Thinning tree selection system, thinning tree selection method, and thinning tree selection program

Abstract

To provide a thinning tree selection system, a thinning tree selection method, and a thinning tree selection program that can select trees to be thinned while taking into account the density of leaves and branches of the trees.SOLUTION: A thinning tree selection system includes: a selection index value calculation unit 102 that calculates a selection index value for selecting trees to be thinned using the height of the trees, the crown area of the trees, and the degree of transmission or reflection of laser light when the laser light is irradiated from above the trees; a tree pair determination unit 104 that determines tree pairs from among a plurality of trees based on the distance between the trees; and a thinning tree selection unit 105 that selects trees to be thinned from among a plurality of trees using the selection index value. When the thinning method for the trees to be thinned is upper layer thinning, the thinning tree selection unit 105 determines the tree with the larger selection index value of the tree pair as the thinning target tree, and when the thinning method for the trees to be thinned is lower layer thinning, determines the tree with the smaller selection index value as the thinning target tree.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a thinning tree selection system, a thinning tree selection method, and a thinning tree selection program for selecting trees to be thinned.

Background Art

[0002] Conventionally, various techniques for selecting trees to be thinned have been proposed. As an example of such a technique, Patent Document 1 discloses a method for selecting thinning trees for selecting trees to be thinned among the trees existing in a thinning target area based on forest resource information in which information on the trees existing in the thinning target area is recorded for each individual tree.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since the method for selecting thinning trees disclosed in Patent Document 1 does not select thinning trees based on the density of the leaves and branches of the trees, there is a problem that it is not possible to select trees to be thinned considering the density of the leaves and branches.

[0005] The present disclosure provides a thinning tree selection system, a thinning tree selection method, and a thinning tree selection program capable of selecting trees to be thinned considering the density of the leaves and branches of the trees.

Means for Solving the Problems

[0006] A thinning tree selection system for selecting trees to be thinned from among a plurality of trees according to the present disclosure is A selection index value calculation unit that calculates a selection index value for selecting thinning target trees using the height of the trees, the crown area of the trees, and the transmittance or reflectance of the laser light when the trees are irradiated with laser light from above; A tree pair determination unit that determines a tree pair based on the distance between trees from among a plurality of trees; A thinning target tree selection unit that selects thinning target trees from among a plurality of trees using the selection index value calculated by the selection index value calculation unit, The thinning target tree selection unit When the thinning method for the thinning target tree is upper-layer thinning, the tree with the larger selection index value among the tree pair is determined as the thinning target tree. When the thinning method for the thinning target tree is lower-layer thinning, the tree with the smaller selection index value among the tree pair is determined as the thinning target tree.

[0007] When the thinning method for the thinning target tree is whole-layer thinning, the thinning target tree selection unit Classifies a plurality of trees into a plurality of groups based on the magnitude of the selection index value, Among the classified groups, at least the trees belonging to the group with the largest selection index value can be determined as the thinning target trees.

[0008] When the thinning method for the thinning target tree is upper-layer thinning, the thinning target tree selection unit Determines whether the transmittance or transmittance ratio of the laser light for each area of the thinning target area, the relative forest illumination having a positive correlation with the transmittance or transmittance ratio, or the sky openness is less than or equal to a predetermined threshold value; When it is determined that the transmittance or transmittance ratio, the relative forest illumination, or the sky openness is less than or equal to the predetermined threshold value, among the tree pairs in the area where it is determined that the transmittance or transmittance ratio, the relative forest illumination, or the sky openness is less than or equal to the threshold value, the tree with the larger selection index value can be determined as the thinning target tree.

[0009] The thinning target tree selection method for selecting thinning target trees from among a plurality of trees according to the present disclosure is such that a computer A step of calculating a selection index value for selecting a thinning target tree by using the height of a tree, the crown area of the tree, and the degree of transmission or reflection of laser light when the tree is irradiated with laser light from above; A step of determining a tree pair based on the distance between trees from among a plurality of trees; Executing a step of selecting a thinning target tree from among a plurality of trees by using the calculated selection index value; The step of selecting a thinning target tree includes: When the thinning method for the thinning target tree is upper-story thinning, a step of determining, as the thinning target tree, the tree with the larger selection index value among the tree pair; When the thinning method for the thinning target tree is lower-story thinning, a step of determining, as the thinning target tree, the tree with the smaller selection index value among the tree pair.

[0010] A thinning target tree selection program for selecting a thinning target tree from among a plurality of trees according to the present disclosure causes a computer to Execute a step of calculating a selection index value for selecting a thinning target tree by using the height of a tree, the crown area of the tree, and the degree of transmission or reflection of laser light when the tree is irradiated with laser light from above; Execute a step of determining a tree pair based on the distance between trees from among a plurality of trees; Execute a step of selecting a thinning target tree from among a plurality of trees by using the calculated selection index value; The step of selecting a thinning target tree includes: When the thinning method for the thinning target tree is upper-story thinning, a step of determining, as the thinning target tree, the tree with the larger selection index value among the tree pair; When the thinning method for the thinning target tree is lower-story thinning, a step of determining, as the thinning target tree, the tree with the smaller selection index value among the tree pair.

Advantages of the Invention

[0011] According to the present disclosure, it is possible to provide a thinning target tree selection system, a thinning target tree selection method, and a thinning target tree selection program capable of selecting a thinning target tree in consideration of the density of leaves and branches of a tree.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0013] <First Embodiment> Hereinafter, an embodiment will be described with reference to the drawings. FIG. 1 is a diagram showing an example of a system according to an embodiment. The system shown in FIG. 1 includes a thinning tree selection device 10, a measuring device 20, and a terminal device 30.

[0014] The thinning tree selection device 10 is an information processing device that selects thinning target trees existing in a thinning target area. The thinning tree selection device 10 communicates data with the measuring device 20 and the terminal device 30 via a network 40 that may include a LAN (Local Area Network) and / or a WAN (Wide Area Network). The thinning tree selection device 10 corresponds to a thinning tree selection system. The configuration of the thinning tree selection device 10 will be described later with reference to FIG. 2.

[0015] The measurement device 20 is a device that measures a plurality of trees existing in the thinning target area from above. Specific examples of the measurement device 20 include LIDAR (Light Detection And Ranging). The measurement device 20 is mounted on a flying object such as a drone or an aircraft and measures the thinning target area from above.

[0016] The terminal device 30 is an information processing device used by an administrator. Based on an instruction from the administrator, the terminal device 30 provides information for selecting the thinning target trees to the thinning target tree selection device 10 and executes a process of selecting the thinning target trees. The information for selecting the thinning target trees includes thinning condition information indicating the thinning conditions of the thinning target trees. The thinning conditions include upper layer thinning, lower layer thinning, and full layer thinning.

[0017] FIG. 2 is a block diagram showing the configuration of the thinning target tree selection device 10 according to an embodiment. The thinning target tree selection device 10 includes a processor 100, a communication interface 110, and a storage device 120.

[0018] The processor 100 is a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) that controls the electronic circuits and devices included in the thinning target tree selection device 10. The processor 100 executes the method according to an embodiment by reading and executing a program from the storage device 120. The processor 100 executes a tree value calculation unit 101, a selection index value calculation unit 102, a tree distance calculation unit 103, a tree pair determination unit 104, and a thinning target tree selection unit 105, which are programs.

[0019] The communication interface 110 is an interface that performs data communication between the thinning target tree selection device 10 and other devices. When the communication interface 110 receives the measurement information transmitted by the measurement device 20, it provides the measurement information to the tree value calculation unit 101. In addition, the communication interface 110 transmits the result of the process executed by the thinning target tree selection device 10 to the terminal device 30.

[0020] The memory device 120 is a memory device that stores various data such as programs executed by the thinning tree selection device 10.

[0021] The tree value calculation unit 101 is a program that calculates values related to trees using the measurement information provided by the measurement device 20. Specifically, the tree value calculation unit 101 uses the measurement information measured from above a plurality of trees to calculate the height of the trees, the crown area of the trees, and the degree of transmission of the laser light when the laser light is irradiated from above the trees. The degree of transmission of the laser light includes the transmittance and the transmission ratio of the laser light.

[0022] The tree value calculation unit 101 can calculate the height of the tree based on Equation 1.

Equation

[0023] For a region of a certain area, the tree value calculation unit 101 determines the laser light reflected at the crown region edge based on the difference in the reflection time from the output of the laser light output from the measurement device 20 and reflected on the ground to the reception, the reflection time from the output of the laser light output from the measurement device 20 and reflected at the crown region edge that defines the crown region when viewed from above to the reception, and the reflection time from the output of the laser light output from the measurement device 20 and reflected at the top of the tree to the reception. Then, the tree value calculation unit 101 can calculate the area surrounded by the specified laser light as the crown area of the tree.

[0024] The tree value calculation unit 101 identifies the laser light reflected by the ground based on the difference between the reflection time from the output to the reception of the laser light output from the measuring device 20 and reflected by the ground for a region of a certain area, and the reflection time from the output to the reception of the laser light that has not been reflected by the ground (for example, the laser light reflected by the branches and leaves of a tree, etc.) output from the measuring device 20. Then, the tree value calculation unit 101 can calculate the ratio of the laser light reflected by the ground to the entire output laser light as the transmission ratio of the laser light. Also, the tree value calculation unit 101 can calculate the transmittance of the laser light from this transmission ratio of the laser light. The tree value calculation unit 101 stores the calculated tree value in the storage device 120. Note that the tree value may be stored for each tree species.

[0025] The selection index value calculation unit 102 is a program that calculates a selection index value for selecting a thinning target tree based on the tree height, the crown area of the tree, and the degree of laser light transmission calculated by the tree value calculation unit 101. When adopting the transmittance as the degree of laser light transmission, the selection index value calculation unit 102 can calculate the selection index value based on Equation 2.

Equation

[0026] The tree distance calculation unit 103 is a program that calculates the distance between one tree and another tree. Specifically, the tree distance calculation unit 103 selects one tree and calculates the distance between the selected tree and the surrounding trees. More specifically, the tree value calculation unit 101, for a region of a certain area, based on the difference in the reflection time from the output of the laser light output from the measuring device 20 and reflected on the ground until reception, the reflection time from the output of the laser light output from the measuring device 20 and reflected at the edge of the tree crown region that defines the tree crown region, and the reflection time from the output of the laser light output from the measuring device 20 and reflected at the apex of the tree, identifies the laser light reflected at the apex of the tree and determines its position. Then, the tree value calculation unit 101 can select one from among the apexes of the plurality of identified trees and calculate the distance between the position of the apex of the selected tree and the positions of the apexes of the other trees as the forest distance.

[0027] The tree pair determination unit 104 is a program that determines a tree pair based on the tree distance calculated by the tree distance calculation unit 103. Specifically, the tree pair determination unit 104 selects one tree and determines the tree with the minimum distance from the selected tree and the selected tree as a tree pair.

[0028] The thinning target tree selection unit 105 is a program that selects thinning target trees from among a plurality of trees using the selection index value calculated by the selection index value calculation unit 102. Details of the process executed by the thinning target tree selection unit 105 will be described later with reference to FIG. 4.

[0029] FIG. 3 is a diagram showing an example of a sequence of processes executed in the system according to the present disclosure. In step S1, the measuring device 20 measures the forest from above. In step S2, the measuring device 20 provides the measurement information obtained by the measurement to the thinning target tree selection device 10. In step S3, the thinning target tree selection device 10 calculates tree values using the measurement information provided by the measuring device 20 and stores them in the storage device 120.

[0030] In step S4, the terminal device 30 sets thinning conditions based on a user's instruction. In step S5, the terminal device 30 transmits thinning condition information indicating the set thinning conditions to the thinning tree selection device 10.

[0031] In step S6, the thinning tree selection device 10 calculates a selection index value for each tree using the tree values stored in the storage device 120. In step S7, the thinning tree selection device 10 executes a thinning tree selection process. In step S8, the thinning tree selection device 10 transmits the result of the thinning tree selection process to the terminal device 30.

[0032] FIG. 4 is a diagram showing an example of a thinning tree selection process executed by the thinning tree selection device 10. In step S10, the tree interval calculation unit 103 selects one tree and calculates the distance between the selected tree and the surrounding trees. In step S11, the tree pair determination unit 104 determines the tree with the minimum tree interval from the selected tree and the selected tree as a tree pair. Here, the tree pair determination unit 104 can determine a plurality of tree pairs for a plurality of trees existing in the thinning target area.

[0033] In step S12, the thinning tree selection unit 105 determines the thinning method for the thinning target tree based on the thinning condition information provided by the terminal device 30. When the thinning tree selection unit 105 determines that the thinning method is upper layer thinning, in step S13, for each tree pair, the tree with the larger selection index value in the tree pair is determined as the thinning target tree, and the thinning tree selection process ends.

[0034] When the thinning tree selection unit 105 determines that the thinning method is lower layer thinning, in step S14, for each tree pair, the tree with the smaller selection index value in the tree pair is determined as the thinning target tree, and the thinning tree selection process ends.

[0035] When the thinning method determination unit 105 determines that the thinning method is full-layer thinning, it classifies the plurality of trees into a plurality of groups based on the magnitudes of the selection index values of the plurality of trees in step S15. For example, when classifying the plurality of trees into three groups, a first threshold value for classifying the selection index values and a second threshold value smaller than the first threshold value are set. The thinning tree selection unit 105 classifies the trees with selection index values greater than or equal to the first threshold value into a first group, which is the group with the largest selection index value. Next, the thinning tree selection unit 105 classifies the trees with selection index values less than the first threshold value and greater than or equal to the second threshold value into a second group, which is the group with medium selection index values. Then, the thinning tree selection unit 105 classifies the trees with selection index values less than the second threshold value into a third group.

[0036] In step S16, the thinning tree selection unit 105 selects at least one of the classified groups. For example, when classifying the plurality of trees into three groups, the thinning tree selection unit 105 can select the first group, that is, the group with the largest selection index value. Alternatively, the thinning tree selection unit 105 may select the second group, that is, the group with medium selection index values, in addition to the first group.

[0037] In step S17, the thinning tree selection unit 105 determines the trees belonging to the group selected in step S16 as the thinning target trees, and the thinning tree selection process ends.

[0038] As described above, in the first embodiment, the selection index value calculation unit 102 calculates a selection index value for selecting thinning target trees using the height of the tree, the crown area of the tree, and the transmittance or transmission ratio of the laser light when the tree is irradiated with laser light from above. Next, the tree pair determination unit 104 determines a tree pair based on the distance between the trees from among a plurality of trees. Then, the thinning target tree selection unit 105 selects thinning target trees from among a plurality of trees using the selection index value calculated by the selection index value calculation unit 102. When the thinning method for the thinning target tree is upper layer thinning, the thinning target tree selection unit 105 determines the tree with the larger selection index value among the tree pair as the thinning target tree, and when the thinning method for the thinning target tree is lower layer thinning, the thinning target tree selection unit 105 determines the tree with the smaller selection index value among the tree pair as the thinning target tree.

[0039] The transmittance or transmission ratio of the laser light when the tree is irradiated with laser light from above reflects the density of the leaves and branches of the tree. Specifically, the greater the transmittance or transmission ratio of the laser light, the smaller the density of the leaves and branches, and the smaller the transmittance or transmission ratio of the laser light, the greater the density of the leaves and branches. By selecting thinning target trees from among a plurality of trees using the selection index value calculated using such a transmittance or transmission ratio of the laser light, it is possible to select thinning target trees in consideration of the density of the leaves and branches.

[0040] Specifically, when the thinning method for the thinning target tree is upper layer thinning, the tree with the larger selection index value among the tree pair, that is, the tree with a smaller density of leaves and branches, can be determined as the thinning target tree. Also, when the thinning method for the thinning target tree is lower layer thinning, the tree with the smaller selection index value among the tree pair, that is, the tree with a smaller density of leaves and branches, can be determined as the thinning target tree.

[0041] In addition, when the thinning method for the trees to be thinned is full-layer thinning, the selective cutting section 105 classifies a plurality of trees into a plurality of groups based on the magnitude of the selection index value, and determines, as the trees to be thinned, the trees belonging to at least the group with the largest selection index value among the classified groups. As a result, when the thinning method for the trees to be thinned is full-layer thinning, it is possible to determine, as the trees to be thinned, the trees belonging to the group with the largest selection index value, that is, the trees belonging to the group with a high density of leaves and branches.

[0042] <Second Embodiment> FIG. 5 is a diagram showing an example of the selective cutting process for thinned trees according to the second embodiment. In the second embodiment, the selective cutting process for the trees to be thinned when the thinning method is upper-layer thinning is different from that in the first embodiment. Steps S10 to S12 and S14 to S17 shown in FIG. 5 are the same as steps S10 to S12 and S14 to S17 shown in FIG. 4, and thus the description thereof is omitted.

[0043] In step S20, the selective cutting section 105 calculates the transmittance of the laser light for each of a plurality of areas (for example, a 10 m × 10 m grid, etc.) in the thinning target area based on the measurement data. As the transmittance of the laser light for each area, for example, a representative value such as the average value or the median value of the transmittance of the laser light related to the area can be adopted. In other embodiments, the transmittance of the laser light may be calculated with the entire thinning target area as one area.

[0044] In step S21, the selective cutting section 105 determines, for each area, whether the calculated transmittance of the laser light is equal to or less than a predetermined threshold value. The threshold value can be any transmittance.

[0045] If it is determined that the calculated transmittance of the laser light is equal to or less than the predetermined threshold value (YES), in step S22, the selective cutting section 105 determines, for each tree pair in the area where it is determined that the transmittance of the laser light is equal to or less than the predetermined threshold value, the tree with the larger selection index value among the tree pairs as the tree to be thinned, and the selective cutting process for thinned trees ends. On the other hand, if it is determined that the calculated transmittance of the laser light is not equal to or less than the predetermined threshold value (NO), the selective cutting process for thinned trees ends.

[0046] As described above, in the second embodiment, when the thinning method for the thinning target trees is upper layer thinning, the thinning tree selection unit 105 determines whether the transmittance of the laser light for each area of the thinning target area is equal to or less than a predetermined threshold value. When it is determined that the transmittance is equal to or less than the predetermined threshold value, the thinning tree selection unit 105 determines, as the thinning target trees, the trees with larger selection index values among the tree pairs in the area where it is determined that the transmittance is less than the threshold value. In other embodiments, instead of the transmittance of the laser light for each area of the thinning target area, the transmission ratio of the laser light may be adopted. Thereby, it is possible to determine the thinning target trees in consideration of the degree of transmission of the laser light in each area of the thinning target area.

[0047] Also, as a modification of the second embodiment, when the thinning method for the thinning target trees is upper layer thinning, the thinning tree selection unit 105 may determine whether the relative forest illuminance, which has a positive correlation with the transmittance or transmission ratio of the laser light for each area of the thinning target area, is equal to or less than a predetermined threshold value. As shown in FIG. 6, the relative forest illuminance has a positive correlation with the transmittance. The predetermined threshold value can be any illuminance. When it is determined that the relative forest illuminance is equal to or less than the predetermined threshold value, the thinning tree selection unit 105 determines, as the thinning target trees, the trees with larger selection index values among the tree pairs in the area where it is determined that the relative forest illuminance is less than the threshold value. Thereby, it is possible to determine the thinning target trees in consideration of the relative forest illuminance in each area of the thinning target area.

[0048] Furthermore, as a modification of the second embodiment, when the thinning method for the thinning target trees is upper layer thinning, the thinning tree selection unit 105 may determine whether the sky openness for each area of the thinning target area is equal to or less than a predetermined threshold value. The predetermined threshold value can be any value. The sky openness is the degree of visible sky when looking up from the ground, and is the same value as the transmittance of the laser light described above. The sky openness includes the sky opening ratio and the sky opening rate. The tree value calculation unit 101 can calculate the sky opening ratio and the sky opening rate using the calculation methods of the transmission ratio and the transmittance of the laser light described above.

[0049] When it is determined that the sky openness is equal to or less than a predetermined threshold value, the thinning target tree selection unit 105 determines, as the thinning target tree, the tree with the larger selection index value among the tree pairs within the area where it is determined that the sky openness is equal to or less than the threshold value. Thereby, it is possible to determine the thinning target tree in consideration of the sky openness of each area of the thinning target area.

[0050] Furthermore, in another embodiment, instead of the transmittance of the laser light, the reflectance of the laser light from above the tree may be adopted. The reflectance of the laser light includes the reflectivity and the reflection ratio of the laser light. When the reflectivity is adopted as the reflectance of the laser light, the selection index value calculation unit 102 can calculate the selection index value based on Equation 3.

Equation

[0051] The reflectivity and the reflection ratio of the laser light reflect the density of leaves and branches. The greater the reflectance of the laser light, the greater the density of leaves and branches, and the smaller the over-reflectance of the laser light, the smaller the density of leaves and branches. The selection index value calculated using such reflectance of the laser light can reflect the density of leaves and branches. By selecting the thinning target tree from among a plurality of trees using such a selection index value, it is possible to select the thinning target tree in consideration of the density of leaves and branches.

[0052] Furthermore, in the above-described embodiment, a single thinning target tree selection device 10 executes the tree value calculation unit 101, the selection index value calculation unit 102, the tree distance calculation unit 103, the tree pair determination unit 104, and the thinning target tree selection unit 105. However, in other embodiments, these programs may be executed by individual information processing devices in a distributed manner.

[0053] In the above example, when the program is loaded into a computer, it includes a set of instructions (or software code) for causing the computer to perform one or more functions described in the embodiments. The program may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, a computer-readable medium or a tangible storage medium includes random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD), or other memory technologies, CD-ROM, digital versatile disk (DVD), Blu-ray (registered trademark) disk, or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage devices. The program may be transmitted on a transient computer-readable medium or a communication medium. By way of example and not limitation, a transient computer-readable medium or a communication medium includes electrical, optical, acoustic, or other forms of propagated signals. Computers include various devices such as personal computers (PCs), servers, central processing units (CPUs), microprocessor units (MPUs), field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), and the like.

[0054] The present disclosure is not limited to the above-described embodiments, and can be appropriately modified without departing from the spirit of the present disclosure.

Description of Reference Numerals

[0055] 10: Thinning tree selection device, 20: Measuring device, 30: Terminal device, 40: Network, 100: Processor, 101: Tree value calculation unit, 102: Selection index value calculation unit, 103: Inter-tree distance calculation unit, 104: Tree pair determination unit, 105: Thinning tree selection unit, 110: Communication interface, 120: Storage device

Claims

1. A thinning target tree selection system for selecting thinning target trees from a plurality of trees, a selection index value calculation unit that calculates a selection index value for selecting the thinning target trees using the height of the trees, the crown area of the trees, and the degree of transmission or reflection of the laser light when the trees are irradiated with laser light from above; a tree pair determination unit that determines tree pairs based on the distance between the trees from among the plurality of trees; and a thinning target tree selection unit that selects thinning target trees from among the plurality of trees using the selection index value calculated by the selection index value calculation unit, wherein the thinning target tree selection unit when the thinning method for the thinning target trees is upper layer thinning, determines the tree with the larger selection index value among the tree pairs as the thinning target tree; when the thinning method for the thinning target trees is lower layer thinning, determines the tree with the smaller selection index value among the tree pairs as the thinning target tree. A thinning target tree selection system.

2. When the thinning method for the thinning target trees is whole layer thinning, the thinning target tree selection unit classifies a plurality of trees into a plurality of groups based on the magnitude of the selection index value, and determines the trees belonging to at least the group with the largest selection index value among the classified groups as the thinning target trees. The thinning target tree selection system according to Claim 1.

3. When the thinning method for the thinning target trees is upper layer thinning, the thinning target tree selection unit determines whether the transmittance or transmission ratio of the laser light for each area of the thinning target area, the relative forest illuminance that has a positive correlation with the transmittance or transmission ratio, or the sky openness is less than or equal to a predetermined threshold value, and when it is determined that the transmittance or transmission ratio, the relative forest illuminance, or the sky openness is less than or equal to the predetermined threshold value, determines the tree with the larger selection index value among the tree pairs within the area where it is determined that the transmittance or transmission ratio, the relative forest illuminance, or the sky openness is less than or equal to the threshold value as the thinning target tree. The thinning target tree selection system according to Claim 1 or 2.

4. A thinning target tree selection method for selecting thinning target trees from a plurality of trees, wherein a computer calculates a selection index value for selecting the thinning target trees using the height of the trees, the crown area of the trees, and the degree of transmission or reflection of the laser light when the trees are irradiated with laser light from above; determines tree pairs based on the distance between the trees from among the plurality of trees; executing a step of selecting thinning target trees from among a plurality of trees using the calculated selected index value; the step of selecting the thinning target trees includes: when the thinning method for the thinning target trees is upper-story thinning, determining, as the thinning target tree, the tree with the larger selected index value among the tree pairs; when the thinning method for the thinning target trees is lower-story thinning, including determining, as the thinning target tree, the tree with the smaller selected index value among the tree pairs; A method for selecting thinning target trees. **Claim 5** A program for selecting thinning target trees from among a plurality of trees, which causes a computer to calculate a selected index value for selecting the thinning target trees using the height of the tree, the crown area of the tree, and the degree of transmission or reflection of the laser light when the tree is irradiated with laser light from above; determine tree pairs based on the distances between the trees from among the plurality of trees; execute a step of selecting thinning target trees from among the plurality of trees using the calculated selected index value; the step of selecting the thinning target trees includes: when the thinning method for the thinning target trees is upper-story thinning, determining, as the thinning target tree, the tree with the larger selected index value among the tree pairs; when the thinning method for the thinning target trees is lower-story thinning, including determining, as the thinning target tree, the tree with the smaller selected index value among the tree pairs; A program for selecting thinning target trees.

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