Afforestation method for equally dividing circumference of five trees

Abstract

The invention provides an afforestation method for equally dividing circumference of five trees, and belongs to the technical field of forest cultivation. Comprising the following steps: determining a circle radius r, a short plant distance Ld, a long plant distance Lc and a circle center distance s according to an afforestation density N; five planting points are determined on the circumference according to the short plant spacing equally divided circumference, no planting point exists in the circle, it is ensured that when any one tree serves as a reference tree (or an analysis object), the reference tree and four nearest adjacent trees can be located on the same circle, and the five trees form a basic afforestation unit; according to the circle center distance s, the basic afforestation units are sequentially arranged till the afforestation land is full of the units. According to the artificial forest built by the method, each tree is an aggregated tree with the same growth advantage, the living space and the light receiving surface are the same, each tree has the same competitive distance and the same number of potential competitors, and the survival rate of the trees is increased while the growth advantage of the aggregated tree is maintained. And the high death rate caused by competition between adjacent woods of a common aggregate is also avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of forest cultivation, in particular to a reforestation method of five-tree equal-circumference. BACKGROUND

[0002] There is no doubt that the contribution of plantations in wood production, carbon sink, soil and water conservation, and wind prevention and sand fixation is significant, but the problem of low productivity and poor stability of global plantations still exists. Most of the literature attributes the poor stability of plantations to the planting of single tree species, ignoring the existence of large areas of natural forests composed of single tree species for hundreds or even thousands of years in high-altitude or high-latitude regions (such as the spruce forests in the Tianshan Mountains in northwest China and the Dahinggan Mountains in northeast China). The existence of these natural pure forests makes people question the tree species diversity-stability hypothesis, and whether the stability of a forest is related to the composition of tree species or the pattern type of forest distribution. The random body-stability hypothesis is thus generated.

[0003] In addition, plantations, as the name implies, are forests planted by humans. The primary problem is what and how to plant on the land to be reforested. For many years, people have always believed that the low productivity of plantations is due to the fact that the selection of planting materials is problematic, and the key technical problem of planting in an unscientific location is ignored. As we all know, good seeds and good methods together affect the formation of productivity. The configuration of planting points in the good method determines the formation of the initial pattern of plantations, and the initial pattern is the key to the formation of the productivity of plantations. At present, the traditional single-tree rectangular (square) and triangular regular configuration method has always been used in forestry production. The traditional simple and convenient rectangular or square configuration allows people to reduce the competition between evenly distributed tree individuals by increasing the distance between trees, but this will lose the contribution of the number of trees to stand productivity. Based on the idea of near-natural forest cultivation, people can artificially create forests with high stability through controlled site reforestation, but the problem of productivity and stability trade-off still exists.

[0004] This paper attempts to propose a new reforestation method, which explains the feasibility of the designed reforestation method from the perspective of logical reasoning, aims to reveal the structural effects of the formation of plantation productivity and the maintenance of stability, and to control the initial link of precise improvement of plantation quality, and to scientifically lead the high-quality development of plantations in the world. SUMMARY

[0005] The purpose of the present application is to provide a new reforestation method, which hopes to construct a new planting mode of aggregates, increase the distance between adjacent trees, and change the orientation of the nearest adjacent trees to avoid the instability of aggregates in forests.

[0006] In order to achieve the above-mentioned application purpose, the present application provides the following technical solutions: (1) According to the afforestation density N, the circle radius r, the short plant spacing l d , the long plant spacing l c and the circle center spacing s are determined; (2) On the afforestation land to be afforested, a point is taken as the origin to make a circle with the radius r, and five planting points are determined on the circumference according to the short plant spacing l d , and the circumference is equally divided to ensure that when any one tree is taken as a reference tree, the four nearest neighboring trees are all on the same circle, and the five trees constitute a basic afforestation unit; (3) According to the circle center spacing s, the basic structure unit is arranged in turn until the afforestation land is covered.

[0007] Preferably, the short plant spacing l d in step (1) is the straight-line distance between two adjacent planting points, as shown in formula 1; (Formula 1); The long plant spacing l c is the straight-line distance between two planting points separated by one planting point, as shown in formula 2; (Formula 2).

[0008] The circle center spacing s is the distance between the centers of two adjacent basic afforestation units, as shown in formula 3 (Formula 3).

[0009] Preferably, the basic structure unit is arranged in turn in a square or an equilateral triangle, and the circle center is the vertex of the square or the equilateral triangle.

[0010] Preferably, when the basic afforestation unit is arranged in a square, s is the side length of the square, and the number n of basic afforestation units is as shown in formula 4-1; (Formula 4-1); The afforestation density is as shown in formula 3-3; (Formula 4-2); According to the afforestation density N, the circle radius r of the circular afforestation can be determined as shown in formula 4-3: (Formula 4-3).

[0011] Preferably, when the basic afforestation unit is arranged in an equilateral triangle, s is the side length of the three sides of the triangle, and the number n of basic afforestation units is as shown in formula 5-1; (Formula 5-1); The afforestation density N is as shown in formula 5-2, and the relationship between the afforestation density N and r at this time is: (Formula 5-2); Based on this afforestation density N, the radius r of a circular afforestation can be determined as shown in Equation 5-3: (Equation 5-3).

[0012] This field describes the uniformity of adjacent trees around a reference tree by judging and statistically analyzing whether the angle formed by the reference tree and its nearest neighbor is greater than the standard angle (72°), thus obtaining the horizontal distribution pattern of trees without the need for precise distance measurement.

[0013] Starting from the reference tree, any two nearest neighbor trees have two included angles. Let the smaller angle be α and the larger angle be β, then α + β = 360°. The angles formed by the reference tree and its nearest neighbors 1 and 2, 1 and 4, 2 and 3, and 3 and 4 are all represented by the smaller angle α. 12 α 14 α 23 α 34 Indicates, such as Figure 1 Typically, the calculation of the angular scale is based on the four nearest neighbor trees. (Formula 6); Angular scale (W) i Angle α is defined as the proportion of angles smaller than the standard angle α0 = 72° out of the four angles under consideration, as shown in Equation 7: (Equation 7) in, .

[0014] According to the principle of angular scaling, the angular scale reflects the uniformity of the distribution of neighboring trees around a reference tree, and its value ranges from 0, 0.25, 0.5, 0.75 to 1. Where: when the angular scale exponent W... i When W = 0 or 0.25, it indicates that the adjacent trees of the reference tree form a uniform distribution pattern. This type of reference tree is simply called a uniform tree, and the structural unit it constitutes is called a uniform body; when W i When W = 0.75 or 1, it indicates that the adjacent trees of the reference tree are clustered, the corresponding reference tree is a clustered tree, and the structural unit formed is an aggregate; when W i When the coefficient of variation is 0.5, the adjacent trees of the reference tree form a random distribution, and the corresponding reference tree is a random tree, whose structural unit is a random body. Therefore, the spatial structure of any forest stand can be deconstructed into an organic combination of three basic units: homogeneous bodies, aggregates, and random bodies. Figure 2 As shown, trees with different structures have different growth characteristics. For aggregates, their spatial configuration has a significant ecological effect. The crowded distribution of adjacent trees creates a three-way light-receiving pattern for the reference tree. The three-way light resource acquisition pattern improves photosynthetic efficiency, which is conducive to the healthy growth of trees and provides them with greater nutrient space and productivity gains. This is consistent with the forest edge or forest window effect theory of tree growth.

[0015] In the artificial forests created by this method, each tree is a cluster with the same growth advantage, the same living space, the same amount of sunlight exposure, and the same competitive distance and number of potential competitors. The ratio of the length of adjacent trees to the distance between adjacent trees in each cluster is equal to 1.618. This golden ratio overcomes the instability caused by the intense competition between adjacent trees in natural clusters, maintaining the growth advantage of clustered trees while avoiding the high mortality rate caused by competition between adjacent trees in natural clusters. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the angle formed by the reference tree and its nearest neighboring tree, with the smaller angle being α and the larger angle being β, where α + β = 360°.

[0017] Figure 2 For the classification of forest trees based on the angular scale.

[0018] Figure 3 This is a line segment structure diagram for the afforestation method of dividing a circle into 5 trees, where C represents the center of the circle, r represents the radius of the circle, and l d Represents short plant spacing or the side length of a regular pentagon, l c Representing long spacing between trees or diagonal lines, T1-T5 represent 5 trees.

[0019] Figure 4 The diagram shows five trees dividing the circle into equal parts.

[0020] Figure 5 The geometric diagram shows the five trees dividing the circle equally.

[0021] Figure 6 This is the basic afforestation unit linking method.

[0022] Figure 7 A square arrangement with 5 trees equally divided into circles.

[0023] Figure 8 The triangle configuration is for 5 trees dividing the circle equally.

[0024] Figure 9 This is a diagram showing the canopy relationships of each tree in different structures with the same density.

[0025] Figure 10 This is a diagram showing the distribution of different structures in the experimental example. Detailed Implementation

[0026] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0027] Example 1

[0028] A method for afforestation that divides a circle into five equal parts.

[0029] (1) Determine the radius r of the circle and the shortest plant spacing l d Long plant spacing l c And the distance between the centers, s; 。

[0030] Among them, the short plant spacing l d The straight-line distance between two adjacent planting points is shown in Equation 1; (Equation 1); The long plant spacing l c The straight-line distance between two planting points that are separated by one planting point is shown in Equation 2; (Equation 2); The center-to-center distance s is the distance between the centers of two adjacent basic afforestation units, as shown in Equation 3; (Equation 3); (2) such as Figure 3 As shown, on the land to be afforested, take a point as the origin and draw a circle with a radius of r meters as a basic afforestation unit. Mark points on the circumference, starting with the first point in the due north direction. Divide the circumference into four equal parts based on short plant spacing to determine the other four planting points. There are no planting points inside the circle. Figure 4 As shown, the nearest distance between any two adjacent planting points is equal, and the central angle of the arc formed by them is 72°. This ensures that when any tree is used as a reference tree, it is on the same circle as its four nearest neighboring trees. The neighbors of each tree and their distribution are shown below. Figure 5 As shown, each tree in the geometric diagram has two adjacent trees with equal shortest distances (shortest tree spacing) and two adjacent trees with equal longest distances (longest tree spacing). Of the four angles formed by each tree and its four nearest neighbors, one is 108° (greater than the standard angle), and three are 36° (less than the standard angle). The angular scale value (Wi) of all trees is equal to 0.75. Therefore, it can be determined that the five trees on the circumference are a cluster of trees with identical angular scale values ​​and distribution patterns.

[0031] (3) such as Figure 6 As shown, s represents the center-to-center distance between two circles. According to the principle of angular scale, the distance of the 4th neighbor of each tree (l) c The distance between the circles must be less than the minimum distance between them to ensure that each tree on a circle is on the same circle as its four nearest neighbors.

[0032] With the distance s between the centers of the circle as the side length of the square, and the center C as the vertex of the square, according to... Figure 7 The basic afforestation units are arranged sequentially until the afforestation area is fully covered. The number of five equal circles (basic afforestation units) and the number n are shown in Equation 4-1. (Equation 4-1); The afforestation density is as shown in Formula 3-3; (Equation 4-2); Based on this afforestation density N, the radius r of a circular afforestation can be determined as shown in Equation 4-3: (Equation 4-3).

[0033] Example 2

[0034] Unlike Example 1, step (3) in this example is: taking the center distance s as the side length of the equilateral triangle and the center c as the vertex of the equilateral triangle, according to... Figure 8 Arrange the basic afforestation units in sequence until the afforestation area is covered. The number of five equal circles (basic afforestation units) n is as shown in Equation 5-1. (Equation 5-1); The afforestation density N is as shown in Equation 4-2. The relationship between the afforestation density N and r is: (Equation 5-2); Based on this afforestation density N, the radius r of a circular afforestation can be determined as shown in Equation 5-3: (Equation 5-3).

[0035] Experimental Example 1

[0036] With the same circle radius, five trees are planted in each circle, with the same density in each circle. The relative positions of the five planting points within each circle are changed, referring to... Figure 2 Make the reference tree angle scale W i The values ​​are 0, 0.5, and 0.75 respectively (red dots represent planting points for reference trees, blue dots represent planting points for adjacent trees; all five dots being red means that trees at all five planting points can be used as reference trees). Five groups of planting point configurations with the same density but different patterns are set up, such as... Figure 9 As shown.

[0037] Figure 9 This visually illustrates the microenvironment for the growth and survival of trees with the same density but different structures. In the first four structures with a central log, both the central log and adjacent logs are likely to face greater competition within their respective structures than in the circular afforestation aggregate without a central log. In the former structures, uniform logs (W... i =0), random wood (W) i =0.5) and general aggregate wood (W i=0.75) The minimum distance between the central tree and its adjacent trees is r. In other words, at this competitive distance r, the central tree has 4 competitors, while the minimum distance between adjacent trees of random trees and general clustered trees may be 0. Circular afforestation has no central tree and is a hollow circle. According to the relationship between the radius of the circle and the side length of the inscribed regular pentagon (i.e., the minimum spacing between trees), the minimum spacing between trees on the circumference is 1.176 times r. Each tree has two competitors at a distance of 1.176 times r and two competitors at a distance of 1.902 times r. That is to say, the central tree of the aforementioned structure faces a smaller competitive distance than the trees on the hollow circle, and at the minimum competitive distance, it faces more direct competitors than the latter, resulting in much greater competitive pressure. When the canopies of the central trees of each structure are tangent to those of adjacent trees but before actual competition begins, contact competition may have already begun between adjacent trees. At this time, the trees on the hollow circle (W) i =0.75) The tree canopies are still some distance apart; when the tree canopies on the hollow circle have just become tangent to two adjacent trees and have not yet truly begun to compete, the structures with the central tree have already experienced deep contact between the central tree and four adjacent trees, as well as between the canopies of the adjacent trees, and the trees are in a clearly competitive environment. Especially for uniform trees, adjacent trees will quickly form canopies with the uniform tree from 3-4 directions, physically blocking each other; and adjacent trees in general aggregates will also experience similar intense competition due to crowding. Therefore, uniform trees or adjacent trees in aggregates are more likely to be in a competitive environment that is not conducive to photosynthesis for a long time; at this time, adjacent trees of random bodies have also had some contact and competition with random trees from 2 directions, or between adjacent trees.

[0038] Experimental Example 2

[0039] This invention was used in a controlled afforestation experiment of Populus tomentosa in Fangshan, Beijing (starting in 2016) to study the crown characteristics and growth of aggregated and random trees in plantations during conventional afforestation. The structure is as follows: Figure 10 The results showed that the canopy characteristics of clustered and random trees in the plantation were better than those of uniform trees (Table 1), and the growth of clustered trees was greater than that of random and uniform trees (Table 2).

[0040] Table 1. Crown characteristics of central wood trees with different structures in the third year after planting (2018)

[0041] Table 1 shows that in the third year after planting, the canopy projection area, canopy extension, canopy roundness, canopy surface area, and canopy volume of trees all increased with the increase of the W value. i =0.5, W i =0.75 Two types and W iThe =0 type showed significant differences, indicating that the canopies of random and clustered trees competed for growth space more effectively than those of uniform trees, and thus made fuller use of space.

[0042] Table 2. Diameter growth of central timber in different structures, 2018-2024

[0043] Table 2 shows that the diameter at breast height (DBH) of the central timber of different structures increased with W over the five years. i As the value increases, the diameter at breast height (DBH) growth and growth rate of the central trees in aggregated structures are significantly greater than those in random and uniform structures. Over five years, the DBH growth rate of aggregated trees reached 64.5%, which is 16.8% higher than that of random trees and 37.2% higher than that of uniform trees. With the increase in unevenness in the forest structure, the spatial ecological niche of trees is improved, the competitive pressure among trees is reduced, and the nutrient space for trees is increased, thus accelerating growth. The ranking of individual tree growth rates for different structures in controlled-location afforestation is: aggregated trees > random trees > uniform trees.

[0044] It is evident that clustered trees generally have a growth advantage over random and uniform trees. In the circular afforestation of this invention, each tree is a clustered tree with the same growth advantage, which avoids the competitive disadvantage of adjacent trees in a general cluster. Therefore, all trees on the hollow circle have a longer time to grow freely, receive sufficient sunlight and nutrients, and maintain metabolic balance. They have a larger living space and a more stable growth environment with lower intensity competition than the central or adjacent trees in a general uniform, random, or clustered structure. The probability of weak trees appearing is reduced, and the probability of survival during natural growth is higher.

[0045] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for afforestation by dividing a circle into five equal parts with five trees, characterized in that, Includes the following steps: (1) Determine the radius r of the circle and the shortest spacing l based on the afforestation density N. d Long plant spacing l c And the distance between the centers, s; (2) On the land to be afforested, take a point as the origin and draw a circle with radius r. On the circumference, according to the short plant spacing l d Five planting points are determined by dividing the circumference into equal parts. There are no planting points inside the circle. This ensures that when any tree is used as a reference tree, it is on the same circle as its four nearest neighboring trees. The five trees constitute a basic afforestation unit. (3) Arrange the basic structural units in sequence according to the center distance s until the afforestation area is covered.

2. The afforestation method as described in claim 1, characterized in that, The short plant spacing l mentioned in step (1) d The straight-line distance between two adjacent planting points is shown in Equation 1; (Equation 1); The long plant spacing l c The straight-line distance between two planting points that are separated by one planting point is shown in Equation 2; (Equation 2); The center-to-center distance s is the distance between the centers of two adjacent basic afforestation units, as shown in Equation 3; (Equation 3).

3. The afforestation method as described in claim 2, characterized in that, The basic afforestation units are arranged in a square or equilateral triangle pattern, with the center of the circle being the vertex of the equilateral triangle or square.

4. The afforestation method as described in claim 3, characterized in that, When the basic afforestation units are arranged in a square, s is the side length of the square, and the number of basic afforestation units n is as shown in Equation 4-1. (Equation 4-1); The afforestation density N is as shown in formula 3-3; (Equation 4-2); Based on this afforestation density N, the radius r of a circular afforestation can be determined as shown in Equation 4-3: (Equation 4-3).

5. The afforestation method as described in claim 3, characterized in that, When the basic afforestation units are arranged in an equilateral triangle, s is the side length of the three sides of the triangle, and the number of basic afforestation units n is as shown in Equation 5-1. (Equation 5-1); The afforestation density N is as shown in Equation 5-2. The relationship between the afforestation density N and r is: (Equation 5-2); Based on this afforestation density N, the radius r of a circular afforestation can be determined as shown in Equation 5-3: (Equation 5-3).

Images