Method for building mangrove forest under difficult site condition

Abstract

The invention discloses a mangrove forest building method under a difficult site condition, belongs to the technical field of coastal zone ecological restoration, and solves the problem of low planting survival rate of mangrove seedlings in a high-salt, barren and strong-tidal-scour mud flat environment. According to the technical scheme, mature coconut shells are selected and longitudinally split to form planting containers, and drain holes are formed in the bottoms of the planting containers; the container is filled with matrixes in a layered mode, a thick oyster shell broken layer is laid on the bottom layer, a mangrove forest intertidal zone sludge layer is filled in the middle layer, and a fine sea sand layer with the thickness of 1-3 cm covers the surface layer; the three coconut shell containers are arranged in an equilateral triangle shape, the adjacent coconut shells form a planting unit through hard connecting pieces, the planting units are arranged in a mud flat or wetland area, and the interval between every two units is 0.5-1.5 m; a mangrove seedling with the height of 30-50 cm is planted in each container, the root neck portion is kept to be 2-4 cm higher than the surface of the matrix, and backfilling and compacting are conducted. The method is used for efficiently building the mangrove forest on the mud flat or the wetland, the anti-scouring capacity and the survival rate of the seedlings are improved, and ecological system restoration is promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of coastal zone ecological restoration, and particularly relates to a method for establishing mangroves under difficult site conditions. Background Art

[0002] Establishing mangroves in difficult site conditions faces significant technical obstacles. High salinity, poor soil, and strong tidal erosion severely reduce the survival rate of mangrove seedlings after establishment. Tidal currents frequently wash over mudflats, resulting in strong sediment mobility, making it difficult for seedling roots to firmly attach. Strong water currents not only directly physically impact the seedlings, but also easily cause the loss of the planting medium, leaving the seedling roots exposed or suspended, and damaging their ability to absorb water and nutrients. At the same time, the high-salt environment causes osmotic stress, interfering with the normal water balance and physiological metabolic processes of the seedlings, while periodic or continuous flooding further aggravates hypoxia stress and inhibits root development. Relevant observation data show that the early mortality rate of mangrove seedlings in such sites remains high.

[0003] Structural issues with mudflat soils also pose a constraint. The soils are generally heavy and have poor drainage, which easily leads to waterlogging and root rot due to lack of oxygen. High salinity is often accompanied by a high soil pH, which concentrates ions like calcium and magnesium, hindering the absorption and utilization of essential trace elements such as iron and phosphorus by mangrove seedlings. While direct backfill with intertidal mud can provide some nutrients, these nutrients lack a long-term slow-release mechanism and are easily lost under constant tidal disturbance and erosion, making it difficult to stably and continuously meet the growth needs of the seedlings.

[0004] Specific microbial communities in native mangrove soils are often significantly absent or underactive in degraded mudflats or artificially reclaimed land. These microorganisms, such as sulfur-reducing bacteria and ammonia-oxidizing bacteria, are crucial for the decomposition of soil organic matter and nutrient cycling. 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 in an attempt to replenish microorganisms, these communities often struggle to establish stably due to environmental adaptability and the persistent effects of tidal disturbances, making it impossible to effectively reestablish healthy soil ecological functions.

[0005] Under strong sunlight and wind, the surface soil of mudflats evaporates rapidly, releasing salt that accumulates on the surface, easily forming a dense salt crust. This crust hinders gas exchange between the soil and air, inhibiting the emergence and initial growth of seedlings. If mulching measures designed to improve the surface structure are inappropriate (e.g., with inappropriate particle size or thickness), they can actually accelerate salt migration to the surface or hinder oxygen diffusion, effectively achieving the opposite effect.

[0006] Previous restoration efforts have often faced challenges in improving soil structure. For example, the addition of coarse particles to the substrate to enhance drainage often results in the mixing of different layers of material and structural damage due to repeated tidal erosion. Introducing specific functional microbial communities is limited by the low survival and colonization success rates of microorganisms in adverse environments. The application of surface covering materials also presents a difficult balance, and inappropriate selection can easily lead to secondary problems. These factors collectively make it difficult to establish stable and efficient mangrove ecosystems in challenging site conditions. Summary of the Invention

[0007] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0008] The present invention at least solves the following technical problems: Address the low survival rate of mangrove seedlings in highly saline, infertile, and tidal mudflat environments. Traditional methods, due to poor drainage of the substrate leading to root hypoxia, salt stress inhibiting physiological metabolism, and tidal erosion damaging the planting structure, result in mass seedling mortality. Stress-resistant planting units are needed to achieve a unified approach of physical anchorage and microhabitat improvement.

[0009] Address the issue of unstable restoration results caused by differences in species adaptability. Different mangrove species have significant differences in their tolerance to salinity and flooding. Blind introductions can easily fail due to environmental mismatches. Specific species need to be screened to adapt to the target site conditions.

[0010] To resist the continuous erosion and damage of tidal water on the planting units, simple container fixation can easily lead to overall displacement or overturning due to insufficient anchoring force. A three-dimensional anchoring system is needed to disperse stress and maintain structural stability.

[0011] Improve the lack of iron bioavailability in alkaline soils. Iron ions tend to precipitate in high pH environments, making conventional iron supplementation ineffective due to tidal leaching. Therefore, a slow-release mechanism is needed to continuously supply effective iron.

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

[0013] Inhibit the growth of harmful microorganisms in the rhizosphere and cause diseases. In high humidity environments, pathogens are prone to grow in the root collar, and chemical agents are prone to polluting the environment. Therefore, it is necessary to develop environmentally friendly slow-release antibacterial materials.

[0014] Enhance the ability of coconut shells to adhere to the surface of organisms to promote the formation of microecology. Smooth coconut shell walls are not conducive to the habitation of sessile organisms (such as barnacles), which weakens the ecological function of the artificial matrix, necessitating the construction of a biomimetic attachment interface.

[0015] Solve the problem of insufficient interfacial bonding strength between ecological substrates and coconut shells. Traditional adhesives are prone to hydrolysis and fall off under tidal immersion, requiring optimization of the composite material formulation and curing process to improve durability.

[0016] Achieve a balance between precise positioning of the plaque template and environmentally friendly degradation. Removal of rigid templates can easily damage the uncured substrate, while biodegradable materials lack shape stability, necessitating the development of intelligent responsive templates.

[0017] Optimize template processing efficiency and structural integrity. Special-shaped composite materials are prone to delamination or deformation during thermal processing, and a graded molding process is required to control the interface bonding quality.

[0018] To achieve these objects and other advantages of the present invention, a method for establishing a mangrove forest 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 create drainage holes with a diameter of 1-2 cm at the bottom of each coconut shell; S2: Fill the coconut shell container with substrate in layers: a 4-6 cm thick layer of oyster shell fragments with a particle size of 10-15 mm is laid on the bottom layer, a mangrove intertidal mud layer is filled in the middle layer, and a 1-3 cm thick layer of fine sea sand is covered on the surface. S3: Arrange three coconut shell containers in an equilateral triangle. Use rigid connectors to connect adjacent coconut shells to form a planting unit. The planting units are placed in a mudflat or wetland area with a spacing of 0.5-1.5 meters between the planting units. S4: Plant a 30-50 cm tall mangrove seedling in each coconut shell container, keeping the root neck 2-4 cm above the substrate surface, backfill the substrate and compact it, continue planting, and complete the construction of the mudflat or wetland area.

[0019] Preferably, the mangrove seedlings are selected from the species Kandelia candel, Avicennia marina, Rhizophora rubrum or Bruguiera gymnorrhiza.

[0020] Preferably, it further comprises an anti-scour anchoring structure, the anti-scour anchoring structure comprising: An anchor rod is driven vertically into the mudflat or wetland area where the center of the planting unit is located. The anchor rod is 1.2-1.5 meters long and the top of the anchor rod is 0.3-0.4 meters above the mudflat surface. An annular hoop is provided on the upper part of the three coconut shell containers to clamp the three coconut shells tightly, and the annular hoop is located at one-half to two-thirds of the height of the coconut shell containers; The transverse struts are arranged between the three corner nodes of the hard 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 zone mud layer, the slow-release iron oxide interlayer being composed of hematite particles with a particle size of 2-4 mm and a laying thickness of 1-2 cm; The chemical composition of the hematite particles meets the following requirements: Fe2O3 content ≥ 92 weight percent, 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 mangrove intertidal zone mud layer and the surface fine sea sand layer, and the phosphorus controlled-release layer is composed of ammonium phosphate particles coated with hydroxyapatite and has a laying thickness of 0.5-1 cm; The particle size of the ammonium phosphate particles is 1-3 mm, the coating rate of the hydroxyapatite coating layer is 40-60%, and the thickness of the coating layer accounts for 15-25% of the total diameter of the particles; The phosphorus controlled-release layer is spaced 1-2 cm apart from the inner wall of the coconut shell container.

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

[0024] Preferably, in the planting unit arrangement of step S3, an ecological substrate layer is attached to the outer wall of the coconut shell container, wherein the ecological substrate layer is composed of oyster shell flakes and chitosan adhesive, and the attachment coverage rate is 50-70% of the surface area of ​​the coconut shell outer wall; The dimensions of the oyster shell pieces are 5-10 mm in length, 3-6 mm in width, and 1-2 mm in thickness, and the chitosan binder 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 contains 3-5 oyster shell pieces, the patch diameter is 15-25 mm, and the distance between adjacent patch edges is 10-20 mm.

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

[0026] Preferably, the plaque positioning template is composed of a seawater-degradable composite matrix material and a shape memory unit, wherein the seawater-degradable composite matrix material comprises 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 microns, and 10-15 parts by weight of a glycerin plasticizer; The shape memory unit is composed of 3-5 shape memory polyurethane ribs embedded in a seawater degradable composite matrix material. The ribs have a width of 5-8 mm, a thickness of 0.5-0.8 mm, and a glass transition temperature of 55-60°C.

[0027] Preferably, the plaque positioning template preparation comprises the following steps: 1) Injection molding shape memory polyurethane into ribs at 180-190°C; 2) Polycaprolactone, calcium alginate and glycerol are blended and granulated in a twin-screw extruder at 90-100°C; 3) Place the ribs in the mold positioning groove, inject the matrix granules, and press at 100-110℃ and pressure 8-12MPa for 10-15 minutes to form an arc-shaped segmented template with a grid cavity.

[0028] The present invention has at least the following beneficial effects: A synergistic physical and chemical microhabitat is created by layering coconut shell containers with a matrix. Oyster shell fragments enhance drainage and slowly release calcium to neutralize alkalinity; intertidal mud provides native microorganisms and organic matter; and a surface layer of fine sea sand inhibits salt migration. The interlocking structure of triangular planting units significantly enhances erosion resistance and ensures stable root growth despite tidal disturbances.

[0029] Limit the list of adaptable species to ensure that the selected mangrove seedlings have physiological tolerances that match the target site (e.g., salinity gradient, flooding duration). This can avoid restoration failures caused by inappropriate species selection and improve the survival rate and successional sustainability of community establishment.

[0030] The three-dimensional anchoring system composed of anchor rod, hoop and strut disperses and conducts the tidal scouring force to the deep soil. The universal joint design allows the unit to swing slightly to reduce the instantaneous impact force, reduce the risk of structural stress concentration, and maintain the geometric stability of the planting unit under strong water flow.

[0031] The hematite particle interlayer utilizes its high specific surface area and pore structure to slowly release active iron ions under tidal immersion. By controlling the dissolution rate to match the iron demand of mangrove seedlings, the iron availability in alkaline soil is continuously improved, preventing iron deficiency chlorosis.

[0032] The hydroxyapatite coating layer forms a physical barrier to release ammonium phosphate on demand during the tidal cycle. The thickness and porosity of the coating layer balance the immediate supply and long-term slow-release needs of phosphorus, reducing nutrient loss while avoiding root salt damage.

[0033] Chitosan-coated alginate particles form a bacteriostatic microenvironment around the roots. The chitosan membrane controls the slow release of bacteriostatic ingredients, targeting the inhibition of pathogen reproduction at the root neck, reducing disease incidence, and avoiding the interference of chemical agents on the intertidal zone ecology.

[0034] The discrete patch-shaped ecological substrate layer mimics the structure of natural reef surfaces, providing heterogeneous habitat interfaces for sessile organisms. The multiscale rough surface of oyster shell pieces promotes the formation of microbial membranes, accelerating the transformation of artificial substrates into natural habitats.

[0035] Nano calcium carbonate nuclei enhance the interfacial bonding force of the primer and coconut shell, and polybutylene succinate improves the hydrolysis resistance of the bonded substrate. The staged curing process ensures that the composite material maintains high strength bonding under tidal immersion, prolonging the service life of the substrate.

[0036] Shape memory ribs enable the template to have high-temperature rigid positioning and low-temperature elastic detachment characteristics. The polycaprolactone / calcium alginate matrix degrades controllably in seawater environment, avoiding damage to the uncured substrate during removal operation, and achieving the unity of precise positioning and environmental protection.

[0037] The rib preforming and matrix step molding process reduces the interface defects of the composite material. Temperature-pressure synergistic control ensures the molecular chain entanglement strength of the rib 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, objects, and features of the present application will be apparent to those skilled in the art from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 The structural schematic diagram of one embodiment of the present application.

[0040] 1. Coconut shell; 2. Anchor rod; 3. Connector; 4. Ring clamp. DETAILED DESCRIPTION

[0041] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

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

[0043] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "set" should be understood in a broad sense, for example, they can be fixedly connected or set, or detachably connected or set, or integrally connected or set. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. The orientations or positional relationships indicated by the terms "transverse", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0044] <Example 1> Mangrove planting was carried out in a high-salinity mudflat area in Zhanjiang City, Guangdong Province. Mature coconut shells (approximately 30 cm in diameter) were cut longitudinally to form semi-cylindrical planting containers. A drainage hole approximately 1.5 cm in diameter was drilled in the center of the bottom. The container was filled with substrate 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. This was then covered with intertidal mud from a nearby mangrove reserve. Finally, a 2 cm thick layer of fine sea sand was evenly applied to the surface.

[0045] Arrange the three coconut shell containers in an equilateral triangle, as shown in the following example: Figure 1 As shown, the containers are approximately 80 cm long on a side, with adjacent containers secured by PVC connecting rods to form triangular planting units. Each unit is placed on the mudflat near the mean tide line, with the center spacing of the units controlled at 1 meter. Avicennia marina seedlings, approximately 40 cm tall, are planted in the center of each coconut shell container. The seedlings are positioned so that the root neck is 3 cm above the substrate surface, and the surrounding substrate is backfilled and compacted. 200 planting units are continuously set up in this pattern, covering approximately 2 hectares of mudflat area.

[0046] Comparison with the closest prior art: the mainstream technology for current difficult site mangrove cultivation is direct transplanting method: after digging holes on the beach, the seedlings with soil clumps are planted, the original soil is backfilled, and simple bamboo supports are set up. This method relies on the structure of the original soil on the beach, but the soil in the high-salt and poor- soil site is generally hard and lacks oxygen, and the bamboo support can only prevent falling down and cannot resist the erosion of the rhizosphere matrix by the tide. After the tide recedes, the seedling roots are often exposed and the matrix is lost.

[0047] In contrast, the present application constructs a closed root growth space through the coconut shell 1 container. The bottom gap structure formed by the oyster shell fragments layer is significantly better than the drainage mode that completely relies on the heavy and sticky beach soil in the direct transplanting method, which can quickly drain excess seawater to prevent root hypoxia. The surface layer of fine sea sand covering layer effectively blocks the accumulation of salt to the root neck part, while the exposed surface layer of the beach in the traditional method is easy to form a hard shell of salt crystals after being exposed to sunlight. The triangularly arranged planting units form an interlocking structure through the hard connecting piece 3, which has much higher overall shear resistance than the single bamboo support method, greatly reducing the risk of unit displacement caused by tidal flow.

[0048] The physical barrier effect of the coconut shell 1 container also solves another defect of the direct transplanting method: in the traditional method, the intertidal mud is directly exposed to the tidal erosion environment, and nutrients are easily lost with the water flow. The present application encloses the mud layer in the middle of the container, which not only retains the original microbial community, but also reduces nutrient leaching through the sandwiching of the oyster shell bottom and the fine sand surface. The design of the drainage hole at the bottom of the container ensures that there will be no water accumulation during periodic flooding, which is different from the common problem of bottom blockage of traditional plastic seedling containers.

[0049] In terms of planting operation, the present application limits the root neck to be higher than the surface of the matrix, avoiding direct contact of the beach salt with the sensitive parts of the seedlings through capillary action. Traditional transplanting often aggravates salt stress due to planting too deep, or insufficient root fixation due to planting too shallow. The spacing of 0.5-1.5 meters of the triangular unit takes into account the growth space requirement of the seedlings and the group anti-erosion efficiency, while the dense planting mode of the direct transplanting method easily causes nutrient competition, and the sparse planting weakens the anti-erosion ability.

[0050] This embodiment overcomes the three major bottleneck problems of matrix loss, poor drainage, and salt accumulation in the prior art through the core innovations of layered container structure and triangular unit arrangement, and does not rely on chemical modifiers throughout the process, which is in line with the basic principles of ecological restoration.

[0051] <Example 2> A restoration project was implemented on the east beach of Zhanjiang National Mangrove Nature Reserve, which is a typical high-salinity sandy beach with a salinity gradient of 22-28‰ near the sea and 18-22‰ inland. Two kinds of seedlings, Aegiceras corniculatum and Kandelia candel, were selected as planting materials. The initial height of Aegiceras corniculatum seedlings was 40±5 cm, and the initial height of Kandelia candel seedlings was 35±5 cm, with 600 seedlings of each kind prepared. The seedlings were planted according to the salinity gradient: High-salinity area (salinity 25-28‰): 300 Aegiceras corniculatum seedlings were planted; Medium-salinity area (salinity 18-22‰): 300 Aegiceras corniculatum seedlings and 300 Kandelia candel seedlings were planted.

[0052] All seedlings were planted using the coconut shell 1 container unit of <Example 1>, and the substrate configuration and triangular unit arrangement parameters were consistent. Regular monitoring was conducted within 12 months after planting.

[0053] Control setting (traditional method): The traditional species selection method was used in the adjacent area of the same beach: 5 kinds of mangrove seedlings (including Bruguiera gymnorrhiza and Sonneratia caseolaris, which are not salt-tolerant species) were mixed and purchased locally, with similar initial heights, and a total of 600 seedlings were planted. The planting conditions were exactly the same as those of the present invention.

[0054] Significant differences in survival rate after 12 months of planting: The survival rate of Aegiceras corniculatum in the high-salinity area of the present invention was 91.8% (±2.3% sampling error); The survival rate of Kandelia candel in the medium-salinity area of the present invention was 85.4% (±3.1%); The survival rate of Aegiceras corniculatum in the traditional method was 82.1% (±5.0%), the survival rate of Kandelia candel was 67.9% (±6.2%), and the survival rate of Bruguiera gymnorrhiza was only 39.7% (±7.5%).

[0055] The survival rate was verified by 20×20 square meter quadrat counting (6 times repeated).

[0056] Salt injury physiological performance: The incidence of leaf salt crystallization in Aegiceras corniculatum in the present invention group was less than 5%, while the same species in the traditional group reached 18%; The yellowing rate of Kandelia candel leaves in the present invention group was 7%, while the traditional group was 24%. In the traditional group, 72% of Bruguiera gymnorrhiza leaves appeared scorched. The verification method was to randomly sample 50 plants and count the proportion of abnormal leaves.

[0057] Essential difference from traditional technology: The traditional method relies on the availability of seedlings for random selection and does not consider the salt tolerance threshold of species. For example, the upper limit of Bruguiera gymnorrhiza salt tolerance is only 20‰, while the salinity of Zhanjiang beach often exceeds 25‰, leading to ion imbalance. The present invention limits Aegiceras corniculatum (salt tolerance 40‰) and Kandelia candel (salt tolerance 30‰), Aegiceras corniculatum actively expels salt through leaf salt glands, and Kandelia candel blocks salt absorption through root kelly band, with significantly better physiological adaptability than traditional mixed planting.

[0058] Traditional methods of interplanting low-salinity species like Bruguiera gymnorrhiza in the same high-salinity zone violate the principles of ecological adaptability. This method precisely deploys species along a salinity gradient: Avicennia marina is placed in offshore high-salinity areas (its finger-like respiratory roots are adapted to long-term flooding), while Kandelia candel is placed in moderate-salinity areas (its prop roots require periodic aeration), achieving salinity-species synergistic adaptation.

[0059] Traditional intercropping results in the mass mortality of vulnerable salt-tolerant species, such as Bruguiera gymnorrhiza, resulting in bald patches and disrupting community continuity. The proposed species combination maintains over 92% of 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 of the same species in the conventional treatment, confirming the effectiveness of salt glands in excreting salt. The sodium ion content in the leaves of Bruguiera gymnorrhiza in the conventional treatment reached 0.52%, far exceeding the tolerance threshold. The taproot damage index of Kandelia candel in the treatment with the invention was 0.12 (undamaged = 0, completely rotten = 1), while that in the conventional treatment reached 0.41, indicating that salt-barrier mechanisms protect root integrity.

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

[0062] <Example 3> Anchoring system testing was conducted on the east coast mudflats of the Zhanjiang National Mangrove Nature Reserve in Guangdong Province, an area subject to an average of three to four typhoons annually (for example, peak tidal currents reached 1.8 m / s during the passage of Typhoon Haiyan in 2024). Fifty triangular planting units (each consisting of three 30 cm diameter coconut shell containers connected by PVC rods to form an equilateral triangle with a side length of 80 cm) were selected. Each unit was equipped with the anchoring system described in the present invention: a 1.4 m long glass fiber reinforced polymer (GFRP) anchor rod was driven vertically into the center mudflat of the unit, with the top 35 cm above the ground. A stainless steel annular clamp was installed at half the height of the coconut shell (40 cm from the bottom) to clamp the three coconut shells together. Three 3 cm diameter carbon fiber transverse struts were used, each connected to the tripod corner node and the top of the anchor rod by a universal joint. The struts were 60 cm long and arranged at equal angles of 120 degrees. A control group set up 50 planting units of the same size, using only traditional single-plant bamboo stakes (8cm diameter stakes buried 1m deep, with individual plants tied and secured). Each planting unit was planted with Avicennia marina seedlings (40±5cm in height) and monitored continuously for 12 months, covering two typhoon seasons.

[0063] Traditional single-pile anchoring relies on a rigid pile body to resist bending, but bamboo piles are prone to fatigue fracture under repeated tidal loads. Their single-point load pattern concentrates stress at the binding point, making it common for binding ropes to break or piles to snap during typhoons. For example, during the passage of Typhoon Haiyan in 2024, the traditional pile fracture rate reached 68%, with fracture surfaces concentrated 20-40 cm below the surface (a zone where alternating tidal dryness and wetness accelerate corrosion). More seriously, traditional methods only secure the plant stems, leaving the entire planting container unprotected. Tidal scouring continuously drains the substrate from the container's base, ultimately causing it to collapse. Post-typhoon inspections revealed that 45% of the coconut shell containers in the traditional group had hollowed-out substrate at an angle exceeding 30°, exposing 40% of the seedling roots.

[0064] The present invention reconstructs the anti-scour logic through triangular mechanical conduction: The annular clamp 4 locks the three containers into a rigid unit, resisting horizontal shear forces. After repeated verification, the clamp's position was selected at half the height of the coconut shell 1 (rather than the top), as this is where the maximum impact torque of the tidal current is applied, preventing the containers from rotating around the bottom support point under the action of waves.

[0065] Anchor 2 penetrates deep into the stable soil layer to bear the vertical load. The GFRP material is resistant to salt and alkali corrosion (compared to bamboo piles, its service life is increased by more than 3 times), and the 1.4m length ensures that the anchor end penetrates the loose silt layer to reach the silty clay bearing layer.

[0066] The three-way struts are articulated via universal joints to form a dynamic balance system. When tides strike the tripod's corner nodes, the struts convert part of the impact force into a pullout force on anchor 2 (deep soil layers offer greater resistance), while part of the energy is dissipated through rotation of the universal joints. Measurements show that during typhoons, the struts can swing by 12-15 degrees, effectively preventing structural damage.

[0067] The core difference lies in the fact that traditional methods aim to "resist" impact, while this invention employs a "channeling and dispersing" mechanism. The design leaves the top of anchor rod 2 exposed 35 cm, allowing for swinging of the rod. The universal joint allows for adaptive adjustment of the impact force direction, avoiding the stress concentration found in traditional rigid connections. Testing of the mud at the base of the coconut shell container 1 revealed that the scour pit depth in the present invention group was only 8-10 cm (compared to over 25 cm 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 of the 50 units in the inventive group remained in place (displacement <5 cm), and two displaced units were located in the geologically weak area at the edge of the tidal creek; 32 units in the traditional group slid as a whole (maximum displacement 28 cm), and 1 coconut shell container in 15 units was scattered.

[0069] Damage characteristics of anchoring components: slight rotational friction marks can be seen on the universal joint of the invention group, and the support rod has no deformation; the breakage rate of bamboo piles in the traditional group is 68%, and the breakage rate of binding ropes is 45%.

[0070] Bio-colonization effectiveness: Excavation after low tide revealed that 93% of the seedlings in the inventive group had their roots completely enclosed within the substrate, with no tilting of the coconut shell. In the conventional group, the roots of the seedlings in the displacement unit were generally exposed (maximum exposed length 15 cm). Due to this difference in root protection, after 12 months, the seedlings in the inventive group increased in height by 42 cm (compared to only 22 cm in the conventional group), and the rate of yellowing leaves due to salt damage was as low as 6% (compared to 35% in the conventional group).

[0071] Verification of technology universality: Extension tests on the sandy mudflats in Dianbai District, Maoming, Guangdong (where the shear strength is only 1 / 3 of that of the silty mudflats in Zhanjiang) showed that: Traditional bamboo piles anchored in sandy soils lack pullout resistance, and their overturning rate after the typhoon reached 51%; The present invention increases the length of the anchor rod 2 to 1.5 m and expands the radial angle of the support rod to 150°, thereby increasing the unit's anti-overturning rate to more than 90%.

[0072] This adjustment validates the practical engineering flexibility of the proposed system within its parameter range (anchor bolts 21.2-1.5m in length, with radially arranged struts), highlighting its adaptability to diverse tidal flat geographies. Compared to concrete base anchoring (costing over 800 yuan per set), the proposed anchoring system's material cost is under 185 yuan, while achieving a 44% improvement in construction efficiency (a skilled worker can install a single 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 filled with a layered matrix structure according to the present invention: a 5-cm-thick layer of crushed oyster shells (12 mm particle size), a middle layer of intertidal silt, and a 2-cm surface layer of fine sea sand. A slow-release iron oxide interlayer as described in claim 4 was added: a 1.5-cm-thick layer of hematite granules was laid between the bottom and middle layers. The granules had a particle size of 3±0.5 mm, an Fe2O3 content of ≥93% as determined by XRF, a BET surface area of ​​6.8 m² / g, and a porosity of 41% as determined by mercury intrusion. The hematite granule layer was laid continuously, with its edge 1 cm from the inner wall of the coconut shell to avoid boundary effects. Avicennia marina seedlings (initial plant height 45±5 cm) were planted and monitored continuously for 12 months.

[0074] Control setting (traditional method): 50 groups of planting units of the same specifications were set up in adjacent areas, and conventional iron amendment measures were adopted: powdered EDTA-chelated iron (Fe content 12%) was evenly mixed into the silt layer at an addition amount of 0.2 kg / m³. The rest of the matrix configuration was consistent with the present invention group.

[0075] Performance Comparison: Maintaining Iron Availability: Six months after planting, the available iron content in the rhizosphere soil of the group using the invention stabilized at 28-32 mg / kg (DTPA extraction method). The traditional group initially reached 45 mg / kg, but after three months, it dropped to 18 mg / kg. Tidal erosion resulted in a loss of over 60% of the chelated iron. Leaf yellowing index monitoring showed that the yellowing rate in the group using the invention remained below 10%, while the yellowing rate in the traditional group rose to 35% from the fourth month.

[0076] Changes in soil chemical properties: After tidal soaking, the hematite granular layer in the invention group formed a local slightly acidic environment (pH 7.2-7.5), which promoted the activation of trapped iron in the upper silt. In the traditional 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 structure stability: after the tide receded, the hematite particle layer of the present invention group remained intact and no particle migration was observed.

[0078] Essential differences from traditional technologies: Traditional iron amendment relies on water-soluble chelating agents, whose ionic iron desorbs under high-frequency tidal submersion and is rapidly lost with pore water. Chelating agents like EDTA decompose rapidly in alkaline environments, with a half-life of less than 30 days, making the iron supply unsustainable. More seriously, excessive chelating agents can complex heavy metal ions (such as Cd and Pb) in the soil, posing secondary ecological risks.

[0079] The present invention utilizes the characteristics of hematite crystals to achieve slow release of iron: Microporous slow release mechanism: The mesoporous structure of hematite (5-8m² / g specific surface area) and hydrogen bonding adsorb tidal water, Fe 3+ Slow dissolution through coordinated hydrolysis (dissolution rate 0.02 mg / cm²·d) to avoid iron phosphate precipitation caused by instantaneous high concentration; In situ pH adjustment: Hematite hydrolysis reaction (Fe2O3+3H2O→2 Fe 3+ +6OH⁻) consumes protons, forming a pH gradient at the particle-sludge interface, reducing the pH in the rhizosphere microzone by 1.0-1.5 units, significantly improving the bioavailability of iron; Anti-scour enhancement: The 2-4mm particle size design enables the critical starting velocity of the particles to reach 0.35m / s, exceeding 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 also acts as a physical barrier, blocking the upward migration of calcium and magnesium ions from the underlying layers, reducing calcium carbonate cementation in the rhizosphere. Electron microscopy revealed that the traditional seedling group had a layer of calcium carbonate crystals (10-15 μm thick) attached to the root surface, hindering iron absorption. The root surface of the seedlings in the invention group was clean, and the root hair density was twofold higher.

[0081] Engineering adaptability verification: Extended testing in the Shenzhen Bay High-Speed ​​Railway disturbance zone (6-8 tidal scours per day) showed: The traditional chelated iron group needs to be supplemented once a quarter due to iron loss, which increases maintenance costs by 40%; After 12 months, the hematite layer of the present invention maintained an effective iron dissolution rate of 78% of its initial value, and the particle disintegration rate was less than 5%. The mineral properties of hematite avoid the introduction of exogenous chemical additives, which conforms to the sustainable principles of coastal wetland ecological restoration.

[0082] <Example 5> A mangrove restoration project in Zhanjiang, Guangdong (soil pH 7.8-8.2, tidal scouring 3-4 times daily) was implemented. A coconut shell container was filled with a matrix structure based on the present invention: a bottom layer of oyster shell fragments (5 cm thick, 12 mm particle size), and a middle layer of intertidal mud (sourced from the native mangrove area of ​​Shenzhen Bay). A phosphorus-controlled release layer was added: a 0.8 cm thick layer of hydroxyapatite-coated ammonium phosphate particles (2.0 ± 0.3 mm in diameter) was laid between the middle mud layer and the surface fine sea sand. Scanning electron microscopy revealed a hydroxyapatite coating rate of 52 ± 3%, with the coating layer thickness accounting for 20 ± 2% of the total particle diameter. The edge of the particle layer was positioned 1.5 cm from the inner wall of the coconut shell to prevent direct scouring by tidal seepage. Avicennia marina seedlings (initial plant height 45 ± 5 cm) were planted and monitored continuously for 12 months.

[0083] A fundamental difference from traditional technologies: Traditional phosphate fertilizer application often involves direct application of diammonium phosphate (DAP) or superphosphate (SSP) directly into the soil. Under high-frequency tidal erosion, water-soluble phosphorus (such as H₂PO⁻) is easily carried away by currents. Observations have shown that phosphorus loss from DAP can reach 38-45% within 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)⁃OH or FePO₄), causing phosphorus bioavailability to plummet to below 15%. For example, in a Pearl River Estuary mudflat experiment, soil available phosphorus content in the traditional group dropped from an initial 35 mg / kg to 8 mg / kg three months after planting, and seedling roots developed typical symptoms of phosphorus deficiency, purpling.

[0084] The present invention reconstructs the phosphorus release mechanism through core-shell structure design: Physical barrier controlled release: Hydroxyapatite (Ca 10 The (PO4)6(OH)2) coating forms a microporous framework (pore size 50-200nm), controlling the dissolution rate of ammonium phosphate through pore diffusion gradients during tidal infiltration. X-ray spectroscopy reveals a calcium-phosphorus molar ratio of 1.67:1 in the coating, similar to that of natural skeletal apatite, demonstrating 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, reducing the local microenvironmental pH to 6.5-7.0, promoting the conversion of phosphate from a closed state to an effective state. Simultaneously, it inhibits the fixation of phosphorus by calcium ions in alkaline soils. Electron microscopic observations show that the calcium phosphate deposit layer on the root surface of the traditional group is 12-18μm thick, while that of the group using the present invention is only 3-5μm. Tidal resistance optimization: The particle size and coating thickness are designed to achieve a critical starting velocity of 0.40m / s (the average tidal velocity at the Pearl River Estuary is 0.25m / s), increasing layer stability by three times. The 1.5cm 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 rate 0.3 m / s, 8 times a 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%; Detection of available phosphorus in rhizosphere soil 6 months after planting (NaHCO3 extraction method): the present invention group maintained at 28-32 mg / kg, while the traditional group dropped to 10-12 mg / kg.

[0087] 2) Differences in physiological responses: Phosphorus content in leaves: The phosphorus content of mature leaves of seedlings in the 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 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 relief: The traditional group had an osmotic regulation imbalance due to phosphorus deficiency, with a leaf edge scorch rate of 32%, while the present invention group had a leaf edge scorch rate of <8%.

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

[0089] Verification of engineering adaptability: Extended tests at the freshwater and saltwater confluence area of ​​Modaomen in Zhuhai (salinity fluctuation 5-25‰) showed that the dissolution rate of the hydroxyapatite coating decreased by 26% when the salinity was >20‰, but the effective phosphorus supply still met the needs of seedlings; 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 practice confirmed that the phosphorus controlled-release layer solved the contradiction between efficient phosphorus utilization and ecological safety under tidal disturbances through the synergy of physical barrier and chemical slow release, providing a controllable nutrient delivery paradigm for coastal wetland restoration.

[0091] <Example 6> A mangrove seedling disease prevention and control trial was conducted in the Zhanjiang Bay tidal flat area of ​​Guangdong Province (salinity 20-25‰). The preparation process of microbial slow-release inhibitor granules is as follows: 1. Seaweed polysaccharide extraction: Local brown algae (Sargassum) was used as the raw material. The crude extract was extracted with hot water at 80°C for 1 hour (repeated three times). The crude extract was then purified after ethanol precipitation to obtain an extract with a fucoidan content of ≥88%.

[0092] 2. Particle forming: Mix seaweed polysaccharide extract with chitosan powder with a deacetylation degree of 92% in a mass ratio of 3:1, add 5% nano-silica modifier, and use an extrusion-spheronization process to form core particles with a particle size of 2.0±0.3 mm.

[0093] 3. Coating process: Fluidized bed coating technology is used, with 10% chitosan-acetic acid solution as the coating liquid (containing calcium carbonate crystal nuclei with a particle size of 80 nanometers), the inlet air temperature is controlled at 40°C, and the atomization pressure is 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 particles were evenly mixed into the surface matrix (fine sea sand layer thickness 2 cm) at a ratio of 0.8% of the fine sand layer volume. After planting Avicennia marina seedlings, the occurrence of root collar disease was tracked and monitored.

[0095] Essential differences from traditional chemical antibacterial agents: Traditional mudflat disease control often relies on chemical fungicides (such as mancozeb and carbendazim) sprayed directly or mixed into the soil. While these agents can quickly inhibit pathogens, their water-soluble components lose over 65% of their water within 72 hours due to tidal wash, necessitating weekly reapplication to maintain effective concentrations. More seriously, chemical agents lack targeted targeting, significantly reducing the abundance of beneficial rhizosphere bacteria (such as ammonia oxidizers and nitrogen-fixing bacteria) by over 40% while killing pathogens, disrupting the microecological balance. Testing of intertidal waters revealed residual levels of phthalate plasticizers reaching 0.15 mg / L in areas where traditional methods were applied, causing acute toxicity to benthic organisms (such as shellfish larvae).

[0096] The present invention reconstructs the antibacterial logic through core-shell structure design: Core Material Function: High-purity fucoidan (containing 28% sulfate groups) absorbs pathogenic bacterial cell membranes (such as Fusarium) through charge interaction, disrupting their ion channels. Fucoidan's slow-release properties result in a daily dissolution rate of only 5% under tidal immersion, maintaining a stable antibacterial concentration.

[0097] Coating Regulation: The chitosan coating selectively degrades under the stimulation of root exudates (such as organic acids), preferentially releasing antibacterial components in high-risk root collar areas. Electron microscopy observations show that the pore expansion rate of the coating in the rhizosphere microenvironment is 2.3 times that of the sand layer, enabling precise targeting of pathogen-rich areas.

[0098] Ecological synergy: Chitosan degradation products promote the growth of actinomycetes, increasing their population by 150% compared to the traditional treatment, forming a secondary line of defense where beneficial bacteria inhibit pathogens. No chemical residues were detected on the mudflat surface after low tide, and the 48-hour survival rate of daphnia in the water reached 100%.

[0099] The core difference lies in the fact that traditional methods aim for broad-spectrum bactericidal efficacy, while this invention employs a three-tiered mechanism: sustained release, targeted therapy, and microecological regulation. The sulfate groups of fucoidan specifically bind to the flagellin proteins of pathogens, inhibiting their motility. The chitosan membrane, under the influence of root secretions, forms a localized microporous structure, achieving an intelligent release mechanism: "roots call for help, antibacterial response."

[0100] Disease prevention and control effect: Conduct three disease surveys within 120 days after planting: 1. Incidence of root neck rot: In the present invention group, the cumulative incidence rate was 8.7% (based on the root collar browning area > 30% as the judgment standard).

[0101] Traditional chemical group: The incidence rate was 32.5%, of which 12% of seedlings died due to rot.

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

[0103] Bacillus accounted for 15.2% in the present invention group, which was significantly higher than 6.8% in the traditional group. 3. Emergency response to salt damage: After the typhoon and heavy rain, the salinity of the mudflat dropped sharply to 5‰. The traditional group experienced leaf wilting due to the intensified infection of pathogens (incidence rate 41%), while only 9% of the seedlings in the group of the present invention showed mild stress.

[0104] Mechanism verification showed that under the stimulation of oxalic acid secreted by the roots, the chitosan film degradation rate of the particles increased to 35% within 48 hours (compared to only 12% in a non-stimulated environment). Simultaneously released fucoidan formed a 10-15μm antibacterial film on the root neck, blocking the attachment of pathogens. Compared to the "global toxicity" of traditional chemical agents, this design achieves intelligent protection against adverse conditions.

[0105] <Example 7> A coconut shell container surface renovation project was carried out on the east coast 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 the present invention: 1. Oyster shell flake pretreatment: Select local discarded oyster shells, crush and screen them into flakes with a length of 8±2 mm, a width of 5±1 mm, and a thickness of 1.5±0.3 mm, soak them in hydrochloric acid to remove impurities, and then dry them.

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

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

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

[0109] The essential difference from traditional attachment substrates: Traditional mangrove restoration efforts to enhance biological attachment to artificial substrates often involve wrapping coconut shell containers with oyster shells (as in patent CN219343265U) or evenly applying a cement-shell mixture. While this method increases the attachment area, it creates a continuous, closed surface, leading to three major drawbacks: Suppression of water disturbance: 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] Intensified biological competition: The uniform surface promotes the dense coexistence of sessile organisms such as barnacles and mussels, with the biological coverage rate reaching more than 85% within 12 months. However, due to competition for space, the predation rate of small crustaceans (such as shrimp) has increased 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-dry cycles, with a shedding rate of 35% after 6 months, causing oyster shells to peel off in pieces.

[0112] This example reconstructs the biological attachment mechanism through discrete patch design: Fluid dynamics optimization: The 10-20 mm gaps between patches create micro-scale turbulence zones. Tidal flow creates localized low pressure, attracting barnacle larvae to settle. On-site flow velocity monitoring shows that the vortex intensity in the gaps is 3.2 times higher than on a continuous surface, increasing larval landing density by 50%.

[0113] Niche Heterogeneity: Patches with diameters of 15-25 mm simulate the spatial distribution of natural reef fragments. Each patch holds 3-5 oyster shells, creating a multi-level pore structure (65% of which are 0.5-2 mm), providing specialized habitats for organisms of varying sizes. Comparative observations show that the population density of gammarids in these patches reaches 35 individuals per square decimeter, 2.8 times that of traditional packaging methods.

[0114] Improved interfacial durability: The chitosan-polybutylene succinate composite adhesive undergoes controlled degradation in seawater environments, and nanosilica enhances the mechanical interlocking of the interface. Accelerated aging tests show that the bond strength after curing only decreases by 12% after 90 days of tidal immersion, compared to a 58% decrease for cement-based adhesives over the same period.

[0115] Verification of synergy with ecological cofferdam technology: The comparison between the oyster shell ecological cofferdam (patent CN219343265U) and the coconut shell 1 patch substrate implemented simultaneously on the Pingle mudflats in Zhanjiang shows that: Functional complementarity: The main cofferdam reduces macro-wave energy (wave height is reduced by 62%), while the coconut shell 1 patches provide 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 either single technology (1.5-2 m / s in the cofferdam area and 2-3 m / s in the pure patch group).

[0116] Biological synergistic effect: Larvae released from the weired oyster reef preferentially attached to the Coconut Shell 1 patch. Six months later, the oyster coverage rate in the patch area reached 75%, 40% higher than that in the area without weirs. 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 conversion of substrate nitrogen.

[0117] Ecological effects: Comparison of biofilm development: In the present invention group, a dominant green diatom biofilm (coverage rate 45%) formed at the edge of the patch within 7 days, and it evolved into a brown algae-bacterial micelle composite film (coverage rate 78%) after 21 days. Traditional cement coating group: The biofilm was uniform but of a single type (diatoms accounted for 95%), and the coverage rate was only 65% ​​after 30 days.

[0118] Sessile biodiversity (12 months after planting): Group Plaque group of the present invention Traditional package group Barnacle density 42 / plaque 68 pieces / coconut shell 1 Number of oyster larvae 15 / plaque 9 pieces / coconut shell 1 Polychaete nests 8 pieces / plaque Not observed Typhoon resistance: After the passage of Typhoon Haikui, the traditional cement-based coating group experienced a 42% shell shedding rate, while the plaque-based coating group experienced only 7% minor edge damage. The biofilm then self-repaired to pre-disaster levels within three days. The independent structure of the discrete plaques effectively dispersed the shear stress of the water flow, preventing overall failure.

[0119] This implementation confirmed that through bionic patch design, the heterogeneous characteristics of natural reefs were reconstructed on an artificial matrix, solving the dual bottlenecks of low biodiversity and poor structural durability caused by traditional uniformly attached substrates, and providing a sustainable microecological engine for the mangrove restoration system.

[0120] <Example 8> The ecological substrate layer was constructed on the surface of coconut shell containers in the Fuyong tidal flat restoration area of ​​Shenzhen Bay. 100 coconut shell containers (30 cm in diameter) were selected and the discrete patch-shaped ecological substrate layer was prepared according to the requirements of the present invention: 1. Interface pretreatment: Use a 10% chitosan acetic acid solution as a primer, add 80-nanometer calcium carbonate crystal cores (4% chitosan dry weight), and evenly apply it to the pre-set patch area (20 mm diameter circle) to form a 0.15 mm transition layer. Pre-cure 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, add 5% acetic acid solution and stir to form a gel-like adhesive substrate; 3. Material mixing: Mix the pretreated oyster shell pieces (size 8×5×1.5mm) with the adhesive substrate in a 1:1 mass ratio, ensuring that each piece of oyster shell is evenly coated with the substrate; 4. Compression molding: Fill the mixture into the arc-shaped plaque positioning template (containing three shape memory polyurethane ribs), apply 0.3MPa pressure and hold the pressure for 45 seconds to ensure that the mixture tightly fills the template cavity; 5.Graded curing: After removing the template, cure in an environment with 80% humidity and 30°C for 22 hours. During this period, auxiliary pressure of 0.1MPa is applied for 5 minutes every 4 hours. The final interface bonding strength reaches 0.48MPa.

[0121] Essential differences from traditional technologies: Existing eco-based substrate bonding technologies (such as patent CN116058254A) typically utilize cement-based or epoxy resin adhesives applied directly to the substrate surface. These materials exhibit significant drawbacks under tidal wet-dry cycles: Cement-based adhesives are too rigid after curing to accommodate the thermal expansion and contraction of the coconut shell, resulting in an interfacial cracking rate exceeding 35% within three months. While epoxy resins offer a high initial bond strength (0.6-0.8 MPa), chloride ion corrosion in seawater causes molecular chain hydrolysis, leading to a 60% decrease in strength within six months. Furthermore, traditional processes lack a transition layer, resulting in a mere mechanical bond between the adhesive and the coconut shell surface, making them susceptible to peeling from the interface under tidal erosion.

[0122] The present invention reconstructs the bonding system through three innovations: Nanocrystalline core-reinforced transition layer: Calcium carbonate crystal cores (80 nm) form a percolation network within the chitosan primer. SEM observations show that these cores fill the micropores (50-200 μm) on the surface of the coconut shell and form a calcium carbonate-cellulose composite structure, increasing the interfacial bonding energy from 28 J / m² (using conventional methods) to 75 J / m². The nanoscale effect of the cores promotes the directional alignment of chitosan molecules on the coconut shell surface, overcoming the poor wettability of smooth coconut shell surfaces. Hydrolysis-resistant adhesive substrate formula: Polybutylene succinate (PBS) and chitosan form an interpenetrating network. The hydrolysis rate of the ester bonds in the PBS molecular chain (half-life 420 days in 25°C seawater) is much lower than that of traditional epoxy resin (half-life 120 days). Nano-silica forms a siloxane barrier layer at the interface, blocking the chloride ion permeation path. Accelerated aging tests show that its ion barrier rate is three times higher than that of pure chitosan substrate. Dynamic pressure curing: A stepped pressurization process (0.3MPa mold pressure + 0.1MPa intermittent auxiliary pressurization) allows the adhesive substrate to continuously penetrate the micro-voids of the oyster shell (depth 50-200μm) during the initial curing phase. Intermittent pressure relief releases interfacial shear stress, preventing microcracks caused by single high-pressure applications. X-ray diffraction analysis shows that the substrate's crystallinity reaches 45% after curing, an 18% increase compared to traditional static curing, significantly improving creep resistance.

[0123] Performance comparison: 1) Interface integrity after tidal immersion: Invention group: After 90 days of tidal immersion (8-10 hours per day), the plaque edge showed no warping or delamination, and microscopic observation showed that the width of the interface crack was <5 μm (the initial value was 3 μm); Conventional cement-based group: local delamination occurred after 45 days (maximum crack width 1.2 mm), and the oyster shell flake shedding rate was 12%; Epoxy resin group: After 60 days, the interface turned white (chloride salt crystallization) and the bonding strength dropped from 0.65 MPa to 0.28 MPa.

[0124] 2) Bio-attachment synergy: Barnacle larvae adhered to the surface of the present invention at a density of 35 per cm² (compared to 15 per cm² for the conventional surface). Electron microscopy revealed that barnacle colloids penetrated deep into the pores of the substrate (20-50 μm in depth), confirming that the substrate's microporous structure facilitates biomechanical anchoring. Conventional cement-based surfaces inhibited barnacle larval settlement due to alkaline exudates (pH > 9.5).

[0125] 3) Process stability verification: During mass production testing in the high humidity environment (RH>85%) on Guishan Island, Zhuhai: The traditional epoxy resin group had a defective rate of 22% due to sensitivity to curing moisture; The graded curing process of the present invention increases the yield to 98%, and shortens the preparation time of a single plaque to 25 minutes (compared to 35 minutes in the traditional process).

[0126] Engineering adaptability expansion: This technology is applied to the splash zone of Zhanjiang, Guangdong (wave impact force>15kPa): The plaque loss rate of the traditional adhesive system was 40% after 6 months; The system of the present invention increases the interface bonding strength to 0.55 MPa by adding nano-silicon dioxide to 8 parts by weight, and controls the plaque loss rate within 5%.

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

[0128] <Example 9> The preparation of a coconut shell container ecological substrate layer was carried out in the Zhanjiang coastal mudflat restoration area. The preparation process of the patch positioning template is as follows: 1) Shape memory polyurethane rib molding: Shape memory polyurethane pellets with a glass transition temperature of 58°C are used and molded into ribs with a width of 7 mm and a thickness of 0.6 mm in an injection molding machine at 185°C. The ribs are then cut to the same length as the arc-shaped split template. 2) Granulation of seawater degradable 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 μm, and 12 parts by weight of glycerol plasticizer were put into a twin-screw extruder and blended and granulated at 95°C; 3) Composite molding: Place three ribs in parallel in the mold positioning groove (groove depth 1 mm), inject the matrix particles, and mold at 105°C and 10 MPa pressure for 12 minutes to form an arc-shaped segmented template with a grid cavity (the curvature radius matches the outer wall of coconut shell 1).

[0129] The resulting template was used to prepare the ecological substrate layer of claim 8: After applying a transition layer to the surface of coconut shell 1, the oyster shell flakes-adhesive substrate mixture was filled into the template grid cavity. After maintaining a pressure of 0.3 MPa for 50 seconds, the template was removed and cured to form discrete patches with a diameter of 20 mm. The template was then used five times in a tidal environment and its structural integrity was checked.

[0130] Essential differences from traditional technologies: Existing biodegradable templates are mostly made of a single material (such as polylactic acid (PL) or starch-based plastics). While this can prevent damage during metal template removal, it also presents significant drawbacks: PLA templates easily soften and deform in humid environments (the softening point is only 60-65°C), and the grid cavity dimensions can vary by as much as ±15% during mold compression and pressure holding, resulting in burrs on the edges of the patches. Starch-based templates swell rapidly in contact with water (a 24-hour linear expansion rate of 12%), making them unsuitable for repeated use. Furthermore, traditional template removal requires prying, resulting in over 30% peeling of the uncured adhesive substrate. The present invention reconstructs the template function through shape memory-degradable composite materials: Thermodynamic response of the ribs: The glass transition temperature of 58°C makes the ribs rigid at the molding temperature (105°C), ensuring the dimensional accuracy of the grid cavity (measured deviation <3%). After the template is removed and the temperature is cooled to the normal beach temperature (25-30°C), the ribs have an elastic recovery rate of 98%, and automatically separate from the cured substrate through flexible deformation, avoiding damage from mechanical prying.

[0131] Gradient matrix degradation: When immersed in seawater, the surface calcium alginate of the polycaprolactone-calcium alginate composite matrix preferentially hydrolyzes to release calcium ions (weight loss of 45% in 72 hours), forming a porous skeleton that accelerates internal degradation. The ribbed polyurethane exhibits strong hydrolysis resistance (weight loss of <5% in 30 days) and is recyclable. A comparison shows that while a conventional PLA template did not fully degrade in 30 days under the same conditions, the matrix component of this invention disintegrates into non-toxic fragments (particle size <2 mm) in 14 days.

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

[0133] Performance comparison: 1) Template reusability: After the template of the present invention is used for 5 cycles, the grid cavity size change rate is less than 2%, and the ribs have 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 plaque edge defect rate after removing the template in the present invention is <3% (microscope observation); The defect rate of the starch-based template group was 35%, and the residual template cavity rate of the adhesive substrate was 28%. 3) Environmental compatibility: The adjacent water body detection showed that the peak value of calcium ion concentration released during the template degradation period was 0.8 mg / L (lower than the background value of seawater), and the survival rate of fry was 100% after 96 hours; the increase of COD in water body was 15 mg / L due to the degradation of traditional PLA to produce propylene glycol monomer.

[0134] Engineering adaptability verification: the application in the high-frequency tidal area of Shenzhen Bay (immersed 3-4 times a day) showed that: The traditional starch-based template loses structural stiffness after a single use; The service life of the template under the action of seawater is prolonged to 7 cycles by increasing the content of calcium alginate to 40 parts by weight. Rib recycling test shows that the shape memory performance retention rate is >90% after 10 times of molding cycles, meeting the technical and economic requirements of sustainable repair equipment.

[0135] <Embodiment 10> The template preparation project was implemented in the mangrove restoration area of Dawanshan Island in Zhuhai Wanshan Archipelago. The patch positioning template was processed according to the requirements: 1) Shape memory polyurethane rib injection molding: polyurethane pellets with a glass transition temperature of 58℃ were selected, and the rib with a width of 7mm and a thickness of 0.6mm was formed in a 185℃ injection molding machine, and was cut into the same length as the arc-shaped 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 microns, and 12 parts by weight of glycerol plasticizer were put into a twin-screw extruder, and blended and granulated at 95℃; 3) Composite molding: three ribs were placed in parallel in the positioning groove (groove depth 1mm) of the mold, and the matrix granules were injected, and molded at 105℃ and 10MPa pressure for 12 minutes to obtain an arc-shaped split template with a grid cavity (the curvature radius matches the outer wall of the coconut shell 1). The template was used for the preparation of the ecological substrate layer of claim 8, and the performance was evaluated after 8 cycles of use in the tidal environment.

[0136] The essential difference between the traditional template technology: the traditional degradable template (such as patent CN112223544A) is made of pure polylactic acid (PLA) injection molding. PLA softens and deforms seriously when molded at high temperature (>100℃), and the actual measurement of the size deviation of the grid cavity at 105℃ is ±15%, resulting in a patch edge burr rate of 42%. More importantly, the PLA template needs to be removed mechanically, and the uncured adhesive substrate is peeled off at a rate of more than 35%; while increasing the release agent will pollute the substrate interface and reduce the bonding strength by 58%. In addition, pure PLA degrades slowly in seawater environment (complete disintegration requires 180 days), and the remaining fragments hinder the attachment of barnacles.

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

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

[0139] 2) Demolding integrity: The plaque edge defect rate after removing the template in the present invention is 3.2% (measured by three-dimensional scanning); The defect rate in the traditional PLA template group was 41.5%, and 28% of the plaques required artificial repair due to adhesion.

[0140] 3) Environmental compatibility: Testing of nearby water bodies showed that the peak calcium ion concentration released during the degradation period of the template of the present invention was 0.85 mg / L (lower than the background calcium content of seawater); the lactic acid produced by the degradation of traditional PLA caused the pH of the local water body to drop to 5.8, resulting in a 65% mortality rate of barnacle larvae around the patch.

[0141] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A method for establishing mangroves under difficult site conditions, characterized in that: The following steps are involved: S1: Select mature coconut shells with a diameter of 28-32 cm, split them longitudinally to form planting containers, and create drainage holes with a diameter of 1-2 cm at the bottom of each coconut shell; S2: Fill the coconut shell container with substrate in layers: a 4-6 cm thick layer of oyster shell fragments with a particle size of 10-15 mm is laid on the bottom layer, a mangrove intertidal mud layer is filled in the middle layer, and a 1-3 cm thick layer of fine sea sand is covered on the surface. S3: Arrange three coconut shell containers in an equilateral triangle. Use rigid connectors to connect adjacent coconut shells to form a planting unit. The planting units are placed in a mudflat or wetland area with a spacing of 0.5-1.5 meters between the planting units. S4: Plant a 30-50 cm tall mangrove seedling in each coconut shell container, keeping the root neck 2-4 cm above the substrate surface, backfill the substrate and compact it, continue planting, and complete the construction of the mudflat or wetland area.

2. The method for establishing mangroves under difficult site conditions according to claim 1, characterized in that: The mangrove seedlings are selected from the species Kandelia officinalis, Avicennia marina, Rhizophora rubrum or Bruguiera gymnorrhiza.

3. The method for establishing mangroves under difficult site conditions according to claim 1, characterized in that: Also included is an anti-scour anchoring structure, the anti-scour anchoring structure comprising: An anchor rod is driven vertically into the mudflat or wetland area where the center of the planting unit is located. The anchor rod is 1.2-1.5 meters long and the top of the anchor rod is 0.3-0.4 meters above the mudflat surface. An annular hoop is provided on the upper part of the three coconut shell containers to clamp the three coconut shells tightly, and the annular hoop is located at one-half to two-thirds of the height of the coconut shell containers; The transverse struts are arranged between the three corner nodes of the hard 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.

4. The method for establishing mangroves under difficult site conditions according to claim 1, characterized in that: 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 zone mud layer, wherein the slow-release iron oxide interlayer is composed of hematite particles with a particle size of 2-4 mm and a laying thickness of 1-2 cm; The chemical composition of the hematite particles meets the following requirements: Fe2O3 content ≥ 92 weight percent, specific surface area 5-8 square meters per gram, and porosity 35-45%.

5. The method for establishing mangroves under difficult site conditions according to claim 1, characterized in that: In the matrix filling of step S2, a phosphorus controlled-release layer is added between the middle mangrove intertidal zone mud layer 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 particle size of the ammonium phosphate particles is 1-3 mm, the coating rate of the hydroxyapatite coating layer is 40-60%, and the thickness of the coating layer accounts for 15-25% of the total diameter of the particles; The phosphorus controlled-release layer is spaced 1-2 cm apart from the inner wall of the coconut shell container.

6. The method for establishing mangroves under difficult site conditions according to claim 1, characterized in that: Evenly mixing microbial slow-release inhibitor particles into the surface fine sea sand layer in step S2, the amount of the 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 a chitosan coating layer, and the particle size is 1-3 mm; The fucoidan content in the seaweed polysaccharide extract is ≥85 weight percent, the coverage rate of the chitosan coating layer is 40-60%, and the thickness of the coating layer accounts for 10-20% of the total diameter of the particles.

7. The method for establishing mangroves under difficult site conditions according to claim 1, characterized in that: In the planting unit arrangement of 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 flakes and chitosan adhesive. The attachment coverage rate is 50-70% of the surface area of ​​the coconut shell outer wall. The dimensions of the oyster shell pieces are 5-10 mm in length, 3-6 mm in width, and 1-2 mm in thickness, and the chitosan binder 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 contains 3-5 oyster shell pieces, the patch diameter is 15-25 mm, and the distance between adjacent patch edges is 10-20 mm.

8. The method for establishing mangroves under difficult site conditions according to claim 7, characterized in that: The preparation of the ecological substrate layer comprises the following steps: 1) Apply a chitosan acetate primer with a mass concentration of 8-12% to the plaque area to form a transition layer with a thickness of 0.1-0.2 mm. The primer contains calcium carbonate nuclei with a particle size of 50-100 nm. The nuclei are added in an amount of 3-5% of the dry weight of chitosan. 2) mixing oyster shell flakes with an adhesive substrate in a mass ratio of 1:0.8-1.2 to obtain a mixture; the adhesive substrate comprising the following components: 70-80 parts by weight of chitosan having a deacetylation degree of 90-95%, 5-8 parts by weight of a nano-silica modifier, and 10-15 parts by weight of polybutylene succinate; 3) Fill the mixed material into the plaque positioning template, with the inner wall of the template matching the plaque size, and apply a pressure of 0.2-0.4 MPa and hold the pressure for 30-60 seconds; 4) After removing the template, cure for 18-24 hours at a humidity of 75-85% and a temperature of 28-32°C to ensure that the interface bonding strength is ≥0.4 MPa.

9. The method for establishing mangroves under difficult site conditions according to claim 8, characterized in that: The plaque positioning template is composed of a seawater-degradable composite matrix material and a shape memory unit. The seawater-degradable composite matrix material comprises 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 microns, and 10-15 parts by weight of a glycerin plasticizer. The shape memory unit is embedded in 3-5 shape memory polyurethane ribs in a seawater degradable composite matrix material. The rib width is 5-8 mm, the thickness is 0.5-0.8 mm, and the glass transition temperature is 55-60°C.

10. The method for establishing mangroves under difficult site conditions according to claim 9, characterized in that: The plaque positioning template preparation comprises the following steps: 1) Injection molding shape memory polyurethane into ribs at 180-190°C; 2) Polycaprolactone, calcium alginate and glycerol are blended and granulated in a twin-screw extruder at 90-100°C; 3) Place the ribs in the mold positioning groove, inject the matrix granules, and press at 100-110℃ and pressure 8-12MPa for 10-15 minutes to form an arc-shaped segmented template with a grid cavity.

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