Table 4-1 Site Types of Fast-growing and High-yield Stands of Larix principis-rupprechtii in North Hebei Province Numbering Altitude (m) Aspect Soil type and soil thickness (cm) Note 1 800 Shade, half shady slope Mountain Brown, >50 2 1400 Half sunny Mountain Brown, >50 3 800 Gully Mountain Brown, >50 Leading environmental factors: altitude, aspect, soil type, and soil thickness. Environmental factor classification: The altitude is divided into 2 levels, the slope direction is divided into 4 levels, and the soil thickness is divided into 2 levels. In the above three types of site conditions, combined with the characteristics of L. principis-rupprechtii, the required soil pH value is below 6.0, the soil is neutral and slightly acidic, the content of gravel in the soil is below 10%, and the texture is medium or light earth. Site requirements can not be seasonal water and flood levels above. In addition, it is required to avoid winds, watersheds and inaccessible land. Second, selection and zoning of afforestation sites (a) Selection of forestation land Before afforestation, all afforestation sites must be surveyed in a unified manner to understand the potential of afforestation sites, and to classify the types of site conditions. In accordance with the principle of appropriate sites, the main contents of surveys include the topography, geomorphology, microclimate, and bedrock of afforestation sites. , soil texture, soil thickness, vegetation types, water conditions, traffic conditions and human and animal activities. Combining the characteristics of Larix principis-rupprechtii tree species, and comprehensive analysis based on the purpose of cultivation, try to be suitable to the right place and give full play to the production capacity of the planting land. Through the above site conditions study, three site conditions suitable for the establishment of Larix principis-rupprechtii were drawn. Combined with years of management experience of Larix principis-rupprechtii, the criteria for selecting the site were as follows: 1 The altitude was between 1000 and 1600 m; 2 The shady slope Semi-shade slope or semi-sunny slope; 3 thick soil layer, thickness over 50cm; 4 Forest brown soil or mountain gray brown soil is better; 5 soil gravel content does not exceed 10%; 6 At the same time pay attention to afforestation sites to avoid the tuyere And watershed; 7 convenient transportation, so that the operation and management of the convenient, ready for the future of timber transport; 8 less harmful to humans and livestock and human activities less area. (II) Zoning of afforestation areas For planning to create a plot of fast-growing and high-yielding forest of North China larch, classification is made according to different site types, and then afforestation division is carried out. The purpose of the zoning is to rationally use the forest land, increase the production capacity of the unit area, and achieve intensive management and convenient management. The contents of the zoning mainly include the following points: 1. Field measurement. Plan actual afforestation area based on slope, soil thickness, etc. to provide accurate data for future site preparation, planting and other operations, and to facilitate mastery and statistics. 2. According to the site conditions and the development direction of cultivated larch, determine a reasonable planting density. 3. Set necessary protective facilities, erect fences or dig protective trenches. 4, operating road design. 5. Comprehensive job surveys, preparation of construction design plans, and reporting to superior leadership. Section 2 Afforestation Models and Density Afforestation model (A) Larch Pure Forest It is a type of stand created from a single tree species of Larix principis-rupprechtii. To create a pure larch forest its design, construction, tending management until harvesting, etc., are relatively simple and easy to operate. However, at the same time, pure forest ecosystems are relatively fragile, natural enemies and other restrictive factors of pests and diseases are few, disasters are prone to disasters, forest fire insurance is of high grade, and pure forests cause land degradation and other shortcomings. The main technical points for building pure forests are: (1) Site preparation is based on small classes, and the site preparation standards and initial planting densities are the same. (2) Cutting off other tree species that affect the growth of larch. (3) Under conditions that do not affect the growth of saplings, attention should be paid to the protection of existing vegetation, and bush species such as Lespedeza chinensis and sea buckthorn should be cultivated to fertilize fertility. (II) Mixed Forest The forest stands mainly composed of larch and include one or more tree species are called mixed forests. 1. The advantage that the larch mixed forest has incomparable pure forest is mainly manifested in: (1) It can make full use of nutrition space. Different tree species with different biological characteristics can be mixed together to occupy larger ground and underground space, which is beneficial to the use of light, moisture, and various nutrients by each tree species in different periods and different levels. (2) The effect of improving site conditions is greater. The canopy thick, large leaf area and complex structure of mixed forests can form a microclimate that is different from pure forests under the same conditions. Mixed forests often accumulate more forest litter than the pure forests with a large number of components. After the decomposition of litter, it has the obvious effect of improving the structure and physical and chemical properties of the soil, regulating water, and improving soil fertility. (3) Strong ability to resist disasters. Mixed forests have low temperatures and high humidity, and combustibles are not easy to burn. In mixed forests, due to changes in the microclimate, the number of beneficial parasites, fungi, and birds in forests is correspondingly higher than that of pure forests. Therefore, pests and diseases are also lighter than pure forests. 2. Mixed species Choosing tree species in mixed forests can be divided into major tree species, associated tree species, and shrub species according to their roles. Selecting the correct mixed species is the key to the success or failure of mixed forests. The main tree species is the target tree species, and its selection target is based on the objective species of afforestation. Generally, it is a tall tree species. To create a fast-growing and high-yield forest of Larix principis-rupprechtii, the main tree species is Larix principis-rupprechtii. Associated tree species are used to assist the main tree species, improve the soil, protect soil and isolate, etc. At the same time, the main tree species are pruned and cultivated for good dry shape. Generally choose shade-resistant, slow-growing small and medium-sized arbor species, such as flower buds, Mongolian alfalfa and so on. The main role of bush tree species is to protect soil, improve soil and fertility, such as sea buckthorn and Lespedeza jasminoides. As a mixed species, tall tree species are sometimes mixed with larch, such as white birch and eucalyptus. It should be pointed out that L. principis-rupprechtii is a tree species with strong positive, fast-growing and shallow root (root system is mainly distributed in 20-50 cm soil layers), and these characteristics must be taken into account when selecting mixed tree species. 3, mixed type (1) The main tree species are mixed with the main tree species. Larch is mixed with white birch, ash, and yellow pineapple. (2) The main tree species and associated tree species are mixed. Larch is mixed with flower buds. (3) Main tree species mixed with shrubs. Larch mixed with seabuckthorn, larch and Lespedeza mixed. (4) Comprehensive mixed type. Larch mixed with eucalyptus, Lespedeza, larch mixed with poplar, birch, seabuckthorn and so on. It should be noted that if the reforestation site was originally a felling site of poplar birch forest, pure forest can be created. Because the forest soil is fertile, the first step will not cause significant land degradation, and it is easy to operate and manage. Mixed forests can also be created by using broad-leaved trees and artificially planted larch to cultivate coniferous and broad-leaved mixed forests; if the forested land is fertile, wet, and barren lands, mixed forests or pure forests can be established, and mixed trees must be selected as shrubs and shrubs; Former locusts are felled in coniferous forests, mixed forests must be established, and mixed trees are broad-leaved trees and shrubs that can improve the soil and fertility, in order to assist the main tree species to achieve the purpose of cultivating fast-growing and high-yield forests. 4. The mixed method refers to the arrangement of the planting points of various tree species in the mixed forest on the forest floor. It is generally divided into six groups of inter-row septa, inter-row mixed, mixed-striped, mixed-blocked, mixed-lined and mixed-planted. Through many years of practical research, it has been cultivated in high-yield larch forests, both technically and technically. In terms of management and management, it is most suitable to use a ribbon blend method. Band mixed: The band composed of young trees of Larix principis-rupprechtii and other tree species are arranged alternately. The bandwidth is generally between 6 and 15 meters. If the band width is too wide, the advantages of mixed forests cannot be shown. In Mengzi Forest Management Bureau, coniferous and broad-leaved mixed forests such as Larix principis-rupprechtii and Betula platyphylla are commonly used, and purpura, yellow dill, seabuckthorn and Lespedeza spp. may also be selected as the mixed species. The advantage of this method is that it solves the problem of inconsistency in management and management of the early growth rate of larch and mixed tree species and the inconsistency of the cutting cycle. Band mixed, the main tree species and the mixed tree species contact between the sideline, less impact on each other, to avoid the species at the same time to compete for growth space, so that the growth of larch is affected. Secondly, the construction of the mixed plantation of the main and the main is beneficial to improve the economic value of the stand. In addition, the broad-leaved tree plays an important role in improving and fertilizing the soil and enhancing the resistance and stability of the stand, which is conducive to the healthy growth of the larch. Because the growth cycle of larch and birch are similar, the mixed forest has overcome the disadvantages of soil compaction and fertility decline after felling of larch pure forest. After the completion of a business cycle, the mixed forest can be used for continuous cropping. It does not affect the productivity of continuous cropping. In the next business cycle, it is also possible to exchange larch belts and mixed distribution belts, so as to achieve the purpose of rapid growth, high yield, and strong resistance of mixed forests. In summary, the ribbon blending model is used in practical applications, whether it is from the stand quality or man-made management, it has advantages that are incomparable with other models. In practice, attention should be paid to the mixed ratio to highlight the economic and social benefits of larch stands. When selecting mixed species, broadleaf tree species should be selected to give full play to their ecological and economic benefits, so that they can complement each other. 5. Mixing Ratio The purpose of establishing fast-growing and high-yielding forests of Larix principis-rupprechtii is mainly to obtain timber and maximize economic benefits. Therefore, the proportion of major tree species must not be low. Regardless of the afforestation area or the number of afforestation plants, they should be 6-70%. Second, the density of forestation (A), determine the significance of the initial planting density Determining the afforestation density is an important task in the process of constructing the fast-growing and high-yield forest of Larix principis-rupprechtii. It is the designer's thorough research, such as site conditions, cultivation objectives, social and economic conditions, market survey and forecast, national policies and other factors. Comparing various plans, after careful decision-making, the initial planting density determined is to determine the number of planted plants per unit area. Only by establishing a reasonable initial planting density can we achieve the expected cultivation goals and investment results through careful scientific and rational management. (II) The role of afforestation density in the process of forest closure 1. The effect of initial planting density of afforestation on the process of canopy closure Forest closure is an important turning point in the growth process of Larix principis-rupprechtii plantation. After the closure of canopy, the stand's resistance to adverse environments is enhanced, and the forest environment is improved. . Increasing the initial planting density of afforestation can accelerate stand closure, but the density is too large, the space for plant growth is limited, and the competition between species is intense, resulting in premature tree differentiation and sparseness in nature, early artificial regulation of thinning, different degrees of waste Woodland productivity is not worth considering from a biological or economic point of view. According to the characteristics of tree species (strong positive, shallow root, fast-growing, fertile and moist), forest conditions and cultivation goals (medium and small diameter timber) and other considerations to see when the closure of vegetation is reasonable. According to a practical survey, the normal time for the closure of Larix principis-rupprechtii forests began five years after afforestation. 2. The effect of afforestation density on the growth of forest trees. Because L. principis-rupprechtii is a plentiful and pleasing tree species, the density of afforestation is too large, the forest stands are closed earlier, the growth of lateral branches and crowns is inhibited, and the individual nutrition space of plants is smaller, which has a greater impact on the individual plant growth. Large, resulting in slow growth of the DBH cross-sectional area, thereby affecting the amount of accumulation on a unit area, for the cultivation of large, medium diameter material delays the maturity time. When the density is too small, young trees cannot be closed, the ability of the forest to resist natural disasters weakens, the stability is also poor, and it is not conducive to cultivating forests. Therefore, the afforestation density is very important for the purpose of forest cultivation. In order to cultivate commercial timber forests, the density must be reasonably determined based on the characteristics of the tree species, cultivation objectives, and operating conditions, combined with site conditions. And this density is an interval, not a constant. In this range, the stand structure of forest stands is reasonable, individual forest trees are robust, have stable growth, and are well-dried, and this zone must be constantly adjusted with the stand growth and development. (III) Determination of afforestation density For the fast-growing and high-yielding forest of Larix principis-rupprechtii, the purpose of harvesting the largest amount of the target material is to obtain the maximum economic benefit while taking into account the other benefits of the forest. According to the practical experience of the 40-year construction of L. principis-rupprechtii by the Mengzi Forest Management Bureau, combined with the market's investigation and prediction of wood demand, and site conditions for reforestation sites, the following three scenarios indicate how to determine a reasonable afforestation density in practice. 1. The determination of afforestation density for the purpose of cultivating small diameter materials The small diameter materials are 4m or less in length and 6～12cm in diameter. According to the site conditions and the growth characteristics of Larix principis-rupprechtii, it was determined that the plant spacing was 1m, the row spacing was 1.5m, and the establishment of pure forest, ie 444 plants/mu, was reasonable. The reason is: North China larch has strong light, fast growth, early closure of the canopy, early thinning and thinning, can make full use of the land, and obtain economic benefits earlier. The conservation rate is calculated as 85%, and the number of preserved plants is 377 per mu. According to actual investigation, the first tending is carried out in about 10 years. The DBH can reach 6.0 cm, the number of plants is 30%, and 2 m long can be produced per mu. About 70 ore mines can realize sales revenue of 210.00 yuan/mu at the current price, and the second thinning at the 15th year. The strength of the number of plants is 20%, and about 60 sticks of 4m long can be produced per mu, which can achieve sales revenue. 600.00 yuan/mu. At this point, 210 to 230 plants are still reserved per acre, which are bred at intervals of 3 years. The strength of the plants is calculated at 20%, and a rotation period can be nurtured 7 times (since the 15th year). Each time, the number of harvested trees per mu, the number of acres reserved, and the sales revenue per mu (Table 4-2). Table 4-2 Pension Intermediate Income Statement content year Number of harvested plants Reserve number Sales revenue 15 48 150 768 18 38 124 722 twenty one 31 104 682 twenty four 25 86 675 27 20 72 640 30 16 60 624 33 12 50 564 From Table 4-2, it can be seen that the number of remaining plants up to 50 plants per mu is the lower limit, and the clear cutting operations will be carried out in the 45th year. The sales income will be 2350.00 yuan per mu. Design afforestation according to 444 points/mu, harvesting at a forest age of 45 years, and the accumulated sales revenue reached 7865.00 yuan/mu, which truly achieved the purpose of fast-growing and high-yielding cultivation of small diameter timber forest. 2. The determination of afforestation density for the purpose of cultivating medium-diameter material The medium-diameter material is a forest product with a small head diameter of between 12 and 17cm. According to the site conditions and the experience of operating larch timber forest for many years, the plant spacing of 1m is determined and the row spacing is 2m. That is 333 points / mu of afforestation density is more appropriate. The reason for this is that in the 154-million-mu management area of ​​the Mengfu Forest Management Bureau, there are relatively few suitable afforestation sites for L. principis-rupprechtii, and most of the larch-constructed land is a cutting site. The annual cutting area is about 10,000 mu. Making good use of the only 10,000 mu of forest land to generate the greatest economic benefit is the top priority for the forestry workers of the Bureau. Combining the forest stands cultivated by the Mengwei Forestry Bureau, most of them are middle-diameter timber forest products, which are calculated based on the initial planting density of 333 holes/mu and the preservation rate of 85%. The number of reserved trees for pure afforestation is 283 plants/mu, up to 35 years. Harvesting, the final number of reserved plants by 50 plants / acre, the average diameter of breast height up to 23-25 ​​cm, can achieve sales revenue 3950.00 yuan / mu. The intermediate tending interval is calculated based on 4 years and can be nurtured 7 times. The number of harvested trees per mu, the number of acres reserved, and sales revenue (Table 4-3). Table 4-3 Table of Income from Tendering Year content Number of harvested plants Reserve number Sales revenue 15 42 241 924 19 48 193 1296 twenty three 38 155 1216 27 31 124 1209 31 25 99 1075 35 20 79 1080 39 13 63 1008 From Table 4-3, it can be seen that the medium-diameter timber accumulated a sales income of 12,668 yuan/mu in one rotation period. Calculated economically, it has achieved the purpose of rapid growth and high yield of medium-diameter timber timber. In addition, 40 million mu of pure forest of Larix principis-rupprechtii and 300,000 mu of mixed forest were passed through the Mengzi Forestry Bureau for 40 years. Most of them are medium-diameter timber. Both have approached or reached the rotation period, and the afforestation density was determined to be 333 holes/mu. It is scientific to cultivate medium-diameter timber forests. 3. Determination of afforestation density for the purpose of cultivating large-diameter materials Large-diameter materials are wood species whose head diameter is more than 18cm. The cultivation of large-diameter timber forest must fully consider site conditions and the growth characteristics of Larix principis-rupprechtii itself. First, under conditions where other climatic factors are suitable, choose the areas with thick soil, gentle slopes, and sunny leeward areas, and the Youpingchuan and Gully blocks. Secondly, the cultivation of large-diameter materials must create sufficient space for plant growth and foster as many side branches as possible to accelerate the growth of DBH. Practice has proved that the smaller the density, the greater the volume of individual plants, but in order to make full use of limited forest resources, combined with production practices, to determine the density of large-diameter materials to the best 166 ~ 222 plants / mu of planting density, through more than three times tending The thinning was optimized so that the number of reserved trees in the last mu was about 30. It has been proved that the diameter of DBH can reach 50CM when the larch reaches mature age under suitable environmental conditions (the diameter of 35-year-old larch is 35cm and the average annual average is 0.92cm) in Mengfu Forest Farm and Longtoushan Forest Farm. Third, the configuration of planting points The arrangement of planting points refers to the arrangement of the planting points on the afforestation ground under the premise of a certain afforestation density. The light distribution of different plants is different, the distribution of nutrient space is different, and the relationship between plants is different, which leads to different growth conditions of the plants. The planting point configuration is generally divided into two major categories: regular shape and irregular shape. In order to facilitate intensive management, the construction of a fast-growing and high-yield forest of Larix principis-rupprechtii was adopted in the regular shape configuration. Regular shape configuration: also called row configuration, that is, each planting point has a regular arrangement. It is characterized by the uniform distribution of planting sites in the reforestation sites and the regularity of the location, which facilitates the calculation and construction of afforestation seedlings, and is a commonly used configuration method in production. According to the arrangement of planting points, it can be divided into rectangular configuration, square configuration, and triangular configuration. 1. Rectangular configuration means that the row spacing is greater than the plant spacing, which is characterized by early closure of the forest and earlier formation of forest groups, which is conducive to the growth and development of forest trees, but uneven distribution of trees, trees often have crown phenomenon. When using this type of configuration, the ratio of row spacing should not be too different, the row spacing should not exceed 2 times the spacing of the plants, and the proportion of rows of row spacing used by Larix principis-rupprechtii is 1:1.5m, 1:2m, and 1:2.5m. 2. The square configuration is the same as the plant spacing and row spacing. It is characterized by uniform distribution of forest trees, equal nutrient space, and well-proportioned development of the crown, which is conducive to the growth of forest trees. However, because of the high lightness of Larix principis-rupprechtii, the spacing of the arranged plants should not be too small, and the ratio of row spacing often used in afforestation is 2m*2m, 1m*1m, and 1.5m*1.5m. 3, product shape (triangle) configuration that adjacent planting points staggered each other, finished font arrangement. The configuration of Larix principis-rupprechtii is often used on the afforestation land where the slope is slightly larger or soil erosion is more likely to occur. Section 3 Site Preparation Third, the role of soil preparation (I) Afforestation Site Preparation Land preparation for afforestation is a technical measure to improve the soil environmental conditions of forest land by clearing and turning over the forest vegetation before afforestation. To build a fast-growing and high-yield forest of Larix principis-rupprechtii must be timely, rationally and meticulously site preparation. It is of great significance to improve the survival rate of afforestation of Larix principis-rupprechtii and promote the growth and development of young trees. (b) Role of afforestation and soil preparation L. principis-rupprechtii is a wet, fertile, well-perforated soil. Soil preparation can effectively improve and adjust soil water content of afforestation land, increase soil thickness, improve permeability, promote decomposition of humus, and promote the effectiveness of various nutrient elements; enhance soil's ability to intercept surface runoff, increase soil moisture, and reduce Soil erosion; increase the survival rate of afforestation and accelerate the growth of saplings. Therefore, it is imperative to make a fine soil preparation, which is also one of the important technical measures for the establishment of a fast-growing and high-yield forest of L. japonica. (c) Way of site preparation The land preparation methods for afforestation can be divided into comprehensive land preparation and local land preparation. Comprehensive land preparation is to turn over the entire soil of the afforestation land. This soil preparation method has a large role in improving the physical and chemical properties of the soil, clearing shrubs and weeds thoroughly, and making the young forest grow well. However, the overall land preparation is more labor-intensive and the cost is higher. At the same time, it is also limited by topographic conditions, environmental conditions, and economic conditions. Since most of the afforestation sites in northern Hebei suitable for the establishment of L. principis-rupprechtii are mountainous lands, it is not appropriate to use all site preparation methods, but to use technically feasible and economically reasonable methods, namely block-like or banded soil preparation methods. 1. The block preparation is square or rectangular. The surface of the hole is slightly inclined to the inside, and the length of the side is more than 50 cm. It is suitable for slopes with thick soil layer, good vegetation and water conditions, slope below 25 degrees. This method is simple and easy to implement, labor-saving, and fast, but it has less effect on improving the conditions of afforestation land and keeps the water and soil effect low. The specific approach is: first cut the shrubs, and then open the side of more than 50 cm long, loose soil layer depth of 30cm or more, the hole distance of 1 ~ 1.5m, spacing 1.5 ~ 2m, digging 220 to 440 points per mu, pick out the hole Stones, grass roots, slopes above 15 degrees above and below the slope of the rows were arranged in a character-shaped array, the outer edge of the hole is higher than the inner edge of 5 ~ 7cm, to facilitate the retention of surface runoff, which is conducive to soil improvement and conservation. 2. The entire belt is slightly inclined toward the inside, with a width of 70 cm or more. This method is a technical measure to carry out the twisting of the afforestation land and regulate the soil moisture and physicochemical properties. Its characteristics are to improve soil physical and chemical properties, remove shrubs and weeds thoroughly, provide space for the normal activities of the root system of L. principis-rupprechtii, and store enough water and nutrients. This method is suitable for gradients below 15 degrees, slope formation, and site conditions. Better plots. The commonly used ribbon preparation method in production is mainly horizontal leveling. The specific approach is: first, line the contour along the contour line on the slope, as the lower edge of the horizontal scale, the length of the line segment depends on the condition of the slope surface, 10 ~100m range. Settling depth 30cm, turn the soil out, and then turn down the soil from the top of the ditch, cut the outer cushion, increase the width of the ditch, and turn the stone or the earth out to make the earth. The topsoil stays in the ditch. Widen more than 70cm to form a step-style, with a low level and a high level on the surface. Up and down from 2.5 to 3.0m, step spacing of 2 ~ 3.0m, the level of the whole level of 220 ~ 330m per acre, seedlings planted in the step. (D) Site preparation specifications include depth, width, length, spacing distance, and soil picking. It must be pointed out that L. principis-rupprechtii is a shallow-rooted surface distribution type with undeveloped main roots and relatively prosperous lateral root development. Studies have shown that the root system of Larix principis-rupprechtii mainly distributes within 20 to 50 cm underground, which accounts for nearly 70% of the total. However, horizontal root system is more developed. Therefore, the depth of the preparation must be more than 30 cm, and the ground breaking surface should also be larger. The ground breaking surface is too large, the cost is relatively large, and it is easy to cause water and soil loss. The production generally requires a hole surface or a bandwidth of 50 to 70 M. In addition, it is required to build rakes on the outskirts, using raw soil, turf, and stones to build an outer edge that is 10 to 15 cm high, so as to retain surface water and increase soil moisture. If the soil is fertile and moist, the level of the surface of the hole can be required to prevent the water content in the soil preparation point from being too large, and the fall afforestation is likely to occur during the freezing. (5) The preparation time is based on the relationship between land preparation time and afforestation time. Generally, the site preparation will be divided into land and land preparation. To build a high-yield larch forest in northern China, it is necessary to play an important role in land preparation and land preparation must be done in advance. The land preparation season changes with the season of afforestation. Generally spring afforestation, land preparation before the rainy season one year before afforestation. Before the rainy season, due to the high temperature and rainy season, weeds are turned into soil before the seed matures, speeding up the decay of grass residues and weeds, and improving the soil. In the autumn afforestation, it is generally required that the role of soil preparation be better before the rainy season. Section IV Strong Seedlings To build a fast-growing and high-yield plantation of Larix principis-rupprechtii, good seed and strong seedlings must be selected. This is the basis. Seeds or cuttings from seed orchard, mother tree or cutting plots are used to cultivate good seedlings and afforestation. Because seedlings and seedlings have good genetic characteristics, the cultivation process of stands can be greatly accelerated. Digital Printing Canvas And Fabrics Digital Printing Canvas,Blank Wallpaper Rolls,Cotton Fabric Large Rolls,Canvas Wall Art Framed Jiangsu Aoli AD Material Co.,Ltd , https://www.aolimaterials.com