Method for transforming artificial timber forest into ecological public welfare forest

文档序号：35670 发布日期：2021-09-24 浏览：29次中文

阅读说明：本技术 一种人工用材林向生态公益林转化方法 (Method for transforming artificial timber forest into ecological public welfare forest ) 是由贺康宁王作枭左亚凡李远航林莎张静于 2021-07-23 设计创作，主要内容包括：本发明公开了一种人工用材林向生态公益林转化的方法,包括比较待转化人工用材林内的对象木与其邻近木胸径、冠幅或/和树高,筛选、确定并标记待采伐对象木；确定林木采伐强度,并进行采伐；然后进行苗木补植。本发明方法简单,方便易行,林木检尺结果准确,采用本发明方法的林地转化效果显著,改造后的林分结构向着复层、异龄、混交方向发展,林分空间结构明显优化,有效地改善了原有的立地条件,混交度增加,种群隔离程度大幅提高；林分叶面积指数下降,林内穿透雨量显著增加；林下枯落物层厚度降低,最大持水量下降,更多的水分渗入土壤层被森林所存储；林下物种多样性、林分稳定性及健康指数得到了提高。(The invention discloses a method for transforming an artificial timber forest into an ecological public welfare forest, which comprises the steps of comparing the breast diameter, the crown width or/and the tree height of an object wood in the artificial timber forest to be transformed with the adjacent trees, screening, determining and marking the object wood to be felled; determining the felling strength of the forest and felling; then, the nursery stock is replanted. The method is simple, convenient and easy to implement, the forest scale detection result is accurate, the forest land transformation effect is obvious by adopting the method, the reconstructed forest stand structure develops towards the direction of multiple layers, different ages and mixed crossing, the spatial structure of the forest stand is obviously optimized, the original standing conditions are effectively improved, the mixed crossing degree is increased, and the population isolation degree is greatly improved; the area index of the forest stand leaves is reduced, and the penetration rainfall in the forest is obviously increased; the thickness of the underground litter layer is reduced, the maximum water holding capacity is reduced, and more water permeates into the soil layer and is stored by the forest; the under forest species diversity, forest stand stability and health index are improved.)

1. A method for transforming an artificial timber forest into an ecological public welfare forest is characterized by comprising the steps of comparing the breast diameter, the crown width or/and the tree height of an object tree in the artificial timber forest to be transformed with the diameter, crown width or/and tree height of an adjacent tree; screening, determining and marking object trees to be felled; after calculating the total cutting strength of the forest land to be converted, cutting and replanting the nursery stock of the forest trees in the forest land according to the requirement that the cutting strength of each time in the cutting process is lower than 30 percent.

2. The method of claim 1, wherein the artificial timberland is selected from the group consisting of high density pure tree species, preferably high density pure pine timberland.

3. The method according to claim 1 or 2, characterized in that the total harvest strength is the number of target trees to be harvested/total number of target trees in the forest land to be transformed x 100%.

4. The method of claim 1 or 2, wherein the crown frames are east-west crown frames x south-north crown frames.

5. A method as claimed in claim 1 or 2, characterized in that, after the nursery stock is replanted in the forest land to be transformed, the forest stand mixing ratio in the forest land is (6-8): (2-4), preferably 7: 3.

6. A method for transforming an artificial timber forest into an ecological public welfare forest is characterized by comprising the following steps of:

1) setting a forest stand transformation sample plot in the artificial timber to be transformed, and setting a strip-shaped buffer area along the periphery in the transformation sample plot, wherein the line-contained area in the strip-shaped buffer area is a forest stand transformation area;

2) taking any one tree in the forest stand transformation sample plot as an origin tree, wherein the number of the origin tree is 1; sequentially numbering all trees in the forest stand transformation sample plot from the original point tree, wherein the total number of all trees in the forest stand transformation sample plot is N;

3) sequentially measuring and recording the tree height, the breast height and the crown width of each tree in the process of numbering the trees in the forest stand transformation sample plot;

4) screening trees to be felled

4-1) firstly determining the number M of plants of adjacent trees B around each object tree A in the forest stand reconstruction area;

4-2) comparing the breast height, crown width or/and tree height of each object tree and the adjacent trees around the object tree in the forest stand reconstruction area in sequence, screening the trees in the reconstruction area according to a selective cutting standard, determining the trees meeting the cutting conditions in the reconstruction area, and marking the trees meeting the cutting conditions correspondingly to be cut; trees which do not meet the cutting conditions are not cut and reserved;

5) forest felling and replanting

5-1) adopting a digging and transplanting mode to cut the trees according to the quantity and the labels of the trees to be cut which are screened in the step 4);

5-2) adopting a seedling planting and afforesting mode to carry out seedling supplementary planting, wherein the mixing ratio after the supplementary planting is (6-8): (2-4).

7. The method as claimed in claim 6, wherein the screening in step 4-2) comprises the steps of:

4-2A) comparing the breast diameters of each object wood and all the adjacent trees around the object wood in the forest stand reconstruction area, and determining that the breast diameter around the object wood is smaller than the number n of the adjacent trees of the object wood; judging and determining whether the object wood meets the selective cutting condition according to the number of strains of adjacent trees around the object wood and the number of strains of adjacent trees smaller than the breast diameter of the object wood and the selective cutting standard, and if the object wood meets the selective cutting condition, marking the object wood as a fellable tree for felling; if the non-cutting condition is met, the object wood is reserved and is not cut;

4-2B) if it cannot be determined whether the subject wood can be harvested or not from the number of strains of adjacent trees around the subject wood, the number of strains of adjacent trees smaller than the breast diameter of the subject wood, comparing the crown widths of the subject wood and all the adjacent trees around the subject wood, and determining that the crown width around the subject wood is smaller than the number m of strains of adjacent trees of the subject wood; judging and determining whether the object wood meets selective cutting conditions or not according to the number of strains of adjacent trees around the object wood, the number of strains of adjacent trees smaller than the breast diameter of the object wood and the number of strains of adjacent trees smaller than the crown width of the object wood, and recording the object wood as a fellable tree for felling if the object wood meets the selective cutting conditions; if the non-cutting condition is met, the object wood is reserved and is not cut;

4-2C) if it cannot be determined whether the target wood can be harvested or not based on the number of strains of adjacent trees around the target wood, the number of strains of adjacent trees smaller than the breast diameter of the target wood, and the number of strains of adjacent trees smaller than the crown width of the target wood, comparing the tree heights of the target wood and all the adjacent trees around the target wood, and determining that the tree height around the target wood is smaller than the number k of strains of adjacent trees of the target wood; judging and determining whether the target wood meets selective cutting conditions or not according to the selective cutting criteria according to the number of strains of adjacent trees around the target wood, the number of strains of adjacent trees smaller than the breast diameter of the target wood, the number of strains of adjacent trees smaller than the crown width of the target wood and the number of strains of adjacent trees smaller than the height of the target wood, and recording the target wood as a fellable tree for felling if the target wood meets the selective cutting conditions; if the non-harvesting condition is met, the object wood is reserved and is not harvested.

8. The method according to claim 6 or 7, wherein the number of plants of the neighboring trees in step 4-1) is determined and judged according to the Thiessen Polygon method in Arcgis or according to the Thiessen Polygon method in Arcgis.

9. The method as claimed in claim 6 or 7, wherein the step 5-2) is carried out by selecting the native tree species of the forest land area transformed by the forest stand.

Technical Field

The invention relates to a forest stand structure adjusting or reforming method, in particular to a forest stand structure conversion method of an artificial timber forest, and belongs to the field of forest stand structures and restoration in forestry science.

Background

Most of the existing artificial timbered forests originate from the tree and grass planting activities in the northwest region from the 80 th century, and the artificial timbered forests formed by the tree planting according to the old afforestation technical specification GB/15776 are pure forests of the same age, are generally high in density and are horizontally and vertically arranged at equal intervals; these stands have contributed greatly over a long period of time to improving vegetation coverage and protecting and restoring the ecological environment.

In the beginning of this century, after the classification and operation of Chinese forestry, large-area artificial forests and secondary forests in northwest were classified into ecological public welfare forests, and the defects of the artificial forests are gradually highlighted after the close-up management of nearly twenty years. Although the artificial forest stand has good water and soil conservation and landscape greening functions, the original structural characteristics greatly influence the exertion of ecological functions of water conservation, carbon fixation and oxygen release, biological diversity protection and the like of the artificial forest stand, because the forest stand structure determines the functions of the forest stand, the species composition and the ecological functions are single, the problems of poor stress resistance, old and small trees and the like are serious, the problems of land fertility decline, slow growth of the forest stand and the like of the existing forest stand are caused, and the comprehensive requirements of the development of the current economic society on ecological services cannot be met. Compared with artificial forests, the stand structure of natural forests has the characteristics of different ages, multiple layers, mixed crossing and the like, can be naturally sparse and naturally updated, and is a stable multifunctional stand.

Therefore, the transformation of the artificial forest into a nearly natural forest with similar forest stand structure and ecological benefit as the natural forest is an important measure for improving the ecological service function of the forest stand.

However, the conventional forest stand structure regulation and control technology usually involves complex structure index calculation (such as an angle scale and a breast diameter size ratio), parameters of the spatial structure index cannot be directly measured, the forest stand spatial structure such as the position distribution, the breast diameter size and the like of each tree needs to be measured, and then the forest stand spatial structure is introduced into the arcGIS to calculate the size ratio and the angle scale of each tree before corresponding cutting is performed. During calculation, each tree in the forest stand adjustment area is respectively used as an object tree and surrounding adjacent trees to compare the breast height to calculate the breast height ratio; the angle of each tree in the forest stand adjustment area is respectively measured as an object tree and each adjacent tree around the object tree, and the angle scale is calculated by comparing the sizes of the measured angles, so that the calculation is extremely complex. All the direct operations in the woodland have great errors, the calculation accuracy can be improved to a certain extent through the arcGIS operation, but certain professional literacy is required. The operation is complex and difficult to implement on the ground, and especially, the angular dimension can generate a large measurement error if being careless; the actual work is comparatively loaded down with trivial details complicacy, is unfavorable for basic level forestry investigator's understanding and implementation, and the result error after the implementation is big, causes the forest stand structure of the forest land after the transformation still to have the defect easily, and traditional forest stand structure adjustment needs to consume a large amount of manpower, material resources moreover, and forest stand structure adjustment is long-consuming time moreover.

The forest land reformed by the method grows gradually to a high-quality and healthy near-natural state, and the number of soil microorganisms, soil nutrients, a forest land water source conservation function and the storage amount are improved; the stability of the forest stand and the production capacity of the forest land are improved.

Disclosure of Invention

The invention aims to solve the technical problems that space structure parameters are difficult to measure and calculate and complex, and the specific operation of basic-level forestry practitioners is not facilitated in the process of converting an existing artificial timber forest to an ecological public welfare forest, and the like, and provides a method for converting the artificial timber forest to the ecological public welfare forest, wherein whether an object tree is felled or not can be determined by comparing the breast diameters, crown widths and tree heights of the object tree and adjacent trees in a forest land, the method is simple to operate, convenient and easy to operate, and the forest scale survey result is accurate; the method has obvious forest land transformation effect, the reformed forest stand structure gradually develops towards the direction of multiple layers, different ages and mixed crossing, the space structure of the forest stand is obviously optimized, and the original standing conditions are obviously improved; the mixing degree is increased, and the population isolation degree is greatly improved; the area index of the forest stand leaves is reduced, so that the penetration rainfall in the forest is obviously increased; the thickness of the under-forest litter layer is reduced, the maximum water holding capacity is reduced, and more water permeates into the soil layer and is stored by the forest; the under forest species diversity, forest stand stability and health index are improved.

In order to achieve the purpose of the invention, the invention provides a method for transforming an artificial timber forest into an ecological public welfare forest, which comprises the steps of comparing the breast diameter, the crown width or/and the tree height of a target tree in the artificial timber forest to be transformed with the adjacent trees; screening, determining and marking object trees to be felled; calculating the total cutting strength of the forest land to be converted, cutting the forest in the forest land according to the requirement that the cutting strength of each time in the cutting process is lower than 30%, and replanting the nursery stock.

Wherein, the artificial timberland is selected from high-density pure tree species, preferably high-density pure Chinese pine timberland.

In particular, the selection density of the artificial wood is more than or equal to 2500 strains/hm²The pure tree species woodland; preferably the density is more than or equal to 2500 strains/hm²More preferably 2625 strain/hm of the pure pinocembrin of (a)²The forest land.

Wherein, the random distribution mode is adopted for forest felling; and (4) adopting a seedling planting and afforesting mode to carry out the seedling replanting.

In particular, the nursery stock is replanted in a random distribution mode.

Particularly, the nursery stock is replanted at the position where the forest gap is wide.

During replanting, the trees are replanted in a low-lying position where water is easy to collect by virtue of topography, and the hollow ground of the trees is avoided as far as possible, so that the trees can grow better after replanting.

Wherein the total cutting intensity is the number of the object trees to be cut/the number of the total object trees in the forest land to be converted multiplied by 100%.

In particular, if the total harvesting strength is greater than 30%, the forest to be harvested in the forest land transformation area is harvested in portions, wherein the harvesting strength in each harvesting process is less than 30%, preferably 10-30%.

In particular, the time interval between two successive harvests is 4 to 5 years, preferably 5 years.

Particularly, the trees are harvested in a random distribution mode, and equidistant harvesting is avoided.

Wherein, the crown breadth is east-west crown breadth multiplied by south-north crown breadth.

Particularly, after the nursery stock is replanted in the forest land to be transformed, the mixing ratio of the forest stands in the forest land is (6-8): (2-4), preferably 7: 3.

Particularly, the replanting is carried out in a random distribution mode, and the forest stand mixing ratio after the replanting is (6-8): (2-4), preferably 7: 3.

Particularly, the local tree species (or the local tree species) of the forest land area to be transformed are selected for seedling replanting.

In particular, the local broad-leaved tree species wild peach or/and wild apricot in the forest land area to be transformed are adopted for seedling replanting.

Particularly, the mixing ratio of the original tree species and the replanting tree species in the transformed forest land after the nursery stock is replanted is (6-8): (2-4), preferably 7: 3.

Particularly, the mixing ratio of the broad-leaved coniferous tree after the nursery stock is replanted is (6-8): (2-4), preferably 7: 3.

When the local tree species are replanted in various proportions, the proportion of the local tree species can be any proportion, and equal proportion replanting is generally preferred.

The invention also provides a method for transforming the artificial timber forest into the ecological public welfare forest, which comprises the following steps in sequence:

3) sequentially measuring and recording the tree height, the breast height and the crown width of each forest (or tree) in the process of numbering the trees in the forest stand transformation sample plot;

4) screening trees to be felled

4-1) firstly determining the number M of plants of adjacent trees B around each object tree A in the forest stand reconstruction area;

5) forest felling and replanting

5-1) adopting a digging and transplanting mode to cut the trees according to the quantity and the labels of the trees to be cut which are screened in the step 4);

5-2) adopting a seedling planting and afforesting mode to carry out seedling supplementary planting, wherein the mixing ratio after the supplementary planting is (6-8): (2-4).

Wherein, the forest stand transformation plots in the step 1) are set to be rectangular plots, preferably square plots.

In particular, the side length L of the square forest stand transformation plot is not less than 20m, preferably 20-30m, and more preferably 24 m.

Wherein the width k of the strip buffer zone is more than or equal to 1m, preferably 1-3m, and more preferably 2 m.

Particularly, the line containing area in the strip-shaped buffer area is a forest stand reconstruction area, and the side length L of the forest stand reconstruction area is L-2 k, wherein L is the side length of a forest stand transformation sample area; k is the width of the band buffer.

In particular, the length of the strip buffer corresponds to the side length of the forest stand conversion plot.

In step 2), all the trees in the sample plot are numbered in sequence in an S-shaped route from the origin tree.

In particular, the origin tree takes the first tree at any corner in the transformation sample plot as the origin tree, and the number of the origin tree is 1; then, all trees in the forest stand transformation sample plot are numbered from the original point tree, and the number of all trees in the forest stand transformation sample plot is N.

In particular, the first tree in the southwest corner of the forest stand transformed plot was used as the origin tree.

In particular, the origin tree is located within a banded buffer.

Wherein, the crown breadth in the step 3) is east-west crown breadth multiplied by south-north crown breadth.

Wherein, the number of the plants of the adjacent trees in the step 4-1) is determined and judged according to a four-plant method or a Thiessen polygon method in arcgis, preferably according to the Thiessen polygon method in arcgis.

In particular, the object wood is located in the forest stand reconstruction zone; the trees in the buffer zone can only be adjacent trees. The trees in the reconstruction zone are both the subject wood and the adjacent wood of another subject wood.

In particular, the number of plants of the neighboring trees is determined and judged to be 4, 5, 6, 7 or 8 plants per the number of plants of the neighboring trees around the subject tree according to the thiessen polygon method in arcgis.

Wherein, the screening in the step 4-2) comprises the following steps:

In particular, the selective cut criteria are as follows:

1: when the number M of plants of the neighboring wood B around the subject wood a is 4, the subject wood is harvested as follows:

first comparing the breast diameters of the subject wood and the adjacent wood, wherein:

1-1: when the plant tree n of the adjacent tree smaller than the breast diameter of the object tree is 0, 3 or 4, the object tree is not felled;

1-2: when the tree number n of the adjacent trees smaller than the breast diameter of the object tree is 1, comparing the crown widths of the object tree and the 4 adjacent trees, wherein:

1-2A: when the number m of the plants of the adjacent trees smaller than the crown width of the object wood is 0 or 4, the object wood is not felled;

1-2B: when the number m of the adjacent trees smaller than the crown width of the target wood is 1, comparing the tree heights of the target wood and 4 adjacent trees, and when the number k of the adjacent trees smaller than the tree height of the target wood is 0, 2, 3 or 4, the target wood is not felled; when the number k of the adjacent trees smaller than the height of the target tree is 1, cutting the target tree;

1-2C: when the number m of the plants of the adjacent trees smaller than the crown width of the object tree is 2, comparing the tree heights of the object tree and the 4 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the object tree is 0, felling the object tree; when the number k of the adjacent trees smaller than the height of the target tree is 1, 2, 3 or 4, the target tree is not felled;

1-2D, when the number m of the adjacent trees smaller than the crown width of the object wood is 3, comparing the tree heights of the object wood and 4 adjacent trees, and when the number k of the adjacent trees smaller than the tree height of the object wood is 0, 1, 3 or 4, the object wood is not felled; when the number k of the adjacent trees smaller than the height of the target tree is 2, cutting the target tree;

2: when the number M of the plants of the neighboring tree B around the target tree a is 5, the target tree is selectively cut as follows:

first comparing the breast diameters of the subject wood and the adjacent wood, wherein:

2-1: when the tree number n of the adjacent trees smaller than the breast diameter of the object tree is 0, comparing the crown widths of the object tree and the 5 adjacent trees, wherein:

2-1A, when the number m of the strains of the adjacent trees smaller than the crown width of the object wood is 0, 2, 3, 4 or 5, the object wood is not felled;

2-1B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 1, comparing the tree heights of the target wood and the 5 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 2, 3 or 4, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 1, cutting the target tree;

2-2: when the tree number n of the adjacent trees smaller than the breast diameter of the object tree is 1, comparing the crown widths of the object tree and 5 adjacent trees, wherein:

2-2A: when the number m of the plants of the adjacent trees smaller than the crown width of the target tree is 0, comparing the tree heights of the target tree and 5 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target tree is 0, felling the target tree; when the number k of the plants of the adjacent trees smaller than the height of the target tree is 1, 2, 3, 4 or 5, the target tree is not felled;

2-2B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 1, comparing the tree heights of the target wood and 5 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 2, 4 or 5, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 1 or 3, cutting the target tree;

2-2C: when the number m of the plants of the adjacent trees smaller than the crown width of the object wood is 2, 3, 4 or 5, felling the object wood;

2-3: when the plant tree n of the adjacent trees smaller than the breast diameter of the object wood is 2, comparing the crown width of the object wood with that of the 5 adjacent trees, wherein

2-3A: when the number m of the plants of the adjacent trees smaller than the crown width of the object wood is 0, 3, 4 or 5, the object wood is not felled;

2-3B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 1, comparing the tree heights of the target wood and 5 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 3 or 5, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 2 or 4, cutting the target tree;

2-3C: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 2, comparing the tree heights of the target wood and the 5 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 3, 4 or 5, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 2, cutting the target tree;

2-4: when the tree number n of the adjacent trees smaller than the breast diameter of the object tree is 3, comparing the crown widths of the object tree and the 5 adjacent trees, wherein:

2-4A: when the number m of the plants of the adjacent trees smaller than the crown width of the object wood is 0, 2 or 4, the object wood is not felled;

2-4B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 1, comparing the tree heights of the target wood and the 5 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 3, 4 or 5, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 2, cutting the target tree;

2-4C: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 3, comparing the tree heights of the target wood and the 5 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 2, 4 or 5, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 3, cutting the target tree;

2-4D: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 5, comparing the tree heights of the target wood and the 5 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 2, 4 or 5, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 3, cutting the target tree;

2-5: when the plant tree n of the adjacent trees smaller than the breast diameter of the object tree is 4, comparing the crown width of the object tree with that of the 5 adjacent trees, wherein

2-5A: when the number m of the plants of the adjacent trees smaller than the crown width of the object wood is 0, 1, 2, 4 or 5, the object wood is not felled;

2-5B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 3, comparing the tree heights of the target wood and the 5 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 3, 4 or 5, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 2, cutting the target tree;

2-6: when the plant tree n of the adjacent trees smaller than the breast diameter of the object tree is 5, comparing the crown width of the object tree with that of the 5 adjacent trees, wherein

2-6A: when the number m of the plants of the adjacent trees smaller than the crown width of the object wood is 0, 1, 2, 3 or 4, the object wood is not felled;

2-6B: when the number m of the plants of the adjacent trees smaller than the crown width of the target tree is 5, comparing the tree heights of the target tree and the 5 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target tree is 0, 2 or 5, the target tree is not felled; of neighbouring trees when less than the height of the subject tree

When the number k of the plants is 1, 3 or 4, cutting the target wood;

3: when the number M of the plants of the neighboring tree B around the target tree a is 6, the target tree is selectively cut as follows:

first comparing the breast diameters of the subject wood and the adjacent wood, wherein:

3-1: when the tree number n of the adjacent trees smaller than the breast diameter of the object tree is 0, comparing the crown widths of the object tree and the 6 adjacent trees, wherein:

3-1A: when the number m of the plants of the adjacent trees smaller than the crown width of the object wood is 3, 5 or 6, the object wood is not felled;

3-1B: when the number m of the plants of the adjacent trees smaller than the crown width of the target tree is 0, comparing the tree heights of the target tree and the 6 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target tree is 0, 1 or 2, felling the target tree; when the number k of the plants of the adjacent trees smaller than the height of the target tree is 3, 4, 5 or 6, the target tree is not felled;

3-1C: when the number m of the plants of the adjacent trees smaller than the crown width of the target tree is 1, comparing the tree heights of the target tree and the 6 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target tree is 0, felling the target tree; when the number k of the plants of the adjacent trees smaller than the height of the target tree is 1, 2, 3, 4, 5 or 6, the target tree is not felled;

3-1D: when the number m of the plants of the adjacent trees smaller than the crown width of the target tree is 2, comparing the tree heights of the target tree and the 6 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target tree is 0, felling the target tree; when the number k of the plants of the adjacent trees smaller than the height of the target tree is 1, 2, 3, 4, 5 or 6, the target tree is not felled;

3-1E: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 4, comparing the tree heights of the target wood and the 6 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 2, 3, 4, 5 or 6, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 1, cutting the target tree;

3-2: when the plant tree n of the adjacent trees smaller than the breast diameter of the object tree is 1, comparing the crown width of the object tree with that of the 6 adjacent trees, wherein

3-2A: when the number m of the plants of the adjacent trees smaller than the crown width of the object tree is 0, felling the object tree;

3-2B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 1, comparing the tree heights of the target wood and the 6 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 2, 3, 5 or 6, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 0, 1 or 4, felling the target tree;

3-3: when the tree number n of the adjacent trees smaller than the breast diameter of the object tree is 2, comparing the crown widths of the object tree and the 6 adjacent trees, wherein:

3-3A: when the number m of the strains of the adjacent trees smaller than the crown width of the target wood is 0, 1, 2, 4, 5 or 6, the target wood is not felled;

3-3B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 3, comparing the tree heights of the target wood and the 6 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 3, 4, 5 or 6, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 2, cutting the target tree;

3-4: when the plant tree n of the adjacent trees smaller than the breast diameter of the object tree is 3, comparing the crown width of the object tree with that of the 6 adjacent trees, wherein

3-4A: when the number m of the strains of the adjacent trees smaller than the crown width of the target wood is 0, 1, 2, 4 or 6, comparing the tree heights of the target wood and the 6 adjacent trees, and when the number k of the strains of the adjacent trees smaller than the tree height of the target wood is 0, 1, 3, 4, 5 or 6, the target wood is not felled;

3-4B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 3, comparing the tree heights of the target wood and the 6 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 2, 4, 5 or 6, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 3, cutting the target tree;

3-4C: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 5, comparing the tree heights of the target wood and the 6 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 2, 3, 4, 5 or 6, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 1, cutting the target tree;

3-5: when the plant tree n of the adjacent trees smaller than the breast diameter of the object tree is 4, comparing the crown width of the object tree with that of the 6 adjacent trees, wherein

3-5A: when the number m of the strains of the adjacent trees smaller than the crown width of the object wood is 0, 1, 2, 3, 4 or 6, the object wood is not felled;

3-5B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 5, comparing the tree heights of the target wood and the 6 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 3, 4, 5 or 6, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 2, cutting the target tree;

3-6: when the plant tree n of the adjacent tree smaller than the breast diameter of the object tree is 5, the object tree is not felled;

3-7: when the tree number n of the adjacent trees smaller than the breast diameter of the object tree is 6, comparing the crown widths of the object tree and the 6 adjacent trees, wherein:

3-7A: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 0, 1, 2, 3, 4 or 5, comparing the tree heights of the target wood and the 6 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 3, 4 or 5, the target wood is not felled;

3-7B: when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 6, cutting the target tree;

4: when the number M of plants of the neighboring tree B around the target tree a is 7, the target tree is selectively cut as follows:

first comparing the breast diameters of the subject wood and the adjacent wood, wherein:

4-1: when the plant tree n of the adjacent trees smaller than the breast diameter of the object wood is 0, comparing the crown width of the object wood with that of 7 adjacent trees, wherein

4-1A: when the number m of the plants of the adjacent trees smaller than the crown width of the object wood is 1, 3, 4, 6 or 7, the object wood is not felled;

4-1B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 0, comparing the tree heights of the target wood and 7 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 1, 2, 3, 4, 5, 6 or 7, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 0, cutting the target tree;

4-1C: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 2, comparing the tree heights of the target wood and 7 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 1, 2, 3, 4, 5, 6 or 7, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 0, cutting the target tree;

4-1D: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 5, comparing the tree heights of the target wood and 7 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 1, 2, 3, 4, 5, 6 or 7, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 0, cutting the target tree;

4-2: when the tree number n of the adjacent trees smaller than the breast diameter of the object tree is 1, comparing the crown widths of the object tree and 7 adjacent trees, wherein:

4-2A: when the number m of the strains of the adjacent trees smaller than the crown width of the target wood is 0, 1, 3, 4, 5, 6 or 7, the target wood is not harvested;

4-2B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 2, comparing the tree heights of the target wood and 7 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 1, 2, 3, 4, 5, 6 or 7, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 0, cutting the target tree;

4-3: when the plant tree n of the adjacent trees smaller than the breast diameter of the object wood is 2, comparing the crown width of the object wood with that of 7 adjacent trees, wherein

4-3A: when the number m of the strains of the adjacent trees smaller than the crown width of the target wood is 0, 1, 2, 3, 4, 6 or 7, the target wood is not harvested;

4-3B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 5, comparing the tree heights of the target wood and 7 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 2, 3, 4, 5 or 6, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 7, cutting the target tree;

4-4: when the plant tree n of the adjacent trees smaller than the breast diameter of the object wood is 3, comparing the crown width of the object wood with that of 7 adjacent trees, wherein

4-4A: when the number m of the strains of the adjacent trees smaller than the crown width of the object wood is 0, 1, 2, 3, 5 or 7, the object wood is not felled;

4-4B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 4, comparing the tree heights of the target wood and 7 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 2, 3, 4, 5 or 6, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 7, cutting the target tree;

4-5: when the plant tree n of the adjacent trees smaller than the breast diameter of the object wood is 4, comparing the crown width of the object wood with that of 7 adjacent trees, wherein

4-5A: when the number m of the strains of the adjacent trees smaller than the crown width of the object wood is 0, 1, 2, 3, 5 or 7, the object wood is not felled;

4-5B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 4, comparing the tree heights of the target wood and 7 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 2, 4, 5, 6 or 7, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 3, cutting the target tree;

4-5C: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 6, comparing the tree heights of the target wood and the 7 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 2, 4, 5, 6 or 7, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 3, cutting the target tree;

4-6: when the plant tree n of the adjacent trees smaller than the breast diameter of the object wood is 5, comparing the crown width of the object wood with that of 7 adjacent trees, wherein

4-6A: when the number m of the strains of the adjacent trees smaller than the crown width of the target wood is 0, 1, 2, 3, 5, 6 or 7, the target wood is not harvested;

4-6B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 4, comparing the tree heights of the target wood and 7 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 3, 4, 5, 6 or 7, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 2, cutting the target tree;

4-7: when the plant tree n of the adjacent trees smaller than the breast diameter of the object wood is 6, comparing the crown width of the object wood with that of 7 adjacent trees, wherein

4-7A: when the number m of the plants of the adjacent trees smaller than the crown width of the object wood is 0, 1, 2, 3 or 4, the object wood is not felled;

4-7B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 5, comparing the tree heights of the target wood and 7 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 3, 4, 5 or 7, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 2 or 6, cutting the target tree;

4-7C: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 6, comparing the tree heights of the target wood and the 7 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 3, 4, 5, 6 or 7, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 2, cutting the target tree;

4-7D: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 7, comparing the tree heights of the target wood and the 7 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 2, 4 or 7, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 3, 5 or 6, felling the target tree;

4-8: when the plant tree n of the adjacent trees smaller than the breast diameter of the object wood is 7, comparing the crown width of the object wood and the crown width of the 7 adjacent trees, wherein

4-8A: when the number m of the strains of the adjacent trees smaller than the crown width of the object wood is 0, 1, 2, 3, 4 or 6, the object wood is not felled;

4-8B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 5, comparing the tree heights of the target wood and the 7 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 2, 3, 4, 5 or 7, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 6, cutting the target tree;

4-8C: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 7, comparing the tree heights of the target wood and the 7 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 2, 3, 4, 5 or 6, the target wood is not felled; when smaller than the target tree

When the number k of the high adjacent trees is 7, cutting the target trees;

5: when the number N of plants of the neighboring tree B around the target tree a is 8, the target tree is selectively cut as follows:

first comparing the breast diameters of the subject wood and the adjacent wood, wherein:

5-1: when the plant tree n of the adjacent tree smaller than the breast diameter of the object tree is 4, 6, 7 or 8, the object tree is not felled;

5-2: when the plant tree n of the adjacent trees smaller than the breast diameter of the object tree is 0, comparing the crown width of the object tree with that of the 8 adjacent trees, wherein

5-2A: when the number m of the strains of the adjacent trees smaller than the crown width of the target wood is 0, 1, 3, 4, 5, 6, 7 or 8, the target wood is not felled;

5-2B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 2, comparing the tree heights of the target wood and 7 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 1, 2, 3, 4, 5, 6, 7 or 8, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 0, cutting the target tree;

5-3: when the plant tree n of the adjacent trees smaller than the breast diameter of the object tree is 1, comparing the crown width of the object tree with that of the 8 adjacent trees, wherein

5-3A: when the number m of the strains of the adjacent trees smaller than the crown width of the target wood is 0, 2, 3, 4, 5, 6, 7 or 8, the target wood is not felled;

5-3B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 1, comparing the tree heights of the target wood and 8 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 3, 4, 5, 6, 7 or 8, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 2, cutting the target tree;

5-4: when the plant tree n of the adjacent trees smaller than the breast diameter of the object wood is 2, comparing the crown width of the object wood with that of the 8 adjacent trees, wherein

5-4A: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 0, comparing the tree heights of the target wood and 8 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 1, 2, 3, 4, 5, 6, 7 or 8, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 0, cutting the target tree;

5-4B: when the number m of the strains of the adjacent trees smaller than the crown width of the target wood is 1, 2, 3, 4, 5, 6, 7 or 8, the target wood is not felled;

5-5: when the plant tree n of the adjacent trees smaller than the breast diameter of the object tree is 3, comparing the crown width of the object tree with that of the 8 adjacent trees, wherein

5-5A: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 0, comparing the tree heights of the target wood and 8 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 2, 3, 5, 6, 7 or 8, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 4, cutting the target tree;

5-5B: when the number m of the strains of the adjacent trees smaller than the crown width of the target wood is 1, 2, 3, 4, 5, 6, 7 or 8, the target wood is not felled;

5-6: when the plant tree n of the adjacent trees smaller than the breast diameter of the object wood is 5, comparing the crown width of the object wood with that of the 8 adjacent trees, wherein

5-6A: when the number m of the strains of the adjacent trees smaller than the crown width of the target wood is 0, 1, 2, 3, 4, 6 or 8, the target wood is not harvested; 5-6B: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 5, comparing the tree heights of the target wood and 8 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 2, 3, 4, 6, 7 or 8, the target wood is not felled; when the number k of the plants of the adjacent trees which are smaller than the height of the target tree is 5, cutting the target tree;

5-6C: when the number m of the plants of the adjacent trees smaller than the crown width of the target wood is 7, comparing the tree heights of the target wood and the 8 adjacent trees, and when the number k of the plants of the adjacent trees smaller than the tree height of the target wood is 0, 1, 2, 3, 4, 5, 7 or 8, the target wood is not felled; when the number k of plants of the neighboring trees smaller than the height of the subject tree is 6, the subject tree is harvested.

Wherein, the step 5-1) also comprises the step of calculating the total felling intensity in the forest stand reconstruction area, and if the total felling intensity is less than or equal to 30 percent, performing primary felling; if the total cutting strength is more than 30%, performing cutting on the trees in the forest stand reconstruction area in different times, wherein the strength of each cutting is less than or equal to 30%, and the time interval between two adjacent cutting is less than or equal to 5 years;

particularly, before the tree is harvested, branches of the tree are trimmed, and the trimmed branches are not more than 30% of the total branches.

Particularly, the method for transplanting the tree felling and collecting part with the soil ball, wherein the transverse width of the soil ball is 8-12 times, preferably 10 times of the breast diameter of the tree; the ratio of the height of the soil ball to the width of the soil ball is (80-120): 100, preferably 80: 100.

wherein, the supplementary planting of the trees in the step 5-2) adopts different tree species from the original tree species in the forest land converted from the forest stand to carry out the seedling supplementary planting.

In particular, the replanting seedlings are selected from seedlings with good growth and root system with the diameter at breast height of 2-4 cm.

Particularly, the tree species of the replanting seedlings are selected from local tree species in a forest stand conversion forest land area.

In particular, the corresponding indigenous broadleaf species within the forest stand transformed area are selected.

In particular, broad-leaved local trees with tenacious vitality are selected to be planted with the wild peaches and the wild apricots.

The native tree species grow in the local area for years, are completely adapted to the existing environment, and are easy to survive after being planted. Moreover, the wild peach and wild apricot with good stress resistance are selected.

Particularly, the forest stand mixing ratio in the forest land after the nursery stock is replanted is (6-8): (2-4), preferably 7: 3.

Particularly, the seedlings are cut in different times, the seedling is replanted after each cut, and the cutting proportion of each cut is adapted to the replanting proportion in the corresponding replanting process, for example, the cutting proportion of the first cut is adapted to the replanting proportion of the first replanting process; the felling proportion of the second felling is suitable for the second replanting proportion.

The division ratio of the divided cutting is divided into the number of the trees cut each time, divided into the total number of the trees needing cutting and multiplied by 100 percent.

The harvesting strength of the branch harvesting is divided by the number of the tree plants harvested each time divided by the total number of the tree plants 100 percent, and the harvesting strength of each time is less than or equal to 30 percent.

Compared with the prior art, the method has the following advantages and benefits:

the method is simple and convenient to operate, is convenient and easy to implement, only needs to measure basic indexes such as breast diameter, tree height and crown width, avoids measuring and calculating complex forest stand structure parameters such as angular scale and size ratio, and remarkably improves the working efficiency.

Indexes related to the forest inspection ruler measured by the method are all familiar to basic forestry workers, the method can be directly operated according to specific standards, complex calculation is not needed, the measurement result is accurate, the effect of felling implementation is accurate, and the method is beneficial to actual operation of basic workers.

After the method is adopted for forest stand transformation and transformation, the forest stand structure of the original artificial forest gradually develops towards the direction of multiple layers, different ages and mixed crossing, and the spatial structure of the forest stand is optimized; in the transformation process from pure forest to mixed forest, the original site conditions are effectively improved, the mixed degree is increased, and the population isolation degree is greatly improved; the area index of the forest stand leaves is reduced, so that the penetration rainfall in the forest is obviously increased; the thickness of the under-forest litter layer is reduced, the maximum water holding capacity is reduced, and more water permeates into the soil layer and is stored by the forest; the under forest species diversity, forest stand stability and health index are improved to different degrees.

The method is convenient for basic-level forestry workers to understand and implement forest stand reconstruction, avoids measuring and calculating complex forest stand space structure parameters such as angle scale, breast height ratio and the like, can dry the forest stand only by simply and easily measuring the breast height, the tree height and the crown width of the tree, is simple in measuring method of the forest scale index, is beneficial to understanding and implementation of the basic-level workers, and can greatly improve the working efficiency.

Drawings

FIG. 1 is a schematic diagram showing the distribution of forest positions in the stand transformation plots in example 1;

FIG. 2 is a schematic view of the position of the felling to be harvested determined by the method of the present invention in example 1;

FIG. 3 is a schematic view showing the position of a forest tree after being replanted by the method of the present invention in example 1;

FIG. 4 is a schematic of angular dimension determination.

Description of the reference numerals

1A, transforming a sample plot in a forest stand; 2A, a strip buffer area; and 3A, a forest stand reconstruction area.

Detailed Description

The invention will be further described with reference to specific embodiments, and the advantages and features of the invention will become apparent as the description proceeds. These examples are illustrative only and do not limit the scope of the present invention in any way. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention, and that such changes and modifications may be made without departing from the spirit and scope of the invention.

In the specific embodiment of the present invention, a high-density pinus tabulaeformis forest of a north mountain forest farm in the east region of Qinghai province is taken as an example for explanation, and the structural parameters are as follows:

other density is more than 2500 strains per hm²The artificial forest is suitable for the invention, especially the high density (the density is more than 2500 strains per hm)²) The Chinese pine forest artificial forest. The invention belongs to the field of ecological restoration, and has good reconstruction effect on the transformation of other high-density Chinese pine artificial timbers to near-natural ecological public welfare timbers besides reconstructing forest stand structures of the high-density Chinese pine artificial timbers in the eastern part of Qinghai province.

Example 1

1. Forest stand sample plot survey

1-1, in high-density pure Chinese pine forest (i.e. artificial timber forest to be transformed, Chinese pine density is 2625 strains/hm)²) In the method, a 24m multiplied by 24m rectangular forest stand transformation sample plot is arranged, and a strip-shaped buffer area with the width of 2m is arranged in the periphery of the sample plot to be transformed; the line containing area in the strip-shaped buffer area is a forest stand reconstruction area, and the side length l of the forest stand reconstruction area is 20m, as shown in figure 1. In FIG. 1, 1A is a forest stand transformation plot; 2A is a band buffer zone; 3A is a forest stand reconstruction area;

taking a first forest of a southwest corner of a forest stand transformation sample plot as an origin tree, and marking the tree with a number of 1;

the side length L of the forest stand transformation sample plot in the embodiment of the invention is illustrated by taking 24m as an example, and other sample plots with the side length L being more than or equal to 20m are all suitable for the invention; the width k of the banded buffer is illustrated as 2m, and other buffer widths k ≧ 1m (preferably 1-3m) are suitable for the present invention; the origin tree may be any one tree in a forest stand transformation sample, or a first forest at any one corner in the forest stand transformation sample, and in the embodiment of the present invention, the first forest at the southwest corner is taken as the origin tree for illustration.

1-2, starting from an original point tree, numbering all trees in a sample plot in sequence by an S-shaped route, wherein the original point tree is numbered 1; a total of 150 pinus tabulaeformis (N150) within the forest stand transformation plots, and the position of the forest within the forest stand transformation plots is schematically shown in fig. 1.

The total number of forest trees in the forest stand transformation plot is N, in this example, N is 150, that is, the total number of Chinese pine trees in the transformation plot is 150.

1-3, sequentially measuring and recording the height, the breast diameter and the crown width (east-west crown width multiplied by south-north crown width) of each tree in the process of numbering the trees, wherein the measurement results are shown in a table 1;

TABLE 1 check rule for each tree in forest stand transformation sample plot

2. Screening trees to be felled

The forest trees in the forest stand reconstruction area are used as object trees and adjacent trees; and the forest trees in the strip-shaped buffer area can only be used as adjacent trees.

The total number of the trees in the forest stand reconstruction area is 105, namely the total number of the object trees A in the reconstruction area is 105.

2-1, determining and judging the number of plants of adjacent trees around the target wood according to the Thiessen polygon method in arcgis, wherein: the number M of subject trees, adjacent trees B around each subject tree, in the reconstruction zone is shown in table 2.

TABLE 2 number of neighboring wood plants around the subject wood

Note: x represents felling; -means no felling.

2-2, performing felling judgment on all object trees in the forest stand reconstruction area according to a felling selection standard (shown in a table 3), and marking to-be-felled trees on the corresponding object trees if the felling judgment meets the felling standard;

TABLE 3 selective cut Standard

The specific screening method is as follows:

1. comparing the breast diameter of each object wood A with the breast diameters of M adjacent trees around the object wood A, and determining that the breast diameter around the object wood is smaller than the number n of the adjacent trees of the object wood; judging and determining whether the target wood meets the selective cutting condition or not according to the number of the plants of the adjacent trees around the target wood and the number of the plants of the adjacent trees smaller than the breast diameter of the target wood, and if the target wood meets the selective cutting condition, marking the target wood as a tree which can be harvested; if the non-cutting condition is met, the object wood is reserved and is not cut;

the mark of the felling is to make a fellable mark on the trunk of the target tree (for example, the fellable mark in the embodiment of the present invention is an "x", and any other mark is applicable) or hang a fellable mark on the target tree;

the non-felling target wood may be marked or not marked, and if marked, the non-felling mark may be made on the trunk of the target wood (for example, the non-felling mark in the embodiment of the present invention is "●", and other marks different from the fellable mark are all applicable), or the non-felling mark may be hung on the target wood.

2. If the tree number M of the adjacent trees around the object tree and the tree number n of the adjacent trees smaller than the breast diameter of the object tree cannot be used for determining whether the object tree can be harvested or not harvested, comparing the crown width of each object tree with the crown width of the M adjacent trees around the object tree, and determining that the crown width around the object tree is smaller than the tree number M of the adjacent trees of the object tree; judging and determining whether the target wood meets the selective cutting condition or not according to the number of strains of adjacent trees around the target wood, the number of strains of adjacent trees smaller than the breast diameter of the target wood and the number of strains of adjacent trees smaller than the crown width of the target wood, and if the target wood meets the selective cutting condition, marking the target wood as a fellable tree; if the non-cutting condition is met, the object wood is reserved and is not cut;

3. if the tree number M of the adjacent trees around the object tree, the tree number n of the adjacent trees smaller than the breast diameter of the object tree and the tree number M of the adjacent trees smaller than the crown width of the object tree cannot be used for determining whether the object tree can be harvested or not, comparing the tree height of each object tree with the tree height of the adjacent trees around the object tree and determining that the tree height around the object tree is smaller than the tree number k of the adjacent trees of the object tree; judging and determining whether the target wood meets the selective cutting condition or not according to the number of strains of adjacent trees around the target wood, the number of strains of adjacent trees smaller than the breast diameter of the target wood, the number of strains of adjacent trees smaller than the crown width of the target wood and the number of strains of adjacent trees smaller than the height of the target wood, and if the target wood meets the selective cutting condition, marking the target wood as a fellable tree; if the non-harvesting condition is met, the object wood is reserved and is not harvested.

Making a fellable mark (in the embodiment of the invention, the X is used as a fellable mark) on the trunk of the target tree, and marking the fellable mark as a fellable tree; otherwise, determining that the object wood can not be harvested.

For example: if there are 4 neighboring trees around the subject wood a, the number of neighboring trees is 4.

1): the breast diameters of 4 neighboring trees around the target tree a are compared, and if the breast diameter around the target tree a is smaller than the number n of neighboring trees of the target tree by 0, 3 or 4, the target tree a is not harvested.

2): if the breast diameter around the object wood A is smaller than the number n of the neighboring trees of the object wood, which is 1 or 2, and it cannot be determined whether the object wood A can be harvested or not, the crown widths of the 4 neighboring trees around the object wood A are compared, wherein,

2-1): if the number n of the plants around the object wood A with the diameter at breast height smaller than the number m of the plants adjacent to the object wood is 1 plant, and the number m of the plants around the object wood A with the diameter smaller than the number m of the plants adjacent to the object wood is 0 or 4 plants, the object wood A is not felled;

2-2) if the chest diameter around the subject wood a is smaller than the number n of the neighboring trees of the subject wood by 1, and the crown width around the subject wood a is smaller than the number m of the neighboring trees of the subject wood by 1, 2 or 3, it is not possible to determine whether the subject wood a can be harvested or not harvested, comparing the tree heights of the 4 neighboring trees around the subject wood a, wherein:

2-2-1) if the number m of the crown around the target wood A is 1 plant which is smaller than the number k of the plants adjacent to the target wood, and the tree height around the target wood A is 0, 2, 3 or 4 plants which is smaller than the number k of the plants adjacent to the target wood, the target wood is not felled;

2-2-2) felling the target wood if the number m of the crown around the target wood A is 1 less than the number k of the plants adjacent to the target wood, and the tree height around the target wood A is less than the number k of the plants adjacent to the target wood;

2-2-3) if the crown width around the target wood A is less than the number m of the plants of the adjacent trees of the target wood and is 2 plants, and the tree height around the target wood A is less than the number k of the plants of the adjacent trees of the target wood and is 1, 2, 3 or 4 plants, the target wood is not felled;

2-2-4) felling the target wood if the number m of the crown around the target wood A is 2 smaller than the number k of the plants adjacent to the target wood, and the number k of the trees around the target wood A is 0 smaller than the number k of the plants adjacent to the target wood;

2-2-5) if the crown width around the target wood A is less than the number m of the plants of the adjacent trees of the target wood and is 3 plants, and the tree height around the target wood A is less than the number k of the plants of the adjacent trees of the target wood and is 0, 1, 3 or 4 plants, the target wood is not felled;

2-2-6) felling the target wood if the number m of the crown around the target wood A is 3 smaller than the number k of the plants adjacent to the target wood, and the number k of the trees around the target wood A is 2 smaller than the number k of the plants adjacent to the target wood;

2-3) if the chest diameter around the object wood A is smaller than the number n of the plants of the adjacent trees of the object wood and is 2, and the crown width around the object wood A is smaller than the number m of the plants of the adjacent trees of the object wood and is 0, 1, 3 or 4, the object wood A is not felled;

2-4) if the number of plants n around the target wood a having a smaller diameter at breast height than the neighboring trees of the target wood is 2 and the number of plants m around the target wood a having a smaller crown width than the neighboring trees of the target wood is 2, it cannot be determined whether the target wood a can be harvested or not harvested, comparing the tree heights of the 4 neighboring trees around the target wood a, wherein:

2-4-1) if the crown width around the target wood A is smaller than the number m of the plants of the adjacent trees of the target wood and is 2 plants, and the tree height around the target wood A is smaller than the number k of the plants of the adjacent trees of the target wood and is 0, 1, 2 or 4 plants, the target wood is not felled;

2-4-2) felling the subject wood if the number m of the canopy around the subject wood a is 2 plants smaller than the number k of the plants adjacent to the subject wood, and the number k of the trees around the subject wood a is 3 plants smaller than the number k of the plants adjacent to the subject wood.

For example:

1) the target wood with the number of 4, the surrounding neighboring wood are 7, and the numbers are respectively: 2. 3, 5, 23, 24, 25, 26;

firstly: comparing the breast diameters of 7 neighboring trees and the target tree, the breast diameters of 6 neighboring trees (numbers 3, 5, 23, 24, 25, 26) are smaller than the target tree according to the measurement results in table 1; according to the selective cutting standard table 3, whether the target wood can be cut or not cannot be judged;

then: comparing the crown widths of 7 adjacent trees and the target tree, according to the results in the table 1, the crown widths of 6 adjacent trees (numbers 2, 3, 23, 24, 25 and 26) are smaller than that of the target tree, and according to the selective cutting standard table 3, whether the target tree can be harvested or not cannot be judged;

then: comparing the tree heights of 7 neighboring trees and the subject tree, the tree heights of 2 neighboring trees (numbers 23, 25) were smaller than the subject tree in total according to the results of table 1; according to the cutting criteria of table 3, it can be judged that the object wood No. 4 needs to be cut, and a mark "x" for cutting is made on the object wood (No. 4).

2) The target wood is marked with 109, the surrounding adjacent wood is 7, and the marks are respectively: 101. 102, 108, 127, 128, 119, 110;

firstly: comparing the breast diameters of 7 adjacent trees and the target tree, and according to the measurement results in the table 1, the breast diameters of 3 adjacent trees (numbers 102, 110 and 119) are smaller than that of the target tree; according to the selective cutting standard table 3, whether the target wood can be cut or not cannot be judged;

then: the crown widths of 7 neighboring trees and the subject tree were compared, and according to the results in table 1, 0 neighboring trees in total were smaller than the subject tree, and according to the cutting criteria, it was judged that the subject tree did not need to be cut, and a cut-enabling mark "●" was made on the subject tree (number 109).

3) The target wood with the reference number 70, the surrounding neighboring wood is 5, and the reference numbers are respectively: 69. 74, 92, 51, 53;

firstly: comparing the breast diameters of 5 neighboring trees and the subject tree, the breast diameters of 5 neighboring trees (numbers 69, 74, 92, 51, 53) are smaller than the subject tree in total according to the measurement results in table 1; according to the selective cutting standard table 3, whether the target wood can be cut or not cannot be judged;

then: the crown widths of 5 neighboring trees and the subject tree were compared, and according to the results in table 1, the crown widths of 2 neighboring trees (nos. 69 and 92) were smaller than that of the subject tree, and according to the cutting criteria in table 3, it was judged that the subject tree No. 70 did not require cutting, and a fellable mark "●" was made on the subject tree (No. 70).

4) The target wood is marked with 68, the surrounding adjacent wood is 6, and the marks are respectively: 53. 54, 55, 67, 75, 69

Firstly: comparing the breast diameters of 6 adjacent trees and the target tree, and according to the measurement results in the table 1, the breast diameter of 1 adjacent tree (number 54) is smaller than that of the target tree; according to the selective cutting standard table 3, whether the target wood can be cut or not cannot be judged;

then: comparing the crown widths of 6 adjacent trees and the target tree, wherein the crown widths of 4 adjacent trees (numbers 53, 54, 67 and 69) are smaller than that of the target tree according to the result in the table 1, and whether the target tree can be felled or not cannot be judged according to the selective cutting standard table 3;

then: comparing the tree heights of the neighboring trees and the subject tree, the tree heights of 4 neighboring trees (numbers 53, 67, 75, 69) are smaller than the subject tree according to the results of table 1; according to table 3, it can be judged that the target wood No. 68 needs to be felled, and a fellable mark "x" is made on the target wood (No. 68).

5) The target wood with the reference number 59 has 8 neighboring wood around it, and the reference numbers are respectively: 60. 61, 62, 65, 63, 58, 39, 38

Firstly: comparing the breast diameters of 8 adjacent trees and the target tree, and according to the measurement results in the table 1, the breast diameters of 3 adjacent trees (numbers 62, 58 and 39) are smaller than that of the target tree; according to the selective cutting standard table 3, whether the target wood can be cut or not cannot be judged;

then: comparing the crown widths of 8 adjacent trees and the target tree, and according to the results in the table 1, totaling 0 adjacent trees (the crown width is smaller than the target tree, and according to the selective cutting standard table 3, whether the target tree can be harvested or not cannot be judged;

then: comparing the tree heights of the adjacent trees and the subject trees, according to the results of table 1, the tree heights of 4 adjacent trees (numbers 62, 63, 58, 39) are smaller than the subject trees; according to table 3, it can be judged that the 59 th object wood needs to be felled, and a fellable mark "x" is made on the object wood (No. 59).

All object trees (105 plants in total) in the forest stand transformation area are respectively screened according to the cutting criteria in the table 3, whether the trees can be harvested or not is determined, and corresponding cutting marks are made. The result of screening all object trees in the forest stand reconstruction area is as follows: the 52 subject trees were harvested and the remaining trees were not harvested, and the screening results are shown in table 2 and fig. 2.

3. Felling and replanting

3-1) in this example, 52 cut trees were cut with a cut strength of 49.52% (cut strength ═ tree of the plants to be cut ÷ total number of plants 100%, 52/105 × 100% ═ 49.52%); the forestry stipulates that the primary felling strength does not exceed 30 percent, so the forest stand transformation land needs to be reformed for 2 times of felling, wherein: the first harvest strength is set to be 30%, namely the harvest 105 is 30% and is approximately equal to 31, and the harvest strength is 29.52%; the second harvest strength was 20.00%, i.e. the remaining 21 pinus tabulaeformis were harvested.

If the harvesting strength of the forest stand transformation sample plot exceeds 30%, performing multi-time harvesting on the forest stand transformation sample plot, and ensuring that the harvesting strength of each time of harvesting is less than or equal to 30%, namely the plant trees of the forest trees harvested each time do not exceed 30% of the total plant trees in the forest stand transformation sample plot, the interval between two adjacent harvesting is 5 years, and after each time of harvesting, performing additional planting.

The cut proportion of the two fellings is 59.62% (31 ÷ 52 × 100%) and 40.38% (21 ÷ 52 × 100%), namely the cut proportion of the first felling is 59.62%; the cut proportion of the second harvest was 40.38%.

The trees are directly cut down in a digging and transplanting mode, so that the trees can grow normally when being transplanted to a new environment. Harvesting is carried out according to conventional methods known in the art.

Before felling and transplanting, pruning the trees under the condition of ensuring the tree shape to be unchanged so as to reduce the transpiration intensity in transportation and keep the tissues full of water, wherein the pruned branches do not exceed 30 percent of the total branches; the cut left after pruning the branch needs to be processed in time to accelerate healing, so that excessive water and nutrients are prevented from being lost.

When the tree is pruned, the original shape of the trunk is kept as much as possible, the main branches and the trunk are kept, diseased dead branches and dead branches are pruned, nutrition waste is avoided, the growth of the trunk is not facilitated, and the branch in the 1 st round at the bottom of the trunk can be removed if necessary. When the planting hole is dug, the related system is followed and the operation is strictly carried out according to the drawing, the marking is carried out after the position is determined, and the planting point and the soil preparation standard are determined according to the type and the specification of the tree.

Before digging, the trunk is tightly bound, so that the tree is prevented from being damaged; digging vertically downwards at a position 120cm away from the tree root, cutting off by a hand saw when the tree root touches a thicker tree root, and avoiding hurting the root; the trunk is pushed down, and the root hair is not hurt;

generally, a manual digging and soft material packaging transplanting method is utilized, the method is suitable for digging round soil balls and trees with the diameter at breast height of 10-15 cm, if the diameter of the trees is large, more branches and leaves need to be removed, then plastic weaving materials or grass sheets and grass ropes are used for packaging, and the trees need to be tightly bundled. In addition, the size of the soil ball is proper and is generally controlled to be about 6 times of the diameter at breast height of the tree, the size of the soil ball can be properly increased when the tree is planted out of season, and the soil ball is not too large to avoid breaking; after digging, safely transporting to the planting place.

Adopting a technical method of transplanting the root with a soil ball, wherein the transverse width of the soil ball is 10 times (usually 8-12 times) of the breast-height diameter of the tree; the height of the soil ball is equal to the width of the soil ball, so that the root system can be well protected by the soil ball.

3-2) forest tree replanting

After the forest is harvested, the supplementary planting is usually carried out in the early spring by adopting a mode of planting seedling afforestation, wherein the mixing ratio after the supplementary planting is 7:3 (usually (6-8): 2-4), namely the ratio of the original tree species in the forest stand transformation sample plot to the new tree species after the supplementary planting is 7: 3.

In this embodiment, the replanted tree species are local tree species of mountain apricots and mountain peaches in the forest stand transformation sample plot, and the mixing ratio of the original tree species after replanting to the new tree species after replanting is 7:3 (i.e. the ratio of Chinese pine to mountain peaches to mountain apricots is 7: 3). The number of replanting trees is (105-52)/7 x 3 is approximately equal to 23, wherein the total number of the original tree species of the pine is 105 in the forest stand reconstruction area, and 52 pinus tabulaeformis are harvested.

After the felling is carried out in the branch in this field, the replanting is carried out in the branch, and the proportion of felling off every time is consistent with the proportion of replanting of corresponding replanting, carry out the first replanting after the first felling promptly, the proportion of replanting for the first time is roughly consistent with the proportion of felling off of the first felling, carry out the second replanting after the second felling, the proportion of replanting for the second time is roughly consistent with the proportion of felling off of the first felling.

In this embodiment, the first cutting proportion and the second cutting proportion are 59.62% and 40.38% respectively, and then the corresponding first replanting proportion and the second replanting proportion are consistent with the first cutting proportion and the second cutting proportion, and the number of new tree species replanted for the first time is 14 (the first replanting proportion is 14 ÷ 23 × 100% ═ 60.87%); the number of new species of the second replanting was 9 (the second step ratio was (23-14) ÷ 23 × 100% ═ 39.13%).

The new tree species for replanting can also be wild peach or wild apricot.

Generally, seedlings with good growth and good root system are selected for 1-2 years; when lifting seedlings, irrigating water near the root system, wrapping the seedling roots with fiber cloth to cover and transport the seedling roots to a forest land needing to be replanted on the principle that most of hairy roots are not exposed, and planting in time; before replanting, the root system of the seedling is dipped with water-retaining agent; then planting according to the technical specification of 'three burying, two stepping and one lifting' and watering the planted trees in time to ensure the survival rate.

In the process of replanting the new tree species after felling, the replanting of the new tree species is carried out according to the conventional method known in the prior art without adopting a replanting form with equal rows and equal intervals.

The replanting is generally carried out in a random distribution mode (the random distribution mode is to carry out the random distribution planting at the open position of the forest gap, the planting is avoided at one position as much as possible, the replanting at the pit position after the felling is avoided, and the replanting in a mode of horizontally, vertically and equidistantly is avoided), and the replanting is carried out at the open position of the forest gap as much as possible.

The final transformation of the forest stand transformed plot after replanting new tree species after two fellings is shown in fig. 3, wherein ● represents the original tree species pine; tangle-solidup represents wild apricot; and delta represents a wild peach.

And (3) selecting different tree species for replanting the replanting seedlings according to the forest stand types guided by different functions, for example: if the forest stand type after forest stand transformation is the water and soil conservation function, spruce, larch and the like are replanted; if the water source has the function of conserving water, white birch and the like are replanted.

The tree species of the replanting seedlings are local tree species of the local forest land to be transformed, the local tree species can meet the local ecological service function requirement and adapt to the local climatic environment condition, the survival rate is high, and the cost is low.

The tree species replanted in the embodiment are local tree species of mountain apricots or/and mountain peaches in forest stand transformation sample plots, and the functions of water and soil conservation, water conservation and landscape greening are considered.

In the fifth year after the first and second replantations, the angle scale, the degree of mixing, the breast diameter size ratio and the biodiversity index of the modified forest land are determined according to the literature method, wherein the angle scale is determined according to the literature method (Hui-rigourg, angle scale-a structural parameter describing the individual distribution pattern of the forest trees [ J ] forestry science, 1999(01): 39-44.); the degree of hybridization was determined according to the literature (Hugang, Huyanbo. study of the expression of the degree of spatial segregation of the species in the hybridized forest [ J ]. scientific study of forestry, 2001(01): 23-27.); the chest diameter size ratio is determined according to the method in the literature (Huygang, Klaus Gadow, Mathias Albert. A new forest stand space structure parameter-size ratio [ J ]. forestry science research, 1999(01): 4-9.); the biodiversity index is determined by using a Shannon-Wiener index according to a method of a literature (Wangshen, Zhengqiong, Guohao, a method for evaluating the conservation value of the diversity of Chinese forest species based on the Shannon-Wiener index [ J ]. scientific research on forestry, 2008(02): 268-) and the like; degree of occlusion: the canopy density is the ratio of the projection of the tree crown to the forest land area in the forest stand, and the range of the value range is [0, 1 ]. Forestry is generally determined by visual assessment. Thickness of litter: five soil sections were dug according to the five-point sampling method, and the litter thickness was measured using a ruler. Leaf area index: taking a picture in a forest stand sample plot by using a canopy analyzer according to a five-point sampling method, and taking three repeated pictures at each sampling point; leaf area index analysis is carried out at the later stage by using Hemiview 2.1, and the average value of all photos is used as the leaf area index of the sample plot; the measurement results are shown in Table 4.

Table 4 example 1 forest stand regulation and control promoting effect after forest stand modification

Through transformation, the stand structure of the original artificial forest gradually develops towards the directions of multiple layers, different ages and mixed crossing, and the space structure of the stand is optimized; in the transformation process from pure forest to mixed forest, the original site conditions are effectively improved, the mixed degree is increased, and the population isolation degree is greatly improved; the area index of the forest stand leaves is reduced, so that the penetration rainfall in the forest is obviously increased; the thickness of the under-forest litter layer is reduced, the maximum water holding capacity is reduced, and more water permeates into the soil layer and is stored by the forest; the under forest species diversity, forest stand stability and health index are improved to different degrees.

Comparative example 1

1. Forest stand sample plot survey

1-1, the same stand transformation plots of the control example as those of example 1;

1-2, taking the first forest of the southwest corner of the forest stand transformation sample plot as an origin tree, and measuring and recording the coordinates of the first forest by using a GPS (global positioning system);

1-3, starting from an original point tree, numbering all trees in a sample plot in sequence by an S-shaped route, wherein the original point tree is numbered as 1; the coordinates of each tree are measured and recorded using GPS.

A schematic representation of the location of the forest trees within the forest transformation plots is shown in FIG. 1 for a total of 150 pinus tabulaeformis within the forest transformation plots.

1-4, determining and judging the number of plants of adjacent trees around the target wood according to the Thiessen polygon method in arcgis, wherein: the number M of subject trees, adjacent trees B around each subject tree, in the reconstruction zone is shown in table 2.

The forest in the forest stand reconstruction area is used as an object tree and an adjacent tree; and the forest trees in the strip-shaped buffer area can only be used as adjacent trees.

1-5, measuring and recording an included angle alpha between two adjacent trees of adjacent trees around each object tree in the transformation area in the clockwise direction, wherein the object tree is taken as the vertex of the included angle alpha; and calculates a standard angle (alpha) of each object wood₀) In which α is₀＝360°/(M+1)。

1-6, calculating the angular scale according to formula (1), wherein formula (1) is as follows:

in the formula (1), w_iThe size of the angle scale of the ith object wood; m is a tree of an adjacent tree; m is_ijThe variable is a discrete random variable and is a value variable of an angular scale; when the included angle alpha of two adjacent wood is smaller than the standard angle alpha₀When m is_ij1 is ═ 1; otherwise, m_ij0, wherein the standard angle α₀＝360°/(M+1)。

In the process of measuring the angle scale, a protractor is needed to measure, at least 4 persons are needed to be matched with each other to finish accurate measurement, namely one person stands near an object wood, the other two persons stand near adjacent wood, the three persons utilize two steel rulers to fix an included angle, and then the fourth person finishes measuring by the protractor and sequentially measures and calculates the angle of the included angle between the two adjacent wood in the clockwise direction around the object wood. In the forest stands with uneven terrain or high density, the operation is not easy to be completed, the needed manpower and material resources are high, and the working efficiency is not high; and formula calculation is carried out subsequently, which is not beneficial to the implementation of the base-level personnel.

As shown in fig. 4, for the object wood i, the number M of adjacent wood is 4, the adjacent wood is marked as a, b, c, d, and is marked as α_ab、α_bc、α_cd、α_daThe angles between adjacent wood a and b, adjacent wood b and c, adjacent wood c and d, and adjacent wood d and a, respectively.

1-7, measuring the breast diameter of each forest in the forest stand transformation sample plot, and then calculating the breast diameter size ratio u according to a formula (2)_iEquation (2) is as follows:

in the formula (2), u_iThe chest diameter size ratio of the ith object wood is shown; when the breast diameter of the object wood i is larger than that of the adjacent wood j, p_ij1 is ═ 1; otherwise, p_ij＝0。

The larger the angle square value is, the more asymmetric the spatial distribution of the forest trees is, and the closer the adjacent trees are to the random distribution. The larger the breast diameter size ratio, the higher the forest size differentiation degree. The results are shown in Table 5.

TABLE 5 Table of structural parameters of object trees in forest space in forest land to be converted

Note: x represents felling; -means no felling.

Through calculation, the average chest diameter size ratio of the trees in the forest stand transformation sample plot of the comparative example 1 is 0.422, and the whole forest stand transformation sample plot is in a moderate state; the average angular dimension is 0.388, the trees belong to random distribution, in order to enable the density of forest stands to be reasonable, object trees with diagonal dimensions in the range of [0, 0.25] and (0.5, 1], or object trees with the breast diameter size ratio number of [0.5, 1] are taken as felling objects, 52 object trees needing to be felled are screened out in total, forest land reconstruction is carried out according to the prior art, forest felling is carried out by adopting the method of the comparative example 1, and the felling positions and the number are the same as those of the embodiment 1, as shown in fig. 2.

The positions, the number and the object trees of the object trees to be harvested in the forest lands to be converted, which are screened according to the method of the invention, are consistent with those screened by the method of the comparative example 1, and the harvested trees selected in the comparative example 1 and the selective cutting trees screened by the method are 52; the selective cutting positions are basically the same; the invention achieves the transformation effect almost the same as the technical case on the premise of greatly reducing the workload.

The above-described embodiments of the present invention are merely exemplary and do not limit the scope of the present invention in any way. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention, and that such changes and modifications may be made without departing from the spirit and scope of the invention.

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