for 5-10 days, then control the water level at 10-20cm. After 10-15 days, connect the water level outside the dike, and dismantle the dike the following year.

3. The method as described in claim 2, characterized in that, The mixed microbial agent includes *Kuenenia stuttgartiensis*, *Anammoxoglobus propionicus*, *Scalindua spp.*, *Candidatus brocadia spp.*, denitrifying bacteria, sulfate-reducing bacteria *Desulfovibrio spp.*, and methanogens *Methano bacterium*.

4. The method as described in claim 1 or 2, characterized in that, The specific preparation steps of the biomass fiber mesh framework for fixing several planting blocks include: 1) Mix alginate and water at a mass ratio of 1:5-10, with the water temperature at 30-50 ℃, and stir until a uniform gel-like liquid is formed to obtain an alginate solution; prepare a solution of chitosan and water at a mass ratio of 1-3:100, and mix it evenly with the alginate solution to form a basic slow-release matrix; then add modified biochar, nano-diatomaceous earth, and zeolite microspheres and continue stirring and mixing; finally add ammonium nitrate, potassium dihydrogen phosphate, urea, phosphate rock powder, plant protein hydrolysate, and seaweed extract, and mix evenly to obtain a slow-release nutrient matrix; 2) Mix the seeds of *Scirpus triquetrum* evenly in the slow-release nutrient substrate, and then spray it evenly on the biomass fiber mesh skeleton with a spray thickness of 1-3 cm. 3) The biomass fiber mesh frame sprayed with slow-release nutrient substrate is placed in a 1-2wt% calcium chloride solution for cross-linking reaction. After the cross-linking reaction is completed, it is dried to obtain nutrient slow-release planting blocks on the biomass fiber mesh frame. 4) Spray the polybutylene succinate-chitosan solution evenly onto the nutrient slow-release planting blocks with a spray thickness of 10-20 μm, let it stand, vacuum dry, and then let it stand for more than 12 hours to obtain a biomass fiber mesh skeleton that fixes several planting blocks.

5. The method as described in claim 4, characterized in that, In step 2), the seeds of *Rubus parvifolius* undergo pretreatment. The pretreatment steps are to first soak the seeds in warm water at 20-30 ℃ for 20-30 minutes, and then place them in a cold storage at 2-5 ℃ and 40-60% humidity for 140-160 days.

6. The method as described in claim 4, characterized in that, In step 3), the drying temperature is 20-40 ℃, the humidity is 30-40%, and the drying time is 12-36 h.

7. The method as described in claim 4, characterized in that, In step 4), the planting block area is 20×20cm. 2 -40×40cm 2 .

8. The method as described in claim 4, characterized in that, In step 4), the vacuum drying vacuum degree is -0.05-0.1MPa, the drying temperature is 20-30℃, and the drying time is 1-2h.

9. The method as described in claim 1 or 2, characterized in that, The biomass fiber mesh skeleton is formed from one or more of the following: coconut shell fiber, ephedra fiber, palm fiber, polylactic acid, chitosan, polybutylene succinate, modified starch, and lignin.

10. The method of claim 4, characterized in that, The biomass fiber mesh skeleton is formed from one or more of the following: coconut shell fiber, ephedra fiber, palm fiber, polylactic acid, chitosan, polybutylene succinate, modified starch, and lignin.

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