Reconstruction regulation and control method for fire-resistant forest structure of temperate zone Chinese pine forest

Abstract

The invention discloses a temperature zone Chinese pine forest fire-resistant forest structure transformation regulation and control method which is used for solving the phenomenon that fire leakage and fire leakage are prone to occurring when combustible regulation and control are conducted through planned burning, and belongs to the technical field of forest management and fire prevention. The method comprises the following steps: step 1, acquiring basic data; 2, making a transformation scheme; through a natural and manual combination mode, a concentrated, continuous and fire-fragile Chinese pine pure forest is transformed and regulated into a fire-resistant and fire-resistant coniferous and broadleaf mixed forest; 3, modification measures are taken; the method aims to reduce the number of Chinese pine plants and increase ventilation and light transmission in a Chinese pine forest, and is suitable for complementary planting, complementary planting and growth of broad-leaved trees. S31, taking a cutting measure, namely tending and cutting the Chinese pines; s32, protection measures are taken, and when the broad-leaved trees are replanted and replanted, the Chinese pines are nursed and cut and the like, all the broad-leaved trees cannot have branch breaking and cutting damage behaviors regardless of the size, nature and manpower; s33, promoting measures; the purpose is to create conditions suitable for growth of broad-leaved trees. And S34, protection measures are taken.

Description

Technical Field

[0001] The present invention belongs to the technical field of forest fire prevention in forestry, and particularly relates to a method for regulating and controlling the transformation of a fire-resistant and fire-proof forest structure in a temperate Chinese pine forest. Background Art

[0002] Forest fuels are the material basis and primary condition for forest fires, and are the only factor that can be controlled in the fire environment. By effectively regulating forest fuels, not only can the occurrence of forest fires be reduced, the resistance of the forest ecosystem be increased, biodiversity be maintained, and the forest health level be improved. The fuel regulation technology is directly related to the efficiency, effect and economic cost of regulation.

[0003] Through means such as regulating the fuel load, changing the fuel bed structure and the combustion environment of fuels, the fuel regulation technology methods mainly have the following forms: mechanical treatment, prescribed burning, silvicultural tending and construction of fire prevention belts. Mechanical treatment mainly refers to mechanical crushing and its cleaning work, and the objects of mechanical crushing are mainly surface coverings, shrubs, and small trees with a breast diameter ≤ 2.5 cm. After forest harvesting, it is also important to promptly remove the wood and small-diameter logs to reduce the fuel load. Prescribed burning uses low-intensity fire to burn the fuels under the forest canopy in the designated area, which can effectively reduce the accumulation of forest fuels and effectively reduce the fire risk level in the forest area. The selection of the prescribed burning time is affected by various factors. Ma Aili et al. believe that factors such as weather conditions, fire risk level, forest land conditions, terrain, fuel structure, fuel distribution, and fuel moisture should be fully considered. Liu Guangju et al. considered factors such as the tree dormancy period, snow cover thickness, topsoil freezing thickness, soil moisture content, and fuel moisture content.

[0004] Constructing a fire prevention belt is one of the fuel management measures at the landscape scale. It can effectively control the spread of forest fires, and due to the shading effect of the belt, reduce the biomass of the living ground cover in the forest and increase its moisture content. In addition to considering the local fire situation, the construction of a fire prevention belt should also comprehensively consider regional factors such as fuels, belt height, terrain, and meteorology. It can also make fire prevention isolation belts according to local conditions based on natural conditions such as forest stands, roads, rivers, mountains, and terrain. A fire prevention belt is to select fire-resistant tree species according to the terrain and landform, divide the forest stand into several areas, and control them separately to prevent the fire from burning continuously over a large area.

[0005] Silvicultural tending measures such as thinning, pruning, site preparation, weeding, and forest stand transformation mainly control the combustion environment of fuels by adjusting the forest stand structure and changing conditions such as light, humidity, and temperature in the forest, and can have a certain positive impact on controlling forest fire behavior.

[0006] Pinus tabuliformis ( Chinese pineIt has excellent materials, is drought-tolerant and barren-tolerant, has developed roots, and strong adaptability. It is one of the most important afforestation tree species in the vast areas of northern China. The Chinese pine forest is the most widely distributed and has the largest area in the forests of Shanxi, and it is a typical forest type. Due to the large amount of flammable rosin contained in Chinese pine, the volatile terpene organic gases in the forest canopy layer, and the large combustible load of the Chinese pine forest, the major and extremely large forest fires that occurred in Shanxi Province basically occurred in the Chinese pine forest. In view of the wide distribution area, large area of Chinese pine and the vulnerability of forest fire combustion, on the basis of detailed investigation and understanding of the basic data such as the forest age, structure and site conditions of the specific Chinese pine forest, the Chinese pine forest is transformed through the combination of natural and artificial forest management measures to become a needle-broadleaf mixed forest structure that is difficult to burn and fire-resistant. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for regulating and controlling the transformation of a fire-resistant and fire-proof forest structure of a temperate Chinese pine forest, which is used to solve the phenomenon of fire leakage that easily occurs during the control of combustibles by planned burning. The present invention proposes a comprehensive application of forest management technical measures to transform and cultivate the middle-aged Chinese pine forest in the warm temperate zone into a fire-resistant and fire-proof forest structure.

[0008] The present invention is realized by adopting the following technical solutions: A method for regulating and controlling the transformation of a fire-resistant and fire-proof forest structure of a temperate Chinese pine forest, comprising the following steps: Step 1: Obtain basic data; Step 2: Formulate a transformation plan; through the combination of natural and artificial means, transform and regulate the concentrated, contiguous and fire-vulnerable pure Chinese pine forest into a fire-resistant and fire-proof needle-broadleaf mixed forest; Step 3: Transformation measures; the purpose is to reduce the number of Chinese pine trees, increase the ventilation and light transmission in the Chinese pine forest, and be suitable for the replanting, resowing and growth of broad-leaved trees; S31. Harvesting measures, thinning and harvesting Chinese pine; S32. Protection measures, during the operations of replanting and resowing broad-leaved trees and thinning and harvesting Chinese pine, all broad-leaved trees, regardless of size, natural or artificial, should not be damaged such as broken branches or felling; S33. Promotion measures; the purpose is to create suitable growth conditions for broad-leaved trees; S34. Protection measures; the first choice for the replanted and resown tree species is the native fire-proof broad-leaved tree species, the purpose is to increase the number and density of broad-leaved trees, and the final target is to retain the density of broad-leaved trees at 30-40 trees per mu.

[0009] Further preferably, the basic data obtained in Step 1 includes the forest age, site conditions, canopy density, concentrated contiguous area, broad-leaved tree species, density and height of the surveyed Chinese pine forest.

[0010] Further preferably, when obtaining basic data in step one, planning is carried out in small classes, and basic data of Pinus tabulaeformis forests in small classes are investigated. The specific operation is to investigate basic data of Pinus tabulaeformis forests in small classes and prepare a combustible material transformation and control table for Pinus tabulaeformis forests.

[0011] Further preferably, the concentrated, contiguous, fire-vulnerable pure Pinus tabulaeformis forest in step 2 includes the following characteristics: the forest is middle-aged or older, the stand is already closed, the Pinus tabulaeformis accounts for more than 80%, the forest is concentrated and contiguous, the soil layer is more than 30 cm, and the slope is less than 25°.

[0012] Further preferably, in S31, when tending and felling Pinus tabulaeformis around broad-leaved trees, the felling intensity should be controlled below 35%; in areas where broad-leaved trees are to be replanted or in areas where broad-leaved trees with a height of less than 1m are distributed, after felling the Pinus tabulaeformis, the forest density of Pinus tabulaeformis should be retained at 0.7, and there should be diffuse light or weak light exposure; in areas where broad-leaved trees with a height of 1-2m are distributed, after felling the Pinus tabulaeformis, the forest density of Pinus tabulaeformis should be retained at 0.55, and there should be relatively strong light exposure; in areas where broad-leaved trees with a height of more than 2m are distributed, there should be sufficient sunlight exposure after felling the Pinus tabulaeformis, the forest density of Pinus tabulaeformis should be retained at 0.4, and finally full light exposure should be achieved.

[0013] Further preferably, in S33, the Chinese pine that affects the growth of broad-leaved trees is felled, and the seedling broad-leaved trees are retained in the end; the shrubs that affect the growth of broad-leaved trees below 1m in height are broken, and at least 1 / 3 of the broad-leaved trees are exposed to the shrubs; the broad-leaved trees with a height of more than 3 trees growing in clusters above 50cm are thinned out to keep the strong ones; pruning measures are taken, and the Chinese pine that is not felled is pruned, and the height under the branches is retained to be more than 3m; measures are taken to level the holes and loosen the soil; during long-term continuous drought seasons or when cultivating precious broad-leaved trees, fertilization and watering are carried out; bud removal, sprout removal, shrub cutting, and pest control are carried out on broad-leaved trees.

[0014] Further preferably, the replanting method in S34 is as follows: S341, natural seeding is preferred; before planting in autumn, the dead layer should be cleared, the soil should be broken and furrows should be dug, and after planting, the soil should be covered artificially to promote regeneration; S342, spot sowing and broadcasting of large seeds; S343, planting.

[0015] Further preferably, the site conditions include soil thickness and slope, slope position and slope direction.

[0016] Further preferably, in S32, all broad-leaved trees are marked prominently, and a technical measures tablet is made in the work area, including precautions for broad-leaved tree protection.

[0017] Further preferably, in S34, poplar, birch or Prunus armeniaca is selected on the sunny slopes in the south-central Shanxi Province; and oak, maple or Acer truncatum is selected on the shady slopes and semi-shady slopes in S34.

[0018] A forest is a complex ecosystem composed of plants, animals, and microorganisms. From the perspective of forest fires, it is an aggregate of combustibles. With a cultivation and harvesting history spanning a hundred years, permanent forest land continuously provides ecological and economic products for humanity. However, the greatest risk in forest cultivation comes from forest fires. A major fire can reduce thousands of hectares of forest to ashes. But existing forest management techniques, including forest tending, transformation of low-yield forests, and forest harvesting, mainly focus on increasing carbon sinks, establishing a stable and diverse forest ecosystem, and giving full play to the ecological and economic benefits of forests. They do not take establishing a fire-resistant forest structure as the main goal of forest management techniques. The present invention makes full use of existing tending techniques, uses forest fuel regulation techniques as a means, and cultivates a coniferous and broad-leaved mixed forest with a fire-resistant structure in forest land with excellent light, heat, water, and site conditions, which can naturally resist small and medium-sized fires and create a favorable forest environment for fire fighting.

[0019] Under suitable site conditions, the present invention transforms the tree species structure of Chinese pine forests, reduces the accumulation of flammable and combustible materials in the forest and the emission of flammable gases in the forest canopy layer, and realizes the sustainable utilization and protection of forest resources. Detailed implementation methods

[0020] In order to more clearly understand the above-mentioned objects, features, and advantages of the present invention, the solution of the present invention will be further described below. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0021] Many specific details are set forth in the following description in order to fully understand the present invention, but the present invention can also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0022] The specific embodiments of the present invention will be described in detail below.

[0023] Example 1, A method for regulating and transforming the fire-resistant structure of a temperate Chinese pine forest. Based on a detailed investigation of stand data such as the age of the Chinese pine forest, site conditions (soil layer thickness, slope, slope position, slope aspect), canopy density, concentrated and contiguous area, broad-leaved tree species, density, and height, according to the theory of near-natural forest management, determine the transformation plan for the Chinese pine forest. Through a combination of natural and artificial means and multiple transformation operations, transform and regulate the concentrated, contiguous, and fire-vulnerable pure Chinese pine forest into a fire-resistant and fireproof coniferous and broad-leaved mixed forest.

[0024] Conditions for transforming the fire-resistant structure of a Chinese pine forest; for stands of middle age or above that have closed, with Chinese pine accounting for more than 80%, concentrated and contiguous, and site conditions with a soil layer of more than 30 cm and a slope less than 25°. Meeting the above conditions is applicable to the method for regulating and transforming the fire-resistant structure of a Chinese pine forest in this embodiment.

[0025] Step 1. Acquisition and planning of basic data for the regulation of combustibles in Chinese pine forests; The regulation of combustibles in Chinese pine forests is planned by sub-compartments. It is necessary to conduct a detailed investigation of the basic data of the Chinese pine forest stands in sub-compartments, as shown in Table 1. Before formulating the regulation plan for combustibles in Chinese pine forests, a regulation plan table for combustibles in Chinese pine forests shall be formed.

[0026]

[0027] Instructions for filling in the form: ① In the column of tree species composition: It refers to the proportion of the number of Chinese pine trees and the proportion of the number of broad-leaved trees in the current main tree layer.

[0028] ② In the column of number of trees per mu: It refers to the total number of Chinese pine and broad-leaved trees per mu in the current main tree layer.

[0029] ③ In the column of AB combination: A: Thickness of soil layer B: Slope A1: Thin, less than 30 cm (25 cm can be considered) B1: Steep, more than 25° A2: Medium, 30 - 60 cm B2: Inclined, 15° - 25° A3: Thick, more than 60 cm B3: Gentle, less than 15° ④ The combination of A and B within a certain area range, such as: A1B1, A1B2, A1B3, A2B1, A2B2, A2B3, A3B1, A3B2, A3B3.

[0030] ⑤ In the column of slope aspect: It refers to one, two or three of the shady slope, sunny slope and semi-shady slope within the range of AB combination.

[0031] ⑥ In the column of density: It refers to the number of broad-leaved trees per mu within the range of AB combination, which is filled in according to 5 grades, including: 0, 1 - 10, 10 - 20, 20 - 30, more than 30. Among them, the three columns of tree height above 2 m, 1 - 2 m, and below 1 m are also filled in according to these 5 grades.

[0032] ⑦ In the column of transformation target: Fill in one of 6 Chinese pines and 4 broad-leaved trees, 5 Chinese pines and 5 broad-leaved trees, 4 Chinese pines and 6 broad-leaved trees. However, the data for filling in this column are: the number of broad-leaved trees calculated from the two columns of tree species composition and number of trees per mu, the final number of Chinese pine trees retained proposed in the column of transformation measures, and the number of broad-leaved trees obtained from the column of broad-leaved tree density (1 - 10 trees per mu, calculated as 5 trees; 10 - 20 trees per mu, calculated as 15 trees; 20 - 30 trees per mu, calculated as 25 trees; more than 30 trees per mu, calculated as 35 trees).

[0033] ⑧ In the column of transformation measures, fill in according to felling measures, replanting measures, promotion measures, and protection measures. Each measure should be further refined and specific.

[0034] Step 2. Technical measures for tending and felling Chinese pine trees; The purpose is to reduce the number of Chinese pine trees, increase ventilation and light penetration within the Chinese pine forest, and facilitate the replanting and growth of broad-leaved trees.

[0035] When carrying out tending felling of Chinese pine, it should be carried out around the distribution of broad-leaved trees, and the intensity of the number of felled trees should be controlled below 35%.

[0036] ② In the area where broad-leaved trees are to be replanted or where there are broad-leaved trees with a height of less than 1 m, after felling the Chinese pine, the canopy density of the Chinese pine forest should be retained at about 0.7, and there should be diffused or weak light irradiation.

[0037] ③ In the area where broad-leaved trees with a height of 1 - 2 m are distributed, after felling the Chinese pine, the canopy density of the Chinese pine forest should be retained at about 0.55, and there should be relatively strong light irradiation.

[0038] ④ In the area where broad-leaved trees with a height of more than 2 m are distributed, after felling the Chinese pine, there should be sufficient sunlight irradiation, and the canopy density of the Chinese pine forest should be retained at about 0.4, and ultimately full sunlight irradiation should be achieved.

[0039] Step Three: Technical measures for protecting broad-leaved trees; During operations such as replanting broad-leaved trees and tending felling of Chinese pine, all broad-leaved trees, regardless of size, natural or artificial, should not be damaged by actions such as branch breaking or felling. Make obvious marks on all broad-leaved trees, and make technical measure steles in the operation area, including precautions for protecting broad-leaved trees.

[0040] Step Four: Technical measures to promote the growth of broad-leaved trees; The purpose is to create suitable growth conditions for broad-leaved trees.

[0041] ① Fell the Chinese pine that affects the growth of broad-leaved trees. If necessary, gradually eliminate the sprouted broad-leaved trees, and ultimately retain the seedling broad-leaved trees.

[0042] ② Shrubs that affect the growth of broad-leaved trees with a height of less than 1 m. Break the branches of the shrubs, and at least 1 / 3 of the broad-leaved trees should be exposed from the shrubs.

[0043] For broad-leaved trees with a height of more than 50 cm and growing in clusters of 3 or more, thinning to keep the strong ones (also known as thinning measures) should be carried out.

[0044] ④ Pruning measures. Prune the Chinese pine that is not felled, and keep the height below the branches at more than 3 m.

[0045] ⑤ Hole cleaning and soil loosening measures.

[0046] ⑥ During long-term continuous drought seasons or when cultivating precious broad-leaved trees, fertilization and watering can be carried out.

[0047] ⑦ Bud rubbing, sprouting removal, shrub cutting, pest and disease control, etc. for broad-leaved trees.

[0048] Step Five: Technical measures for replanting broad-leaved trees.

[0049] The first choice for tree species to be replanted is native broad-leaved fire-resistant tree species. In the sunny slopes of the central and southern parts of Shanxi Province, choose poplar and birch species, Prunus armeniaca, etc. In the shady slopes and semi-shady slopes, choose Quercus, Acer mono, Acer ginnala, etc. The purpose is to increase the number and density of broad-leaved trees. The ultimate goal is to retain a density of 35 broad-leaved trees per mu.

[0050] Replanting methods: First, the first choice is natural seeding; before the seeds fall in autumn, clean the litter layer, break the soil and dig ditches. After the seeds fall, cover the soil manually to promote regeneration.

[0051] Second, direct seeding and broadcasting of large seeds, such as Quercus.

[0052] Third, planting; bare-root seedlings, cup seedlings, etc. are all acceptable.

[0053] Step Six: Transformation period and others There are two origins of the existing Chinese pine forests in Shanxi Province: one is the remaining secondary natural Chinese pine forests, and the other is the artificial forests established by aerial seeding, planting seedlings, and sowing. The proportion of Chinese pine is large, the forest structure is unstable, and its fire resistance is poor. In suitable sites, continuous transformation towards a fire-resistant and fire-retardant coniferous and broad-leaved uneven-aged structure is needed. Cultivating more precious fire-resistant and fire-retardant forest trees should be the main work of forest management and transformation, and the technical system should be continuously improved.

[0054] Example Two, demonstration of controlling combustibles in the pure Chinese pine forest in the Qinbi working area of the Duanyuhe Forest Farm.

[0055] Natural geographical conditions: The Duanyuhe Forest Farm is located in the northern part of the Zhongtiao Mountains. The landform within the forest farm belongs to medium-undulating erosive mountains, with an altitude of 700 - 1490 meters. The overall structural feature is mainly dominated by faulting. The rocks within the territory are mainly sandy rocks, and the surface is covered with Quaternary loess parent material. The climate of the forest farm belongs to the warm-temperate continental monsoon climate, with distinct four seasons, less snow and drought in winter, windy and dry in spring, concentrated rainfall in summer, mild and dry climate, an average annual temperature of about 11°C, an annual precipitation of 527.7 millimeters, mostly concentrated in July to September, an annual frost-free period of 133 days, an average wind speed of 2.6 meters per second, and strong winds mostly in March and April. Due to the annual alternation of winter and summer monsoons, it is cold, dry and windy in winter and spring, and humid and rainy in summer and autumn. Therefore, forest fire prevention must be strengthened in winter and spring.

[0056] Situation of Plot 226b: This plot is located in the southwestern part of the forest farm, about 7 kilometers away from the forest farm. It belongs to the jurisdiction of the Jiebeiling Management Station of the forest farm. The altitude within the working area is 1115 - 1205m, the soil types are leached cinnamon soil and brown soil, the soil layer thickness is more than 60cm, and the slope is about 15 - 25°.

[0057] The 2260b small class is an artificial pure forest with Chinese pine as the dominant tree species, and scattered distribution of hard broad-leaved tree species such as birchleaf pear and Chinese hophornbeam. There are seedlings of Quercus wutaishanica regenerated and distributed under the forest, and the growth condition is general. The density of the upper-layer trees is 96 trees, including 86 Chinese pine trees per mu and 10 broad-leaved trees per mu. The average breast diameter is 11.9 cm, the average tree height is 6.3 m, and the canopy density is above 0.85. There is a forest road passing through the operation area, and the operation area is 194.8 mu. The object of tending and transformation is the middle-aged forest in the artificial public welfare forest, and the forest type is water conservation forest.

[0058] Technical measures: (1)The management goal of target trees in the artificial pure forest of Chinese pine: Guided by optimizing the tree species structure, improving forest quality, cultivating Chinese pine with a large diameter (above 40 cm), replanting Quercus wutaishanica, comprehensively protecting associated broad-leaved tree species, increasing the forest volume of the whole forest, and constructing a stable, healthy and high-value forest ecosystem, and finally cultivating a 5-pine and 5-broadleaved multi-layered uneven-aged coniferous and broad-leaved mixed forest ecological forest to play the ecological functions of the forest stand such as carbon sequestration, soil and water conservation, water source conservation, and air purification.

[0059] (2) Transformation plan: ①Tending and felling measures: Plan to conduct tending and felling in the small class 3 times. One time in 2023, the felling intensity is 15%. One time in 2026, the felling intensity is 15%. In 2029, the felling intensity is 21%. Finally, 35 Chinese pine trees per mu are reserved. The felling numbers adhere to the principle of cutting the inferior and retaining the superior, cutting the weak and retaining the strong, cutting the dense and retaining the sparse to release the growth space of broad-leaved trees.

[0060] ②Carry out tending management on broad-leaved trees in the forest, including hole expansion, soil loosening, weeding, thinning, pruning, and shrub cutting.

[0061] ③Forest land and biodiversity protection: Retain all shrubs that do not affect the growth of trees. Protect the seedlings and young trees under the forest. Minimize the damage to the litter layer under the forest to protect biodiversity to the greatest extent.

[0062] ④Sow Quercus wutaishanica seeds in forest gaps greater than 5 m in the autumn of 2023, and sow the seeds as soon as they are collected. 2 The seeds are sown immediately after collection.

[0063] (3)Interim effect: In the autumn survey in 2024, the upper-layer coniferous and broad-leaved trees grew well after tending management, and some of the Quercus wutaishanica seedlings at the bottom were exposed from the shrubs. Quercus wutaishanica seeds were sown in forest gaps in the autumn of 2023, and the emergence rate was above 85%, and the growth was strong.

[0064] Example 3. Demonstration of the transformation and regulation of the Chinese pine forest in the 636 small class of Gema Gully in Qijiahe Forest Farm.

[0065] Natural geographical conditions: Qijiahe Forest Farm is located in the southern part of Shanxi Province. The annual average temperature is 13.3 °C, and the annual rainfall is 550 mm. The rainfall is concentrated from July to September. The altitude within the territory ranges from 300 to 1566 m, with a relative height difference of 1266 m. The state-owned management area of the jurisdiction is 11,806.5 ha, belonging to the low and middle mountain natural forest area.

[0066] Situation of Sub-compartment 636: This sub-compartment belongs to the jurisdiction of Gema Gou Management Station of the forest farm. The altitude within the operation area ranges from 850 to 1100 m, and the soil types are leached cinnamon soil and brown soil.

[0067] Sub-compartment 636 is a man-made forest with Chinese pine as the dominant tree species. The main tree species include sumac, oak, date plum, and locust tree. The density of the upper-layer trees is 72 trees per mu, among which there are 58 Chinese pine trees per mu, and the density of broad-leaved trees is 14 trees per mu. The average breast diameter is 14.2 cm, the average tree height is 6.5 m, and the canopy density is 0.89. There are more than 28 saplings with a height of more than 0.5 m in the lower layer. There is a forest road passing through the operation area, and the operation area is 127.8 mu. Among them, the soil layer thickness is 30 - 60 cm, and the slope is below 15° for 50 mu, on the semi-shady slope; the soil layer thickness is 30 - 60 cm, and the slope is above 25° for 47.8 mu, on the sunny slope; the soil layer thickness is below 30 cm, and the slope is above 25° for 30 mu, on the shady slope. The objects of tending and transformation are the middle-aged forests in the artificial public welfare forests, and the forest category is water conservation forest.

[0068] Technical measures: (1) Objectives of target tree management for pure Chinese pine plantations: Guided by optimizing tree species structure, improving forest quality, cultivating Chinese pine with a large diameter (above 50 cm), comprehensively protecting associated broad-leaved tree species, increasing the forest volume of the whole forest, and constructing a stable, healthy, and high-value forest ecosystem, ultimately cultivating and forming a 5 Chinese pine - 5 broad-leaved tree multi-layered uneven-aged coniferous and broad-leaved mixed forest ecological forest to play ecological functions such as carbon sequestration, soil and water conservation, water source conservation, and air purification of the forest stand.

[0069] (2) Transformation plan: ① Tending and felling measures: For the 47.8 mu of forest stands with a soil layer thickness of 30 - 60 cm and a slope above 25° in the sub-compartment, and the 30 mu of forest stands with a soil layer thickness below 30 cm and a slope above 25°, no tending and felling will be carried out. For the 50 mu of forest stands with a soil layer thickness of 30 - 60 cm and a slope below 15° in the sub-compartment, it is planned to carry out tending and felling twice. One time in 2023 with a felling intensity of 15%, and one time in 2026 with a felling intensity of 15%. Finally, 35 Chinese pine trees per mu will be retained. The felling numbers adhere to the principle of cutting the inferior and retaining the superior, cutting the weak and retaining the strong, cutting the dense and retaining the sparse to release the growth space of broad-leaved trees.

[0070] ② Carry out tending management for broad-leaved trees in the forest, including hole widening, soil loosening, weeding, thinning, pruning, and shrub cutting.

[0071] ③Forest land and biodiversity conservation: All shrubs that do not affect the growth of trees are retained. Seedlings and saplings under the forest are protected. The destruction of the litter layer under the forest is minimized to protect biodiversity to the greatest extent possible.

[0072] (3) Stage effect: In the autumn survey in 2024, the upper-layer coniferous and broad-leaved trees grew well after tending management. Some seedlings of Rhus verniciflua and Quercus aliena in the lower layer emerged from the shrubs, and their height growth entered the rapid stage.

[0073] Example 4: Demonstration of regulation and control of the transformation of Pinus tabuliformis forest in Subcompartment 478 of Xigou, Qijiahe Forest Farm; Natural geographical conditions: Qijiahe Forest Farm is located in the southern part of Shanxi Province. The annual average temperature is 13.3 °C, and the annual rainfall is 550 mm. The rainfall is concentrated in July and September. The altitude within the jurisdiction ranges from 300 to 1566 m, with a relative height difference of 1266 m. The state-owned management area of the jurisdiction is 11806.5 ha, belonging to the low and middle mountain natural forest area.

[0074] Conditions of Subcompartment 478: This subcompartment belongs to the jurisdiction of Xigou Management Station of the forest farm. The altitude within the operation area ranges from 850 to 1105 m, and the soil type is leached cinnamon soil.

[0075] Subcompartment 478 is a plantation with Pinus tabuliformis as the dominant tree species. The main tree species are Rhus verniciflua, Quercus aliena, Diospyros lotus, and Robinia pseudoacacia. The density of the upper-layer trees is 61 trees per mu, including 55 Pinus tabuliformis trees per mu and 6 broad-leaved trees per mu. The average breast diameter is 15.5 cm, the average tree height is 6.8 m, and the canopy density is above 0.8. There are more than 5 saplings over 0.5 m in the lower layer; there is a forest road passing through the operation area, and the operation area is 226.2 mu. The thickness of all soil layers is 30 - 60 cm, and the slope is 15°. It is a semi-shady slope with excellent site conditions. The object of tending and transformation is the middle-aged forest in the artificial public welfare forest, and the forest type is water conservation forest.

[0076] Technical measures: (1) Target tree management objective for pure Pinus tabuliformis plantation: Optimize the tree species structure, improve forest quality, cultivate high-diameter Pinus tabuliformis timber (above 50 cm), comprehensively protect associated broad-leaved tree species, increase the forest volume of the whole forest, and guide the construction of a stable, healthy, and high-value forest ecosystem. Ultimately, cultivate a 5 Pinus - 5 broad-leaved tree multi-layered and uneven-aged coniferous and broad-leaved mixed forest ecological forest to give play to the ecological functions of the forest stand such as carbon sequestration, soil and water conservation, water source conservation, and air purification.

[0077] (2) Transformation plan: ① Tending and felling measures: The subcompartment is planned to be tended and felled 3 times. It is felled once in 2023 with an intensity of 10%, once in 2026 with an intensity of 10%, and once in 2029 with an intensity of 11%. Finally, 35 Pinus tabuliformis trees per mu are retained. The felling numbers adhere to the principle of cutting the inferior and retaining the superior, cutting the weak and retaining the strong, and cutting the dense and retaining the sparse to release the growth space of broad-leaved trees.

[0078] ② Carry out nurturing management of broad-leaved trees in the forest by enlarging holes, loosening soil, weeding, thinning seedlings, pruning branches, and cutting shrubs.

[0079] ③ Protection of forest land and biodiversity: All shrubs that do not affect the growth of trees should be preserved. Seedlings and young trees under the forest should be protected. The damage to the dead branches and leaves under the forest should be reduced as much as possible to protect biodiversity to the maximum extent.

[0080] ④ Replanting measures: In autumn 2023, in the 2 Liaodong oak seeds are sown in forest gaps, and the seeds are sown as soon as they are collected, with more than 30 plants per mu.

[0081] (3) Phased effects: According to the autumn survey in 2024, the upper coniferous and broad-leaved trees grew well after nurturing and management, and the emergence rate of the sown Liaodong oak reached 90%. Hole expansion and weeding operations were carried out.

[0082] It should be noted that: 1. Conditions for the transformation of fire-resistant structures of Pinus tabulaeformis forests According to the growth and development law of Pinus tabulaeformis forest, no matter natural or artificial Pinus tabulaeformis forest, only after middle age, the growth and development differentiation is strong, and the individuals with excellent performance are clearly distinguished. After decades of growth and succession, the fire-resistant and fire-resistant broad-leaved trees under the forest begin to migrate or grow in large numbers under the forest and in the gaps. At this time, the poorly growing Pinus tabulaeformis is cut down, and the precious fire-resistant and fire-resistant broad-leaved trees are liberated or replanted. This is in line with the law of forest development and helps to form a multi-layer mixed coniferous and broad-leaved forest of different ages. The leaves of the broad-leaved forest fall in autumn, reducing the distribution of combustibles in the canopy layer in the trapezoidal three-dimensional space by more than 30%. The fallen leaves decompose in the same year, reducing the accumulation of combustibles on the forest surface by more than 25% each year. At the same time, compared with the pure Pinus tabulaeformis forest, the coniferous and broad-leaved mixed forest has less connection between branches and leaves, reducing the probability of crown fire. Broad-leaved trees need more water and nutrients to grow than coniferous trees. Broad-leaved trees can only be cultivated into forests and timber when the slope is less than 25° and the soil thickness is greater than 30cm.

[0083] 2. The importance of basic data acquisition and planning for fire-resistant structure renovation and control of Pinus tabulaeformis forests The basic data of the forest age, tree height, breast diameter, broad-leaved tree density, slope and soil thickness of the forest stand before the transformation of the Pinus tabulaeformis forest are the key to formulating the control plan for the transformation of the fire-resistant and fire-resistant structure of the Pinus tabulaeformis forest. The five aspects of forest age, site conditions, canopy density, concentrated and continuous situation, and forest stand composition are comprehensively considered to determine whether to plan the transformation. According to the density of broad-leaved trees before the transformation, the density of broad-leaved tree replanting and replanting is determined, and the final ratio of Pinus tabulaeformis and broad-leaved trees is cultivated to be 5:5. 70 trees / mu are retained in the semi-humid areas of Shanxi Province, including 35 Pinus tabulaeformis and 35 broad-leaved trees. According to the distribution of broad-leaved trees of various tree heights, the plans such as tending and felling measures and measures to promote the growth of broad-leaved trees are determined.

[0084] 3. Beneficial effects of tending and felling Pinus tabulaeformis The object of the fire-resistant structure transformation of Chinese pine forests is the pure Chinese pine forests created historically. Although they grow well, they are not conducive to resisting major fires and also not conducive to giving full play to the comprehensive benefits of forests. They are not low-yield forests in the traditional sense. The purpose of tending is to cultivate a fire-resistant and fire-retardant structure of coniferous and broad-leaved mixed forests. Therefore, the retained broad-leaved trees are the first target trees, and the second target trees are the well-growing Chinese pines. Therefore, in a certain area, in order to retain broad-leaved trees, it is necessary to have the courage to take strong measures and fell the Chinese pines that affect the growth of broad-leaved trees. Then, as the broad-leaved trees' shade tolerance decreases with age and tree height, it is necessary to determine the intensity of tending for light penetration felling based on the distribution of broad-leaved trees of various tree heights.

[0085] 4. Technical measures for protecting broad-leaved trees In the history of forest management in China, due to the fact that pure Chinese pine forests grow neatly and are easy to manage uniformly, clear-cutting has been used to transform large areas of high-quality uneven-aged multi-layered natural forests into pure Chinese pine forests, and insufficient attention has been paid to broad-leaved trees. In the past thirty years, with the development of the academic research on establishing a multi-functional and stable forest ecological structure and the forest carbon sink, water reservoir, food reservoir, and money reservoir forestry, it has been recognized that the comprehensive benefits of broad-leaved forests are superior to those of Chinese pine needle-leaved forests. In forest management and production, it is necessary to protect broad-leaved trees, and broad-leaved trees are more fire-resistant and fire-retardant than needle-leaved trees.

[0086] 5. Measures to promote the growth of broad-leaved trees The Chinese pine forest before transformation is a middle-aged and highly closed pure forest. During the transformation process, by protecting, retaining, and replanting broad-leaved trees, a certain density of broad-leaved trees has been achieved. However, in this process, broad-leaved trees are still in a weak position in the growth competition of the entire forest ecosystem. It is necessary to take tending and transformation measures such as light penetration felling, pruning of shrubs, fertilization, and watering to cultivate broad-leaved trees under light, water, and fertilizer conditions that are conducive to competitive growth.

[0087] The above are only specific implementation manners of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been made with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered by the protection scope of the claims.

Claims

1. A method for regulating and controlling the fire-resistant forest structure transformation of a temperate pine forest, characterized in that: The steps include: Step 1: Obtain basic data; Step 2: Formulate a transformation plan; through a combination of natural and artificial means, transform and regulate the concentrated, contiguous, fire-vulnerable pure Pinus tabulaeformis forests into fire-resistant and fire-resistant coniferous and broad-leaved mixed forests; Step 3: Transformation measures; The purpose is to reduce the number of Pinus tabulaeformis trees, increase ventilation and light transmission in the Pinus tabulaeformis forest, and make it suitable for the replanting, reseeding and growth of broad-leaved trees; S31. Felling measures: tending and felling of Pinus tabulaeformis; S32. Protection measures: When replanting broad-leaved trees, tending and felling Chinese pine, all broad-leaved trees, regardless of size, whether natural or artificial, must not be broken or cut down; S33. Promotion measures; the purpose is to create conditions suitable for the growth of broad-leaved trees; S34. Protection measures: Native fire-resistant broad-leaved tree species are preferred for replanting, with the aim of increasing the number and density of broad-leaved trees. The ultimate goal is to maintain a broad-leaved tree density of 30 to 40 trees per mu.

2. The method for controlling the fire-resistant and fire-resistant forest structure transformation of a temperate pine forest according to claim 1, characterized in that: Step 1: The basic data obtained include the age, site conditions, canopy density, concentrated contiguous area, broad-leaved tree species, density and height of the investigated Pinus tabulaeformis forest.

3. The method for controlling the fire-resistant and fire-resistant forest structure transformation of a temperate Pinus tabulaeformis forest according to claim 2, characterized in that: When obtaining basic data in step one, planning is carried out in small classes, and the basic data of small-class Pinus tabulaeformis forests are investigated. The specific operation is to investigate the basic data of small-class Pinus tabulaeformis forests and prepare a combustible material transformation and control table for Pinus tabulaeformis forests.

4. The method for controlling the fire-resistant and fire-resistant forest structure transformation of a temperate Pinus tabulaeformis forest according to claim 1, characterized in that: The concentrated, contiguous, fire-vulnerable pure Pinus tabulaeformis forests in step 2 include the following characteristics: above middle-aged, closed stands, Pinus tabulaeformis accounting for more than 80%, concentrated and contiguous, soil layer above 30 cm and slope less than 25°.

5. The method for controlling the fire-resistant forest structure transformation of a temperate pine forest according to claim 1, characterized in that: In S31, Pinus tabulaeformis is cultivated and felled around the distribution of broad-leaved trees, and the felling intensity should be controlled below 35%; in areas where broad-leaved trees are to be replanted or in areas where broad-leaved trees with a height of less than 1m are distributed, after felling the Pinus tabulaeformis, the forest density of Pinus tabulaeformis should be retained at 0.7, and there should be diffuse light or weak light exposure; in areas where broad-leaved trees with a height of 1-2m are distributed, after felling the Pinus tabulaeformis, the forest density of Pinus tabulaeformis should be retained at 0.55, and there should be relatively strong light exposure; in areas where broad-leaved trees with a height of more than 2m are distributed, there should be sufficient sunlight exposure after felling the Pinus tabulaeformis, the forest density of Pinus tabulaeformis should be retained at 0.4, and finally full light exposure should be achieved.

6. The method for controlling the fire-resistant and fire-resistant forest structure transformation of a temperate Pinus tabulaeformis forest according to claim 5, characterized in that: In S33, the Chinese pine trees that affect the growth of broad-leaved trees will be felled, and the broad-leaved trees will be retained in the end; the shrubs that affect the growth of broad-leaved trees with a height of less than 1m will be broken off, and at least 1 / 3 of the broad-leaved trees will be exposed to the shrubs; the broad-leaved trees with a height of more than 3 trees growing together will be thinned out to keep the strong ones; pruning measures will be taken, and the Chinese pine trees that will not be felled will be pruned, and the height under the branches will be retained at more than 3m; measures such as hole preparation and soil loosening will be taken; during long-term continuous drought seasons or when cultivating precious broad-leaved trees, fertilization and watering will be carried out; bud removal, sprout removal, shrub cutting, and pest control will be carried out on broad-leaved trees.

7. The method for controlling the fire-resistant forest structure transformation of a temperate pine forest according to claim 6, characterized in that: The replanting method in S34 is as follows: S341, natural seeding is preferred; before planting in autumn, the dead layer should be cleared, the soil should be broken and furrows should be dug, and after planting, the soil should be covered artificially to promote regeneration; S342, spot sowing and broadcasting of large seeds; S343, planting.

8. A method for regulating and controlling the fire-resistant forest structure transformation of a temperate pine forest according to any one of claims 1 to 7, characterized in that: Site conditions include soil thickness and slope, slope position and slope direction.

9. A method for regulating and controlling the fire-resistant forest structure transformation of a temperate pine forest according to any one of claims 1 to 7, characterized in that: In S32, all broad-leaved trees are marked prominently, and technical measures plaques are made in the work area, including precautions for broad-leaved tree protection.

10. A method for regulating and modifying the fire-resistant forest structure of a temperate Pinus tabulaeformis forest according to any one of claims 1 to 7, characterized in that: In S34, poplar, birch or Prunus armeniaca was selected on the sunny slopes in central and southern Shanxi Province; in S34, oak, maple or Acer truncatum was selected on the shady and semi-shady slopes in central and southern Shanxi Province.

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