Method for repairing tree hole of ancient tree with aerial roots based on filling method

Abstract

The invention discloses a method for repairing tree holes of ancient trees with aerial roots based on a filling method, which belongs to the technical field of protection of ancient and famous trees and comprises the steps of rooting, pretreatment, filling and growth induction. A three-layer structure is arranged in the tree hole, and a supporting structure is formed in the initial stage of repairing by matching with a fixing structure of the cover net and the anchor bolts; the living body supporting structure is formed by lignification of the aerial roots, and the supporting structure has the advantages of being stable for a long time, good in compatibility with tree bodies, small in influence on growth of the tree bodies and free of repeated repairing in the later period, and is particularly suitable for tree hole repairing of ancient trees with aerial root characteristics in the tropical high-temperature and high-humidity environment.

Description

Technical Field

[0001] This invention belongs to the field of ancient and famous tree protection technology, specifically involving a method for repairing tree cavities with aerial roots in ancient trees based on the filling method. Background Technology

[0002] Ficus ( Ficus There are many ancient trees in this genus, and most species in this genus have aerial roots, such as the small-leaved banyan (Ficus microcarpa). Ficus concinna In Hainan, there are ancient banyan trees with an age of over 700 years, forming a unique landscape where a single tree can form a forest. These ancient and famous trees are important natural heritage sites with extremely high ecological, cultural, and scientific research value.

[0003] Tree cavities are a common problem in ancient trees caused by aging, decay, and external damage. In severe cases, they can affect the stability of the tree and even lead to its collapse and death. Current tree cavity repair methods mostly employ the "filling method," which involves removing decayed tissue, setting up a framework, filling with material, and sealing the cavity. While effective in the short term, this method is problematic in hot and humid tropical environments. The different coefficients of thermal expansion between the filling material and the living bark and xylem can easily cause cracks at the interface, leading to cracking, detachment, and poor repair results. Furthermore, ancient trees continue to grow slowly after repair, and traditional rigid filling cannot adapt to the slight changes in trunk diameter, potentially compressing living tissue or creating new voids. Additionally, the filling materials are often resin or cement, resulting in a constant physical bond between the filling and the tree. Over time, the filling may detach, requiring repeated repairs, and the method has poor biocompatibility. Summary of the Invention

[0004] To address the technical problems of existing methods that use rigid artificial materials for filling ancient trees, which negatively impact tree growth and fail to provide long-term stable filling, this invention aims to provide a method for repairing tree cavities with aerial roots based on a filling method. This invention utilizes a three-layer structure within the tree cavity, along with a covering net and anchor bolts for fixation. This creates a supporting structure in the initial repair phase, effectively inhibiting secondary decay. Aerial root induction tubes, extending through the sealing layer at both ends, are embedded in the framework matrix layer. These tubes absorb and conduct moisture using a capillary water-holding layer, providing a continuous high-humidity microenvironment for aerial root growth. After entering the framework matrix layer, the aerial roots gradually lignify, forming multi-point embedding with the transverse framework and the covering net's mesh during growth. As the biodegradable framework gradually degrades, the root network develops into a stable, self-supporting living structure, achieving a natural transition from artificial support to living support. The repaired living support structure offers advantages such as long-term stability, good compatibility with the tree, minimal impact on tree growth, and no need for repeated repairs. It is particularly suitable for repairing tree cavities with aerial root characteristics in tropical, hot, and humid environments.

[0005] The objective of this invention is achieved by including the following steps: S1. Rooting: Select a branch above the tree hole, scratch the branch and apply growth hormone to promote the growth of aerial roots and new roots. S2. Pretreatment: Clean the decayed tissue inside the tree cavity of the ancient tree with aerial roots down to the healthy xylem, spray with broad-spectrum fungicide and insecticide and air dry, and then set anchoring holes along the healthy xylem inside the tree cavity. S3. Filling: Palm fiber, bamboo charcoal granules, and slow-release antibacterial agent are mixed evenly. The microporous structure of the bamboo charcoal granules is used to control humidity. This mixture is laid in the tree cavity as a flexible antibacterial inner layer. A first cover net is laid on top of this flexible antibacterial inner layer, and anchor bolts are driven through the first cover net into the anchoring holes to fix the first cover net and cover the flexible antibacterial inner layer. A horizontal skeleton is installed in the tree cavity. The horizontal skeleton is a biodegradable material with a degradation period of 2-3 years. The ends of the skeleton are fixed to the ends of the anchor bolts. Coconut coir and well-rotted organic matter are mixed evenly and filled into the gaps between the skeleton to form a skeleton matrix layer. During the filling process, multiple aerial root induction tubes are longitudinally buried into the skeleton matrix layer. A second cover net is laid on top of the skeleton matrix layer. The edge of the second cover net is fixed to the corresponding anchor bolt, and the middle part of the second cover net is fixed to the corresponding end of the skeleton. Epoxy resin, wood powder, and diatomaceous earth are mixed evenly and applied to the second cover net. A 0.5cm to 2cm gap is left at the junction of the hole edge and the bark. The gap is filled with sealant to form a sealing layer. Both ends of the aerial root induction tube extend out of the sealing layer. The upper end of the aerial root induction tube extends upward along the trunk, and the lower end extends downward along the trunk. The aerial root induction tube includes a tube body. A capillary water-holding layer is provided along the tube wall inside the tube body. The tube body is provided with root holes and micropores. The tube body of the aerial root induction tube located outside the tree hole is fixed to the trunk by a buckle (such as a U-shaped buckle, which is directly inserted into the trunk). The capillary water-holding layer can be made of coconut fiber felt or non-woven fabric. Coconut fiber felt and non-woven fabric are porous hydrophilic materials with strong capillary water absorption capacity. The tube body can be made of PVC tube or biodegradable tube with evenly distributed root holes and micropores. The root hole diameter is 8mm~12mm, preferably 10mm, and the micropore diameter is 1~2mm, preferably 1mm.

[0006] S4. Induced growth: The newly grown aerial roots are placed into the aerial root induction tube through the upper end of the tube. The aerial roots grow downward along the aerial root induction tube and pass through the root holes into the skeleton matrix layer to form a living support structure.

[0007] For the sealing layer, a tree trunk texture can be made on its outer surface and painted with the corresponding color to make the sealing layer look beautiful and uniform with the tree trunk.

[0008] It should be noted that in the early stages of induction, the aerial root induction tube maintains gas exchange through micropores in the tube wall and the bottom opening; as the root system gradually fills the induction tube, the aerenchyma of the aerial roots themselves can maintain aerobic respiration of the roots within the tube. Meanwhile, the coconut coir and decomposed organic matter in the skeletal matrix layer are both highly porous materials, and the aerial roots of plants such as banyan trees also contain antibacterial components.

[0009] The induced growth process mainly consists of three stages: Stage 1: Aerial roots grow downwards along the tube inside the induction tube. The capillary water-holding layer provides water for the aerial roots. Since this is the early stage of induction, the root system has not yet filled the induction tube. The induction tube exchanges gases with the outside world through micropores located outside the tree cavity. In areas like Hainan, rainfall is abundant. Rainwater, especially trunk runoff, enters the induction tube through the root holes outside the tree cavity and the upper opening of the induction tube. The capillary water-holding layer maintains high humidity, while free water can seep down along the tube wall. Excess free water is discharged from the lower end of the induction tube. As the aerial roots grow, the root tips penetrate the root holes, causing the root system to expand bidirectionally inside and outside the tube wall. As the root system thickens, the root system itself becomes the anchor point between the induction tube and the surrounding substrate. Second stage: After the aerial roots enter the skeletal matrix layer, they branch extensively in coconut coir and decomposed organic matter, forming a network root system. During growth, the root system forms multi-point anchorage with the transverse skeletal framework and through the mesh openings of the first and second cover nets; the roots exposed to air (the part above the induction tube inlet) can transport oxygen downwards through intercellular spaces to the roots inside the tube; Third stage: Some roots penetrate the mesh of the first cover net and come into contact with the flexible antibacterial inner layer, while others extend along the healthy xylem surface of the inner wall of the tree cavity.

[0010] During the root growth process, during non-rainy periods, due to the tropical high temperature and humidity environment, the upper and lower parts of the aerial root induction tube are located in a high humidity environment (outside the tree cavity). Multiple aerial root induction tubes work simultaneously, and through capillary effect, water is conducted along the fiber gaps to the low humidity area (inside the tree cavity). If the environmental humidity is insufficient, water can also be sprayed onto the aerial root induction tubes manually and periodically.

[0011] The degradation cycle of the lateral framework (e.g., 2-3 years) is designed after the third stage of induced growth. At this time, the slow-release antibacterial agent in the flexible antibacterial inner layer has been fully released, and the matrix layer and the aerial root network of the flexible antibacterial inner layer have formed a self-supporting three-dimensional structure. The intertwining of roots, the embedding of roots with the cover net / anchor, and the adhesion of roots to the inner wall of the tree cavity together constitute a stable living support system. The degradation of the lateral framework does not cause the support to disappear, but rather it is a transition from temporary artificial support to permanent living support. In addition, the same biodegradable material as the lateral framework can be used for the induction tubes to avoid long-term residual effects on the tree after repair.

[0012] Preferably, in step S2, the diameter of the anchoring holes is 6 mm to 8 mm, the depth is 5 cm to 8 cm, and the hole spacing is 5 cm to 30 cm.

[0013] Preferably, the aerial root induction tube in step S3 is U-shaped or V-shaped.

[0014] It should be noted that the aerial root induction tube is U-shaped or V-shaped, but this does not mean that its shape is a standard U or V. Rather, the transition at the bend should not have a small angle; the angle should be as large as possible. Figure 1 The near-U-shaped structures in the tube all have a 120° angle, which is beneficial for guiding the free water in the upper part of the tube to flow to the lower part of the tube, and for draining excess free water out of the tube.

[0015] Preferably, in step S3, palm fiber, bamboo charcoal granules, and slow-release antibacterial agent are mixed evenly at a mass ratio of 5:1:0.01~0.2. The slow-release antibacterial agent should be selected to minimize the impact on root growth while ensuring the preservation of the xylem in the tree cavity. Coconut coir and decomposed organic matter are mixed evenly at a mass ratio of 5:3. Epoxy resin, wood flour, and diatomaceous earth are mixed evenly at a mass ratio of 4:3:2.

[0016] The beneficial effects of this invention are: 1. This invention, through the fixed structure of a flexible antibacterial inner layer, a first cover net, and anchor bolts, forms a stable antibacterial isolation layer at the bottom of the tree cavity. This effectively inhibits microbial infection of healthy xylem and provides a reliable anchoring foundation for the upper skeleton matrix layer and the induction tubes. The sealing layer serves to seal the opening in the early stage of repair and also forms a support between it and the transverse skeleton. In the later stage of repair, as the transverse skeleton degrades and the root system grows, even if the sealing layer falls off, it will not affect the already formed internal living support structure, avoiding the problem of repeated filling and sealing and multiple repairs required by existing technologies. This invention embeds aerial root induction tubes longitudinally in the skeleton matrix layer. These induction tubes maintain a high humidity environment inside the tube through a capillary water-holding layer, and the micropores in the tube wall ensure gas exchange. The root holes provide a preset channel for the roots to emerge. Together, these three elements form a microenvironment suitable for the growth of aerial roots. The oxygen required by the roots inside the tree cavity is self-sufficient through the oxygen transport mechanism of the aerial root ventilation tissue outside the tree cavity. At the same time, the mesh of the first cover net provides a channel for the aerial roots to penetrate the flexible antibacterial layer and contact the inner wall of the tree cavity in the later stage. 2. After the aerial roots of this invention enter the skeleton matrix layer through the induction tube, they lignify under the induction of the matrix, forming a root network with a certain mechanical strength. On the other hand, during the growth process, the roots form multi-point embedding with the transverse skeleton and through the mesh of the first and second cover nets. When the biodegradable skeleton gradually degrades within 2 to 3 years, the lignified root network constitutes a stable self-supporting living structure through the mutual entanglement between the roots and the embedding relationship with the anchoring and cover net mesh, realizing a smooth transition from artificial temporary support to living permanent support. As the ancient tree grows slowly, the roots, as the supporting structure, thicken synchronously, realizing the dynamic adaptation of the tree cavity repair structure to the tree growth, avoiding the compression problem caused by the thickening of the tree due to traditional rigid filling. This helps to improve the long-term stability and stress resistance of the repaired tree. Attached Figure Description

[0017] Figure 1 A schematic diagram of the structure for filling tree holes; Figure 2 This is a schematic diagram of the internal structure of the aerial root induction tube; In the diagram: 1- Flexible antibacterial inner layer, 2- First cover net, 3- Anchor bolt, 4- Transverse skeleton, 5- Skeleton matrix layer, 6- Aerial root induction tube, 601- Tube body, 602- Capillary water-holding layer, 603- Root hole, 604- Buckle, 7- Second cover net, 8- Sealing layer. Detailed Implementation

[0018] The present invention will be further described below with reference to the embodiments and accompanying drawings, but this does not limit the present invention in any way. Any changes or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention. Example 1

[0019] This example uses a banyan tree in Hainan that is approximately 140 years old. Ficus microcarpa The ancient tree is the object of restoration. There is a hole in the trunk of the tree, with an opening measuring approximately 40 cm × 35 cm and a depth of approximately 25 cm. There is no obvious water accumulation inside the hole, and the tree is growing well. (See attached image.) Figures 1-2 As shown, this embodiment of the tree cavity restoration method for ancient trees with aerial roots based on the filling method includes the following steps: S1. Rooting: Select a healthy branch above the tree hole that is free from pests and diseases. Make a cut on the branch and apply growth hormone. Then wrap the cut area with moist sphagnum moss and then wrap the sphagnum moss with a film to promote the growth of aerial roots and new roots. Note that the new roots should face the tree hole to facilitate subsequent rooting. When the new aerial roots grow to the tree hole, proceed to the next step. S2. Pretreatment: Clean the decayed tissue, insect-eaten powder, and loose debris from the tree cavity of the ancient tree with aerial roots until the healthy xylem is exposed. Mix 500 times diluted 50% carbendazim wettable powder and 1000 times diluted 2.5% high-efficiency cyhalothrin emulsifiable concentrate and spray the tree cavity until the surface is moist but not dripping. Be careful not to spray the new roots. Let it air dry for 48 hours. Set anchoring holes along the healthy xylem inside the tree cavity. The anchoring holes should be 8 mm in diameter and 6 cm deep, with a spacing of 5 cm to 10 cm. Clean up the debris after drilling. S3. Filling: Mix palm fibers (3cm-5cm in length), bamboo charcoal granules (5mm-10mm in diameter), and microcapsule slow-release antibacterial agent at a mass ratio of 5:1:0.1. Lay this mixture evenly in the tree cavity to a thickness of approximately 3cm, forming the flexible antibacterial inner layer 1. The main function of this layer is to continuously release antibacterial components, preventing further damage to healthy xylem, and providing a buffer base for the structure above. Lay a first cover mesh 2 (2cm × 2cm mesh size) made of stainless steel on top of the flexible antibacterial inner layer 1. Insert stainless steel anchor bolts 3 through the first cover mesh 2 and into the anchoring holes to fix the first cover mesh 2 and cover the flexible antibacterial inner layer 1. Leave approximately 2cm of space at the head of the anchor bolt 3. A 1 cm exposed section is used for subsequent fixation. A horizontal framework 4 made of polylactic acid (PLA) material with a degradation period of 2-3 years is installed in the tree cavity. The ends of the horizontal framework 4 are fixed to the exposed ends of the anchor bolts 3 using stainless steel cable ties. All horizontal frameworks 4 are arranged horizontally within the tree cavity. Coconut coir and well-rotted organic matter are mixed evenly in a 5:3 mass ratio and filled into the gaps between the frameworks 4 to form a framework matrix layer 5. The thickness of the framework matrix layer 5 extends 4-7 cm near the opening to leave space for the subsequent sealing layer. During filling, four aerial root induction tubes 6 are vertically embedded into the framework matrix layer 5, ensuring that the aerial root induction tubes 6 avoid the horizontal frameworks 4. The aerial root induction tubes 6 are spaced 10 cm apart and are U-shaped, with each bend of the U-shape having an angle of 120°. A mesh with a 1 cm × 1 cm aperture is then laid on the framework matrix layer 5. The second cover net 7 is made of stainless steel. The edges of the second cover net 7 are fixed to the ends of the corresponding anchor bolts 3 (through holes can be pre-drilled at the ends for easy passage of stainless steel cable ties) using stainless steel cable ties. The middle of the second cover net 7 is fixed to the ends of the corresponding frame 4 (through holes can be pre-drilled for easy passage of cable ties) using polylactic acid cable ties. Note that the second cover net 7 should be as taut and flat as possible. Epoxy resin, 80-mesh wood powder, and 200-mesh diatomaceous earth are mixed evenly in a mass ratio of 4:3:2 and applied evenly to the second cover net 7. An opening of approximately 1 cm is left at the junction of the opening and the bark. A 3cm slit is filled with sealant to form a sealing layer 8. Both ends of the aerial root induction tube 6 extend beyond the sealing layer 8. At the junction of the aerial root induction tube 6 and the sealing layer 8, ensure the sealant is applied smoothly without leaving gaps. The upper end of the aerial root induction tube 6 extends vertically upwards along the trunk, and the lower end extends vertically downwards along the trunk. Use U-shaped clips 604 to secure the portion of the aerial root induction tube 6 outside the tree cavity to the surface of the trunk, ensuring the tube is stable and does not wobble. The aerial root induction tube 6 includes a tube body 601 with an inner diameter of 3cm and a wall thickness of 2mm. The inner wall of the tube body 601 has a capillary water-holding layer 602 with a thickness of approximately 5mm. A thin cable tie can be used to pass through the root hole 603 and the capillary water-holding layer 602 to firmly fix the capillary water-holding layer 602 to the inner wall of the tube body 601. The tube body 601 has root holes 603 with a diameter of 8mm and micropores with a diameter of 1mm (Note: micropores are not included in the text). Figure 1 (as shown in the image) S4. Induced growth: The newly grown aerial roots are placed into the aerial root induction tube 6 through the upper end of the tube opening; the aerial roots grow downward along the aerial root induction tube 6 and pass through the root hole 603 into the skeleton matrix layer 5 to form a living support structure. Six months after restoration, tests showed that the aerial roots had covered the 5th layer of the skeletal matrix, the root system was well lignified, and a preliminary living support structure had been formed. Twelve months after restoration, the root network had thickened further and was closely attached to the inner wall of the tree cavity. Some areas of the biodegradable skeletal structure showed signs of natural degradation, but the root network had formed a self-supporting system, and the tree was growing well.

Claims

1. A method for restoring tree cavities in ancient trees with aerial roots based on a filling method, characterized in that... Includes the following steps: S1. Rooting: Select a branch above the tree hole, scratch the branch and apply growth hormone to promote the growth of aerial roots and new roots. S2. Pretreatment: Clean the decayed tissue inside the tree cavity of the ancient tree with aerial roots down to the healthy xylem, spray with broad-spectrum fungicide and insecticide and air dry, and then set anchoring holes along the healthy xylem inside the tree cavity. S3, Filling: Mix palm fiber, bamboo charcoal granules, and slow-release antibacterial agent evenly and lay them in the tree cavity as a flexible antibacterial inner layer (1). Lay a first cover net (2) on the flexible antibacterial inner layer (1) and insert anchor bolts (3) through the first cover net (2) into the anchoring holes to fix the first cover net (2) and cover the flexible antibacterial inner layer (1). Install a horizontal skeleton (4) in the tree cavity. The horizontal skeleton (4) is a biodegradable material with a degradation cycle of 2 to 3 years. Fix the ends of the skeleton (4) to the ends of the anchor bolts (3). Mix coconut coir and decomposed organic matter evenly and fill the gaps in the skeleton (4) to form a skeleton matrix layer (5). During the filling process, embed multiple aerial root induction tubes (6) longitudinally into the skeleton matrix layer (5). In the skeleton matrix layer (5) A second cover net (7) is laid on the top, and the edge of the second cover net (7) is fixed to the corresponding anchor bolt (3). The middle part of the second cover net (7) is fixed to the end of the corresponding skeleton (4). Epoxy resin, wood powder and diatomaceous earth are mixed evenly and applied to the second cover net (7). A gap is reserved at the junction of the edge of the hole and the bark. The gap is filled with sealant to form a sealing layer (8). Both ends of the aerial root induction tube (6) extend out of the sealing layer (8). The upper end of the aerial root induction tube (6) extends upward along the trunk, and the lower end of the aerial root induction tube (6) extends downward along the trunk. The aerial root induction tube (6) includes a tube body (601). A capillary water-holding layer (602) is provided along the tube wall inside the tube body (601). The tube body (601) is provided with root holes (603) and micropores. S4. Induced growth: The newly grown aerial roots are placed into the aerial root induction tube (6) through the upper end of the tube opening; the aerial roots grow downward along the aerial root induction tube (6) and pass through the root hole (603) into the skeleton matrix layer (5) to form a living support structure.

2. The method for restoring tree cavities with aerial roots based on the filling method according to claim 1, characterized in that... In step S2, the anchoring hole diameter is 6 mm to 8 mm, the depth is 5 cm to 8 cm, and the hole spacing is 5 cm to 30 cm.

3. The method for restoring ancient tree cavities with aerial roots based on the filling method according to claim 1, characterized in that... The aerial root induction tube (6) in step S3 is U-shaped or V-shaped.

4. The method for restoring tree cavities with aerial roots based on the filling method according to claim 1, characterized in that... In step S3, palm fiber, bamboo charcoal granules, and slow-release antibacterial agent are mixed evenly at a mass ratio of 5:1:0.1; coconut coir and decomposed organic matter are mixed evenly at a mass ratio of 5:3; epoxy resin, wood powder, and diatomaceous earth are mixed evenly at a mass ratio of 4:3:2.

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