Growth strain measurement method based on wood form
Patent Information
- Application Number
- CN202510615091.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-14
- Publication Date
- 2025-09-26
AI Technical Summary
Existing technologies for measuring wood growth strain in artificial forests have problems such as insufficient sample representativeness, excessive data variability, and cumbersome operations. In addition, traditional measurement methods cannot be combined with the complexity of artificial forest terrain and the actual growth conditions of wood.
The cross-tree selection method was used to select sample trees. Measurement points were set at both ends of the major and minor diameters of the trunk at breast height, and resistance strain gauges and intelligent resistance strain gauges were used to measure growth strain. The sample boundary was determined in combination with GPS and compass, and the sample trees were distributed according to the undulating terrain.
It improves the uniformity and continuity of sample selection, makes the data more representative, is convenient to operate, and makes the measurement more accurate. It significantly improves the accuracy and precision of the test and can better reflect the actual state of wood growth stress.
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Figure CN120702320A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of wood growth strain measurement, and in particular to a growth strain measurement method based on wood morphology. Background Art
[0002] Plantation timber often experiences high growth stress due to its rapid growth rate and short growth lifespan. The release of growth stress is a key factor in wood cracking and deformation during its utilization. Variations in the properties of stressed wood can also affect subsequent processing and utilization. Currently, the most commonly used method for measuring growth stress is the strain gauge method. This involves attaching a strain gauge to the wood's xylem. Grooves or holes are cut or drilled into the gauge to release the stress, generating growth strain. The strain gauge then converts the strain into a signal, which is then transmitted to a strain gauge, indirectly characterizing the growth stress.
[0003] The key technology of the strain gauge method lies in its minimal interference during measurement and its ability to precisely measure a specific location. Currently, traditional growth strain measurements in plantations generally use the average tree method for tree selection, which can lead to issues such as insufficient representativeness, excessive data variability, and a high risk of overfitting. Furthermore, measurement points are primarily selected along the four axes of east, south, west, and north. However, this method fails to account for the complexity and variability of plantation topography and cannot be correlated with actual wood growth. Traditional methods require selecting an average tree for measurement after measuring tree height and diameter at breast height (DBH), a cumbersome procedure. Furthermore, the method selects trees with uniform height and DBH for growth strain testing, resulting in highly uniform growth strain values within the plots and failing to capture the variability in growth strain across trees within the plot. Therefore, there is an urgent need for a new measurement method that can avoid the underrepresentational nature of traditional random tree selection while establishing a scientific pattern for strain monitoring point placement based on wood morphological characteristics. Summary of the Invention
[0004] In order to solve the above technical problems, the present invention provides a growth strain measurement method based on wood morphology, which aims to more accurately measure the growth strain of sample wood by reasonably selecting the number of measurement samples and measurement points, so that the data can better represent the actual growth conditions of artificial forests, thereby forming a simple, convenient, accurate, time-saving and labor-saving growth strain measurement method suitable for various types of artificial forests.
[0005] To achieve the above objectives, the present invention provides the following technical solutions:
[0006] A method for measuring growth strain based on wood morphology includes the following steps:
[0007] (1) Determination of artificial forest quadrat;
[0008] (2) Cross-selection method: Taking the central upright growth target tree as the benchmark, select several target trees growing upright in the same row and line as the central upright growth target tree, and use spray paint to sort and number the selected trees;
[0009] (3) Selection of sample tree measurement points: Select the two ends of the major and minor diameters of the trunk of the standing tree at breast height, a total of 4 points, numbered clockwise starting from the north;
[0010] (4) Measure the growth strain of the sample wood.
[0011] Preferably, the determination of the artificial forest sample plot in step (1) is to clearly identify the target tree species to be investigated in the artificial forest. In an artificial forest with upright growth and uniform and regular planting point configuration, the sample plot is determined using a systematic sampling method, and the boundaries of the sample plot are determined using tools such as GPS, compass and measuring rope, and are marked with flags, paint and small wooden stakes.
[0012] Preferably, in step (2), if the sample plot is in an area with large terrain undulations, the distribution of sample trees may be distorted with the ups and downs of the terrain, and the sample trees should be selected in accordance with the terrain.
[0013] Preferably, in step (2), when the planting points of adjacent rows of artificial forests are consistent, the number of sample trees selected in the same column should be consistent with the number of trees in the same row; when the planting points of adjacent rows of artificial forests are staggered, two adjacent rows of upright growth target living trees can be appropriately selected as sample trees, and the number of sample trees selected should be consistent with the number of trees in the same row, and this method of selecting sample trees is not only applicable to the selection of trees in horizontal and vertical rows, but also to the selection of trees in oblique cross rows.
[0014] Preferably, in step (3), the trunks are uniform and the long and short diameters cannot be distinguished. If the sample plot is established on a flat slope, the growth strain of the sample trees in the sample plot is measured in the east, south, west and north directions; if the sample plot is established on a slope, the sample trees are marked clockwise starting from the uphill position of the trunk at breast height, and a point is marked every 90°, for a total of four points to measure the growth strain.
[0015] Preferably, in step (4), the growth strain of the sample wood is measured by peeling off the outer bark, phloem tissue and cambium structure at a selected point on the trunk and polishing it; wiping the surface of the wood with a solvent using absorbent cotton until the surface of the absorbent cotton is colorless, evenly applying fast-curing glue on the surface of the wood, pasting the resistance strain gauge and covering it with sulfuric acid paper and continuously pressing; checking the connectivity between the resistance strain gauge and the wood, connecting the wire of the resistance strain gauge to the intelligent resistance strain gauge and adjusting it to zero; drilling holes above and below the resistance strain gauge with an electric drill and then cutting grooves along the holes with a hand saw; when the strain gauge displays an initial reading, it means that the growth stress begins to be released, and the value displayed on the strain gauge is read after it stabilizes, then the strain gauge is turned off and the wire is removed, and another sample wood is tested.
[0016] Compared with the prior art, the present invention has the following beneficial effects:
[0017] The present invention adopts the cross-tree selection method to make the sample selection unified and continuous, and the test data is more representative and the operation is more convenient; furthermore, the method of the present invention selects the long and short diameters at breast height as the test point, and obtains larger extreme values in connection with the trunk morphological variation, which significantly improves the accuracy and precision of the test while making the test data closer to the actual state of wood growth stress, providing strong data support for the optimization of tree breeding and cultivation technology. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 This is a schematic diagram of selecting sample trees when the planting points of adjacent rows of pure forest plantations are consistent in the cross-tree selection method of the present invention.
[0019] Figure 2 This is a schematic diagram of selecting sample trees when the planting points of adjacent rows of pure forest plantations are staggered in the cross tree selection method of the present invention.
[0020] Figure 3 Schematic diagram of the growth strain measured at four points of the major and minor axes in step (3) of the method of the present invention.
[0021] Figure 4 This is a schematic diagram of point selection for measuring growth strain when the major and minor diameters of a tree trunk on a slope cannot be distinguished in step (3) of the method of the present invention.
[0022] Figure 5 This is a schematic diagram of measuring growth strain at eight points in the long and short axes, east, south, west and north in step (3) of comparative example 1. DETAILED DESCRIPTION
[0023] The following is a detailed description of the specific embodiments in conjunction with the accompanying drawings, but it should be understood that the scope of the present invention is not limited by the specific embodiments. Unless otherwise specified, the raw materials and reagents used in the examples are all commercially available. The fast curing glue used in the examples is commercially available KYOWACC-33A glue.
[0024] Example 1
[0025] The cross tree selection method of the present invention ( Figure 1 ) and selection of sample measurement points ( Figure 3 ) as an example, a growth strain measurement method based on wood morphology, the operation steps are as follows:
[0026] (1) Determination of plantation plots: A pure Eucalyptus grandis plantation with upright growth and uniform and regular planting sites was selected from the Hengxian Afforestation Department of Liangfengjiang National Forest Park in Guangxi. A 20 m × 20 m plot was determined using a systematic sampling method. The boundaries of the plot were determined using a compass and a measuring rope, and the plot was marked as plot number 1 with yellow spray paint.
[0027] (2) Cross selection method: select the upright growing Eucalyptus rufipogon in the center of the sample plot, and use this as a benchmark to select the upright growing Eucalyptus rufipogon in the same row and line, a total of 9 trees, such as Figure 1 As shown, use red spray paint to sort and number the selected Eucalyptus grandis trees at a height of 2m, marking them 1, 2, 3, 4, and 5 from top to bottom. Then, with 3 as the central sample, the numbers from left to right are 6, 7, 8, and 9, to facilitate the next step.
[0028] (3) Selection of measurement points for sample trees: Use a digital vernier caliper (TK13-CD-P20M) to confirm the four points of the major and minor diameters at the breast height of the tree, and mark the major diameter C1, minor diameter D1, major diameter C2, and minor diameter D2 with the north direction as the starting point (e.g. Figure 3 As shown in the figure), select the compensation point about 50 cm below the long diameter C1 and the short diameter D1;
[0029] (4) Measuring growth strain of sample trees: peel off the outer bark, phloem tissue and cambium structure of 9 selected tree trunks (size 4cm×4cm), use 220-600 grit sandpaper to polish the wood surface to expose a fresh and smooth wood surface; wipe the wood surface with absorbent cotton dipped in anhydrous ethanol until the surface of the absorbent cotton is colorless, evenly apply fast-curing glue on the wood surface, and place the strain gauge in the grid along the direction of the wood fiber, cover it with sulfuric acid paper and press it moderately and continuously with the thumb for 40 seconds to ensure light strain. The gauge does not fall off and the edge of the strain gauge does not warp; check the connectivity between the resistance strain gauge and the wood, connect the wire of the resistance strain gauge to the intelligent resistance strain gauge (YJW-8), and adjust the zero; use an electric drill to drill holes above and below the resistance strain gauge and then use a hand saw to cut grooves along the holes. When the strain gauge shows the initial reading, the strain release process begins. Continue monitoring until the strain gauge reading tends to stabilize, which takes about 2 minutes. Once the reading stabilizes, immediately record the value, then turn off the strain gauge, remove the wire, and test another sample. The measured growth strain data of the sample wood is shown in Table 1:
[0030] Table 1
[0031]
[0032] The average value of the axial growth strain of the long diameter C1, long diameter C2, short diameter D1, and short diameter D2 at the breast height of 9 vigorous trees of Eucalyptus grandis was 1255×10 -6 , 592×10 -6 , 1100×10 -6 , 641×10 -6 The standard deviation of the axial growth strain at the chest height of the nine Eucalyptus grandis trees was 1.1×10 -4 .
[0033] Example 2
[0034] The cross tree selection method of the present invention ( Figure 2 ) and selection of sample measurement points ( Figure 4 ) as an example, a growth strain measurement method based on wood morphology, the operation steps are as follows:
[0035] (1) Determination of plantation plots: A pure Acacia nigra plantation with upright growth and uniform and regular planting sites was selected in the Liuwan Forest Farm in Guangxi. A systematic sampling method was used to determine 20 m × 20 m plots on the upper, middle, and lower slopes of the south slope. The boundaries of the plots were determined using a compass and a measuring rope, and three plots were marked with yellow spray paint.
[0036] (2) Cross-selection method: Select the upright black acacia in the center of the sample plot, and use this as a benchmark to select upright black acacia in the same row and line, with 5 trees in one sample plot, for a total of 15 trees; use red spray paint to sort and number the selected giant tail eucalyptus trees at a height of 2m, marking them as 1, 2, and 3 from top to bottom, with 2 as the central sample tree, and 4 and 5 from left to right, to facilitate the next step; in areas with large terrain undulations, sample trees should be selected according to the terrain;
[0037] (3) Selection of measuring points for sample trees: If the long and short diameters of the selected sample trees are not obvious when using a digital vernier caliper (TK13-CD-P20M) at the breast height of the tree, the sample trees are marked clockwise starting from the uphill position of the trunk at breast height and marking a point every 90° clockwise, for a total of 4 points: A, B, C, and D (e.g. Figure 4 As shown in the figure, select the compensation point about 50 cm below points A and B;
[0038] (4) Measuring growth strain of sample trees: peel off the outer bark, phloem tissue and cambium structure of 15 selected tree trunks (size 4cm×4cm), use 220-600 grit sandpaper to polish the wood surface to expose the fresh and smooth wood surface, wipe off the excess sap of the wood with cotton cloth, wipe the wood surface with absorbent cotton dipped in anhydrous ethanol until the surface of the absorbent cotton is colorless, and dry it. After no sap emerges from the wood, evenly apply quick-curing glue on the wood surface, and place the strain gauge in the grid along the direction of the wood fiber. Cover with sulfuric acid paper and apply moderate, continuous pressure with your thumb for 60 seconds, ensuring the strain gauge does not fall off or warp when gently pulled. Check the connectivity of the resistance strain gauge to the wood. Connect the wires of the resistance strain gauge to the intelligent resistance strain gauge (YJW-8) and adjust to zero. When the strain gauge displays the initial reading, which marks the beginning of the strain release process, continue monitoring until the strain gauge reading stabilizes, which takes approximately 2 minutes. Once the reading stabilizes, immediately record the value, then turn off the strain gauge, remove the wires, and test another sample. The measured growth strain data for the sample wood is shown in Table 2:
[0039] Table 2
[0040]
[0041]
[0042] The average axial growth strains at breast height of the five Acacia nigra trees on the uphill slope, at points A, B, C, and D, were 1479×10 -6 , 1134×10 -6 , 408×10 -6 ,861×10 -6 The standard deviation of the axial growth strain at breast height on the surface of the five Acacia nigra trees was 1.7×10 -3 The average value of the axial growth strain at breast height of 5 Acacia nigra trees on the middle slope is 2112×10 -6 ,787×10 -6 , 397×10 -6 , 622×10 -6 The standard deviation of the axial growth strain at breast height of the five Acacia nigra trees was 2.3×10 -3 The average axial growth strain of the five Acacia nigra trees at breast height on the downhill slope is 1278×10 -6 ,878×10 -6 , 522×10 -6 ,849×10 -6 The standard deviation of the axial growth strain at breast height on the surface of the five Acacia nigra trees was 2.1×10 -3 .
[0043] Comparative Example 1
[0044] The cross tree selection method of the present invention ( Figure 1 ) to select trees, such as Figure 5 The method for measuring the growth strain based on wood morphology is shown in the figure, comparing the traditional method for measuring the growth strain based on wood morphology (4 points in the east, south, west and north) with the method for measuring the growth strain based on wood morphology (4 points in the long and short diameters) of the present invention. The operation steps are as follows:
[0045] (1) Determination of artificial forest quadrat: same as in Example 1;
[0046] (2) Cross-tree selection method: same as in Example 1;
[0047] (3) Selection of sample tree measurement points: Use a handheld SLAM three-dimensional laser scanner (Huace Rushi RS10) to measure all the living trees in the sample plot, determine the long and short diameters of the five sample trees to be measured, and mark the long diameter C1, short diameter D1, long diameter C2, short diameter D2, east, south, west, and north (such as Figure 5 As shown), select the compensation point about 50 cm below the long axis A and the north direction;
[0048] (4) Measuring growth strain of sample wood: The same as in Example 1, the results are shown in Table 3 below, and the standard deviation is calculated based on the data obtained in Table 3, and the results are shown in Table 4.
[0049] Table 3:
[0050]
[0051] Table 4
[0052]
[0053] Table 3 shows that the proposed method is superior in capturing growth strain extremes compared to traditional methods. A comparison of standard deviations in Table 4 shows that the proposed method achieves higher standard deviations than traditional methods, demonstrating that it more comprehensively captures stress gradient variations across the trunk cross section and is particularly sensitive to extreme values that are often missed by traditional methods. These data statistically validate the technical advantages of the proposed method's method for selecting measurement points based on wood morphology, both in characterizing growth strain distribution gradients and detecting extreme values.
[0054] Comparative Example 2
[0055] The cross tree selection method of the present invention and the traditional standard tree selection method are used to select trees. The selection of sample wood measurement points of the present invention is used as an example to illustrate a growth strain measurement method based on wood morphology. The operation steps are as follows:
[0056] (1) Determination of artificial forest quadrat: same as in Example 1;
[0057] (2) Tree selection method:
[0058] ① Cross selection method: select the upright growing Eucalyptus rufipogon in the center of the sample plot, and use this as a benchmark to select the upright growing Eucalyptus rufipogon in the same row and column, a total of 9 trees, such as Figure 1 As shown, use red spray paint to number the selected Eucalyptus grandis trees at a height of 2m, marking them 1, 2, 3, 4, and 5 from top to bottom. Then, with 3 as the center, mark them 6, 7, 8, and 9 from left to right to facilitate the next step.
[0059] ② Traditional standard tree selection method: After the sample plot is established, the basic data such as the diameter at breast height and tree height of all trees in the sample plot are measured, and the average value of the sample stand is calculated (average diameter at breast height: calculated by the arithmetic mean of the diameters at breast height of all trees; average tree height: obtained based on the tree height of all trees). The trees with the diameter at breast height and tree height closest to the stand average are selected, a total of 9 trees, and red spray paint is used to rank the selected giant eucalyptus trees at a height of 2m and number them 10-18.
[0060] (4) Numbering of remaining standing trees in the sample plot: Select unnumbered standing trees in the sample plot and use red spray paint to sort and number the selected Eucalyptus grandis trees at a height of 2 m from left to right. There are 23 trees in total, which means that there are 41 standing trees in the sample plot.
[0061] (5) Selection of sample measurement points: same as in Example 1;
[0062] (6) Measurement of growth strain of sample wood: Same as Example 1. The results are shown in Table 5 below.
[0063] Table 5
[0064]
[0065]
[0066]
[0067] From the data analysis in Table 5, we can see that the average values of the axial growth strain of the major diameter C1, major diameter C2, minor diameter D1, and minor diameter D2 at the breast height of the 41 living trees in this sample plot are 776.49×10 -6 ,869.10×10 -6 ,765.49×10 -6 ,774.80×10 -6 The overall growth strain standard deviation is 3.68×10 -4 The average value of the axial growth strain of the long diameter C1, long diameter C2, short diameter D1 and short diameter D2 at the chest height of 9 Eucalyptus grandis measured by the cross-tree selection method in the present invention is 799.11×10 -6 ,839.11×10 -6 ,811.33×10 -6 ,804.22×10 -6 The standard deviation of growth strain is 2.62×10 -4 The average value of the axial growth strain of the long diameter C1, long diameter C2, short diameter D1, and short diameter D2 at the chest height of 9 Eucalyptus grandis measured by the traditional standard tree selection method was 785.56×10 -6 , 825.67×10 -6 ,911.89×10 -6 , 725.33×10 -6 The standard deviation of growth strain is 4.32×10 -4. According to the above data analysis, the growth strain values and their standard deviations of the sample trees screened out by the method of the present invention at the four monitoring points of long and short diameters are closer to the overall distribution characteristics of all 41 standing trees in the forest stand, proving that the cross-tree selection method in the method of the present invention can more accurately reflect the true situation of wood growth strain in the forest stand. Compared with the traditional standard wood selection method, the method of the present invention does not need to rely on the time-consuming steps of measuring each tree (such as the measurement of basic data such as breast diameter and tree height) and calculating the forest stand average in the traditional process. Instead, it adopts continuous screening based on the morphological characteristics of standing trees to directly obtain the sample group; this method significantly improves the integrity and reliability of wood growth strain data while ensuring sample adequacy and spatial coverage, which helps to more accurately measure the growth strain of wood.
[0068] The data in Table 5 were subjected to ANOVA analysis, and the results are shown in Table 6. It can be seen that the difference between the method of the present invention and the traditional method for the whole sample is not significant, indicating that the data obtained by the measurement of the present invention is comparable to that of the traditional method.
[0069] Table 6 ANOVA analysis
[0070]
[0071]
[0072] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.
Claims
1. A method for measuring growth strain based on wood morphology, characterized in that: The following steps are included: (1) Determination of artificial forest quadrat; (2) Cross-tree selection method: Taking the central upright growth target tree as the benchmark, select several target trees growing upright in the same row and line as the central upright growth target tree; (3) Selection of sample tree measurement points: select the two ends of the long diameter and short diameter of the trunk of the standing tree at breast height, a total of 4 points; (4) Measure the growth strain of the sample wood.
2. The method for measuring growth strain based on wood morphology according to claim 1, characterized in that: The determination of the artificial forest sample plot in step (1) is to clarify the target tree species to be investigated in the artificial forest. In the artificial forest with upright growth and uniform and regular planting point configuration, the sample plot is determined using a systematic sampling method, and the boundary of the sample plot is determined and marked.
3. The method for measuring growth strain based on wood morphology according to claim 1, characterized in that: In step (2), when the sample plot is located in an area with large terrain undulations, the distribution of sample trees is distorted with the ups and downs of the terrain, and sample trees should be selected according to the terrain.
4. The method for measuring growth strain based on wood morphology according to claim 1, characterized in that: In step (2), when the planting points of adjacent rows of artificial forests are consistent, the number of sample trees selected in the same row should be consistent with the number of trees in the same row; when the planting points of adjacent rows of artificial forests are staggered, two adjacent rows of upright growth target living trees can be selected as sample trees, and the number of sample trees selected should be consistent with the number of trees in the same row.
5. The method for measuring growth strain based on wood morphology according to claim 1, characterized in that: In step (3), the trunks are uniform and the long and short diameters cannot be distinguished. If the sample plot is set up on a flat slope, the growth strain of the sample trees in the sample plot is measured in the east, south, west and north directions; if the sample plot is set up on a slope, the sample trees are marked clockwise starting from the uphill position of the trunk at breast height, and a point is marked every 90°, for a total of four points to measure the growth strain.
6. The method for measuring growth strain based on wood morphology according to claim 1, characterized in that: The growth strain of the sample wood described in step (4) is measured by peeling off the outer bark, phloem tissue and cambium structure at the selected point of the trunk and polishing it; wiping the surface of the wood until it is colorless, applying fast-curing glue on the surface of the wood, pasting the resistance strain gauge and covering it with sulfuric acid paper and continuously pressing; checking the connectivity between the resistance strain gauge and the wood, connecting the wire of the resistance strain gauge to the intelligent resistance strain gauge and zeroing it; drilling holes above and below the resistance strain gauge and then slotting along the holes; when the strain gauge displays the initial reading, it means that the growth stress begins to be released, and the reading is obtained after the value displayed on the strain gauge tends to be stable.