Plant blanket, preparation method and application of plant blanket in coastal wetland ecological restoration

Abstract

The invention relates to the technical field of coastal wetland ecological restoration and improvement, in particular to a plant blanket, a preparation method and application of the plant blanket in coastal wetland ecological restoration. The plant blanket is of a three-layer composite structure comprising a lower high-density fiber layer, a middle mixed fiber layer and an upper sparse fiber layer. The middle mixed fiber layer is loaded with a composite modifier, and the composite modifier comprises biochar, a sepiolite-chitosan composite material, a water-retaining agent and coastal wetland soil, and is integrated with growth-promoting microbial agent microcapsules and salt-tolerant plant seeds. Through physical protection of the plant blanket, salt adsorption and soil improvement of biochar and sepiolite, fixation and slow-release energy supply of chitosan to microorganisms, and moisture regulation and control of the water-retaining agent, the purpose of improving the quality of the wetland in the coastal wetland area with dynamically changed tide and salt is achieved. And synergistic and efficient restoration of bank slope stabilization, soil improvement, microbial activity maintenance and vegetation restoration is realized. The method is convenient to construct and durable in repairing effect and has a good application prospect.

Description

Technical Field

[0001] This invention relates to the field of coastal wetland ecological restoration and improvement technology, specifically to a plant blanket, its preparation method, and its application in coastal wetland ecological restoration. Background Technology

[0002] Coastal wetlands, as key ecological units where land and sea meet, possess powerful carbon capture and sequestration capabilities, playing a vital role in mitigating global climate change. However, due to the combined effects of rising sea levels caused by global warming, frequent extreme weather events, and human activities such as industrial pollution and agricultural non-point source pollution, coupled with their inherent ecological fragility and sensitivity, coastal wetlands are facing problems such as shrinking area, increased soil salinization, and declining biodiversity. Their ecological functions are severely threatened, necessitating the development of efficient ecological restoration technologies.

[0003] Erosion-resistant biofilm is a commonly used ecological slope protection technology in wetland conservation. It integrates grass seeds, water-retaining agents, and other materials into composite fiber fabrics and is directly laid on key areas such as riverbanks. It not only physically blocks water erosion and stabilizes the slope, but also enhances soil stabilization and improves the microenvironment through vegetation, achieving synergy between ecological restoration and landscape greening. Biochar improvement technology is also a research hotspot in coastal wetland restoration, currently focusing on three main aspects: first, optimizing biochar application to improve soil structure and reduce salinity; second, utilizing the porous structure of biochar as a carrier to promote the colonization of functional microorganisms, but tidal-induced water and salt dynamics can easily lead to microbial loss; and third, leveraging the carbon sequestration function of biochar to enhance the carbon sink potential of wetlands, but its insufficient protection of microbial activity limits the synergistic improvement of nutrient cycling and salinity reduction.

[0004] Patent CN120188688A improves soil and promotes the growth of *Scirpus triqueter* using *Spartina alterniflora* biochar, but only focuses on the improvement of soil and plants by biochar, without considering the need for bank slope stability. Patent CN1063881150A provides an acidic biochar amendment and its preparation method, which has positive value for improving saline-alkali soil, but relies on the biochar itself to improve the soil and does not address the problem of low microbial activity in high-salt environments. Patent CN116200296A provides microbial immobilized microspheres and their preparation method, which solves the problems of low viable cell count and short shelf life of traditional microbial agents by encapsulating plant probiotics in microspheres, but the carrier lacks synergistic improvement capabilities and does not consider the impact of tidal erosion on bank slopes. The four-layer composite structure ecological grass mat of patent CN120240238A is effective in inland restoration, but its water-soluble film dissolves uncontrollably under tidal salinity fluctuations and lacks a salinity buffering mechanism, which cannot meet the multiple needs of coastal wetlands for slope erosion resistance, salinity regulation and microbial colonization.

[0005] In summary, existing technologies are insufficient to achieve a synergistic effect of slope stability, soil improvement, and maintenance of microbial activity in coastal wetland environments with tidal and salinity fluctuations. Summary of the Invention

[0006] In view of this, the present invention provides a plant blanket for ecological restoration of coastal wetlands and its preparation and application method, in order to solve the technical problems of easy loss of amendments, difficulty in microbial colonization, poor soil structure and slow vegetation recovery in the ecological restoration of coastal wetlands with alternating fresh and salt water.

[0007] Specifically, this plant carpet, through its layable integrated structure, can effectively prevent the loss of amendments, provide immediate protection against soil erosion, stabilize the rhizosphere microenvironment and buffer salt stress, while introducing and fixing salt-tolerant growth-promoting microorganisms to continuously activate soil nutrients. Ultimately, it achieves rapid vegetation cover and long-term maintenance of ecological functions, promoting positive succession and self-repair of coastal wetland ecosystems. It is particularly suitable for coastal wetland environments affected by tides and dynamic fluctuations in soil salinity.

[0008] The technical solution of this invention is implemented as follows: In a first aspect, the present invention provides a plant mat for ecological restoration of coastal wetlands, comprising a middle layer of mixed fiber layer loaded with a composite modifier, wherein the composite modifier comprises biochar and sepiolite-chitosan composite material; wherein the sepiolite-chitosan composite material is composed of sepiolite particles coated with a chitosan membrane.

[0009] Specifically, the biochar of this invention is rich in hydroxyl and carboxyl groups on its surface, which can be combined with sepiolite-chitosan composite material; at the same time, the natural clay mineral sepiolite can be used as a carrier, and its unique layered porous structure and high specific surface area, combined with the biocompatibility and film-forming properties of chitosan, fix salt-alkali resistant functional microorganisms inside and on the surface of the microspheres through the dual effects of physical adsorption and chemical binding.

[0010] Preferably, the plant carpet further includes a lower high-density fiber layer and an upper sparse fiber layer; the lower high-density fiber layer, the middle mixed fiber layer and the upper sparse fiber layer are sequentially arranged on the surface of the coastal wetland to be restored.

[0011] Furthermore, by synergistically integrating the aforementioned biochar technology, sepiolite-chitosan composite microbial immobilization technology, and erosion-resistant bio-blanket composite technology, it is highly adaptable to the complex and dynamic environment of coastal wetlands, achieving multiple restoration goals such as slope stabilization, soil improvement, enhancement of biological activity, and carbon pool protection, thereby improving the efficiency and long-term effectiveness of ecological restoration.

[0012] Preferably, the composite amendment comprises, by weight, 100 parts: 25-50 parts biochar, 25-50 parts sepiolite-chitosan composite material, 3-5 parts water-retaining agent, and the remainder being coastal wetland soil.

[0013] If there is too little biochar, the nutrient supply will be limited and the effect on improving soil nutrients will not be obvious, which may not be able to meet the needs of plant growth; if there is too much, the soil pore structure will be overfilled, the aeration and permeability will be poor, and high amounts of biochar may cause an imbalance in the soil carbon-nitrogen ratio. During the decomposition of microorganisms, a large amount of nitrogen will be consumed, resulting in nitrogen deficiency for plant growth.

[0014] Excessive use of the sepiolite-chitosan composite material may lead to local soil compaction due to its strong gelling properties, and chitosan may inhibit microorganisms or plant roots at high concentrations; insufficient use will reduce the total number of colonized microorganisms and weaken the remediation effect.

[0015] Excessive water-retaining agent, after absorbing water and expanding, may clog soil pores, reduce soil permeability, and hinder nutrient absorption; insufficient water-retaining agent weakens the soil's water-holding capacity and affects plant growth.

[0016] More preferably, the composite modifier comprises, by weight, 100 parts: 40 parts biochar, 35 parts sepiolite-chitosan composite material, 5 parts water-retaining agent, and 20 parts coastal wetland soil.

[0017] Preferably, the biochar has a particle size of 0.5-2 mm; and the sepiolite particles have a particle size of 1-5 mm.

[0018] If the biochar particle size is too large, it may not be able to effectively fill the soil pores, leading to the loss of water and nutrients; if the sepiolite particle size is too large, the effective space available for microorganisms to attach and inhabit will be reduced, resulting in a decrease in microbial load, and the excessively large hard particles may hinder the interaction between plant roots and soil; if the biochar and sepiolite particle size is too small, they are easily carried away by the water flow when washed by seawater.

[0019] Preferably, the preparation method of the sepiolite-chitosan composite material includes the following steps: S1-1. Crush, wash and dry the sepiolite to obtain sepiolite particles; S1-2. Dissolve chitosan in acetic acid solution to obtain chitosan solution; S1-3. The sepiolite particles are immersed in the chitosan solution, stirred, separated and dried to form a solidified chitosan coating on the surface of the sepiolite particles.

[0020] Preferably, the middle layer of mixed fiber also contains salt-tolerant plant growth promoters and salt-tolerant plant seeds.

[0021] Furthermore, the porous structure of sepiolite provides a stable habitat for microorganisms, effectively resisting osmotic pressure changes and hydraulic erosion caused by tidal alternation, reducing microbial loss. The amino and hydroxyl groups in chitosan molecules can form hydrogen bonds with microbial surface groups, significantly enhancing the binding strength between microorganisms and the carrier. At the same time, the slow-release properties of chitosan can slowly release nutrients, creating a synergistic effect with the improved soil water and fertilizer retention capacity after biochar amendment, continuously providing energy for microorganisms and ensuring their metabolic activity. In addition, the ion exchange capacity of sepiolite can also help reduce soil salinity and alkalinity, further improving the soil amendment effect.

[0022] Preferably, the salt-tolerant plant growth-promoting bacteria include one or more of nitrogen-fixing spirochetes, Bacillus, Pseudomonas fluorescens, Streptomyces, and salt-tolerant rhizobia; the salt-tolerant plant seeds include one or more of Suaeda salsa seeds, Reed seeds, Portulaca grandiflora seeds, and Bermuda grass seeds.

[0023] Preferably, the lower high-density fiber layer is 12-14 mesh and has a thickness of 3-5 mm; the middle mixed fiber layer is 6-8 mesh and has a thickness of 8-12 mm; and the upper sparse fiber layer is 8-10 mesh and has a thickness of 3-5 mm.

[0024] Specifically, mesh count refers to the number of fiber weave holes per inch; the lower high-density fiber layer is relatively dense and mainly provides overall tensile strength and erosion resistance; the middle mixed fiber layer has a loose and porous structure and serves as a functional layer for loading composite amendments; the upper sparse fiber layer is soft and sparse in texture and is used to protect seeds and microcapsules from falling off and to allow seedlings to easily penetrate, while slowing down surface moisture evaporation.

[0025] In terms of thickness design, the middle layer of mixed fiber is relatively thick to facilitate the support of the core material and provide a suitable environment for the growth of microorganisms and plants; the lower high-density fiber layer and the upper sparse fiber layer are of appropriate thickness, because if they are too thin, they cannot provide physical protection for the core material of the plant carpet; if they are too thick, they will affect the rooting and germination of plants.

[0026] In a second aspect, the present invention provides a method for preparing a plant blanket as described in the first aspect, comprising the following steps: S1. Prepare biochar, sepiolite-chitosan composite material and water-retaining agent respectively, and mix them with coastal wetland soil and granulate to obtain composite amendment; S2. Encapsulate salt-tolerant plant growth-promoting bacteria to obtain microcapsules of bacterial agents; S3. Provide salt-tolerant plant seeds and granulate them to obtain seed pellets; S4. The above-mentioned composite improver, microcapsules of fungicide and seed particles are laid on the middle layer of mixed fiber, fixed to the lower layer of high-density fiber by needle punching, and then the upper layer of sparse fiber is needle punched to form a plant carpet.

[0027] Preferably, the amount of the composite modifier, microbial agent microcapsules, and seed particles laid on the middle layer of mixed fiber is: 550-750 g / m² of composite modifier. 2 Microcapsules of microbial agent 40-60 g / m 2 Seed size 15-25 g / m³ 2 .

[0028] If too much of the composite amendment is used, it will clog the pores of the fiber network, making the middle layer of the plant carpet dense and compacted. Furthermore, excessive addition of biochar and sepiolite will cause drastic fluctuations in soil pH and salinity in the short term, affecting plant germination and growth. If too little is used, the amendment effect will be insufficient, and the amendment will slowly decompose, be lost or fixed in the environment. Insufficient initial dosage will greatly shorten its effective period.

[0029] Excessive use of the microbial agent microcapsules can lead to competition among microorganisms for resources such as oxygen and nutrients. The metabolites of certain microbial species may also inhibit the growth of other beneficial bacteria or plant roots and may interfere with the natural recovery process of native microbial communities. Insufficient use can prevent foreign microbial species from occupying ecological niches in the competition, ultimately resulting in colonization failure.

[0030] When too many seeds are laid out, the germinating seedlings compete for resources such as light, water, and nutrients, which can easily lead to thin plants and a high rate of weak seedlings; when too few seeds are laid out, effective vegetation cover cannot be formed quickly, resulting in poor soil and water conservation and landscape restoration.

[0031] Thirdly, the present invention provides an application of the plant blanket as described in the first aspect in the ecological restoration of coastal wetlands.

[0032] Compared with existing technologies, the functional plant mat with integrated composite modifier provided by this invention has the following advantages and positive effects: (1) The present invention integrates and fixes the modifier, microbial agent and plant seeds in the plant blanket in advance, realizing the shaping and integration of the repair material. Only one laying operation is required during construction, which greatly simplifies the process and effectively avoids the problems of scattering, loss and uneven distribution of modifier in traditional step construction. It ensures the accuracy of repair dosage and the reliability of repair effect, and realizes convenient construction.

[0033] (2) The three-layer composite structure of the plant blanket of the present invention provides effective physical protection. Among them, the high-density fiber lower layer effectively resists tidal erosion and reduces soil erosion; the mixed fiber middle layer has a loose structure that can accommodate the amendment; the sparse fiber upper layer is relatively sparse to prevent erosion and allow plant seedlings to penetrate. Casuarina equisetifolia branches are used to fix the blanket body, ensuring the structural stability of the blanket body.

[0034] (3) The coconut shell biochar of the present invention has a well-developed pore structure and a high specific surface area, and sepiolite has a good ion exchange capacity. The two work together to effectively adsorb and fix sodium ions and chloride ions in the soil, which can buffer the fluctuation of soil salinity caused by alternating light and salt water, reduce the stress of salt on plants and microorganisms, and make the plant carpet have good salt adsorption and buffering functions.

[0035] (4) The sodium alginate-bentonite composite water-retaining agent of the present invention can efficiently absorb and slowly release water, and work together with the organic fibers of the plant blanket to significantly improve the soil’s water and fertilizer retention capacity, creating a good rhizosphere environment for plant growth.

[0036] (5) The salt-tolerant plant growth-promoting bacteria agent immobilized by the microencapsulation technology of this invention is protected and can effectively resist environmental stress, significantly improving the colonization survival rate in the soil. These functional microorganisms can continuously play roles such as nitrogen fixation, phosphorus solubilization, and secretion of growth-promoting substances, activating soil nutrients, constructing a healthy and active rhizosphere microecological environment, and promoting plant growth. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the structure of the plant blanket of the present invention; Among them, 1-lower high-density fiber layer 1; 2-middle mixed fiber layer 2; 3-upper sparse fiber layer; Figure 2 This is a schematic diagram of branch cuttings used for fixing the plant blanket according to the present invention; Figure 3 This is a construction layout diagram of the plant blanket of the present invention; Figure 4 (a) The effects of different ratios of the amendments of the present invention on the early germination and survival of Suaeda salsa; (b) The effects of different ratios of the amendments of the present invention on the bulk density and cation exchange capacity of coastal saline soils; (c) The distribution of soil microbial diversity (Shannon index) under different treatments of the present invention. Figure 5 This is a flowchart illustrating the preparation process of the plant blanket of the present invention; Figure 6 This is a flowchart illustrating the on-site construction and maintenance process of the plant blanket of this invention. Detailed Implementation

[0039] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0040] The core innovation of this invention lies in constructing a multi-faceted synergistic restoration system integrating "erosion-resistant biofilm, biochar remediation, and microbial immobilization technology." The erosion-resistant biofilm first lays the foundation for slope stability and vegetation establishment. Simultaneously, coconut shells, a common waste material in coastal wetlands, are used to create biochar, which not only aligns with the concept of resource utilization but also improves soil physicochemical properties and achieves carbon sequestration and nutrient supply. The sepiolite-chitosan composite material enables efficient and sustained immobilization of halophilic bacteria. Combined with sodium alginate-bentonite water-retaining agent, it enhances the soil's water and fertilizer retention capacity. The functions of each component complement each other, comprehensively improving the restoration effect of coastal wetlands. Furthermore, this technology fully considers the dynamic characteristics of tidal alternation in coastal wetlands. Through the physical protection of the erosion-resistant biofilm, the structural stability optimization of coconut shell biochar, and the combined application of the sepiolite-chitosan composite material, it ensures the high efficiency and stability of this technology in the freshwater-saltwater alternating environment of coastal wetlands. This effectively solves the problem of fluctuating application effects of existing technologies, providing a more reliable and efficient technical solution for the ecological restoration of coastal wetlands.

[0041] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0042] In this document, the terms “containing,” “comprising,” or “including” are open-ended expressions, meaning they include the contents specified in this invention but do not exclude other aspects.

[0043] In this document, the terms “optionally,” “optionally,” or “optionally” generally refer to an event or condition that may, but may not, occur, and the description includes both cases in which the event or condition occurs and cases in which the event or condition does not occur.

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 protection scope of the present invention.

[0045] This embodiment provides a plant blanket for coastal wetland ecological restoration and its preparation and application method, including four parts: raw material processing method, plant blanket structure, compounding of amendment and plant blanket, and blanket fixation method, specifically including the following steps: (1) Raw material preparation: ① Preparation of biochar (taking coconut shell biochar, which is common in Hainan, as an example): a. Raw material pretreatment: Select naturally aged or accidentally fallen coconut shells from near Coconut Island in Tengqiao River, Sanya, Hainan. Rinse with fresh water to remove soluble impurities and salts, and air dry or dry in a 70 ℃ oven to constant weight; use a crusher to crush them into pieces with a particle size of 1-3 cm. b. Pyrolysis and carbonization: The crushed coconut shells are placed in a temperature-controlled anaerobic tube furnace; the temperature is programmed to rise to 450 ℃ at a heating rate of 10 ℃ / min, and held at this final temperature for 2 h to carry out full carbonization; c. Post-processing: After naturally cooling to room temperature, remove the product and coarsely crush it using a pulverizer, then grind it using a ball mill. After grinding, pass it through an upper 10-mesh sieve and a lower 35-mesh sieve to obtain granular coconut shell biochar with a particle size of 0.5-2 mm. Seal and store it in a dry place for later use. ② Preparation of sepiolite-chitosan composite material: a. Sepiolite pretreatment: The raw sepiolite ore (purchased from Shijiazhuang Kaiqi Mineral Products Co., Ltd.) is fed into a jaw crusher for crushing. The particles with a diameter of 1-5 mm are obtained by passing through a 4-mesh upper screen and a 20-mesh lower screen. The particles are then washed with deionized water until neutral and dried for later use. b. Chitosan solution preparation: Chitosan powder (purchased from Henan Anrui Biotechnology Co., Ltd.) was slowly added to a 5% acetic acid solution and a 0.01 g / mL chitosan solution was prepared by magnetic stirring. c. Composite material molding: The pretreated sepiolite particles are immersed in a chitosan solution and stirred thoroughly to make the surface of the particles uniformly coated with a chitosan liquid film, and then filtered out; the coated wet particles are dried in a ventilated environment at 80°C to allow the chitosan film to solidify and form a sepiolite-chitosan composite material. ③ Preparation of microcapsules of salt-tolerant plant growth-promoting bacteria: One or more salt-tolerant plant growth-promoting bacteria can be selected for compound use. Recommended strains include, but are not limited to: Azotobacter, Bacillus, Pseudomonas fluorescens, Streptomyces, salt-tolerant rhizobia, etc. a. Preparation of bacterial agent: Taking Bacillus as an example, commercially available salt-tolerant Bacillus licheniformis (purchased from Beihai Yeshengwang Biotechnology Co., Ltd.) was selected. The bacterial suspension was prepared according to the following ratio: powder: brown sugar: pure water = 1:2:50 (mass ratio). The mixed bacterial suspension was placed in a constant temperature incubator and activated and cultured at 30 ℃ and 150 r / min. The activated bacterial strain was inoculated into LB liquid medium containing 5 wt.% NaCl and cultured with shaking at 37 ℃ and 180 rpm for 12 h. If multiple strains are used, they are mixed in equal volume ratios under aseptic conditions to prepare a compound bacterial agent. b. Encapsulation of bacterial agents: The collected bacterial cells are resuspended in a 3 wt.% sodium alginate solution. The bacterial suspension is then dripped into a 2 wt.% calcium chloride solution using a dropper or spray device to form sodium alginate-calcium gel microcapsules. The microcapsules are collected by filtration, rinsed with sterile water, and then coated with the chitosan acetate solution from step ② to enhance stability. The coating process is the same as in step ②. Finally, the microcapsules are aseptically air-dried for later use. The dried bacterial agent microcapsules are sealed and packaged, and stored in a cool, dark place at 4°C for no more than 30 days. ④ Preparation of water-retaining agent: A composite water-retaining agent is selected by mixing sodium alginate (purchased from Guangzhou Shengxuan Biotechnology Co., Ltd.) and bentonite (purchased from Guangzhou Shengxuan Biotechnology Co., Ltd.) at a mass ratio of 1:2; before use, it is premixed with dry quartz sand at a mass ratio of 1:8 and ground evenly to ensure uniform dispersion. ⑤ Selection and seed treatment of salt-tolerant plants: Based on the water and salt conditions and ecological goals of the actual restoration area, one or more salt-tolerant plant seeds can be selected for mixed sowing. Recommended plants include, but are not limited to: Suaeda salsa, Phragmites australis, Portulaca oleracea, Bermuda grass, etc. Taking Suaeda salsa seeds (purchased from Jiangsu Aquatic Plant Base) as an example, before sowing, the seeds were soaked in a 100 mmol / L CaCl2 solution for 6 hours, and then rinsed with deionized water. Subsequently, the treated seeds were mixed with hydroxymethyl cellulose binder (purchased from Guangzhou Bofeng Chemical Technology Co., Ltd.), humic acid (purchased from Jinan Changhong Chemical Technology Co., Ltd.), and diatomaceous earth (purchased from Qingdao Shengpulin Environmental Protection Technology Co., Ltd.), and made into uniform seed particles with a diameter of about 3-5 mm in a granulator to increase weight and provide initial nutrition. (2) Structure of the plant mat: The plant mat adopts a three-layer integrated composite structure; like Figure 1 As shown, the lower high-density fiber layer 1 is a high-density web of coconut and palm fibers, with a mesh size of 12-14 mesh and a unit area weight of approximately 300 g / m². 2 With a thickness of approximately 3-5 mm, it primarily provides overall tensile strength and erosion resistance. The middle layer, a blended fiber layer 2, is a mixture of coconut fiber, palm fiber, and composite modifiers. It has a moderate needle-punching density of 6-8 mesh and a unit area weight of approximately 100 g / m². 2 It has a thickness of about 8-12 mm and its fiber mesh structure is loose and porous, serving as a functional layer for loading composite modifiers. The upper sparse fiber layer 3 is a relatively sparse web of coconut and palm fibers, with a mesh size of 8-10 mesh and a unit area weight of approximately 200 g / m². 2 It is about 3-5 mm thick, with a soft and sparse texture. It is used to protect seeds and microcapsules of fungicide from falling off and to allow seedlings to easily penetrate, while slowing down the evaporation of surface moisture. (3) Preparation of composite amendment and plant mat: ① Prepare the raw materials for the composite modifier according to the weight ratio: a. Coconut shell biochar: 25-50 parts, preferably 40 parts; b. Sepiol-chitosan composite material: 25-50 parts, preferably 35 parts; c. Water-retaining agent: 3-5 parts, preferably 5 parts; d. Coastal wetland soil: as a filler phase, it is floatable to replenish 100 parts of the baseline; ② Method for mixing compound modifiers: According to the above proportions, the coastal wetland soil, coconut shell biochar, sepiolite-chitosan composite material and water-retaining agent are mixed in a double helix conical mixer for 20 minutes until uniform to make a 1-5mm particle composite amendment. ③ Methods for preparing plant blankets: S1. Coconut fiber and palm fiber are mechanically laid together to form a lower high-density fiber layer 1; S2. On top of the lower high-density fiber layer 1, lay a layer of coconut fiber and palm fiber mixed fiber mesh with a moderate mesh count and loose structure as the middle mixed fiber layer 2. S3. According to the weight ratio, the coastal wetland soil, coconut shell biochar, sepiolite-chitosan composite material, and water-retaining agent are mixed in a double helix conical mixer to form a granular composite modifier. S4. On the already laid intermediate mixed fiber layer 2, sequentially and evenly spread granular composite improver, microbial agent microcapsules, and plant seeds. S5. On top of the middle layer of mixed fiber layer 2 where the functional materials have been spread, a layer of sparse coconut fiber and palm fiber mesh is laminated as the upper sparse fiber layer 3. S6. The above three layers of fiber network are intertwined and densified by needle punching process, and the spread amendment, fungicide and seeds are fixed inside the fiber network to form a plant carpet. S7. Roll up the finished plant blanket and transport it to the construction site for use. The composite conditioner, microbial agent capsules, and Suaeda salsa seed granules are evenly spread on the surface of the middle mixed fiber layer 2 according to the following range: a. Composite modifier: 550-750 g / m 2 700 g / m 2 ; b. Microcapsules of microbial agent: 40-60 g / m³ 2 50 g / m 2 ; c. Suaeda salsa seeds: 15-25 g / m 2 20 g / m 2 ; (4) Blanket fixing method: Plant branches or tree trunks are used as anchors; taking casuarina branches as an example, select casuarina branches with a diameter of 1.5-2.0 cm and a length of 30-40 cm, let them dry naturally, and then sharpen one end to make them easier to insert into the soil; When anchoring, after laying the plant carpet flat, use a mallet or similar tool to insert casuarina branches vertically downwards into the lower soil from the four corners and the center of the plant carpet surface. The insertion depth should be no less than 25 cm, and the exposed end length should be 5-10 cm. The branches inserted from the center should be 5-10 cm deeper than the four corners to resist tidal erosion. like Figure 2-3 As shown, the anchor points are arranged in a cross shape, with a spacing of 1.0 m × 1.0 m in the central area of ​​the carpet; the anchor spacing is increased to 0.5 m × 0.5 m in areas prone to erosion, such as the edges of the carpet, overlapping joints, slope tops, and areas with fluctuating water levels.

[0046] Example 1

[0047] In this embodiment, Suaeda salsa seeds were used, and saline soil from the Tengqiao River estuary in Sanya City, Hainan Province was used as the test soil. An outdoor simulated pond experiment was conducted for 30 days, with a control group and five experimental groups, each with five replicates. The test parameters were: seed germination rate after 7 days, plant survival rate after 30 days, soil bulk density after 30 days, soil aggregate content after 30 days, cation exchange capacity after 30 days, microbial diversity index after 30 days, and microbial abundance after 30 days. The experimental group settings were as follows: In the control group, the middle mixed fiber layer 2 contained only 20 g / m² of Suaeda salsa seeds. 2 It does not contain compound modifiers; The middle layer of the experimental group, the mixed fiber layer 2, contained 700 g / m² of composite modifier. 2 Its composition includes coconut shell biochar, sepiolite-chitosan composite material, coastal wetland soil, and water-retaining agent; it also contains 50 g / m³ of Bacillus microcapsules. 2 Suaeda salsa seeds 20 g / m³ 2The specific combinations for each group are as follows; The middle layer of the mixed fiber layer 2 in experimental group 1 contains: 25 parts of coconut shell biochar, 50 parts of sepiolite-chitosan composite material, 20 parts of coastal wetland soil, and 5 parts of water-retaining agent. The middle layer of the mixed fiber layer 2 in experimental group 2 contains: 30 parts of coconut shell biochar, 45 parts of sepiolite-chitosan composite material, 20 parts of coastal wetland soil, and 5 parts of water-retaining agent. The middle layer of the mixed fiber layer 2 in experimental group 3 contains: 35 parts of coconut shell biochar, 40 parts of sepiolite-chitosan composite material, 20 parts of coastal wetland soil, and 5 parts of water-retaining agent. The middle layer of the mixed fiber layer 2 in experimental group 4 contains: 40 parts of coconut shell biochar, 35 parts of sepiolite-chitosan composite material, 20 parts of coastal wetland soil, and 5 parts of water-retaining agent. The middle layer of the mixed fiber layer 2 in experimental group 5 contains: 50 parts of coconut shell biochar, 25 parts of sepiolite-chitosan composite material, 20 parts of coastal wetland soil, and 5 parts of water-retaining agent. The control group and the experimental group were identical in all conditions except for the formulation of the middle layer composite amendment. Specifically, the lower high-density fiber layer 1 had a mesh size of 13 and a thickness of 4 mm; the middle mixed fiber layer 2 had a mesh size of 7 and a thickness of approximately 10 mm; and the upper sparse fiber layer 3 had a mesh size of 9 and a thickness of approximately 4 mm. Germination rate after 7 days (7d), survival rate after 30 days (30d), soil bulk density, cation exchange capacity, and Shannon Index (also known as the Shannon-Wiener Index) were tested on both the experimental and control groups.

[0048] Experimental methods for 7-day germination rate and 30-day survival rate: Polyethylene plastic pots with an upper diameter of 20cm and a height of 15cm were used. Sanya Tengqiao River Estuary coastal saline soil was used. Three groups were set up: blank, control, and experimental. Each group was repeated 5 times. 0.5g of Suaeda salsa seeds were weighed for each experiment. The pots were kept moist by spraying daily in a greenhouse at 25-30℃. On the 7th day, the percentage of germinated seeds in each treatment group was counted out of the total number of seeds sown, which was the 7-day germination rate. On the 30th day, the percentage of surviving plants (strong seedlings with green leaves) out of the total number of seedlings that had germinated on the 7th day was counted, which was the 30-day survival rate.

[0049] Soil bulk density test method: Collect undisturbed soil using a ring sampler of known volume, weigh it, and then dry it in an oven at 105℃ until constant weight. Weigh the dry soil and divide the dry soil mass by the volume of the ring sampler to obtain the soil bulk density.

[0050] Cation exchange capacity test method: The soil sample is repeatedly rinsed with ammonium acetate solution at pH=7.0 to allow the soil to adsorb ammonium ions, and then the adsorption amount is determined by distillation titration.

[0051] The Shannon index testing method involves collecting soil or plant rhizosphere samples, extracting total DNA, amplifying the target gene using PCR (polymerase chain reaction), and sequencing. The obtained sequences undergo quality control, are clustered into OUT (operational taxa), and the abundance of each OTU is calculated. A diversity index is then calculated based on the OTUs at each sample site.

[0052] The formula for the Shannon index is:

[0053] in, H’ This is the Shannon Index (diversity index). S This represents the total number of species (or categories). P i For the first i The proportion of each species (or category) is usually... ; n i For the first i The number of individuals of a species N This represents the total number of individuals of all species.

[0054] Experimental results are as follows Figure 4 As shown in the figure, Figure (a) shows the effect of different ratios of soil conditioner on the early germination and survival of Suaeda salsa; Figure (b) shows the effect of different ratios of soil conditioner on the bulk density and cation exchange capacity of coastal saline soil; Figure (c) shows the distribution of soil microbial diversity (Shannon index) under different treatments. From experimental groups 1 to 4, as the biochar content increased, the soil bulk density decreased, the porosity increased, and the cation exchange capacity increased. Experimental group 4 showed the highest germination rate at 7 days and the highest survival rate at 30 days, indicating that this ratio could provide sufficient nutrients for plant growth and microbial reproduction. In experimental group 5, the amount of sepiolite-chitosan was relatively low, reducing the space for controlled microbial colonization and leading to a decrease in microbial diversity.

[0055] Experimental results showed that, compared with the control group, the use of plant mats significantly promoted the germination and survival of Suaeda salsa. Simultaneously, it effectively improved soil physicochemical properties, reduced soil bulk density, enhanced cation exchange capacity, and made the soil structure more porous. This improvement is beneficial to plant root respiration and alleviates the stress of soil salinity on plants, creating a more suitable environment for plant growth. Furthermore, plant mats significantly enhanced the biodiversity of soil microorganisms, demonstrating good potential for ecological improvement. Among them, experimental group 4 (40 parts coconut shell biochar and 35 parts sepiolite-chitosan composite material) showed better performance in all indicators than other ratios.

[0056] Comparative Example 1 The difference between this comparative example and the experimental group 4 above is that the middle mixed fiber layer 2 of comparative example 1 does not contain sepiolite-chitosan composite material, that is, the composite modifier composition includes 75 parts of coconut shell biochar, 20 parts of coastal wetland soil, and 5 parts of water-retaining agent; other conditions are the same.

[0057] The experimental results showed that the seed germination rate and seedling survival rate of *Suaeda salsa* in Comparative Example 1 were significantly lower than those in Experimental Group 4, and the soil microbial diversity index and abundance were significantly reduced. This indicates that without sepiolite-chitosan composite material as a microbial immobilization carrier, the colonization effect of salt-tolerant plant growth-promoting bacteria was poor, resulting in the inability to sustain their functions of promoting growth, fixing nitrogen, and solubilizing phosphorus, thus limiting the soil improvement effect and failing to establish a stable rhizosphere microecology.

[0058] Comparative Example 2 The difference between this comparative example and the experimental group 4 above is that the middle mixed fiber layer 2 of comparative example 2 does not contain biochar, that is, the composite modifier composition includes 75 parts of sepiolite-chitosan composite material, 20 parts of coastal wetland soil, and 5 parts of water-retaining agent, with other conditions being the same.

[0059] The experimental results showed that in Comparative Example 2, the plants grew slowly and exhibited symptoms of malnutrition, and the microbial activity decreased significantly in the later stages. Insufficient soil nutrient supply limited the synergistic repair effect between plants and microorganisms. The lack of biochar weakened the system's nutrient supply and retention capacity, affecting the long-term survival and function of plants and microorganisms.

[0060] Comparative Example 3 The difference between this comparative example and experimental group 4 above is that the sepiolite-chitosan composite material in comparative example 3 was replaced with washed sepiolite particles without chitosan coating, while other conditions were the same.

[0061] The experimental results showed that in Comparative Example 3, because the sepiolite was not coated with chitosan, its binding ability with biochar and fiber layer was weak, the attachment of microorganisms on the carrier was unstable, the activity maintenance time was short, plant growth was inhibited, and the soil improvement effect was not ideal.

[0062] Example 2

[0063] The difference between Example 2 and Experimental Group 4 is that the composite improver, microbial agent microcapsules, and Suaeda salsa seed particles are evenly spread on the surface of the middle mixed fiber layer 2 according to the following range: a. Composite improver: 550 g / m 2 b. Microcapsules of microbial agent: 40g / m 2 c. Suaeda salsa seeds: 15 g / m 2 ; The lower high-density fiber layer 1 has a mesh count of 14 and a thickness of 3 mm; the middle mixed fiber layer 2 has a mesh count of 8 and a thickness of approximately 8 mm; and the upper sparse fiber layer 3 has a mesh count of 10 and a thickness of approximately 3 mm. All other aspects are the same as in experimental group 4.

[0064] Experimental results show that although the indicators of Example 2 are slightly lower than those of Experiment 4, they are better than those of the control group. This indicates that Example 2 can effectively improve soil properties, promote plant growth and enhance microbial activity. Moreover, the plant mat structure is stable and can resist general tidal erosion.

[0065] Example 3

[0066] The difference between Example 2 and Experimental Group 4 is that the composite improver, microbial agent microcapsules, and Suaeda salsa seed particles are evenly spread on the surface of the middle mixed fiber layer 2 according to the following range: a. Composite improver: 750 g / m 2 b. Microcapsules of microbial agent: 60g / m³ 2 c. Suaeda salsa seeds: 25 g / m 2 ; The lower high-density fiber layer 1 has a mesh count of 12 and a thickness of 5 mm; the middle mixed fiber layer 2 has a mesh count of 6 and a thickness of approximately 12 mm; and the upper sparse fiber layer 3 has a mesh count of 8 and a thickness of approximately 5 mm. All other aspects are the same as in experimental group 4.

[0067] Experimental results showed that the plants in Example 3 exhibited more vigorous early growth and further improved soil improvement indicators, particularly in salt adsorption and microbial activity. Although the amount of material and the thickness of the fiber layer increased slightly, it did not lead to excessive weight of the blanket or a decrease in permeability, and it maintained good adhesion and impact resistance during actual installation.

[0068] Application Example 1 This application example demonstrates directly laying a plant mat and waiting for the seeds to germinate naturally. It is suitable for scenarios with short construction periods, where rapid installation is desired, and natural conditions are relied upon to promote seed germination. Construction should be carried out in spring (March-May) or autumn (September-October) when temperatures are moderate and tide levels are low, which is conducive to seed germination and seedling transplanting. The specific steps are as follows: Before construction, the target wetland was surveyed, and the mid-high tide zone was selected as the construction area. The site was leveled, and large pieces of debris and stones were removed to maintain the natural soil structure. After the tide receded and the beach surface was slightly dry, the rolled plant mat was spread out from top to bottom along the slope, with a 5-8 cm overlap between mats. Then, casuarina branches were used as anchors, vertically inserted into the soil to a depth of 25-35 cm. The anchor points were arranged in a cross shape, with a spacing of 1.0 m × 1.0 m in the central area and a density of 0.5 m × 0.5 m at the edges, overlapping areas, and easily eroded areas, ensuring that the mat was in close contact with the ground. Within 1-2 months after construction, if seedlings were damaged due to extreme weather, appropriate artificial reseeding could be carried out. In the event of continuous dry weather, fresh water could be sprayed once to moisten the surface soil and activate the amendment and seeds.

[0069] The results showed that after 2-3 months, the plants had established a lawn, the soil structure had improved, and the soil erosion had basically disappeared.

[0070] Application Example 2 This application example demonstrates seedling cultivation before installation, employing a seedling-in-plant construction method suitable for restoration areas requiring high immediate vegetation coverage, survival rate, and initial erosion resistance. Before construction, the plant carpet is pre-cultured in a greenhouse or nursery until the seeds germinate, then transplanted to the site as a whole. Specific procedures are as follows: First, pre-cultivation is carried out in a controlled greenhouse environment. The prepared plant mat rolls, which contain a compound of amendments, immobilizing agents, and plant seeds, are unfolded and laid flat on a cultivation bed. Regular irrigation with slightly saline water or a semi-strong nutrient solution is maintained, and the temperature is controlled at 20-30℃. After approximately 4-6 weeks of cultivation, the plant seeds generally germinate, and the seedlings grow to 5-10 cm in height. The root systems are fully developed and penetrate the fiber network, firmly integrating with the mat to form a unified whole. After pre-cultivation, water is moderately controlled before transplanting, and the established vegetation mats are carefully rolled up and transported to the restoration site. On-site construction is carried out after low tide when the beach surface is slightly dry. The plant mat rolls with seedlings are gently unfolded and laid flat along the slope from top to bottom, and then reinforced with casuarina branches for anchoring. If there is a prolonged period without rain after construction, fresh water can be sprayed 1-2 times as needed to alleviate transplant stress.

[0071] The results show that this method can achieve immediate ecological and protective effects, eliminates the need for reseeding, and accelerates the vegetation recovery process.

[0072] The embodiments described above are some, but not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A plant blanket, characterized in that, The middle layer of mixed fiber (2) includes a loaded composite modifier, the composite modifier including biochar and sepiolite-chitosan composite material; the sepiolite-chitosan composite material is composed of sepiolite particles coated with a chitosan membrane.

2. The plant mat according to claim 1, characterized in that, It also includes a lower high-density fiber layer (1) and an upper sparse fiber layer (3); the lower high-density fiber layer (1), the middle mixed fiber layer (2) and the upper sparse fiber layer (3) are sequentially arranged on the surface of the coastal wetland soil to be restored.

3. The plant mat according to claim 1, characterized in that, The composite amendment, in 100 parts by weight, includes: 25-50 parts biochar, 25-50 parts sepiolite-chitosan composite material, 3-5 parts water-retaining agent, and the remainder being coastal wetland soil.

4. The plant mat according to claim 1, characterized in that, The biochar has a particle size of 0.5-2 mm; the sepiolite particles have a particle size of 1-5 mm.

5. The plant mat according to claim 1, characterized in that, The middle layer of mixed fiber (2) also contains salt-tolerant plant growth promoters and salt-tolerant plant seeds.

6. The plant mat according to claim 1, characterized in that, The preparation method of the sepiolite-chitosan composite material includes the following steps: S1-1. Crush, wash and dry the sepiolite to obtain sepiolite particles; S1-2. Dissolve chitosan in acetic acid solution to obtain chitosan solution; S1-3. The sepiolite particles are immersed in the chitosan solution, stirred, separated and dried to form a solidified chitosan coating on the surface of the sepiolite particles.

7. The plant mat according to claim 2, characterized in that, The lower high-density fiber layer (1) is 12-14 mesh and 3-5 mm thick; the middle mixed fiber layer (2) is 6-8 mesh and 8-12 mm thick; the upper sparse fiber layer (3) is 8-10 mesh and 3-5 mm thick.

8. A method for preparing a plant mat according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Prepare biochar, sepiolite-chitosan composite material and water-retaining agent respectively, and mix them with coastal wetland soil and granulate to obtain composite amendment; S2. Encapsulate salt-tolerant plant growth-promoting bacteria to obtain microcapsules of bacterial agents; S3. Provide salt-tolerant plant seeds and granulate them to obtain seed pellets; S4. The above-mentioned composite improver, microcapsules of fungi and seed particles are laid on the middle mixed fiber layer (2), fixed to the lower high-density fiber layer (1) by needle punching, and then the upper sparse fiber layer (3) is needle punched to form a plant carpet.

9. The preparation method according to claim 8, characterized in that, The amount of the composite modifier, microbial agent microcapsules, and seed particles laid on the middle layer of mixed fiber is: composite modifier 550-750 g / m². 2 Microcapsules of microbial agent 40-60 g / m 2 Seed size 15-25 g / m³ 2 .

10. The application of the plant carpet according to any one of claims 1-7 in the ecological restoration of coastal wetlands.

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