Near-natural transformation method for masson pine artificial forest

Abstract

The invention relates to a near-natural transformation method for a masson pine man-made forest. The near-natural transformation method comprises the following steps: (1) selecting and cultivating target trees, resin trees and other trees in a middle-age masson pine man-made forest, and growing interference trees and pitaya trees; (2) cultivating and cutting off resin trees; complementary planting of broad-leaved tree species and tending are carried out, and a different-age pine and broad-leaved mixed forest is obtained; and (3) selecting and marking second-generation target trees in the broad-leaved tree species subjected to complementary planting, selectively cutting interference trees and cultivating the second-generation target trees, then selectively cutting mature masson pine target trees and the second-generation target trees in sequence, and then continuously using the target tree single-plant operation method for operation to complete near-natural transformation. According to the transformation method, masson pine large-diameter wood cultivation and rosin production are both considered, tree species composition and space structure are improved, biodiversity is enriched, forest health is maintained, multiple functions of the forest are fully played, and healthy, stable, high-quality and efficient close-to-nature man-made forests are cultivated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of forest management and operation, in particular to a near-nature reconstruction method of Pinus massoniana plantation. BACKGROUND

[0002] At present, the development mode of Pinus massoniana plantation is mainly large-area pure forest. The single tree species structure and backward management mode not only cause single product production, low wood quality, low forest value, but also cause a series of ecological problems such as land degradation, productivity decline, frequent occurrence of pests and diseases, poor ecological system stability, and seriously restrict the sustainable development of Pinus massoniana plantation.

[0003] A large number of researches and practices show that the root of the problem lies in the lack of the most essential understanding of forest ecosystem and forest management in the traditional management mode, and the lack of theory and technical measures for managing forest by using natural forces. Therefore, it is very critical to reconstruct the existing low-efficiency plantation to improve its growth capacity and economic benefit. SUMMARY

[0004] In order to solve the above technical problems, the purpose of the present application is to provide a near-nature reconstruction method of Pinus massoniana plantation. Through the reconstruction method of the present application, the excellent economic performance of Pinus massoniana is played by taking into account the cultivation of large-diameter Pinus massoniana and turpentine production. By improving the tree species composition and spatial structure, the growth of trees and the productivity and economic value of forest land are improved, the biological diversity is enriched, the forest health is maintained, the multiple functions of forest are fully played, the economic, ecological and social benefits are coordinated, and a healthy and stable, high-quality and efficient near-nature plantation is cultivated.

[0005] The technical scheme for solving the above technical problems of the present application is as follows: The purpose of the present application is to provide a near-nature reconstruction method of Pinus massoniana plantation, comprising the following steps: (1) Forest land selection: dividing the trees in the middle-aged Pinus massoniana plantation into first-generation target trees, king trees, disturbance trees, tapping trees and other trees; marking the first-generation target trees, selecting the first-generation target trees, the tapping trees and the other trees, and cutting the disturbance trees and the king trees; (2) Cultivating the tapping trees and implementing tapping tree felling to form a plantation gap; replanting broad-leaved species in the plantation gap and tending, to obtain a mixed forest of different ages of Pinus and broad-leaved trees; (3) Operating the mixed forest of different ages of Pinus and broad-leaved trees, selecting and marking second-generation target trees in the replanted broad-leaved species according to the target tree single-tree operation method, cutting the disturbance trees affecting the growth of the second-generation target trees in the mixed forest of different ages of Pinus and broad-leaved trees and cultivating the second-generation target trees, and then cutting the first-generation target trees and the second-generation target trees in turn after they are mature, and then continuing to operate using the target tree single-tree operation method to complete the near-nature reconstruction of the Pinus massoniana plantation.

[0006] The present application has the advantages that: through the transformation method of the present application, the excellent economic performance of Pinus massoniana is played by taking into account the cultivation of large-diameter timber and turpentine production; through improving the tree species composition and spatial structure, the growth of forest trees and the productivity and economic value of forest land are improved, the biological diversity is enriched, the forest health is maintained, the multiple functions of the forest are fully played, the economic, ecological and social benefits are coordinated, and a healthy and stable, high-quality and efficient near-natural artificial forest is cultivated.

[0007] On the basis of the above technical scheme, the present application can also be improved as follows.

[0008] Further, the stand age of the middle-aged Pinus massoniana pure forest is 16-22 years.

[0009] Further, the selection criteria of the target tree are as follows: a. The growth advantage is obvious, and it is the tree with the highest height and the largest diameter in the stand. The diameter is not less than 1.2 times the average diameter; b. The stem shape is straight, and there is no low branch or the branch position is higher than 8m; the branch is thin, or thick branches are rare and appear above 4m of the tree height; c. The crown development is uniform, there is no obvious crown, the leaf color is dark green, and the crown height ratio is greater than 0.4; d. There is no damage to the leaves and trunk caused by squirrels, pine caterpillars and other pests (animals), and there is no damage or only small area of skin damage below 9m of the trunk.

[0010] The tapping wood is the forest tree with a diameter of 20-30cm in the Pinus massoniana forest, which is suitable for tapping operation; the interference tree is the forest tree which directly affects the growth of the target tree and significantly affects the light conditions of the target tree, and needs to be cut in the near future; the king tree is the non-purpose tree species forest tree which is located above the target tree and has a large crown, and affects the normal growth of the target tree, and needs to be removed; the other tree is the forest tree in the stand except the target tree, the tapping wood, the auxiliary tree and the interference tree.

[0011] Further, the marking method of the first generation target tree is as follows: a ring-shaped mark is brushed on the first generation target tree with red paint.

[0012] Further, the target tree single tree operation method is as follows: the target tree is selected and marked in the broad-leaved tree species selected for re-planting, the interference tree of the target tree is cut, and the target tree is cultivated.

[0013] Further, the selection method of the second generation target tree refers to the selection method of the first generation target tree, and the density is also 90-120 trees per hectare.

[0014] Further, the interference tree of the second generation target tree is a tree which directly adversely affects the growth of the second generation target tree, significantly affects the light condition of the target tree, and needs to be cut in the near future.

[0015] Further, after the growth cutting in step (1), the stand density of the middle-aged Pinus massoniana artificial forest is 20-30 trees per mu.

[0016] The beneficial effect of the above further scheme is that the stand density is adjusted, and the over-dense and poorly growing trees are cut, so that the growth of the excellent trees is accelerated, and the stand quality is improved.

[0017] Further, the broad-leaved tree species include at least one of Cinnamomum chekiangense, Artocarpus heterophyllus, Michelia maudiae, M. platypoda, Dalbergia odorifera, and Artocarpus heterophyllus.

[0018] The beneficial effect of the above further scheme is that the native tree species supplemented under the canopy of the middle-aged Pinus massoniana forest are mainly rare timber trees with strong ecological adaptability, shade tolerance, and high timber value.

[0019] Further, after the growth cutting in step (1), the canopy density of the middle-aged Pinus massoniana artificial forest is 0.6-1.

[0020] Further, after the growth cutting in step (1), the first generation target tree of the middle-aged Pinus massoniana artificial forest is 85-95 trees per hectare.

[0021] Further, when the cutting is performed in step (2), the diameter at breast height of the tapping wood to be cut is 20-30 cm.

[0022] The beneficial effect of the above further scheme is that the dual-purpose forest management of the Pinus massoniana fatwood is oriented by economic benefits, the short-term benefits are combined with the long-term benefits, the economic benefits are combined with the forest multiple functions such as sustainable fertilization, water conservation, and biodiversity enhancement, and the structure of the stand during the tending is beneficial to the growth of the large-diameter timber pine target and the high yield and stable yield of the tapping wood; during the formation process of the pine-broadleaf multi-age complex forest, the timing of supplementing the target tree species and the determination of the number of trees are used to improve the tree species composition of the stand and quickly form the pine-broadleaf complex.

[0023] Further, when the tapping wood is cut, the outer layer of rough bark is scraped off in the cutting section of the current year with a sharp scraper to the extent that no fat flows; a special tapping knife is used to lightly cut a V-shaped tapping channel, the depth is preferably 0.2-0.3 cm, the tapping surface formed by the two cuts does not exceed half the circumference, the tapping season is the growing season, from the middle of April to the beginning of October, and the tapping is performed for 10 years.

[0024] Further, the target trees are cultivated and managed, and are pruned appropriately to a height of 9 m, and live branches of the target trees below 9 m are cut off with a high branch pruner or a hand saw, and dead branches are also cut off, the cut of the live branches is flat with the trunk, and the dead branches are not left with stubs. Harvesting residue treatment and planting point shrub cleaning: the harvesting residues are stacked in the nearest pine target tree base within a 3 m radius, and long branches over 2 m are cut off during harvesting or timber processing, and the residues are irregularly stacked in small blocks or strips according to the amount of residues, and enough space is reserved for subsequent young forest cultivation.

[0025] Further, in step (2), the shrub planting points in the forest are 80-100 shrubs per hectare, and 4-9 trees are planted in each shrub with a distance of 1.8-2.2 m.

[0026] The beneficial effects of the above further scheme are that after the tapping wood is thinned in the Pinus massoniana forest, the canopy density is reduced to form gaps, windows, and empty spaces in the forest, and the target tree species are planted under the canopy or in the windows to adjust the tree species structure and forest density, and to improve the productivity and ecological function of the forest land.

[0027] Further, in step (3), when the mixed forest of different-aged pines and broad-leaved trees is managed, the natural pruning of the broad-leaved tree species is 6-8 m, and the selection and marking of the second-generation target trees are started.

[0028] Further, in step (3), the density of the second-generation target trees is 90-120 trees per hectare.

[0029] Further, in step (3), after the second-generation target trees are selected, artificial pruning is needed, and the pruning height is 8-10 m. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a schematic diagram of the residue cleaning and broad-leaved tree planting point configuration under the canopy in step (2) of Example 1 of the present application. DETAILED DESCRIPTION

[0031] The principles and characteristics of the present application are described below, and the examples are only used to explain the present application, and are not used to limit the scope of the present application. If the specific technology or conditions are not specified in the examples, the technology or conditions are described in the literature in the art, or according to the product instructions. If the reagents or instruments are not specified by the manufacturer, they are conventional products that can be purchased through regular channels.

[0032] Example 1: Method for modifying Pinus massoniana plantation (1) Forest classification management period: select the 16-22 years old Pinus massoniana plantation for transformation. First, select the target trees for cultivating large-diameter P. massoniana, tapping trees (P. massoniana trees with a diameter of more than 20 cm, suitable for tapping operations), interference trees (trees that directly affect the growth of target trees and significantly affect the light conditions of target trees, which need to be harvested in the near future), king trees (non-purpose tree species located above the target trees, with large canopies that affect the normal growth of target trees, which need to be removed), and other trees (trees in the stand other than target trees, tapping trees, auxiliary trees, and interference trees). The target trees are marked with a red paint ring at breast height, and then growth thinning is carried out to remove interference trees that affect the growth of target trees. The interference trees harvested are preferentially selected from adjacent trees of the target trees and king trees that affect the target trees. The direction of felled wood is controlled to protect the target trees from damage. After growth thinning, the stand density is not less than 0.6, and the total number of reserved trees per hectare, including target trees, is 600 (of which 90 target trees per hectare are used for cultivating large-diameter timber). The average diameter at breast height after thinning is not less than the average diameter at breast height before thinning.

[0033] The selection criteria for target trees are as follows: a. The growth advantage is obvious, and it is the tallest and largest tree in the stand. The diameter is not less than 1.2 times the average diameter; b. The stem shape is straight, with no low branches or branch positions higher than 8 m. The branches are thin, or thick branches are rare and appear above 4 m in height; c. The crown is well-proportioned, with no obvious crown deviation, dark green leaves, and vigorous growth, with a crown height ratio greater than 0.4; d. There is no damage to the leaves and trunk by animals such as squirrels and pine caterpillars, and the trunk below 9 m has no damage or only small area of bark damage.

[0034] (2) Tapping management period for pine forest: After the tapping trees reach 31 years of age and the average diameter reaches 22 cm, tapping operations begin. The tapping wood is cut from the bottom up each year. The outer layer of bark is removed with a sharp knife before cutting to prevent the flow of resin. A special tapping knife is used to cut two V-shaped tapping channels with a depth of 0.2-0.3 cm. The cutting surface formed by the two cuts should not exceed half the circumference. The tapping season is from mid-April to early October, and the tapping season lasts for 10 years. The target trees are cultivated and managed, and the branches are appropriately pruned to a height of 9 m. The live branches below 9 m of the target trees are cut off with a high branch cutter or a handsaw, and dead branches are also removed. The cut ends of the live branches are cut flat with the trunk, and the dead branches are not left with stubs. Harvesting residue treatment and planting site weed cleaning: the harvesting residues are stacked within a radius of 3 m from the base of the nearest pine target tree. Long branches over 2 m are cut off during harvesting or timber processing. The residues are irregularly stacked in small blocks or strips according to the amount of residues, and enough space is reserved for subsequent reforestation and young forest cultivation, as shown in Figure 1 ; (3) Pine forest canopy underplanting period: immediately after the harvesting of the resin-producing wood, underplanting is carried out in the spring or rainy season using red pine container seedlings as the underplanting species (red pine 2-year-old seedlings with a height of 0.8 m to 1.5 m). The underplanting points are selected in the center of the artificial forest gap between the Pinus massoniana target trees. Small block soil preparation is carried out, with a planting hole specification of 35 cm x 35 cm x 30 cm to form planting blocks. Soil preparation is completed before planting in the dry season, or the soil is prepared while planting in the rainy season or in forest areas with relatively loose soil. The underplanting blocks are unevenly distributed in the forest. There are 90 clusters per hectare, with 9 seedlings per cluster, and the distance between clusters is 2.0 m. The distance between clusters is larger for faster-growing clusters, ranging from 2.5-3.5 m, and smaller for slower-growing clusters, ranging from 1.0 m-1.8 m; Young seedling cultivation: within 3 years after planting, grass or weed cultivation is carried out in the planting blocks, 2-3 times per year, until the average height of the young trees reaches 1.5 m. The weeds and shrubs outside the planting blocks are not treated to protect the growth of native tree species and promote the increase of forest species diversity; (4) Mixed pine and broadleaf forest management period: the Pinus massoniana is 36-47 years old, and the broadleaf trees underplanted in step (3) are 4-14 years old. The mixed pine and broadleaf forest community is formed and enters the growth period. The diameter of the Pinus massoniana target trees increases by more than 1 cm per year, and the volume growth peak appears and continues to grow rapidly. The height of the artificially regenerated young trees in the understory continues to accelerate until the growth peak appears. The natural pruning intensity of the trunk increases, gradually forming a good trunk, and the growth competition between the regenerated young trees becomes stronger, and is suppressed by the growth of the upper Pinus massoniana target trees. In the later stage, the trees show obvious differentiation; (5) Near-naturalization initial stage of stand: the age of Pinus massoniana is 48-63 years, the age of broad-leaved trees supplemented is 15-30 years, the height of broad-leaved trees regenerated under the canopy reaches the sub-canopy or main canopy of mixed forest, the dominant tree is up to 15 m or more, the competition among trees in the planting cluster is intense, the diameter class differentiation is obvious, when the natural pruning height is more than 7 m, the selection and marking of the second generation target trees are started: the broad-leaved trees are selected as the second generation target trees, the selection method of the second generation target trees is carried out according to LY / T2617-2016, and the cultivation is carried out according to LY / T2618-2016. One strain of vigorous growth, good stem development, no damage and excellent wood is selected as the second generation target tree in each planting cluster, the number of second generation target trees selected per hectare is 90-120, and the second generation target trees are pruned once after selection, and the pruning height is 9 m. The target trees are selected and immediately after the interference trees are harvested; After the selection of the second generation target trees is completed, the diameter at breast height of Pinus massoniana target trees reaches the target diameter class of 22 cm, and the growth is mature target trees of Pinus massoniana. The mature target trees of Pinus massoniana are harvested, and the stand is completely converted from a coniferous forest to a broad-leaved forest at the same time. During the selection of the target trees of Pinus massoniana, the broad-leaved trees also start natural regeneration and form pure broad-leaved forests of different ages; (6) Late stage of near-naturalization of stand: the supplemented broad-leaved trees are continuously cultivated according to step (3), the over-dense naturally regenerated saplings are thinned, and the third generation target trees are cultivated; the second generation target trees are harvested after reaching the target diameter class, and finally the near-natural artificial forest with complex structure, strong function and significant benefit is formed.

[0035] Example 2: Modification method two of Pinus massoniana plantation (1) Period of classified management of trees: the Pinus massoniana plantation with an age of 16-22 years is selected for modification, first, the target trees for cultivating large-diameter Pinus massoniana, the tapping trees (the trees with a diameter at breast height of more than 20 cm in Pinus massoniana forest, which are suitable for tapping operation except the target trees), the interference trees (the trees which directly affect the growth of the target trees, such as significantly affecting the light conditions of the target trees, and need to be harvested in the near future), the king trees (the non-purpose tree species trees which are located above the target trees and have large canopies, and affect the normal growth of the target trees, and need to be removed), and other trees (the trees in the stand except the target trees, the tapping trees, the auxiliary trees and the interference trees) are selected, the target trees are marked with a red paint in a ring at breast height, and then the interference trees affecting the growth of the target trees are thinned; the interference trees harvested are preferentially selected from the adjacent trees of the target trees and the king trees affecting the target trees. The direction of felled trees is controlled to protect the target trees from damage. After the thinning, the stand density is not less than 0.6, the total number of reserved trees per hectare including the number of target trees is 600 (of which the number of target trees per hectare is 90 for cultivating large-diameter trees), and the average diameter at breast height of the stand after thinning is not less than the average diameter at breast height before thinning.

[0036] The selection criteria of the target trees are as follows: a. Growth advantage is obvious, is the highest tree height, diameter at breast height of the largest trees in the stand. Diameter at breast height is not less than 1.2 times the average diameter at breast height; b. Straight stem shape, no low branch or branch position higher than 8m; thin branch, or thick branch rarely and appear above 4m of tree height; c. Crown development uniform, no obvious crown, leaf color dark green, vigorous, crown height ratio is greater than 0.4; d. No squirrel, pine moth and other pests (animals) damage to leaves and tree trunk, no injury or only small area of skin injury below 9m of tree trunk.

[0037] (2) Pine forest tapping management period: tapping wood forest age reaches 31 years, average diameter at breast height reaches 22cm, tapping operation is started, tapping wood cutting is carried out from bottom to top every year, outer thick skin is scraped off in the cutting section of the year, and the depth of the cutting is 0.2cm~0.3cm. The cutting surface formed by the two cuts is not more than half the circumference. The tapping season is from mid-April to early October every year, and the tapping is carried out for 10 years; The target trees are cultivated and managed, and the height of the pruning is up to 9m. The live branches below 9m of the target trees are cut off with high pruning shears or hand saw, and the dead branches are also cut off. The live branch cut is cut flat with the trunk, and the dead branch does not leave a stump. The remaining material is treated and the planting point is cleaned: the remaining material is stacked within 3m radius of the nearest pine target tree base, and the long branches over 2m are cut off during cutting or material making. According to the amount of remaining material, strip stacking is carried out, and enough space is reserved for subsequent young forest cultivation; (3) Pine forest under canopy reforestation period: immediately after the tapping wood is cut, reforestation is carried out in spring or rainy season, and container seedlings of Pinus massoniana are used as reforestation species (Pinus massoniana is 2 years old, seedling height is 0.4m~0.8m). The planting point is selected in the center of the artificial forest gap between Pinus massoniana target trees. Small block soil is prepared, and the planting hole specification is 35cm×35cm×30cm, forming a planting block. The soil is prepared before planting in dry season, or it is planted while digging in rainy season or in forest with loose soil. The planting blocks are unevenly distributed in the forest; 90 clusters per hectare, 6 plants per cluster, cluster distance is about 2.0m, faster growing clusters have larger distance of 2.5-3.5m, and slower growing clusters have smaller distance of 1.0m-1.8m; Young seedling cultivation: within 3 years after planting, the soil is cultivated or the grass is cut every year 2-3 times, until the young trees grow to an average height of 1.5m. The grass and shrubs outside the planting block are not treated, the growth of the original native tree species is protected, and the diversity of the forest stand is increased; Good dry shape culture: artificial pruning is carried out 1 year before the end of young forest tending, mainly removing weak main stems and thick branches of low branch trees, and the pruning method and requirements are carried out according to GB / T 15781, and the crown height ratio is kept at 0.5. With the increase of forest age, the relationship between the regenerated trees develops from mutual benefit to competition, and the natural pruning from weak to strong, until the natural pruning main stem is as high as 6m-8m; (4) Mixed forest of different ages: the age of Pinus massoniana is 36-47 years, and the age of broad-leaved trees supplemented in step (3) is 4-14 years, the mixed forest of different ages forms a community to the growth period. The target tree diameter of Pinus massoniana increases by more than 1 cm per year, the volume growth peak appears, and continues to grow at a high speed; the height growth of the artificial regeneration seedlings under the forest continues to accelerate until the growth peak appears; the natural pruning strength of the trunk increases continuously, and a good main stem is gradually formed, and the growth competition between the regenerated seedlings becomes stronger and stronger, and is suppressed by the growth of the upper layer of pine target trees, and the differentiation of the later forest trees is obvious; (5) Initial stage of near-natural forest stand: the age of Pinus massoniana is 48-63 years, and the age of broad-leaved trees supplemented is 15-30 years, the height of the broad-leaved trees regenerated under the canopy reaches the sub-canopy or main canopy of the mixed forest, and the dominant tree is as high as 15m or more, the competition among the trees in the planting cluster is intense, and the diameter class differentiation is obvious, when the natural pruning reaches more than 7m, the selection and marking of the second generation of target trees begins: the broad-leaved trees are selected as the second generation of target trees, the selection method of the second generation of target trees refers to the selection method of the first generation of target trees, and the density is also 90-120 trees per hectare. Select 1 tree with good growth and good stem shape without damage as the second generation of target trees per planting cluster, select 100 trees per hectare as the second generation of target trees, and perform one-time artificial pruning on the second generation of target trees after selection, and the pruning height is 9m. Disturbance tree harvesting is carried out immediately after the selection of the target trees is completed; After 15 years of completing the selection of the second generation of target trees, the diameter at breast height of Pinus massoniana target trees reaches the target diameter of 22cm, and the growth is mature Pinus massoniana target trees, and the mature Pinus massoniana target trees are harvested, and at the same time, the forest stand completes the overall conversion from coniferous forest to broad-leaved forest, and the broad-leaved trees also begin natural regeneration during the harvesting of the Pinus massoniana target trees, and form a mixed forest of different ages of broad-leaved trees; (6) Late stage of near-natural forest stand: continue to cultivate supplemented broad-leaved trees according to step (3), and take light thinning on the over-dense natural regeneration seedlings, and cultivate the third generation of target trees; the second generation of target trees is harvested when reaching the target diameter, and finally forms a near-natural artificial forest with complex structure, strong function and significant benefits.

[0038] Example 3: Method three for transforming Pinus massoniana plantation (1) Forest classification management period: select 16-22 years old Pinus massoniana plantation for transformation, first select target trees for cultivating large-diameter P. massoniana, tapping trees (P. massoniana trees with a diameter of more than 20 cm suitable for tapping operations, except target trees), interference trees (trees that directly affect the growth of target trees, such as significantly affecting the light conditions of target trees, and need to be harvested in the near future), king trees (non-purpose tree species located above the target trees, with large canopies that affect the normal growth of target trees, which need to be removed), and other trees (trees in the stand except target trees, tapping trees, auxiliary trees, and interference trees). The target trees are marked with a red paint ring at breast height, and then growth thinning is carried out, that is, thinning interference trees that affect the growth of target trees; the interference trees harvested are preferentially selected from adjacent trees of target trees and king trees that affect target trees. Control the direction of felled wood to protect target trees from damage. After growth thinning, the stand density is not less than 0.6, and the total number of reserved trees per hectare, including target trees, is 600 (of which 90 target trees per hectare are used for cultivating large-diameter timber); the average diameter at breast height is not less than the average diameter at breast height before harvesting.

[0039] The selection criteria for target trees are as follows: a. The growth advantage is obvious, and it is the tallest and largest tree in the stand. The diameter is not less than 1.2 times the average diameter; b. The stem shape is straight, with no low branches or branch positions higher than 8 m; the branches are thin, or thick branches are rare and appear above 4 m in height; c. The crown is evenly developed, with no obvious crown, dark green leaves, and vigorous growth, with a crown height ratio greater than 0.4; d. No squirrels, pine caterpillars, or other pests (animals) damage the leaves and trunk, and the trunk has no damage below 9 m or only small area of skin damage.

[0040] (2) Pine tapping management period: After the tapping trees are 31 years old and the average diameter reaches 22 cm, tapping operations begin. The tapping wood is cut from the bottom up every year. The outer thick bark is scraped off with a sharp scraper to the extent that no resin flows. A special tapping knife is used to cut two V-shaped tapping channels, with a depth of 0.2-0.3 cm, and the tapping surface formed by the two cuts does not exceed half the circumference. The tapping season is the growing season, from mid-April to early October, and the tapping is done for 10 years. Cultivation management and pruning of target trees, pruning height to 9m. The living branches below 9m of the target trees are cut off with high pruning shears or hand saws, and dead branches are also removed. The cut of the living branches is flat with the trunk, and the dead branches are not left with stumps. Harvesting and planting point shrub cleaning: the harvesting residues are stacked within a radius of 3m from the base of the nearest pine target tree. Long branches over 2m are cut off during harvesting or timber processing. The residues are stacked in strips according to their quantity, and enough space is reserved for subsequent reforestation and young forest cultivation; (3) Pine forest canopy underplanting period: immediately after the harvesting of the resin-producing wood, underplanting is carried out in the spring or rainy season using containerized large seedlings of Pinus massoniana as the underplanting species (Pinus massoniana is 2-year-old seedlings with a height of 0.4-0.8m). The underplanting points are selected in the center of the artificial forest gap between Pinus massoniana target trees. Small-scale land preparation is carried out, with a planting hole specification of 35cm x 35cm x 30cm to form planting blocks. Land preparation is completed before planting in the dry season, or planting is carried out while digging in the rainy season or in forest land with relatively loose soil texture; the planting blocks are unevenly distributed in the forest; 90 clusters per hectare, with 4 plants per cluster, and a cluster distance of about 2.0m. The cluster distance is larger for faster-growing clusters, ranging from 2.5-3.5m, and smaller for slower-growing clusters, ranging from 1.0-1.8m; Young seedling cultivation: within 3 years after planting, shovel or cut grass cultivation is carried out in the planting block, 2-3 times per year, until the average height of the young trees reaches 1.5m. No treatment is given to weeds and shrubs outside the planting block to protect the growth of native tree species and promote the increase of forest species diversity; Good dry shape cultivation: artificial pruning is carried out 1 year before the end of young forest cultivation, mainly to remove weak trunks and thick branches of low branches. Pruning methods and requirements are carried out according to GB / T 15781, with a crown height ratio of about 0.5. As the forest age increases, the relationship between the young trees develops from mutual benefit to competition, and natural pruning from weak to strong until the natural pruning trunk reaches 6-8m; (4) Mixed pine and broadleaf forest management period: Pinus massoniana is 36-47 years old, and the broadleaf trees underplanted in step (3) are 4-14 years old. The mixed pine and broadleaf forest community is formed and enters the growth period. The diameter of the Pinus massoniana target trees increases by more than 1cm per year, the volume growth peak appears, and continues to grow at a high speed; the height growth of the young trees in the understory artificial regeneration accelerates continuously until the growth peak appears; the natural pruning intensity of the trunk increases continuously, and a good trunk is gradually formed. The growth competition between the young trees is increasingly strong, and is strengthened by the growth suppression of the upper Pinus massoniana target trees. In the later stage, the trees show obvious differentiation; (5) Near-naturalization initial stage of stand: the age of Pinus massoniana is 48-63 years, the age of broad-leaved trees replanted is 15-30 years, the height of broad-leaved trees regenerated under the canopy reaches the sub-canopy or main canopy of mixed forest, the dominant tree is up to 15 m or more, the competition among trees in the planting cluster is intense, the diameter class is obviously differentiated, when the natural pruning height is more than 7 m, the selection and marking of the second generation of target trees are started: the broad-leaved trees are selected as the second generation of target trees, and the selection and cultivation methods of the second generation of target trees refer to those of the first generation of target trees. One vigorous and well-shaped broad-leaved tree without damage is selected as the second generation of target tree in each planting cluster, and the number of the second generation of target trees selected per hectare is 90-120, the second generation of target trees is pruned once after being selected, the pruning height is 9 m, and the interference trees are cut down immediately after the selection of the target trees is completed; After the selection of the second generation of target trees is completed, the diameter at breast height of Pinus massoniana reaches 22 cm, and Pinus massoniana grows into mature target trees, the mature target trees of Pinus massoniana are cut down, and the stand is completely transformed from a coniferous forest into a broad-leaved forest during the cutting of the target trees of Pinus massoniana, and the broad-leaved trees also start natural regeneration and form a pure broad-leaved forest with different ages during the cutting of the target trees of Pinus massoniana; (6) Late stage of near-naturalization of stand: the replanted broad-leaved trees are cultivated according to step (3), the over-dense naturally regenerated saplings are thinned, and the third generation of target trees is cultivated; the second generation of target trees is cut down when reaching the target diameter class, and finally the near-natural artificial forest with a complex structure, strong function and significant benefits is formed.

[0041] Comparative Example 1: Modification method of Pinus massoniana plantation A pure Pinus massoniana forest is constructed at a density of 2 m*2 m, and in the three years before afforestation, the first year, 3 times of tending are carried out, each time interval is 4 months; the second year, 2 times of tending are carried out, each time interval is two months; the third year, 1 time of tending is carried out in June, the tending adopts block tending, weeds within a range of 1 m in diameter of Pinus massoniana are removed, and the roots of the weeds are also removed, the weeds outside the range of 1 m in diameter of Pinus massoniana are treated by cutting and pruning, and only ten centimeters of the weeds on the ground are reserved. Thinning is carried out in the 7th year, the 11th year and the 15th year, respectively, 30-40% of Pinus massoniana with poor growth are screened out, and finally 40-50 trees per mu are reserved. Pine resin is collected in the whole forest from the 20th year, after 10 years of continuous collection, the forest is clear-cut and the mountain is reforested.

[0042] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A method for near-natural transformation of Masson pine plantations, characterized in that, The modification method includes the following steps: (1) Forest selection: The Masson pine in the middle-aged Masson pine plantation is divided into first-generation target trees, dominant trees, interference trees, resin tapping trees, and other trees; the first-generation target trees are marked, the first-generation target trees, the resin tapping trees, and the other trees are selected for cultivation, and the interference trees and dominant trees are cut down. (2) Cultivate the resin-producing trees and harvest them to form artificial forest gaps; replant broad-leaved tree species in the artificial forest gaps and tend them to obtain a mixed pine and broad-leaved forest of different ages; (3) To manage the mixed pine and broad-leaved forest of different ages, select and mark the second-generation target trees in the replanted broad-leaved tree species according to the single-tree target tree operation method, select and cut down the interfering trees in the mixed pine and broad-leaved forest of different ages that affect the growth of the second-generation target trees and cultivate the second-generation target trees. After the first-generation target trees and the second-generation target trees mature, they are cut down in sequence. Then, the single-tree target tree operation method is used to continue the management to complete the near-natural transformation of the Masson pine plantation.

2. The method for near-natural transformation of Masson pine plantations according to claim 1, characterized in that, After the growth cut described in step (1), the stand density of the middle-aged Masson pine plantation is 20-30 trees per mu.

3. The method for near-natural transformation of Masson pine plantations according to claim 1, characterized in that, After the growth cut described in step (1), the canopy closure of the middle-aged Masson pine plantation is 0.6~1.

4. The method for near-natural transformation of Masson pine plantations according to claim 3, characterized in that, After the growth felling described in step (1), the density of the first generation target trees in the middle-aged Masson pine plantation is 85-95 trees per hectare.

5. The method for near-natural transformation of Masson pine plantations according to claim 1, characterized in that, When harvesting in step (2), the diameter at breast height of the resin-producing trees harvested is 20-30 cm.

6. The method for near-natural transformation of Masson pine plantations according to claim 1, characterized in that, The broad-leaved tree species include at least one of the following: Red Castanopsis, Gynostemma pentaphyllum, Michelia champaca, Michelia yunnanensis, Dalbergia odorifera, and Milo.

7. The method for near-natural transformation of Masson pine plantations according to claim 1, characterized in that, In step (2), the number of clumps planted in the forest during replanting is 80 to 100 per hectare, with 4 to 9 trees planted in each clump and a distance of 1.8 to 2.2 meters between clumps.

8. The method for near-natural transformation of Masson pine plantations according to claim 1, characterized in that, In step (3), when managing the mixed pine and broadleaf forest of different ages, the selection and marking of the second-generation target trees shall begin when the natural pruning of the replanted broadleaf trees reaches 6-8m.

9. The method for near-natural transformation of Masson pine plantations according to claim 1, characterized in that, The density of the second-generation target trees in step (3) is 90 to 120 trees per hectare.

10. A method for near-natural transformation of Masson pine plantations according to claim 1, characterized in that, After selecting the second-generation target tree in step (3), manual pruning is required, with a pruning height of 8-10m.

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