Method for constructing mangrove forest in difficult site conditions

Abstract

The application discloses a method for cultivating mangrove in difficult conditions, and belongs to the technical field of coastal ecological restoration. The method is used for solving the problem of low survival rate of mangrove seedlings in the environment of high salt, poor soil and strong tidal scouring. The technical scheme comprises the following steps: selecting mature coconut shells, longitudinally splitting the coconut shells to form planting containers, and opening a drainage hole at the bottom of each container; filling substrates in the containers in layers, laying a thick oyster shell fragment layer at the bottom, filling a mangrove intertidal mud layer in the middle layer, and covering a 1-3 cm thick fine sea sand layer on the surface layer; arranging three coconut shell containers in an equilateral triangle, using a hard connecting piece to form a planting unit between adjacent coconut shells, placing the planting unit in a beach or wet area, and spacing the units at 0.5-1.5 m; and planting mangrove seedlings with a height of 30-50 cm in each container, keeping the root neck part 2-4 cm higher than the surface of the substrate, and backfilling and compacting. The method is used for efficiently cultivating mangrove in a beach or wetland, improving the scouring resistance and survival rate of seedlings, and promoting the recovery of an ecological system.

Description

Technical Field

[0001] This invention belongs to the field of coastal ecological restoration technology, specifically relating to a method for creating mangrove forests under difficult site conditions. Background Technology

[0002] Establishing mangrove forests under challenging site conditions presents significant technical obstacles. High salinity, poor soil, and intense tidal erosion severely reduce the survival rate of mangrove seedlings. Frequent tidal currents erode the mudflats, resulting in highly mobile sediment that makes it difficult for seedling roots to firmly attach. Strong water flows not only directly impact the seedlings physically but also easily cause the loss of planting substrate, exposing or suspending the seedling roots and impairing their ability to absorb water and nutrients. Simultaneously, the high salinity environment causes osmotic stress, disrupting the seedlings' normal water balance and physiological metabolic processes, while periodic or continuous flooding further exacerbates hypoxia stress, inhibiting root development. Related observational data show that the early mortality rate of mangrove seedlings in such sites remains high.

[0003] The structural problems of the intertidal soil also pose a constraint. The soil is generally heavy and has poor drainage, which easily leads to waterlogging and root rot due to lack of oxygen. The high-salt environment is often accompanied by a high soil pH and an accumulation of calcium and magnesium ions, which hinders the absorption and utilization of essential trace elements such as iron and phosphorus by mangrove seedlings. Although the direct backfilling with intertidal silt can provide some nutrients, these nutrients lack a long-term slow-release mechanism and are easily lost under continuous tidal disturbance and erosion, making it difficult to stably and continuously meet the needs of seedling growth.

[0004] Specific microbial communities in native mangrove soils are often significantly absent or poorly active in degraded mudflats or artificially modified lands. These microorganisms, such as sulfur-reducing bacteria and ammonia-oxidizing bacteria, are crucial for the decomposition of soil organic matter and the cycling and transformation of nutrients. Their absence leads to decreased soil enzyme activity and reduced nutrient cycling efficiency, affecting the healthy growth of seedlings. Furthermore, even when exogenous silt is introduced to replenish microorganisms, the communities often struggle to establish themselves stably due to environmental adaptability and the continuous influence of tidal disturbances, failing to effectively rebuild healthy soil ecological functions.

[0005] Under strong sunlight and wind, the surface soil of tidal flats evaporates water rapidly, causing salt to precipitate and accumulate on the surface, easily forming a dense salt crust. This hard crust hinders gas exchange between the soil and air, inhibiting seedling emergence and early growth. Covering measures intended to improve surface structure, if the materials are inappropriate (such as unsuitable particle size or thickness), may actually accelerate salt migration to the surface or impede oxygen diffusion, having the opposite effect.

[0006] Past restoration practices have often faced challenges in improving soil structure. For example, adding coarse-grained materials to the substrate to enhance drainage often results in the failure of mixing different layers of materials due to repeated tidal erosion, leading to structural damage. Introducing specific functional microbial communities is limited by the low survival and colonization success rates of these microorganisms in adverse environments. The application of surface cover materials also presents a balancing act; inappropriate selection can easily trigger secondary problems. These factors collectively contribute to the difficulty of establishing stable and efficient mangrove ecosystems under challenging site conditions. Summary of the Invention

[0007] One object of the present invention is to solve at least the above-mentioned problems and to provide at least the advantages that will be described later.

[0008] This invention solves at least the following technical problems: This study aims to address the low survival rate of mangrove seedlings planted in high-salt, infertile, and tidal-eroded tidal flat environments. Traditional methods suffer from poor substrate drainage, leading to root hypoxia, salt stress inhibiting physiological metabolism, and tidal erosion damaging the planting structure, resulting in high seedling mortality. A more robust planting unit is needed to achieve a balance between physical anchorage and microhabitat improvement.

[0009] Addressing the issue of unstable restoration outcomes due to differences in species adaptability. Different mangrove species exhibit significant differences in their tolerance to salinity and flooding; indiscriminate introduction of new species can easily fail due to environmental incompatibility. Therefore, it is necessary to select specific species to adapt to the target site conditions.

[0010] To resist the continuous erosion and damage of tidal currents on the planting units. Simple container fixation is prone to overall displacement or overturning due to insufficient anchoring force. A three-dimensional anchoring system is required to distribute stress and maintain structural stability.

[0011] To address the problem of insufficient bioavailability of iron in alkaline soils. Iron ions tend to precipitate in high pH environments, and conventional iron supplementation measures become ineffective due to tidal leaching; therefore, a slow-release mechanism needs to be designed to continuously supply available iron.

[0012] Controlling the rapid loss of phosphorus under tidal disturbances is crucial. Soluble phosphorus in the silt layer is easily carried away by water flow, making direct fertilization inefficient. Physical coating is necessary to achieve gradient release of phosphorus.

[0013] Inhibit diseases caused by the proliferation of harmful microorganisms in the rhizosphere. Pathogens easily proliferate at the root collar in high humidity environments, and chemical agents can easily pollute the environment, necessitating the development of environmentally friendly slow-release antibacterial materials.

[0014] Enhancing the bio-attachment capacity of coconut shells can promote the formation of a micro-ecosystem. The smooth coconut shell wall is not conducive to the habitation of attached organisms (such as barnacles), weakening the ecological function of artificial substrates. Therefore, it is necessary to construct a biomimetic attachment interface.

[0015] This addresses the issue of insufficient interfacial bonding strength between the eco-friendly substrate and coconut shell. Traditional adhesives are prone to hydrolysis and detachment under tidal immersion, necessitating optimization of composite material formulations and curing processes to improve durability.

[0016] Achieving a balance between precise positioning of patch templates and environmentally friendly degradation is crucial. Removing rigid templates can easily damage the uncured substrate, while biodegradable materials lack shape stability. Therefore, the development of intelligent, responsive templates is necessary.

[0017] Optimize template processing efficiency and structural integrity. Irregularly shaped composite materials are prone to delamination or deformation during hot processing, requiring graded molding processes to control interface bonding quality.

[0018] To achieve these objectives and other advantages of the present invention, a method for establishing mangrove forests under difficult site conditions is provided, comprising the following steps: S1: Select mature coconut shells with a diameter of 28-32 cm, split them longitudinally to form planting containers, and make drainage holes with a diameter of 1-2 cm at the bottom of each coconut shell; S2: Fill the coconut shell container with a layered matrix: the bottom layer is a 4-6 cm thick layer of oyster shell fragments with a particle size of 10-15 mm, the middle layer is filled with a mangrove intertidal silt layer, and the top layer is covered with a 1-3 cm thick layer of fine sea sand. S3: Arrange three coconut shell containers in an equilateral triangle, with rigid connectors used between adjacent coconut shells to form a planting unit. The planting unit is placed in a mudflat or wetland area, with a spacing of 0.5-1.5 meters between planting units. S4: Plant mangrove seedlings 30-50 cm tall in each coconut shell container, keeping the root collar 2-4 cm above the substrate surface, backfill the substrate and compact it, continue planting, and complete the creation of the mudflat or wetland area.

[0019] Preferably, the mangrove seedlings are selected from species such as Kandelia candel, Avicennia marina, Rhizophora stylosa, or Rhizophora spp.

[0020] Preferably, it also includes an anti-scour anchoring structure, which comprises: Anchor bolts are driven vertically into the mudflat or wetland area where the center of the planting unit is located. The anchor bolts are 1.2-1.5 meters long, and the top of the anchor bolt protrudes 0.3-0.4 meters above the mudflat surface. A ring-shaped clamp is installed on the upper part of the three coconut shell containers to tighten the three coconut shells. The ring-shaped clamp is located at one-half to two-thirds of the height of the coconut shell containers. The transverse struts are set between the three corner nodes of the rigid connector and the top of the anchor rod. The three transverse struts are arranged radially at equal angles, and the two ends of each transverse strut are hinged to the corner nodes and the top of the anchor rod through universal joints.

[0021] Preferably, in the matrix filling of step S2, a slow-release iron oxide interlayer is added between the bottom oyster shell fragment layer and the middle mangrove intertidal mud layer. The slow-release iron oxide interlayer is composed of hematite particles with a particle size of 2-4 mm and a thickness of 1-2 cm. The chemical composition of the hematite particles meets the following requirements: Fe2O3 content ≥ 92% by weight, specific surface area 5-8 square meters per gram, and porosity 35-45%.

[0022] Preferably, in the matrix filling of step S2, a phosphorus controlled-release layer is added between the middle layer of mangrove intertidal silt and the surface fine sea sand layer. The phosphorus controlled-release layer is composed of ammonium phosphate particles coated with hydroxyapatite and has a thickness of 0.5-1 cm. The ammonium phosphate particles have a particle size of 1-3 mm, the coating layer of hydroxyapatite has a coating rate of 40-60%, and the coating layer thickness accounts for 15-25% of the total particle diameter; The controlled-release phosphorus layer is spaced 1-2 cm from the inner wall of the coconut shell container.

[0023] Preferably, microbial slow-release inhibitor particles are uniformly mixed into the surface fine sea sand layer in step S2. The amount of microbial slow-release inhibitor particles added is 0.5-1.0% of the volume of the fine sea sand layer. The microbial slow-release inhibitor particles are composed of seaweed polysaccharide extract and chitosan coating layer, and the particle size is 1-3 mm. The seaweed polysaccharide extract contains ≥85% fucoidan by weight, the chitosan coating layer has a coating rate of 40-60%, and the coating layer thickness accounts for 10-20% of the total particle diameter.

[0024] Preferably, in the planting unit arrangement in step S3, an ecological substrate layer is attached to the outer wall of the coconut shell container. The ecological substrate layer is composed of oyster shell fragments and chitosan adhesive, and the attachment coverage rate is 50-70% of the surface area of ​​the outer wall of the coconut shell. The oyster shell pieces are 5-10 mm in length, 3-6 mm in width, and 1-2 mm in thickness, and the chitosan adhesive accounts for 10-15% of the dry weight of the composite layer; The ecological substrate layer is distributed in the form of discrete patches, each patch containing 3-5 oyster shell pieces, the patch diameter is 15-25 mm, and the distance between the edges of adjacent patches is 10-20 mm.

[0025] Preferably, the preparation of the ecological substrate layer includes the following steps: 1) Apply a chitosan acetate primer with a mass concentration of 8-12% to the patch area to form a transition layer with a thickness of 0.1-0.2 mm. The primer contains calcium carbonate crystal nuclei with a particle size of 50-100 nanometers, and the amount of crystal nuclei added is 3-5% of the dry weight of chitosan. 2) Mix oyster shell flakes with adhesive substrate at a mass ratio of 1:0.8-1.2 to obtain a mixture; the adhesive substrate is composed of the following components: 70-80 parts by weight of chitosan with a degree of deacetylation of 90-95%, 5-8 parts by weight of nano silica modifier, and 10-15 parts by weight of polybutylene succinate. 3) Fill the mixture into the patch positioning template, ensuring the inner wall of the template matches the patch size, and apply a pressure of 0.2-0.4 MPa and hold for 30-60 seconds; 4) After removing the template, cure for 18-24 hours under conditions of 75-85% humidity and 28-32℃ to achieve an interface bonding strength ≥0.4 MPa.

[0026] Preferably, the patch positioning template is composed of a seawater degradable composite matrix material and a shape memory unit. The seawater degradable composite matrix material contains the following components: 40-50 parts by weight of polycaprolactone with a molecular weight of 70,000-90,000, 30-40 parts by weight of calcium alginate with a particle size of 100-150 micrometers, and 10-15 parts by weight of glycerol plasticizer. The shape memory unit is embedded in 3-5 shape memory polyurethane ribs in a seawater biodegradable composite matrix material. The ribs are 5-8 mm wide, 0.5-0.8 mm thick, and have a glass transition temperature of 55-60℃.

[0027] Preferably, the preparation of the plaque localization template includes the following steps: 1) Shape memory polyurethane is injection molded into ribs at 180-190℃; 2) Polycaprolactone, calcium alginate, and glycerol are co-blended and granulated in a twin-screw extruder at 90-100℃; 3) Place the ribs in the mold positioning groove, inject the matrix granules, and mold them for 10-15 minutes at 100-110℃ and 8-12MPa to form an arc-shaped segmented template with grid cavities.

[0028] The present invention has at least the following beneficial effects: A synergistic physical-chemical microenvironment is constructed by layering substrates in coconut shell containers. Oyster shell fragments enhance drainage and slowly release calcium to neutralize alkalinity; intertidal mud provides native microorganisms and organic matter; and a fine sea sand surface layer inhibits salt uplift. The triangularly arranged planting units form an interlocking structure, significantly improving erosion resistance and ensuring stable establishment of seedling roots under tidal disturbances.

[0029] A limited list of adaptable species should be established to ensure that the selected mangrove seedlings possess the physiological tolerance to match the target site (e.g., salinity gradient, duration of flooding). This will prevent restoration failures due to inappropriate species selection and improve the survival rate and successional sustainability of the community.

[0030] The three-dimensional anchoring system, consisting of anchor bolts, clamps, and struts, disperses and transmits tidal erosion forces to the deeper soil layers. The universal joint hinge design allows for slight swaying of the unit to mitigate instantaneous impact forces, reduce the risk of structural stress concentration, and maintain the geometric stability of the planting unit under strong water flow.

[0031] Hematite particle interlayers utilize their high specific surface area and porous structure to slowly release active iron ions under tidal immersion. By controlling the dissolution rate to match the iron requirements of mangrove seedlings, the availability of iron in alkaline soils can be continuously improved, preventing iron deficiency chlorosis.

[0032] The hydroxyapatite coating forms a physical barrier, allowing ammonium phosphate to be released on demand during the tidal cycle. The coating thickness and porosity are designed to balance the immediate supply of phosphorus with the long-term slow-release requirement, reducing nutrient loss while preventing root salt damage.

[0033] Chitosan-coated seaweed polysaccharide particles create an antibacterial microenvironment around the roots. The chitosan membrane controls the slow exudation of antibacterial components, targeting and inhibiting the reproduction of pathogens at the root collar, reducing the incidence of disease, and avoiding the interference of chemical agents on the intertidal ecosystem.

[0034] The discrete, patchy ecological substrate layer mimics the surface structure of natural reefs, providing a heterogeneous habitat interface for sessile organisms. The multi-scale rough surface of oyster shells promotes microbial film formation, accelerating the transformation of the artificial substrate into a natural ecological niche.

[0035] Nano-calcium carbonate crystal nuclei enhance the interfacial adhesion between the primer and coconut shell, while polybutylene succinate improves the hydrolysis resistance of the adhesive substrate. A graded curing process ensures the composite material maintains high-strength adhesion under tidal immersion, extending the service life of the substrate.

[0036] Shape memory ribs enable the template to possess the characteristics of rigid positioning at high temperatures and elastic release at low temperatures. The polycaprolactone / calcium alginate matrix is ​​controllably degradable in seawater environments, avoiding damage to the uncured substrate during removal operations, thus achieving a balance between precise positioning and environmental friendliness.

[0037] The step-by-step molding process of rib preforming and matrix reduces interface defects in composite materials. Temperature-pressure coordinated control ensures the molecular chain entanglement strength between the ribs and the matrix, maintains the structural integrity of the template during high-temperature and high-pressure processing, and improves the template reuse rate.

[0038] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of an embodiment of the present invention.

[0040] 1. Coconut shell; 2. Anchor bolt; 3. Connector; 4. Ring clamp. Detailed Implementation

[0041] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0042] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0043] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are conventional methods, and the reagents and materials mentioned are commercially available. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "setting" should be interpreted broadly. For example, they can refer to fixed connection or setting, detachable connection or setting, or integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. The terms "lateral," "longitudinal," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0044] <Example 1> Mangrove restoration was carried out in a high-salinity tidal flat area in Zhanjiang City, Guangdong Province. Mature coconut shells with a diameter of about 30 cm were selected and longitudinally cut to form semi-cylindrical planting containers, with a drainage hole of about 1.5 cm in diameter drilled in the center of the bottom. The substrate inside the container was filled in layers from bottom to top: first, a 5 cm thick layer of oyster shell fragments with a particle size of 12 mm was laid; then, a layer of intertidal silt taken from a nearby mangrove reserve was laid on top; and finally, a layer of fine sea sand about 2 cm thick was evenly laid on the surface.

[0045] Arrange the three coconut shell containers in an equilateral triangle, as follows: Figure 1 As shown, each container, approximately 80 cm on each side, is fixed to an adjacent container using PVC connecting rods to form a triangular planting unit. Each unit is placed on the mudflat near the mean tide line, with a center-to-center spacing of 1 meter. A seedling of *Avicennia marina*, approximately 40 cm tall, is planted in the center of each coconut shell container. The seedling's position is adjusted so that the root collar is 3 cm above the substrate surface, and the surrounding substrate is backfilled and compacted. This method is repeated to create 200 planting units, covering approximately 2 hectares of mudflat area.

[0046] Comparison with the closest existing technology: The mainstream technique for mangrove replanting in challenging sites is direct transplantation: seedlings with soil clumps are planted in holes dug in the tidal flats, backfilled with native soil, and supported by simple bamboo poles. This method relies on the original soil structure of the tidal flats, but the soil in high-salt, infertile sites generally suffers from compaction and oxygen deficiency. Furthermore, bamboo pole support can only prevent lodging and cannot resist the erosion of the root zone by tides. After the tide recedes, seedling roots are often exposed, and the substrate is lost.

[0047] In contrast, this invention constructs a closed root growth space using a coconut shell container 1. The underlying porous structure formed by the oyster shell fragment layer is significantly superior to the drainage method in direct transplanting, which relies entirely on heavy clay tidal flat soil, and can quickly drain excess seawater to prevent root hypoxia. The surface layer of fine sea sand effectively prevents salt from accumulating at the root neck, whereas the exposed tidal flat surface in traditional methods is prone to forming a hard salt crystal crust after sun exposure. The triangularly arranged planting units form an interlocking structure through rigid connectors 3, and its overall shear resistance far exceeds that of single-plant bamboo pole support, significantly reducing the risk of unit displacement caused by tidal currents.

[0048] The physical barrier effect of the coconut shell container also solves another drawback of the direct transplanting method: in traditional methods, intertidal mud needs to be directly exposed to the tidal erosion environment, and nutrients are easily lost with the water flow. This invention seals the mud layer in the middle of the container, which not only preserves the native microbial community, but also reduces nutrient loss through the protection of the oyster shell bottom layer and the fine sand surface layer. The drainage hole design at the bottom of the container ensures that water will not accumulate during periodic flooding, unlike the bottom clogging problem commonly found in traditional plastic seedling containers.

[0049] At the planting operation level, this invention limits the root collar to be higher than the substrate surface, preventing tidal flat salt from directly contacting the sensitive parts of the seedlings through capillary action. Traditional transplanting often exacerbates salt stress due to planting too deep, or results in insufficient root anchorage due to planting too shallow. The 0.5-1.5 meter spacing of the triangular units balances the seedling's growth space needs with the overall erosion resistance of the group, while the dense planting mode of direct transplanting easily leads to nutrient competition, and sparse planting weakens erosion resistance.

[0050] This implementation method overcomes the three major bottleneck problems of existing technologies—matrix loss, poor drainage, and salt accumulation—through core innovations such as layered container structure and triangular unit arrangement. The entire process does not rely on chemical modifiers and conforms to the basic principles of ecological restoration.

[0051] <Example 2> A restoration project was carried out on the mudflats on the eastern side of the Zhanjiang National Mangrove Nature Reserve in Guangdong Province. This area is a typical high-salinity sandy mudflat, with a salinity gradient of 22-28‰ near the sea and 18-22‰ near the land. Two seedlings, Avicennia marina and Kandelia candel, were selected as planting materials. The initial height of the Avicennia marina seedlings was 40±5 cm, and the initial height of the Kandelia candel seedlings was 35±5 cm, with 600 seedlings of each type prepared. Planting was carried out in blocks according to the salinity gradient. High salinity area (salinity 25-28‰): Plant 300 Avicennia marina plants; In the medium-salt area (salinity 18-22‰): plant 300 Avicennia marina plants and 300 Kandelia candel plants.

[0052] All plants were grown using the coconut shell container unit from Example 1, with substrate configuration and triangular unit arrangement parameters consistent. Regular monitoring was conducted for 12 months after planting.

[0053] Comparison settings (traditional method): In adjacent areas of the same tidal flat, a traditional species selection method was used: five locally sourced mangrove seedlings (including non-salt-tolerant species such as Rhizophora stylosa and Sorbus amurensis) with similar initial heights were mixed and planted, totaling 600 seedlings. The planting conditions were exactly the same as those of the present invention.

[0054] Significant differences in survival rates 12 months after planting: The survival rate of *Avicennia marina* in high-salinity areas according to this invention is 91.8% (sampling error ±2.3%). In this invention, the survival rate of Kandelia candel in salt-grown areas was 85.4% (±3.1%). In the traditional method, the survival rate of Avicennia marina was 82.1% (±5.0%), the survival rate of Kandelia candel was 67.9% (±6.2%), and the survival rate of Rhizophora stylosa was only 39.7% (±7.5%).

[0055] Survival rate was verified by counting in 20×20 square meter quadrats (6 replicates).

[0056] Physiological manifestations of salt damage: Salt crystallization in the leaves of *Avicennia marina* occurred in less than 5% of the plants in this invention group, compared to 18% in the traditional group of the same species. The yellowing rate of leaves in *Kandelia candel* was 7% in this invention group, compared to 24% in the traditional group. In the traditional group, 72% of the leaves of *Rhizophora stylosa* showed scorching. The verification method involved randomly sampling 50 plants and statistically analyzing the proportion of abnormal leaves.

[0057] The essential difference from traditional technologies: Traditional methods rely on random selection based on seedling availability, without considering the salt tolerance threshold of the species. For example, the salt tolerance limit of *Rhizophora stylosa* is only 20‰, while the salt tolerance of the Zhanjiang tidal flats often exceeds 25‰, leading to an imbalance in its ion regulation. This invention limits the species to *Avicennia marina* (salt tolerance 40‰) and *Kandelia candel* (salt tolerance 30‰). *Avicennia marina* actively excretes salt through salt glands on its leaves, while *Kandelia candel* blocks salt absorption through the Casparian strip in its roots, resulting in significantly better physiological adaptability than traditional hybrid planting methods.

[0058] Traditional methods of intercropping low-salt-tolerant species such as Rhizophora stylosa in the same high-salt area violate the laws of ecological adaptation. This invention uses precise deployment according to salinity gradients: Avicennia marina is placed in a near-shore high-salt area (its finger-like breathing roots are adapted to long-term flooding), while Kandelia candel is placed in a medium-salt area (its prop roots require periodic aeration), achieving salinity-species synergistic adaptation.

[0059] Traditional intercropping methods lead to the mass mortality of salt-tolerant but vulnerable species (such as Rhizophora stylosa), creating bare patches and disrupting community continuity. The species composition of this invention maintains over 92% ground cover, compared to only 68% with traditional methods.

[0060] The sodium ion content in the leaves of *Avicennia marina* was 0.15% (dry weight), 37% lower than that in the conventional group of the same species, confirming the effectiveness of salt gland excretion. In the conventional group, the sodium ion content in the leaves of *Rhizophora stylosa* reached 0.52%, far exceeding the tolerance threshold. In the *Kandelia candel* group, the main root damage index was 0.12 (no damage = 0, complete decay = 1), while it reached 0.41 in the conventional group, indicating that the salt barrier mechanism protects the root system integrity.

[0061] By limiting the salt-tolerant species and their gradient configuration, the success rate of seedling establishment in high-salt sites was significantly improved, solving the ecological adaptability problem caused by the indiscriminate introduction of species in traditional restoration.

[0062] <Example 3> An anchoring system test was conducted on the mudflats of the eastern coast of the Zhanjiang National Mangrove Nature Reserve in Guangdong Province. This area is hit by 3-4 typhoons annually (for example, the peak tidal current velocity reached 1.8 m / s during the passage of Typhoon Haiyan in 2024). Fifty triangular planting units were selected (each unit consists of three 30cm diameter coconut shell containers 1 connected by PVC connecting rods to form an equilateral triangle structure with a side length of 80cm). Each unit was equipped with the anchoring system described in this invention: 1.4m long glass fiber reinforced polymer (GFRP) anchor rods 2 were vertically driven into the mudflats at the center of the unit, with the top end protruding 35cm above the ground surface; stainless steel ring clamps 4 were installed at half the height of the coconut shell 1 (40cm from the bottom) to secure the three coconut shell 1s; three 3cm diameter carbon fiber transverse struts were used, with both ends connected to the corner nodes of the triangular frame and the top of the anchor rods 2 via universal joints, with the struts 60cm long and radially distributed at 120° equal angles. Fifty identical planting units were set up as a control group, using only traditional single-sapling bamboo stake anchoring (8cm diameter bamboo stakes buried 1m deep, single-sapling tied and fixed). All planting units were planted with Avicennia marina seedlings (40±5cm in height), and continuous monitoring was conducted for 12 months covering two typhoon seasons.

[0063] Traditional monopile anchoring relies on the rigidity of the pile body to resist bending, but bamboo piles are prone to fatigue fracture under repeated tidal loads. Their single-point stress mode leads to stress concentration at the binding point, often resulting in rope breakage or pile fracture during typhoons. For example, during Typhoon Haiyan in 2024, the fracture rate of traditional piles reached 68%, with fractures concentrated 20-40cm below the ground surface (an area where alternating tides accelerate corrosion). More seriously, traditional methods only secure the plant stems, failing to protect the entire planting container. Tidal erosion causes continuous loss of substrate at the bottom of the container, ultimately leading to collapse – post-typhoon inspections showed that 45% of the coconut shell containers in the traditional group tilted at angles exceeding 30° due to substrate erosion, with 40% of the seedling roots exposed.

[0064] This invention reconstructs anti-erosion logic through triangular mechanical transmission: The ring clamp 4 locks the three containers into a rigid whole, resisting horizontal shear forces. The clamp position was selected after repeated verification at 1 / 2 of the height of the coconut shell 1 (rather than the top), because this is the point of application of the maximum impact torque of the tidal current, which can prevent the container from rotating around the bottom fulcrum under the action of waves.

[0065] Anchor 2 penetrates deep into the stable soil layer to bear the vertical load. The GFRP material has the characteristics of being resistant to salt and alkali corrosion (more than 3 times longer than bamboo piles), and the 1.4m length ensures that the anchor end penetrates the loose silt layer and reaches the silty clay bearing layer.

[0066] The three-way struts are hinged together via universal joints to form a dynamic balance system. When the tide impacts the corner joints of the tripod, the struts convert part of the impact force into the pull-out force of the anchor rods 2 (the deeper soil layers have stronger resistance), and part of the energy is dissipated through the rotation of the universal joints. Actual measurements show that the struts swing amplitude reaches 12°-15° during typhoons, effectively preventing structural damage.

[0067] The core difference lies in the fact that traditional methods aim to "counter" impacts, while this invention employs a "guidance-dispersion" mechanism. The design of the anchor rod 2 with its top exposed 35cm allows for strut swing space, and the universal joint enables adaptive adjustment of the impact force direction, avoiding stress concentration issues found in traditional rigid connections. Detection of silt at the base of the coconut shell container 1 shows that the scour pit depth in this invention group is only 8-10cm (compared to over 25cm in the traditional group), confirming that the three-dimensional anchoring system effectively disperses the shear force of the bottom water flow.

[0068] After Typhoon Haiyan passed through, 48 out of 50 units in the invention group remained in place (displacement <5cm), and 2 displaced units were located in the geologically weak area at the edge of the tidal channel; 32 units in the traditional group slid as a whole (maximum displacement 28cm), and 15 units of coconut shell container 1 were scattered.

[0069] Damage characteristics of anchoring components: The universal joint of the present invention shows slight rotational friction marks, and the strut is not deformed; the bamboo pile of the traditional assembly has a breakage rate of 68%, and the binding rope has a breakage rate of 45%.

[0070] Biological colonization effect: After the tide receded, an inspection revealed that 93% of the seedlings in the invention group had their roots completely encased in the substrate, and the coconut shell 1 showed no tilting; in the traditional group, the seedling roots in the displacement units were generally exposed (maximum exposed length 15cm). Due to the difference in root protection, after 12 months, the seedlings in the invention group increased in height by 42cm (compared to only 22cm in the traditional group), and the rate of yellowing leaves due to salt damage was as low as 6% (compared to 35% in the traditional group).

[0071] Verification of the universality of the technology: Extension tests on sandy tidal flats in Dianbai District, Maoming, Guangdong (where the shear strength is only 1 / 3 of that of silty tidal flats in Zhanjiang) show that: Traditional bamboo pile anchoring has insufficient pull-out resistance in sandy soil, and the overturning rate after a typhoon reaches 51%. This invention increases the unit's overturning resistance rate to over 90% by increasing the length of the anchor rod 2 to 1.5m and expanding the radial angle of the strut to 150°.

[0072] This adjustment verifies the practical engineering flexibility of the parameter range (anchor bolts 21.2-1.5m, radial arrangement of struts) in this invention, highlighting its adaptability to different tidal flat geological conditions. Compared to concrete base anchoring (costing over 800 yuan per set), the material cost of the anchoring system in this invention is controlled within 185 yuan, and the construction efficiency is improved by 44% (skilled workers can install one set in just 15 minutes), providing an economical solution for large-scale tidal flat restoration.

[0073] <Example 4> Fifty coconut shell planting units were set up in the tidal flat area. Each unit was filled in layers according to the substrate structure of this invention: the bottom layer was a 5cm thick layer of oyster shell fragments (particle size 12mm), the middle layer was an intertidal silt layer, and the top layer was a 2cm layer of fine sea sand. A slow-release iron oxide interlayer as described in claim 4 was added: a 1.5cm thick layer of hematite particles with a particle size of 3±0.5mm was laid between the bottom and middle layers. XRF analysis showed an Fe2O3 content ≥93%, a BET specific surface area of ​​6.8m² / g, and a porosity of 41% as determined by mercury intrusion porosimetry. The hematite particle layer was laid continuously, with the edge 1cm from the inner wall of the coconut shell to avoid boundary effects. After planting Avicennia marina seedlings (initial plant height 45±5cm), continuous monitoring was conducted for 12 months.

[0074] Control group (traditional method): 50 planting units of the same specifications were set up in adjacent areas and conventional iron improvement measures were adopted: powdered EDTA chelated iron (Fe content 12%) was evenly mixed into the silt layer at an addition rate of 0.2 kg / m³, and the remaining substrate configuration was the same as that of the present invention group.

[0075] Performance Comparison: Iron Availability Maintenance: Six months after planting, the available iron content in the rhizosphere soil of the invention group remained stable at 28-32 mg / kg (DTPA extraction method), while the initial available iron content in the traditional group reached 45 mg / kg, but decreased to 18 mg / kg after 3 months, with tidal erosion causing a loss rate of over 60% of chelated iron. Leaf yellowing index monitoring showed that the yellowing rate of the invention group remained below 10%, while the yellowing rate of the traditional group rose to 35% from the 4th month onwards.

[0076] Changes in soil chemical properties: In the present invention group, the hematite particle layer formed a locally slightly acidic environment (pH 7.2-7.5) after tidal soaking, which promoted the activation of closed-state iron in the upper silt. In the conventional group, the soil pH rose to 8.6 due to the decomposition of chelated iron, and the amount of calcium carbonate deposition increased by 27% (X-ray diffraction analysis).

[0077] Physical structural stability: After excavation and inspection following low tide, the hematite particle layer of this invention remained intact, with no particle migration observed.

[0078] The fundamental difference from traditional technologies: Traditional iron improvement relies on water-soluble chelating agents, whose ionic iron desorbs under high-frequency tidal immersion and is rapidly lost with pore water. Chelating agents such as EDTA decompose more rapidly in alkaline environments, with a half-life of less than 30 days, leading to an unsustainable iron supply. More seriously, excessive chelating agents can complex heavy metal ions (such as Cd and Pb) in the soil, triggering secondary ecological risks.

[0079] This invention utilizes the crystal properties of hematite to achieve slow iron release: Microporous slow-release mechanism: Hematite's mesoporous structure (5-8 m² / g specific surface area) and hydrogen bonding adsorb tidal water, Fe 3+ Slow dissolution via coordination hydrolysis (dissolution rate 0.02 mg / cm²·d) avoids precipitation of iron phosphate caused by excessively high instantaneous concentration; In-situ pH adjustment: Hematite hydrolysis reaction (Fe₂O₃ + 3H₂O → 2Fe) 3+ +6OH⁻) consumes protons, forming a pH gradient at the particle-sludge interface, which reduces the pH of the rhizosphere microzone by 1.0-1.5 units, significantly improving iron bioavailability; Erosion resistance enhancement: The 2-4mm particle size design enables the critical starting velocity of the particles to reach 0.35m / s, which exceeds the common tidal flow velocity (0.15-0.25m / s), and the layer stability is better than that of powder materials.

[0080] The hematite layer acts as a physical barrier, preventing the upward migration of calcium and magnesium ions from the underlying layer and reducing rhizosphere calcium carbonate cementation. Electron microscopy observations showed that the root surface of seedlings in the conventional group was covered with a calcium carbonate crystal layer (10-15 μm thick), which hindered iron absorption; the root surface of the group of this invention was clean, and the root hair density was increased by 2 times.

[0081] Engineering adaptability verification: Extended testing in the Shenzhen Bay high-speed railway disturbance zone (6-8 tidal surges per day) shows that: Traditional chelated iron groups require reapplication once a quarter due to iron loss, increasing maintenance costs by 40%. The hematite layer of this invention maintains an effective iron leaching rate of 78% of its initial value after 12 months, with a particle disintegration rate of <5%. The mineral properties of hematite avoid the introduction of exogenous chemical additives, which is in line with the sustainability principle of coastal wetland ecological restoration.

[0082] <Example 5> Engineering applications were carried out in the mangrove restoration area of ​​Zhanjiang, Guangdong (soil pH 7.8-8.2, tidal erosion 3-4 times daily). The substrate structure of this invention was used to fill coconut shell containers in layers: a bottom layer of oyster shell fragments (5cm thick, 12mm particle size), a middle layer of intertidal silt (taken from the native mangrove area of ​​Shenzhen Bay). A phosphorus control-release layer was added: a 0.8cm thick phosphorus control-release layer composed of ammonium phosphate particles coated with hydroxyapatite (particle size 2.0±0.3mm) was laid between the middle silt layer and the surface fine sea sand layer. Scanning electron microscopy showed that the hydroxyapatite coating rate was 52±3%, and the coating layer thickness accounted for 20±2% of the total particle diameter; the edge of the particle layer was 1.5cm from the inner wall of the coconut shell 1 to avoid direct tidal erosion. After planting Avicennia marina seedlings (initial plant height 45±5cm), continuous monitoring was conducted for 12 months.

[0083] The fundamental difference from traditional techniques: Traditional phosphate fertilizer application often involves directly mixing diammonium phosphate (DAP) or superphosphate (SSP) into the soil. Under high-frequency tidal erosion, water-soluble phosphorus (such as H₂PO₄⁻) is easily carried away by the water flow; observations show that the phosphorus loss rate of DAP reaches 38-45% in a single tidal cycle. More seriously, high concentrations of calcium, magnesium, and iron ions in coastal saline-alkali soils combine with phosphate to form insoluble precipitates (such as Ca₅(PO₄)₃OH or FePO₄), causing the bioavailability of phosphorus to plummet to below 15%. For example, in a Pearl River Estuary tidal flat experiment, after three months of planting in the traditional group, the available phosphorus content in the soil decreased from an initial 35 mg / kg to 8 mg / kg, and the seedling roots exhibited typical phosphorus deficiency purpuria symptoms.

[0084] This invention reconstructs the phosphorus release mechanism through core-shell structure design: Physical barrier controlled release: Hydroxyapatite (Ca 10 The (PO4)6(OH)2) coating layer forms a microporous framework (pore size 50-200 nm), and the dissolution rate of ammonium phosphate is controlled by the diffusion gradient of the pores during tidal infiltration. X-ray energy dispersive spectroscopy shows that the calcium-to-phosphorus molar ratio in the coating layer is 1.67:1, which is similar to that of natural skeletal apatite, indicating that it has ion exchange buffering capacity.

[0085] Chemical synergistic activation: Acidic substances (such as organic acids and CO2) in the silt layer slowly erode the hydroxyapatite coating, lowering the local microenvironment pH to 6.5-7.0 and promoting the conversion of phosphate from a closed state to an available state. Simultaneously, it inhibits the fixation of phosphorus by calcium ions in alkaline soils. Electron microscopy observations show that the calcium phosphate deposition layer on the root surface of the conventional group is 12-18 μm thick, while that of the group in this invention is only 3-5 μm thick. Tidal resistance optimization: The particle size and coating layer thickness design enable a critical initiation velocity of 0.40 m / s (the average tidal velocity in the Pearl River Estuary is 0.25 m / s), improving hierarchical stability by 3 times; a 1.5 cm interval zone forms a buffer zone, reducing preferential flow scouring caused by the container wall effect.

[0086] Performance comparison: 1) Dynamic maintenance of phosphorus: Tidal simulation experiments (flow velocity 0.3 m / s, 8 times per day) showed that the cumulative phosphorus loss rate in the traditional DAP group was 82% after 10 days, while that in the phosphorus controlled release layer group was only 31%. Six months after planting, the available phosphorus in the rhizosphere soil was measured (NaHCO3 extraction method): the phosphorus level in the invention group remained at 28-32 mg / kg, while that in the conventional group decreased to 10-12 mg / kg.

[0087] 2) Differences in physiological responses: Phosphorus content in leaves: The phosphorus content in mature leaves of seedlings in this invention group was 0.22% (dry weight), while that in the traditional group was only 0.15% (phosphorus deficiency threshold 0.18%). Root system architecture: The number of secondary lateral roots in the present invention group was 65% higher than that in the traditional group, and the root hair density was increased by 40% (root system scanning analysis). Salt damage mitigation: In the traditional group, phosphorus deficiency led to an imbalance in osmotic regulation, resulting in a leaf margin scorch rate of 32%, while in the group of this invention, it was <8%.

[0088] 3) Environmental compatibility: Monitoring of reactive phosphorus (SRP) in adjacent water bodies showed that the peak SRP level in the conventional group after low tide reached 0.15 mg / L (the limit of Class IV water quality standard is 0.3 mg / L), while the peak level in the group of this invention was only 0.06 mg / L, reducing the risk of algal blooms.

[0089] Engineering adaptability verification: The extended test in the Zhuhai Modaomen brackish water confluence area (salinity fluctuation 5-25‰) showed that the dissolution rate of the hydroxyapatite coating layer decreased by 26% when the salinity was >20‰, but the effective phosphorus supply still met the seedling needs; the precipitation rate of traditional DAP increased by 40% under high salinity conditions, while the root phosphorus absorption efficiency of the phosphorus controlled release layer group remained above 85%.

[0090] This study demonstrates that the phosphorus controlled-release layer, through the synergy of physical barrier and chemical slow release, resolves the contradiction between efficient phosphorus utilization and ecological security under tidal disturbances, providing a controllable nutrient transport paradigm for coastal wetland restoration.

[0091] <Example 6> A disease control experiment for mangrove seedlings was conducted in the tidal flats of Zhanjiang Bay, Guangdong (salinity 20-25‰). The preparation process of the microbial slow-release inhibitor granules is as follows: 1. Extraction of seaweed polysaccharides: Local brown algae (Sargassum) were selected as raw materials and extracted with hot water at 80℃ for 1 hour (repeated three times) to obtain crude extract. After ethanol precipitation and purification, an extract with fucoidan content ≥88% was obtained.

[0092] 2. Granulation: The seaweed polysaccharide extract and chitosan powder with a deacetylation degree of 92% are mixed at a mass ratio of 3:1, and 5% nano silica modifier is added. The mixture is then extruded and rolled to form core material particles with a particle size of 2.0±0.3 mm.

[0093] 3. Coating process: Fluidized bed coating technology is adopted, using a 10% chitosan-acetic acid solution as the coating liquid (containing calcium carbonate crystal nuclei with a particle size of 80 nanometers), controlling the inlet air temperature at 40℃ and the atomization pressure at 0.3MPa, so that the coating layer thickness accounts for 18% of the total particle diameter and the coating rate reaches 55%.

[0094] The prepared granules were evenly mixed into the surface substrate (fine sea sand layer thickness 2cm) at a ratio of 0.8% of the volume of the fine sand layer, and then planted into Avicennia marina seedlings. The occurrence of root collar diseases was monitored.

[0095] The fundamental difference between traditional chemical antibacterial agents and conventional methods: Traditional tidal flat disease control often involves direct spraying or mixing chemical fungicides (such as mancozeb and carbendazim) into the soil. While these agents can quickly inhibit pathogens, their water-soluble components are lost at a rate exceeding 65% within 72 hours due to tidal erosion, requiring weekly reapplication to maintain effective concentrations. More seriously, chemical agents lack targeting, significantly reducing the abundance of beneficial rhizosphere bacteria (such as ammonia-oxidizing bacteria and nitrogen-fixing bacteria) by more than 40% while killing pathogens, disrupting the microecological balance. Intertidal water testing shows that phthalate plasticizer residues in areas where traditional methods are used reach 0.15 mg / L, causing acute toxicity to benthic organisms (such as larvae of shellfish).

[0096] This invention reconstructs the antibacterial logic through a core-shell structure design: Core material function: High-purity fucoidan (containing 28% sulfate groups) adsorbs onto the cell membranes of pathogenic bacteria (such as Fusarium) through electrostatic interactions, disrupting their ion channels. The slow-release properties of fucoidan result in a daily dissolution rate of only 5% under tidal immersion, maintaining stable antibacterial concentration.

[0097] Encapsulation regulation: The chitosan coating layer selectively degrades under the stimulation of root exudates (such as organic acids), allowing antibacterial components to be preferentially released into the high-risk area of ​​the root collar. Electron microscopy observations show that the pore expansion rate of the coating layer in the rhizosphere microenvironment is 2.3 times that in the sand layer area, achieving precise targeting of pathogen-rich areas.

[0098] Ecological synergy: Chitosan degradation products promote the reproduction of actinomycetes, increasing their population by 150% compared to the traditional group, forming a secondary defense line of beneficial bacteria suppressing pathogens. No chemical residues were detected on the surface of the tidal flats after low tide, and the survival rate of Daphnia in the water reached 100% within 48 hours.

[0099] The core difference lies in the fact that traditional methods aim for "broad-spectrum bactericidal action," while this invention employs a three-tiered mechanism of "slow release, targeted action, and microecological regulation." The sulfate groups of fucoidan specifically bind to the flagellin of pathogenic bacteria, inhibiting their motility, while the chitosan membrane forms a localized microporous structure under the action of root exudates, achieving intelligent release in response to "root distress calls and antibacterial action."

[0100] Disease control effectiveness: Three disease surveys were conducted within 120 days after planting. 1. Incidence of root collar rot: The cumulative incidence rate in this invention group was 8.7% (based on the criterion that the browning area of ​​the root collar was >30%).

[0101] Traditional chemical group: morbidity rate 32.5%, of which 12% of seedlings died due to rotting.

[0102] 2. Changes in the microbial community: High-throughput sequencing of rhizosphere soil showed that the relative abundance of Fusarium in the present invention group was 0.08%, while that in the conventional group was 0.53%.

[0103] Bacillus accounted for 15.2% of the total in this invention group, which was significantly higher than the 6.8% in the conventional group. 3. Emergency salt damage response: After a typhoon and heavy rain, the salinity of the tidal flats dropped sharply to 5‰. In the traditional group, leaf wilting occurred due to increased pathogen infection (incidence rate 41%), while in the group of this invention, only 9% of the seedlings showed mild stress.

[0104] Mechanism verification shows that, under the stimulation of oxalic acid secreted by roots, the chitosan membrane degradation rate of the particles of this invention increases to 35% within 48 hours (compared to only 12% in the unstimulated environment). Simultaneously released fucoidan forms a 10-15 μm antibacterial film layer at the root collar, blocking pathogen attachment. Compared to the "all-area poisoning" of traditional chemical agents, this design achieves enhanced intelligent protection under adverse conditions.

[0105] <Example 7> A project to modify the surface of coconut shell containers was carried out on the eastern coastal mudflats of the Zhanjiang National Mangrove Nature Reserve in Guangdong Province. 200 triangular planting units (a total of 600 coconut shell containers) were selected, and an ecological substrate layer was prepared according to the method of this invention. 1. Oyster shell pretreatment: Local waste oyster shells are selected, crushed and screened into flakes with a length of 8±2 mm, a width of 5±1 mm and a thickness of 1.5±0.3 mm, soaked in hydrochloric acid to remove impurities and then dried.

[0106] 2. Preparation of adhesive substrate: Mix 75 parts by weight of chitosan with a degree of deacetylation of 92%, 6 parts by weight of nano silica modifier, and 12 parts by weight of polybutylene succinate, and add 5% acetic acid solution to stir into a gel.

[0107] 3. Patch positioning and shaping: Mark the center point of the patch on the outer wall of coconut shell 1, and control the distance between adjacent center points to 30 mm; apply 10% chitosan acetic acid primer (containing 80 nano-calcium carbonate crystal nuclei, added at 4%) to form a 0.15 mm transition layer; mix oyster shell pieces and adhesive substrate at a mass ratio of 1:1 and fill them into an arc-shaped patch template (diameter 20 mm), apply 0.3 MPa pressure and hold for 45 seconds.

[0108] 4. Curing treatment: After removing the template, cure for 20 hours in an environment with 80% humidity and 30℃ to obtain discrete patches with an interfacial bonding strength of 0.45 MPa and a coverage rate controlled at 60%.

[0109] The essential difference from traditional substrates: In traditional mangrove restoration, to enhance the bio-adhesion of artificial substrates, oyster shells are often used to completely wrap coconut shell containers (such as patent CN219343265U) or to uniformly apply a cement-shell mixture slurry. While the complete wrapping method increases the adhesion area, it creates a continuous, closed surface, leading to three major drawbacks: Water flow disturbance suppression: The continuous shell hinders the vortex motion of tidal flow on the surface of coconut shell 1, weakening the water exchange efficiency. Actual measurements show that the oxygen diffusion rate is 40% lower than that of bare coconut shell 1, which is not conducive to the oxygen uptake of juvenile barnacles.

[0110] Increased biological competition: The uniform surface promotes dense symbiosis of sessile organisms such as barnacles and mussels, with a biological coverage of over 85% within 12 months. However, due to spatial competition, the predation rate of small crustaceans (such as amphipods) increases by 60%, and the biodiversity index is 1.2 lower than that of natural reefs.

[0111] Structural failure risk: Cement-based adhesives are prone to powdering under tidal wet and dry cycles, with a detachment rate of 35% after 6 months, and oyster shells peeling off in pieces.

[0112] This embodiment reconstructs the biological attachment mechanism through discrete patch design: Fluid dynamics optimization: 10-20 mm gaps between patches create microscale turbulent regions, generating localized low pressure when tidal flows through, attracting barnacle larvae to settle. On-site flow velocity monitoring shows that the eddy current intensity in the gap region is 3.2 times higher than that on the continuous surface, increasing the larval landing density by 50%.

[0113] Niche heterogeneity: Patches with a diameter of 15-25 mm simulate the spatial distribution of natural reef fragments. Each patch carries 3-5 oyster shells, forming a multi-level porosity (0.5-2 mm pores account for 65%), providing exclusive habitats for organisms of different sizes. Comparative observations show that the amphipod population density in the patch area reaches 35 individuals / square decimeter, which is 2.8 times that of the traditional wrapping method.

[0114] Improved interfacial durability: The chitosan-polybutylene succinate composite adhesive undergoes controlled degradation in seawater, with nano-silica enhancing the interfacial mechanical interlocking. Accelerated aging tests show that the bond strength after curing decreases by only 12% after 90 days of tidal immersion, while cement-based adhesives experience a 58% decrease during the same period.

[0115] Synergy verification with ecological cofferdam technology: A comparison of oyster shell ecological dikes (patent CN219343265U) and coconut shell patch substrates implemented simultaneously on the mudflats of Pingluo, Zhanjiang, shows that: Functional complementarity: The main body of the cofferdam reduces macroscopic wave energy (wave height is reduced by 62%), while the coconut shell patch 1 provides microhabitat construction. The combination of the two reduces the water disturbance intensity in the seedling planting area to 0.8-1.2 m / s, which is better than single technology (1.5-2 m / s in the cofferdam area and 2-3 m / s in the pure patch group).

[0116] Biosynergistic effect: The larvae released from the oyster reef of the enclosure preferentially attach to the coconut shell 1 patch. After 6 months, the oyster coverage rate in the patch area reached 75%, which is 40% higher than that in the area without enclosure. The barnacle-oyster symbiotic community increased the abundance of nitrogen cycling bacteria on the surface of coconut shell 1 by 2.1 times, accelerating the transformation of matrix nitrogen.

[0117] Ecological effects: Comparison of biofilm development: The invention group: a green diatom-dominant biofilm (45% coverage) forms at the edge of the patch within 7 days, and evolves into a brown algae-fungus floc composite film (78% coverage) after 21 days. Traditional cement-wrapped group: The biofilm is uniform but of a single species (diatoms account for 95%), and the coverage rate is only 65% ​​after 30 days.

[0118] Permaculture (planted for 12 months): Groups This invention patch group Traditional parcel group Barnacle density 42 / plaque 68 pieces / coconut shell Number of oyster larvae 15 / plaque 9 per coconut shell Polychaete nests 8 / plaque No observations were made. Performance against typhoon disturbances: After the passage of Typhoon Haikui, the oyster shell loss rate of the traditional cement-based encapsulated group was 42%, while only 7% of the patch group of this invention showed slight edge damage, and the biofilm self-repaired to the pre-disaster level within 3 days. The independent structure of the discrete patches effectively dispersed the shear stress of the water flow, avoiding overall failure.

[0119] This implementation demonstrates that the heterogeneous characteristics of natural reefs can be reconstructed on artificial substrates through biomimetic patch design, solving the dual bottlenecks of low biodiversity and poor structural durability caused by traditional uniformly attached substrates, and providing a sustainable micro-ecological engine for mangrove restoration systems.

[0120] <Example 8> An ecological substrate layer was constructed on the surface of coconut shell containers in the Fuyong tidal flat restoration area of ​​Shenzhen Bay. One hundred coconut shell containers (30cm in diameter) were selected, and discrete patchy ecological substrate layers were prepared according to the requirements of this invention. 1. Interface pretreatment: Use a 10% (w / w) chitosan acetic acid solution as a primer, add calcium carbonate crystal nuclei with a particle size of 80 nm (addition amount 4% of chitosan dry weight), and uniformly coat it on the preset patch area (circular with a diameter of 20 mm) to form a 0.15 mm transition layer. Pre-cur at room temperature for 30 minutes. 2. Preparation of adhesive substrate: Mix 78 parts by weight of chitosan with a deacetylation degree of 92%, 6 parts by weight of nano silica modifier, and 13 parts by weight of polybutylene succinate, and add 5% acetic acid solution to stir into a gel-like adhesive substrate. 3. Material mixing: Mix the pretreated oyster shell pieces (size 8×5×1.5mm) with the adhesive substrate at a 1:1 mass ratio to ensure that each oyster shell piece is evenly coated with the substrate; 4. Compression molding: The mixture is filled into the arc-shaped patch positioning template (containing 3 shape memory polyurethane ribs), and a pressure of 0.3MPa is applied and held for 45 seconds to make the mixture tightly fill the template cavity; 5. Graded curing: After removing the template, the mixture is cured for 22 hours in an environment with 80% humidity and 30℃. During this period, 0.1MPa auxiliary pressure is applied for 5 minutes every 4 hours, and the final interface bonding strength reaches 0.48MPa.

[0121] The fundamental difference from traditional technologies: Existing eco-friendly substrate bonding technologies (such as patent CN116058254A) mostly use cement-based or epoxy resin adhesives directly applied to the substrate surface. These materials have significant defects under tidal and wet cycles: cement-based adhesives are too rigid after curing and cannot adapt to the thermal expansion and contraction of the coconut shell 1, with an interface cracking rate exceeding 35% within 3 months; although epoxy resin has high initial bonding strength (0.6-0.8MPa), chloride ion corrosion in seawater causes molecular chain hydrolysis, resulting in a strength decrease of up to 60% within 6 months. More seriously, traditional processes do not include a transition layer, and the adhesive and the coconut shell 1 surface rely solely on mechanical bonding, making them prone to peeling off at the interface under tidal erosion.

[0122] This invention reconstructs the bonding system through three innovations: Nanocrystalline nuclei enhance the transition layer: Calcium carbonate nuclei (80 nm) form a percolation network in the chitosan primer. SEM observation shows that they fill the micropores (50-200 μm) on the surface of coconut shell 1 and generate a calcium carbonate-cellulose composite structure, increasing the interfacial bonding energy from 28 J / m² in the traditional method to 75 J / m². The nanoscale effect of the nuclei promotes the directional arrangement of chitosan molecules on the surface of coconut shell 1, overcoming the problem of poor wettability on the smooth surface of coconut shell 1. Hydrolysis-resistant adhesive substrate formulation: Polybutylene succinate (PBS) and chitosan form an interpenetrating network. The hydrolysis rate of ester bonds in the PBS molecular chain (half-life of 420 days in seawater at 25℃) is much lower than that of traditional epoxy resin (half-life of 120 days). Nano-silica forms a siloxane barrier layer at the interface, blocking the chloride ion penetration pathway. Accelerated aging experiments show that its ion barrier efficiency is 3 times higher than that of pure chitosan substrate. Dynamic pressure curing process: Stepped pressure (0.3MPa molding + 0.1MPa intermittent auxiliary pressure) allows the adhesive substrate to continuously penetrate the micro-pores of oyster shells (depth 50-200μm) during the initial curing stage, while intermittent pressure relief releases interfacial shear stress, avoiding micro-cracks caused by single high pressure. X-ray diffraction shows that the crystallinity of the substrate after curing reaches 45%, which is 18% higher than that of traditional static curing, significantly improving creep resistance.

[0123] Performance comparison: 1) Interface integrity after tidal immersion: The invention group: After 90 days of tidal immersion (immersion for 8-10 hours per day), the edge of the patch showed no warping or delamination, and microscopic observation showed that the width of the interface crack was <5μm (initial value was 3μm); Traditional cement-based group: Local delamination appeared after 45 days (maximum crack width 1.2mm), and the oyster shell detachment rate was 12%; Epoxy resin group: After 60 days, the interface turns white (chloride crystallization), and the bond strength decreases from 0.65MPa to 0.28MPa.

[0124] 2) Bio-attachment synergy: The attachment density of barnacle larvae on the patch surface of this invention reached 35 larvae / cm² (compared to 15 larvae / cm² in the conventional group). Electron microscopy showed that the barnacle gel penetrated deep into the pores of the substrate (depth 20-50 μm), confirming that the microporous structure of the substrate promotes biomechanical anchoring. Conventional cement-based surfaces inhibit barnacle larvae settling due to alkaline exudates (pH>9.5).

[0125] 3) Process stability verification: In batch production testing in a high-humidity environment (RH>85%) on Guishan Island, Zhuhai: Traditional epoxy resin products have a 22% defect rate due to their sensitivity to curing humidity. The graded curing process of this invention increases the yield to 98% and reduces the preparation time of a single patch to 25 minutes (compared to 35 minutes for the traditional process).

[0126] Engineering Adaptability Extension: Applying this technology to the splash zone in Zhanjiang, Guangdong (wave impact force > 15kPa): Traditional adhesive systems showed a 40% plaque loss rate after 6 months. The present invention increases the interfacial bonding strength to 0.55 MPa and controls the patch loss rate to within 5% by increasing the amount of nano-silica to 8 parts by weight.

[0127] The synergistic effect of PBS and chitosan in the adhesive substrate also improved environmental compatibility—no toxic leaching substances such as bisphenol A were detected after 180 days of seawater immersion, and the survival rate of oyster larvae in the adjacent waters was 98%, meeting the environmental safety standards for coastal ecological restoration materials.

[0128] <Example 9> In the coastal mudflat restoration area of ​​Zhanjiang, a coconut shell container ecological substrate layer was prepared. The preparation process of the patch positioning template is as follows: 1) Shape memory polyurethane rib molding: Shape memory polyurethane granules with a glass transition temperature of 58℃ are selected and molded into ribs with a width of 7 mm and a thickness of 0.6 mm in an injection molding machine at 185℃, and then cut into lengths equal to the arc-shaped segment template. 2) Granulation of seawater biodegradable matrix: 45 parts by weight of polycaprolactone with a molecular weight of 80,000, 35 parts by weight of calcium alginate with a particle size of 120 micrometers, and 12 parts by weight of glycerol plasticizer are fed into a twin-screw extruder and granulated at 95°C. 3) Composite molding: Place three ribs parallel to each other in the mold positioning groove (groove depth 1 mm), inject the matrix granules, and mold for 12 minutes at 105℃ and 10MPa pressure to form an arc-shaped segmented template with grid cavity (curvature radius matches the outer wall of coconut shell 1).

[0129] The prepared template was used in the preparation of the ecological substrate layer of claim 8: After coating a transition layer on the surface of coconut shell 1, the oyster shell-adhesive substrate mixture was filled into the template grid cavity, and the template was removed after holding the pressure at 0.3 MPa for 50 seconds. After curing, discrete patches with a diameter of 20 mm were formed. The template was used 5 times in a tidal environment and the structural integrity was checked.

[0130] The fundamental difference from traditional technologies: Existing biodegradable templates mostly use a single material (such as polylactic acid PLA or starch-based plastics). Although this avoids the damage caused by removing metal templates, it has significant drawbacks: PLA templates are prone to softening and deformation in humid environments (softening point is only 60-65℃), and the grid cavity size deviation during molding and pressure holding can reach ±15%, resulting in burrs on the edges of the patches; starch-based templates expand too quickly when exposed to water (24-hour linear expansion rate of 12%), making them unable to withstand multiple uses. More seriously, traditional templates require external prying to remove, and the uncured adhesive substrate is peeled off at a rate exceeding 30%. This invention reconstructs template function using shape memory-degradable composite materials: Thermodynamic response of the ribs: The glass transition temperature of 58℃ is designed to make the ribs rigid at the molding temperature (105℃), ensuring the dimensional accuracy of the grid cavity (measured deviation <3%). When the temperature drops to room temperature (25-30℃) after the template is removed, the elastic recovery rate of the ribs reaches 98%, and they automatically separate from the cured substrate through flexible deformation, avoiding mechanical prying damage.

[0131] Matrix Gradient Degradation: When the polycaprolactone-calcium alginate composite matrix is ​​immersed in seawater, the surface calcium alginate preferentially hydrolyzes, releasing calcium ions (45% weight loss in 72 hours), forming a porous framework that accelerates internal degradation; while the ribbed polyurethane exhibits strong hydrolysis resistance (<5% weight loss in 30 days) and can be recycled. Comparative analysis shows that traditional PLA templates did not completely degrade in the same environment after 30 days, while the matrix components of this invention disintegrated into non-toxic fragments (particle size <2 mm) in 14 days.

[0132] Interfacial stress relief: During the molding process, the ribs and the matrix form molecular chain entanglements in the molten state, and the interfacial shear strength reaches 8MPa after cooling. Traditional bonded composite templates (such as CN101456227A) have an interfacial cracking rate of 40% under the same process.

[0133] Performance comparison: 1) Template reusability: After five cycles of use, the grid cavity size change rate of the template of this invention is less than 2%, and the ribs show no plastic deformation. After two uses, the cavity width of the PLA control group increased by 18%, and the edge warping height reached 1.2 mm. 2) Demolding integrity: The defect rate of the patch edge after template removal in this invention is <3% (microscopic observation); The defect rate of starch-based templates was 35%, and the residual template cavity rate of adhesive substrates reached 28%. 3) Environmental compatibility: Monitoring of nearby water bodies showed that the peak concentration of calcium ions released during the template degradation period was 0.8 mg / L (lower than the background value of seawater), and the survival rate of fish fry was 100% after 96 hours; lactide monomers produced by traditional PLA degradation caused the COD of the water body to increase by 15 mg / L.

[0134] Engineering adaptability verification: Extended application in the high-frequency tidal zone of Shenzhen Bay (3-4 daily submersions) shows that: Traditional starch-based templates lose their structural rigidity after a single use. The template of this invention extends the working life under seawater action to 7 cycles by increasing calcium alginate to 40 parts by weight. Rib recycling and reuse tests show that the shape memory performance retention rate is >90% after 10 molding cycles, meeting the technical and economic requirements of sustainable repair equipment.

[0135] <Example 10> A template preparation project was carried out in the mangrove restoration area of ​​Da Wanshan Island in the Wanshan Archipelago of Zhuhai. Patchette positioning templates were fabricated according to requirements. 1) Shape memory polyurethane rib injection molding: Polyurethane granules with a glass transition temperature of 58℃ are selected and molded into ribs with a width of 7 mm and a thickness of 0.6 mm in an injection molding machine at 185℃, and then cut into lengths equal to the arc template. 2) Degradable matrix granulation: 45 parts by weight of polycaprolactone with a molecular weight of 80,000, 35 parts by weight of calcium alginate with a particle size of 120 micrometers, and 12 parts by weight of glycerol plasticizer are fed into a twin-screw extruder and blended and granulated at 95°C. 3) Composite molding: Place three ribs parallel to each other in the mold positioning groove (groove depth 1 mm), inject the matrix granules, and mold for 12 minutes at 105℃ and 10MPa pressure to obtain an arc-shaped segmented template with grid cavity (curvature radius matches the outer wall of coconut shell 1). The template was used to prepare the ecological substrate layer of claim 8, and its performance was evaluated after being cycled 8 times in a tidal environment.

[0136] The fundamental difference from traditional template technology: Traditional biodegradable templates (such as patent CN112223544A) are made of pure polylactic acid (PLA) through injection molding. PLA softens and deforms severely during high-temperature molding (>100℃), with measured grid cavity size deviations reaching ±15% at 105℃, resulting in a burr rate of 42% at the patch edges. More significantly, PLA templates require mechanical prying to remove, and the uncured adhesive substrate is peeled off at a rate exceeding 35%; adding release agents contaminates the substrate interface, reducing bond strength by 58%. Furthermore, pure PLA degrades slowly in seawater (complete disintegration takes 180 days), and residual fragments hinder barnacle adhesion.

[0137] This invention reconstructs the template manufacturing logic through a hierarchical composite process: Rib thermal stability control: The glass transition temperature (58℃) of the shape memory polyurethane is higher than the lower limit of the molding temperature (100℃), ensuring that the ribs maintain rigidity throughout the molding process. Infrared thermal imaging shows that the rib temperature remains ≤85℃ during molding, and the grid cavity size deviation is controlled within ±3%. Matrix-rib interface reinforcement: During molding, molten polycaprolactone penetrates into the micropores on the rib surface (depth 50-200μm), forming a mechanically interlocking structure after cooling. Tensile testing shows that the interfacial bonding strength reaches 8.2MPa, which is 3 times that of traditional adhesive bonding methods; Controlled degradation synergy: The calcium alginate component preferentially dissolves upon contact with seawater, and the matrix disintegrates into fragments of <2mm within 14 days; while the ribs, due to the strong hydrolysis resistance of polyurethane (weight loss rate of <5% in 30 days), can be recycled and reused more than 8 times without performance changes.

[0138] Performance comparison: 1) Machining accuracy stability (after 8 cycles): The template grid cavity width variation rate of this invention is <2%, and the radius of curvature deviation of the arc surface is ≤1.5%. After three uses, the cavity width of the PLA control group increased by 19%, and the arc deformation resulted in a gap of 3mm between the cavity and the coconut shell 1.

[0139] 2) Demolding integrity: The defect rate of the patch edge after removing the template was 3.2% (measured by three-dimensional scanning). Traditional PLA templates have a defect rate of 41.5%, and 28% of the patches require manual repair due to adhesion.

[0140] 3) Environmental compatibility: Monitoring of adjacent water bodies showed that the peak concentration of calcium ions released during the degradation period of the template of this invention was 0.85 mg / L (lower than the background calcium content of seawater); the lactic acid produced by the degradation of conventional PLA caused the local water pH to drop to 5.8, resulting in a mortality rate of up to 65% for barnacle larvae around the patches.

[0141] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.

Claims

1. A method for creating a mangrove forest in a difficult site, characterized by, Includes the following steps: S1: Select mature coconut shells with a diameter of 28-32 cm, split them longitudinally to form planting containers, and make drainage holes with a diameter of 1-2 cm at the bottom of each coconut shell; S2: Fill the coconut shell container with a layered matrix: the bottom layer is a 4-6 cm thick layer of oyster shell fragments with a particle size of 10-15 mm, the middle layer is filled with a mangrove intertidal silt layer, and the top layer is covered with a 1-3 cm thick layer of fine sea sand. S3: Arrange three coconut shell containers in an equilateral triangle, and use rigid connectors to connect adjacent coconut shells to form a planting unit. Place the planting unit in the mudflat or wetland area, with a spacing of 0.5-1.5 meters between the planting units. S4: Plant mangrove seedlings 30-50 cm tall in each coconut shell container, keeping the root collar 2-4 cm above the substrate surface, backfill the substrate and compact it, continue planting, and complete the creation of the mudflat or wetland area; This also includes an anti-scour anchoring structure, which comprises: Anchor bolts are driven vertically into the mudflat or wetland area where the center of the planting unit is located. The anchor bolts are 1.2-1.5 meters long, and the top of the anchor bolt protrudes 0.3-0.4 meters above the mudflat surface. A ring-shaped clamp is installed on the upper part of the three coconut shell containers to tighten the three coconut shells. The ring-shaped clamp is located at one-half to two-thirds of the height of the coconut shell containers. The transverse struts are set between the three corner nodes of the rigid connector and the top of the anchor rod. The three transverse struts are arranged radially at equal angles. The two ends of each transverse strut are hinged to the corner nodes and the top of the anchor rod through universal joints. In the planting unit arrangement in step S3, an ecological substrate layer is attached to the outer wall of the coconut shell container. The ecological substrate layer is composed of oyster shell fragments and chitosan adhesive, and the attachment coverage rate is 50-70% of the surface area of ​​the outer wall of the coconut shell. The oyster shell pieces are 5-10 mm in length, 3-6 mm in width, and 1-2 mm in thickness, and the chitosan adhesive accounts for 10-15% of the dry weight of the composite layer; The ecological substrate layer is distributed in the form of discrete patches, each patch containing 3-5 oyster shell pieces, the patch diameter is 15-25 mm, and the distance between the edges of adjacent patches is 10-20 mm.

2. The method of establishing a mangrove forest in difficult site conditions according to claim 1, wherein The mangrove seedlings were selected from species such as Kandelia candel, Avicennia marina, Rhizophora stylosa, or Rhizophora spp.

3. The method of establishing a mangrove forest in difficult site conditions according to claim 1, wherein In the matrix filling of step S2, a slow-release iron oxide interlayer is added between the bottom oyster shell fragment layer and the middle mangrove intertidal mud layer. The slow-release iron oxide interlayer is composed of hematite particles with a particle size of 2-4 mm and a thickness of 1-2 cm. The chemical composition of the hematite particles meets the following requirements: Fe2O3 content ≥ 92% by weight, specific surface area 5-8 square meters per gram, and porosity 35-45%.

4. The method for establishing mangrove forests under difficult site conditions according to claim 1, characterized in that, In the matrix filling in step S2, a phosphorus controlled-release layer is added between the middle layer of mangrove intertidal silt and the surface fine sea sand layer. This phosphorus controlled-release layer is composed of ammonium phosphate particles coated with hydroxyapatite and has a thickness of 0.5-1 cm. The ammonium phosphate particles have a particle size of 1-3 mm, the coating layer of hydroxyapatite has a coating rate of 40-60%, and the coating layer thickness accounts for 15-25% of the total particle diameter; The phosphorus controlled-release layer is spaced 1-2 cm from the inner wall of the coconut shell container.

5. The method for establishing mangrove forests under difficult site conditions according to claim 1, characterized in that, Microbial slow-release inhibitor particles are uniformly mixed into the surface fine sea sand layer in step S2. The amount of microbial slow-release inhibitor particles added is 0.5-1.0% of the volume of the fine sea sand layer. The microbial slow-release inhibitor particles are composed of seaweed polysaccharide extract and chitosan coating layer, and the particle size is 1-3 mm. The seaweed polysaccharide extract contains ≥85% fucoidan by weight, the chitosan coating layer has a coating rate of 40-60%, and the coating layer thickness accounts for 10-20% of the total particle diameter.

6. The method for establishing mangrove forests under difficult site conditions according to claim 5, characterized in that, The preparation of the ecological substrate layer includes the following steps: 1) Apply a chitosan acetate primer with a mass concentration of 8-12% to the patch area to form a transition layer with a thickness of 0.1-0.2 mm. The primer contains calcium carbonate crystal nuclei with a particle size of 50-100 nanometers, and the amount of crystal nuclei added is 3-5% of the dry weight of chitosan. 2) Mix oyster shell flakes with adhesive substrate at a mass ratio of 1:0.8-1.2 to obtain a mixture; the adhesive substrate is composed of the following components: 70-80 parts by weight of chitosan with a degree of deacetylation of 90-95%, 5-8 parts by weight of nano silica modifier, and 10-15 parts by weight of polybutylene succinate. 3) Fill the mixture into the patch positioning template, ensuring the inner wall of the template matches the patch size, and apply a pressure of 0.2-0.4 MPa and hold for 30-60 seconds; 4) After removing the template, cure for 18-24 hours under conditions of 75-85% humidity and 28-32℃ to achieve an interface bonding strength ≥0.4 MPa.

7. The method for establishing mangrove forests under difficult site conditions according to claim 6, characterized in that, The patch positioning template is composed of a seawater biodegradable composite matrix material and a shape memory unit. The seawater biodegradable composite matrix material contains the following components: 40-50 parts by weight of polycaprolactone with a molecular weight of 70,000-90,000, 30-40 parts by weight of calcium alginate with a particle size of 100-150 micrometers, and 10-15 parts by weight of glycerol plasticizer. The shape memory unit is embedded in 3-5 shape memory polyurethane ribs in a seawater biodegradable composite matrix material. The ribs are 5-8 mm wide, 0.5-0.8 mm thick, and have a glass transition temperature of 55-60℃.

8. The method for establishing mangrove forests under difficult site conditions according to claim 7, characterized in that, The preparation of the patch localization template includes the following steps: 1) Shape memory polyurethane is injection molded into ribs at 180-190℃; 2) Polycaprolactone, calcium alginate, and glycerol are co-blended and granulated in a twin-screw extruder at 90-100℃; 3) Place the ribs in the mold positioning groove, inject the matrix granules, and mold them for 10-15 minutes at 100-110℃ and 8-12MPa to form an arc-shaped segmented template with grid cavities.

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