An under-forest canopy simulation device

Abstract

The utility model provides a kind of understory canopy density simulation device, comprising: support rod, height adjusting structure is provided, and can be inserted to ground at an angle;Sunshade net, edge is provided with eyelet;Fixed assembly, including pull rope, connecting structure, one end of the pull rope passes through eyelet and is detachably connected with sunshade net, and the other end is fixed with support rod or ground through connecting structure;By adjusting the height of support rod, or adjusting the fixed position of connecting structure on support rod, sunshade net can be tensioned, and height-adjustable simulation space is formed between sunshade net surface and ground planting area;By adjusting the number of layers of sunshade net, adjust the canopy density range of simulation space.The understory canopy density simulation device of the utility model is flexible, reusable, portable and practical, and the installation process does not require complex foundation and tools, and a single person can complete the layout and disassembly.

Description

Technical Field

[0001] This utility model belongs to the field of agricultural and forestry experimental equipment, and in particular relates to a canopy closure simulation device for simulating the light environment under forest canopy. Background Technology

[0002] In forestry, ecology, and understory economics such as forest-medicinal herb and forest-fungus intercropping, simulating forest canopy closure is crucial for screening suitable species and studying plant physiological and ecological responses. Technical methods for simulating forest canopy closure are relatively limited in this field. The conventional and mainstream approach is to use a simulation scheme combining a fixed arched steel frame with shade netting. Based on the size of the test plot, a steel arched frame is pre-customized and welded to form the fixed skeleton structure of the entire device. Subsequently, shade netting with a specific light transmittance is laid or suspended on this frame, and the target canopy closure environment is simulated by changing the netting with different shading rates.

[0003] However, practice has shown that this traditional method suffers from several drawbacks. Firstly, it lacks flexibility and is not reusable. The device is a fixed structure built only once, and its dimensions, shape, and arch height cannot be altered after construction. If the experimental design changes, such as adjusting the treatment gradient, changing the test location, or altering the simulation area, the original device is almost incompatible and must be discarded and redesigned. Furthermore, its bulky and fixed nature prevents flexible movement or rapid deployment between different test locations, significantly limiting the flexibility and scalability of the experiment. Secondly, it suffers from poor economic efficiency and high manufacturing and maintenance costs. The steel arch frame has high raw material costs and requires specialized welding and construction, resulting in significant initial investment. During use, the steel structure is easily damaged or deformed by wind, rain, external forces, or corrosion, making repair difficult and costly. From a life-cycle perspective, the overall cost of using this "disposable" fixed device remains high, making it unsuitable for large-scale screening experiments requiring multiple locations, multiple gradients, and repeatability, leading to a waste of resources in scientific research and production operations.

[0004] Therefore, there is an urgent need in this field for a low-cost, flexible, reusable, and easily deployable and adjustable canopy closure simulation technology to overcome the inherent defects of existing fixed simulation devices and meet the needs of modern, high-efficiency forest research and production. Summary of the Invention

[0005] In view of this, the present invention aims to propose a forest canopy closure simulation device to solve the problems of poor flexibility, non-reusability and high maintenance costs.

[0006] To achieve the above objectives, the technical solution of this utility model is implemented as follows: A forest canopy closure simulation device includes a support rod with a height adjustment structure that can be inserted obliquely into the ground; a shade net with eyelets along its edges; and a fixing assembly including a pull rope and a connecting structure, one end of which passes through the eyelets and is detachably connected to the shade net, and the other end of which is fixed to the support rod or the ground via the connecting structure. By adjusting the height of the support rod or the fixed position of the connecting structure on the pull rope, the shade net can be tensioned, creating a height-adjustable simulated space between the shade net surface and the planting area on the ground. The canopy closure range of the simulated space can be adjusted by changing the number of layers of the shade net.

[0007] Furthermore, the surface of the support rod is provided with an anti-slip structure, which is an axial anti-slip texture, knurling, or protrusion arranged on the surface of the support rod.

[0008] Furthermore, the support rod surface is provided with scale markings to indicate its insertion depth or effective height.

[0009] Furthermore, the connecting structure is a clamp, which is sleeved on the support rod and can slide and lock along the support rod; the clamp is composed of two identical semi-circular structures joined together; the inner wall of the semi-circular structure is provided with an anti-slip structure, and both ends are provided with connecting ears with through holes; the connecting ears are locked by fasteners passing through the through holes; the clamp is provided with a connection point for connecting the pull rope; the connection point is a through hole, hook or hanging ring fixedly set on the outer wall of the clamp.

[0010] Furthermore, one end of the support rod is provided with a sharp part, and the support rod is obliquely inserted into the ground through the sharp part; the sharp part is detachably connected to one end of the support rod, and the detachable connection is a threaded connection, a snap-fit ​​connection or a pin lock connection.

[0011] Furthermore, the edge of the shade net is provided with a plurality of buttonholes, which are spaced apart along the four edges of the shade net.

[0012] Furthermore, the buttonholes are evenly spaced along the edge of the shade net, with a spacing of 50 to 100 cm between adjacent buttonholes.

[0013] Furthermore, the buttonholes on at least one edge of the shade net can be connected to corresponding buttonholes on another shade net via connecting ropes, thereby enabling the splicing and expansion of multiple shade nets.

[0014] Furthermore, the shade net is configured with multiple layers, and each layer of the shade net can be independently adjusted and fixed to the support rod by its own pull rope, so as to form different canopy closure gradients by stacking layers.

[0015] Furthermore, the height adjustment structure is a locking adjustment mechanism, which includes a threaded sleeve locking mechanism, a set screw locking structure, and a pin-controlled adjustment mechanism.

[0016] Compared with existing technologies, the forest canopy closure simulation device of this invention has the following advantages: (1) The forest canopy closure simulation device described in this utility model consists of only three core components, has a simple structure, can be operated by a single person, is easy to install, and can be disassembled and deployed as needed to achieve reuse.

[0017] (2) The forest canopy closure simulation device described in this utility model can adjust the number of shade nets according to different canopy closure requirements, splice the shade nets according to the actual area requirements, and set the number of support rods according to the actual area of ​​the shade nets, thus meeting the requirements for constructing a customized simulation experimental field.

[0018] (3) The forest canopy closure simulation device described in this utility model can conduct small-area experiments through precise simulation, saving experimental costs; by artificially simulating canopy closure, other variables can be strictly controlled, eliminating the influence of factors other than canopy closure on the experimental results; it can flexibly cope with various experimental scenarios, and determine the required number of shade nets according to the specific area of ​​the experimental plot; by superimposing different layers of shade nets, it can simulate forest conditions of three different canopy closure levels: high, medium, and low; the application area and canopy closure level can be adjusted at any time; the materials after use can be disassembled and reused repeatedly, and disassembly and movement are convenient and do not affect the secondary assembly of materials; the deviation rate of the simulation of light intensity of forest land of three different canopy closure levels is low, and it can complete the simulation task well and achieve the canopy closure simulation effect. Attached Figure Description

[0019] The accompanying drawings, which form part of this utility model, are used to provide a further understanding of the utility model. The illustrative embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute an undue limitation of the utility model. In the drawings: Figure 1 This is a schematic diagram of the canopy closure simulation experimental device as described in this embodiment of the present invention; Figure 2 This is a schematic diagram of the support rod described in an embodiment of the present utility model; Figure 3 This is an enlarged view of area A as described in an embodiment of the present invention; Figure 4 This is an enlarged view of region B as described in an embodiment of the present invention; Figure 5 This is a schematic diagram of the connection structure described in an embodiment of the present utility model; Figure 6This is a schematic diagram of the connection structure described in an embodiment of the present utility model from another angle; Figure 7 This is a schematic diagram of the height adjustment structure described in an embodiment of the present utility model; Figure 8 This is a schematic diagram of the shade net described in an embodiment of the present utility model; Figure 9 This is a schematic diagram of the shading net splicing method described in an embodiment of this utility model; Figure 10 This is a schematic diagram of the multi-layer shading netting layout according to an embodiment of the present invention.

[0020] Explanation of reference numerals in the attached figures: 1-Support rod; 11-Sharp point; 12-Connecting structure; 121-Connecting point; 122-Connecting ear; 123-Anti-slip structure; 13-Height adjustment structure; 131-Setting screw; 2-Shade net; 21-Hole; 3-Pull rope; 4-Connecting rope. Detailed Implementation

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0022] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0023] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0024] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0025] like Figure 1 As shown, a forest canopy closure simulation device includes: a support rod 1 with a height adjustment structure 13, which can be inserted obliquely into the ground; a shade net 2 with eyelets 21 on its edges; a pull rope 3 and a connecting structure 12, one end of which passes through the eyelet 21 and is detachably connected to the shade net 2, and the other end is fixed to the support rod 1 or the ground via the connecting structure 12; by adjusting the height of the support rod 1 or adjusting the fixed position of the connecting structure 12 on the support rod, the shade net 2 can be tensioned, and a height-adjustable simulated space can be formed between the net surface of the shade net 2 and the planting area on the ground; by adjusting the number of layers of the shade net 2, the canopy closure range of the simulated space can be adjusted.

[0026] Specifically, in a preferred embodiment, the support rod is a multi-section cylindrical hollow metal rod, with the sections fixedly connected by a height adjustment structure; the connecting structure is fixed or detachable and is set on the top of the other end of the support rod, so that the height of the simulated space above the ground can be adjusted by adjusting the height of the support rod; another form is that it is detachably sleeved on the support rod, in which the height of the simulated space above the ground can be adjusted by sliding the position of the connecting structure on the support rod or by adjusting the height of the support rod.

[0027] In the first embodiment, the connecting structure is a hook directly welded to the top of the other end of the support rod. In the second embodiment, the connecting structure is a U-shaped clamp bolted to the top of the rod. In the third embodiment, the connecting structure is a sleeve fitted onto the support rod.

[0028] The shade net has a light transmittance of 50% and multiple eyelets around its perimeter. Based on the 50% light transmittance, the theoretical light transmittance of a single-layer shade net is calculated to be 50%, corresponding to a canopy closure of 0.5; the theoretical light transmittance of a two-layer shade net is 25%, corresponding to a canopy closure of 0.75; and the theoretical light transmittance of a three-layer shade net is 12.5%, corresponding to a canopy closure of 0.88. Based on the experimentally measured illuminance, the corresponding illuminance ranges were adjusted, and the adjusted results are shown in Table 1 below.

[0029] Table 1: Relationship between the number of shade net layers and simulated canopy closure The results of the comparison between the number of shade net layers and the simulated canopy closure show that the range of simulated canopy closure can be adjusted by changing the number of shade net layers.

[0030] During setup, the support poles are inserted obliquely into the ground, with the insertion depth controlled between 20-40cm depending on soil compaction. One support pole is inserted every 1m around the experimental plot. The number of shade net layers is determined according to the desired canopy closure. The shade net is connected to the support poles using ropes through the eyelets along the net's edge. The height of the shade net from the ground is set according to the distance between the top of the experimental plant and the lowest point of the shade net. During the experiment, the height of the shade net is adjusted as needed based on plant growth, ensuring the distance between the highest point of the plant and the lowest point of the shade net remains within 10cm-20cm. Once set up, an adjustable canopy closure simulation space is created.

[0031] As can be seen from the deployment process, the device provided by this scheme has only three core components. It has a simple structure, high flexibility, can be moved at will, and can be reused. Moreover, the operation process is simple and convenient, and a single person can complete the deployment and dismantling work. In addition, the components used are low in cost, but the simulation effect is sufficient to meet the experimental requirements, making up for most of the shortcomings of the simulation methods currently used.

[0032] like Figure 2 One end of the support rod 1 is provided with a sharp part 11, which is detachably connected to one end of the support rod 1; the connecting structure 12 is sleeved on the support rod 1 and can slide and lock along the support rod 1. The support rod 1 is provided with a height adjustment structure 13.

[0033] Specifically, the pointed part 11 adopts a high-strength cone head, the outer wall of the connecting part of the cone head is provided with external threads, and the inner wall of the connecting end of the support rod 1 and the cone head is provided with matching internal threads. The pointed part is tightened and fixed to one end of the support rod by threaded connection.

[0034] In addition to the threaded connection described in this embodiment, the connection between the pointed part and the support rod can also adopt other conventional connection methods, such as snap-fit ​​connection and pin lock connection.

[0035] This detachable connection method allows for easy separation of the sharp part from the support rod. On the one hand, it facilitates later maintenance, as the sharp part is directly stressed when the support rod is inserted into the ground, which can easily cause wear and tear, requiring replacement. On the other hand, it also facilitates production and transportation. The detachable structure enables modular production and ensures convenient and safe transportation.

[0036] like Figure 3 , Figure 4 As shown, the surface of support rod 1 is provided with an anti-slip structure and scale markings.

[0037] Specifically, in a preferred embodiment, the anti-slip structure is an anti-slip texture that covers the entire outer surface of the support rod. This serves two purposes: firstly, to increase the friction between the support rod and the connecting structure, strengthening the locking effect of the connection; and secondly, to increase the friction between the support rod and the ground, enhancing the stability of the device. The scale markings are in centimeters, printed from the end of the support rod connected to the pointed end to the other end. The scale markings help operators quickly identify the depth of the support rod inserted into the ground and indicate the effective height, compensating for errors that may arise from traditional visual estimation. This achieves rapid, accurate, and standardized height adjustment, facilitating operation while ensuring the precision, consistency, and repeatability of experimental procedures.

[0038] In addition to the axial anti-slip texture used in this embodiment, the anti-slip structure can also adopt other structures that can increase friction, such as knurling, protrusions, and anti-slip sleeves.

[0039] like Figure 5 , Figure 6 As shown, the connecting structure 12 is a clamp, which is fitted onto the support rod 1 and can slide and lock along the support rod 1. The clamp is composed of two identical semi-circular structures joined together. The inner wall of the semi-circular structure is provided with an anti-slip structure 123, and both ends are provided with connecting ears 122 with through holes. The bolt passes through one side of the through hole and is tightened with a nut on the other side to lock the connecting structure to the support rod. The clamp is provided with a connection point 121 for connecting the pull rope. The connection point 121 is a hanging ring fixedly set on the outer wall of the clamp.

[0040] In addition to the hanging ring described in this embodiment, perforations and hooks can also be used as connection points.

[0041] Specifically, the anti-slip structure on the inner wall of the semi-circular structure is an anti-slip pad; the anti-slip pad, the axial anti-slip grooves on the support rod, and the fasteners that play a locking role work together to enhance the locking effect of the connection structure.

[0042] The clamp design enables stepless, continuous, and precise height adjustment. It can slide and lock at any axial position on the support rod, and the scale markings on the support rod allow for centimeter-level height control of the shade net. Furthermore, the fasteners on both ears make height adjustment quick and easy; simply loosening one fastener allows the clamp to slide. Additionally, the anti-slip design enhances the stability and durability of the structure. The clamp structure uses standardized parts, is inexpensive, robust, and durable, achieving the low-cost and high-precision requirements of the device.

[0043] like Figure 7 As shown, the height adjustment structure 13 is a fastening screw locking structure.

[0044] Specifically, the support rod 1 includes at least two sections of rod that can slide relative to each other, and a set screw locking mechanism is provided on the rod. This set screw locking mechanism includes a connecting block located at the top of the lower section of the rod, the connecting block having a threaded hole and a set screw 131 that mates with the threaded hole. When height adjustment is required, the set screw 131 is loosened, allowing the upper section of the rod to be freely pulled out. After adjustment to the desired scale, the set screw is tightened, its end firmly contacting the outer wall of the upper section of the rod, and the two sections of the rod are securely locked by friction. This, combined with the anti-slip texture on the support rod, enhances the locking capability. This structure is simple, easy to operate, and has low manufacturing cost, and can achieve stepless adjustment and stable fixation.

[0045] In addition to the set screw locking mechanism used in this embodiment for height adjustment, other conventional height adjustment methods are also applicable to this solution. For example, a threaded sleeve locking mechanism that achieves telescopic locking by rotating an internally or externally threaded sleeve, or a pin hole adjustment mechanism that fixes the height by setting multiple pin holes on the rod and inserting pins.

[0046] This telescopic height-adjustable structure, combined with the detachable tip, allows the support rod to be disassembled for transport, greatly improving portability. It also allows users to quickly replace specialized parts according to experimental needs, such as different soil types or different shade net specifications, improving the adaptability and efficiency of the device and reducing long-term maintenance costs.

[0047] like Figure 8 As shown, the shade net 2 has multiple buttonholes 21 along its edge, with the buttonholes 21 spaced apart along the perimeter of the shade net 2. The buttonholes 21 are evenly spaced along the edge of the shade net 2, with a spacing of 100cm between adjacent buttonholes 21.

[0048] Specifically, the shade net is made of polyethylene with 3 stitches per inch and a light transmittance of 50%. It is reinforced with six-line edging, and metal eyelets with a diameter of 12mm are installed every 1 meter around the perimeter. This 100cm eyelet spacing ensures the net is evenly and flatly tensioned, achieving structural stability and guaranteeing the uniformity and repeatability of the simulated environment. Furthermore, the uniform eyelet spacing simplifies the installation process, eliminating the need for field measurements. The binding positions of the guy ropes can be quickly determined based on experience or simple counting, such as one fixed point per meter, greatly reducing deployment time and operational complexity. This overcomes the shortcomings of traditional methods, such as poor flexibility and slow deployment.

[0049] like Figure 9 As shown, the buttonhole 21 on at least one edge of the shade net 2 can also be connected to the corresponding buttonhole 21 on another shade net 2 via a connecting rope 4, so as to realize the splicing and expansion of multiple shade nets 2.

[0050] Specifically, the uniform and consistent buttonhole design facilitates the splicing of shade nets, improving their modularity, compatibility, and scalability. This allows operators to splice nets according to actual needs, expanding the simulation range and adapting to different experimental areas. However, in practical use, when the splicing width exceeds 2 meters, support poles should be installed between the plots to ensure the uniformity of the simulated environment and the reliability of the experimental data. Connecting rope 4 is a flexible connecting rope, using a crisscrossing method to connect two shade nets through buttonholes.

[0051] The connecting rope can be replaced by other connecting components such as buckles that can make the two shade nets fit together tightly.

[0052] like Figure 10 As shown, the shade net 2 is configured with multiple layers, and each layer of the shade net 2 can be independently adjusted and fixed to the support rod 1 by its respective pull rope 3, so as to form different canopy closure gradients by stacking layers.

[0053] Specifically, multiple layers can achieve different canopy closure levels, changing the traditional method of customizing or replacing expensive shade nets with different light transmittance. By simply increasing or decreasing the number of layers of shade nets of the same specification, a stable and repeatable canopy closure gradient can be quickly and continuously created at the same location, enabling large-scale, multi-gradient comparative experiments to be carried out at low cost and greatly improving experimental efficiency.

[0054] Furthermore, independent tensioning and fixing avoids wrinkles or adhesion problems caused by stacking multiple layers of netting. This solves the problems of uneven shading, localized hotspots, or environmental fluctuations that may result from simple stacking, providing a reliable and consistent environmental variable for plant growth response and ensuring the scientific validity and accuracy of the experimental results.

[0055] Finally, independent adjustment not only changes the number of layers but also the interlayer height, tilt angle, and tension. This allows researchers to simulate more complex real-world forest light environments, not just vertical shading, greatly expanding the device's scientific applications and meeting diverse research hypotheses and experimental designs.

[0056] After the setup was completed, the following experiment was conducted to simulate the effect of the test device: Experiment 1: Simulation Effect Experiment of Forest Canopy Closure Simulation Device 1. Experimental objective: To verify whether the simulation effect of the forest canopy closure simulation device can meet the requirements of the canopy closure simulation experiment.

[0057] 2. Experimental Design: 1) Measurement of simulated illuminance using a forest canopy closure simulation device: Select an area with no vegetation growth on the ground as the simulation area, divide the simulation area into 4 groups, and set up three experimental plots in each group. Three types of forest canopy closure simulation devices are set up in each experimental plot. One layer of shade netting is set up in simulation area 1, two layers of shade netting are set up in simulation area 2, and three layers of shade netting are set up in simulation area 3. Each simulation area is a 1m×1m square plot. Adjust the height of the shade netting so that the lowest point of the shade netting is 15cm above the ground. Use the instrument to measure the illuminance value. Take the average value of the 4 sets of data with the same number of shade netting layers as the simulated illuminance value corresponding to that number of layers.

[0058] 2) Determination of actual canopy closure illuminance value: Select forest land with canopy closure levels of low canopy closure, medium canopy closure and high canopy closure. Select 4 surface points as control points for each canopy closure level and directly measure the illuminance value. The average illuminance value of the 4 points is taken as the actual illuminance value of the forest under the corresponding canopy closure level.

[0059] 3. Test instrument: The light intensity measuring instrument is the Linshang LS330 handheld spectroradiometer.

[0060] 4. Illuminance measurement method: 1) The measurement point for the canopy closure simulation area is selected as the center point of the simulation area, i.e., the intersection of the diagonals of the square plot. Place the handheld illuminometer on the measurement point and let it stand for 1-2 minutes until the reading stabilizes. Then fix the reading and record it. 2) The actual canopy occupancy illuminance under the forest was measured at a ground point with no direct sunlight and no weeds. The handheld illuminance meter was placed on the measurement point and left to stand for 1-2 minutes until the reading stabilized. The reading was then fixed and recorded.

[0061] 5. Experimental Results Table 2 below shows a comparison of simulated and real forest illuminance values ​​measured according to the above-described experimental and measurement methods: Table 2. Comparison of light intensity under simulated canopy closure and actual canopy closure for different shade net layers. Based on the actual setup results in Table 2, the deviation rate of the actual illuminance values ​​corresponding to each simulated canopy closure level did not exceed 20%, indicating that the simulation effect of the device is good and can meet the requirements of the canopy closure simulation test.

[0062] Experiment 2: Method for screening suitable canopy closure for Isatis indigotica using a forest canopy closure simulation device 1. Experimental objective: To use the forest canopy closure simulation device described in this scheme to complete a full forest canopy closure screening experiment, so as to demonstrate the application scenario and specific steps of the device described in this scheme.

[0063] 2. Experimental Design According to the technical method of this invention, an introduction experiment of suitable understory medicinal plants based on canopy closure was carried out at the TEDA Plant Resource Bank Experimental Base on the Eighth Avenue of the Tianjin Binhai New Area Economic and Technological Development Zone. This experiment selected four gradient treatments with canopy closure levels of high, medium, low, and bare ground, corresponding to experimental group 1, experimental group 2, experimental group 3, and experimental group 4. The canopy closure simulation used a three-layer shade net for high canopy closure, a double-layer shade net for medium canopy closure, and a single-layer shade net for low canopy closure, with a light transmittance of 50%. Each treatment was a 1m × 1m square plot. The medicinal plant variety used in the experiment was Isatis indigotica. Finally, core growth indicators were measured to determine the optimal canopy closure range for the experimental subjects.

[0064] 3. Experimental Procedure S1. Select a flat plot of land with suitable previous crop and good drainage as the experimental field. Two weeks before sowing, plow the plot to a depth of 30cm, rake the soil finely and level it, and remove stones, weeds and roots of previous crops. Apply quicklime evenly at a rate of 50-75 kg per mu, and apply well-rotted farmyard manure and 20 kg of calcium phosphate per mu as base fertilizer. Use a rotary tiller to mix the fertilizer evenly with the top 20cm of soil. After land preparation, make flat beds and divide the experimental field into four 1m×1m experimental areas. Sow the same batch of Isatis indigotica in each area and water it thoroughly once. S2. Deploy forest canopy closure simulation devices and create canopy closure gradients in the experimental area. The specific deployment process is as follows. 1) Insert the support rod with the tip pointing downwards and at a 100-degree angle to the test ground. Set up a support rod every 1m and read the scale on the support rod to adjust the insertion depth to a uniform 30cm. 2) Create a canopy closure gradient: Experimental group 1 (high canopy closure): 3 shade nets were taken and fixed to the support poles by pulling ropes. The initial height of the shade nets from the ground was 15cm. Experimental group 2 (medium canopy closure): Two shade nets were taken and fixed to the support poles by pulling ropes. The initial height of the shade nets from the ground was 15cm. Experimental group 3 (low canopy closure): Take one shade net and fix it to the support pole by pulling rope. The initial height of the shade net from the ground is 15cm. Experimental group 4 (control group, full sunlight), without shade netting.

[0065] S3. During the growth of the experimental subjects, their height is monitored regularly, and the height of the shade net is adjusted as needed to maintain the predetermined distance between the shade net and the canopy of the experimental subjects. Experimental Group 1 (High Canopy Closure): During the growth of Isatis indigotica, weeding, pest control, watering, and fertilization were carried out according to growth requirements. The height of the plant was monitored regularly, and the height of the shade net was adjusted as needed to maintain the predetermined distance between the shade net and the canopy of the experimental subject. In this embodiment, after Isatis indigotica sowing: 52 days, the height of the shade net above the ground was adjusted to 20cm; 72 days, the height of the shade net above the ground was adjusted to 25cm; and 94 days, the height of the shade net above the ground was adjusted to 30cm.

[0066] Experimental Group 2 (Medium Canopy Closure): During the growth of Isatis indigotica, weeding, pest control, watering, and fertilization were carried out according to growth requirements. The height of the plant was monitored regularly, and the height of the shade net was adjusted as needed to maintain the predetermined distance between the shade net and the canopy of the experimental subject. In this embodiment, after Isatis indigotica sowing: 52 days, the height of the shade net above the ground was adjusted to 20cm; 72 days, the height of the shade net above the ground was adjusted to 25cm; and 94 days, the height of the shade net above the ground was adjusted to 30cm.

[0067] Experimental Group 3 (Low Canopy Closure): During the growth of Isatis indigotica, weeding, pest control, watering, and fertilization were carried out according to growth requirements. The height of the plant was monitored regularly, and the height of the shade net was adjusted as needed to maintain the predetermined distance between the shade net and the canopy of the experimental subject. In this embodiment, after Isatis indigotica sowing: 52 days, the height of the shade net above the ground was adjusted to 20cm; 62 days, the height of the shade net above the ground was adjusted to 25cm; and 86 days, the height of the shade net above the ground was adjusted to 30cm.

[0068] Experimental Group 4 (Control Group, Full Sunlight): During the growth of Isatis indigotica, weeding, pest control, watering, and fertilization were carried out according to growth requirements. The height of the plant was monitored regularly, and the height of the shade net was adjusted as needed to maintain the predetermined distance between the shade net and the canopy of the experimental plant. In this embodiment, after Isatis indigotica sowing: 52 days, the height of the shade net was adjusted to 20cm; 62 days, the height of the shade net was adjusted to 25cm; and 86 days, the height of the shade net was adjusted to 30cm.

[0069] S4. Determination of core growth indicators: 128 days after sowing, the above-ground parts of Isatis indigotica were harvested and weighed fresh. After washing and drying until the weight was constant, the dry weight of Isatis indigotica was weighed.

[0070] 4. Experimental Results The growth data of the aboveground parts of Isatis indigotica after harvesting for each treatment are shown in the table below. From the growth data, the fresh weight and dry weight of the aboveground parts of treatment 3 are the highest among the four treatments. Therefore, the optimal canopy closure level of Isatis indigotica is "low", and the optimal canopy closure value range is 0.40-0.59.

[0071] Table 3. Determination of core growth indicators of aerial parts of Isatis indigotica under different treatments Experimental group 1 3 high 99.97 11.46 12.03 Experimental group 2 2 middle 146.76 17.65 11.46 Experimental group 3 1 Low 1252.76 138.11 11.02 Experimental group 4 0 Dewy Field 1149.51 125.02 10.88 It should be noted that the application of the simulation device and simulation method described in this invention is not limited to the screening of canopy closure for medicinal plants; it is also applicable to the study of canopy closure adaptability or decomposition rate of other understory objects, such as edible fungi and litter. The final measured "core growth index" will differ for different research objects. For example, for plants and macrofungi, the core index is usually the dry weight yield, reflecting their material accumulation; for litter, the core index is the dry weight of the remaining litter after a predetermined decomposition cycle. By comparing the loss rate of litter dry weight under different canopy closures, the influence of canopy closure on the decomposition rate can be studied.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A forest canopy closure simulation device, characterized in that, include: The support rod (1) is equipped with a height adjustment structure (13) and can be inserted obliquely into the ground; Shade net (2), with buttonholes (21) on the edge; The fixing component includes a pull rope (3) and a connecting structure (12). One end of the pull rope (3) passes through the buttonhole (21) and is detachably connected to the shade net (2). The other end is fixed to the support rod (1) or the ground through the connecting structure (12). By adjusting the height of the support rod (1) or adjusting the fixed position of the connecting structure (12) on the support rod, the shade net (2) can be tensioned, and an adjustable simulated space can be formed between the shade net (2) and the ground planting area. The canopy closure range of the simulated space can be adjusted by adjusting the number of layers of the shade net (2).

2. The forest canopy closure simulation device according to claim 1, characterized in that: The surface of the support rod (1) is provided with an anti-slip structure.

3. The forest canopy closure simulation device according to claim 1, characterized in that: The support rod (1) has scale markings on its surface to indicate its insertion depth or effective height.

4. The forest canopy closure simulation device according to claim 1, characterized in that: The connecting structure (12) is a clamp, which is sleeved on the support rod (1) and can slide and lock on the support rod (1); The clamp is composed of two identical semi-circular structures joined together; The inner wall of the semi-circular structure is provided with an anti-slip structure, and both ends are provided with connecting ears with through holes. The connecting lug is locked in place by a fastener passing through the through hole; The clamp is provided with a connection point for connecting the pull rope (3).

5. The forest canopy closure simulation device according to claim 1, characterized in that: One end of the support rod (1) is provided with a sharp part (11), and the support rod (1) is obliquely inserted into the ground through the sharp part (11); the sharp part (11) is detachably connected to one end of the support rod (1).

6. The forest canopy closure simulation device according to claim 1, characterized in that: The edge of the shade net (2) is provided with a plurality of buttonholes (21), which are spaced apart along the four edges of the shade net (2).

7. The forest canopy closure simulation device according to claim 6, characterized in that: The buttonholes (21) are evenly spaced along the edge of the shade net (2), and the distance between adjacent buttonholes (21) is 50 to 100 cm.

8. The forest canopy closure simulation device according to claim 1, characterized in that: The buttonholes (21) on at least one edge of the shade net (2) can also be connected to the corresponding buttonholes (21) on another shade net (2) by a connecting rope (4) to achieve splicing and expansion of multiple shade nets (2).

9. The forest canopy closure simulation device according to claim 1, characterized in that: The shade net (2) is set in multiple layers, and each layer of the shade net (2) can be independently adjusted and fixed to the support rod (1) by its respective pull rope (3) so as to form different canopy closure gradients by stacking layers.

10. The forest canopy closure simulation device according to claim 1, characterized in that, The height adjustment structure (13) is a locking adjustment mechanism.

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