Cultivation method of cyclobalanopsis gilgii and phoebe zhejiangensis mixed forest

Abstract

The invention discloses a cultivation method of a cyclobalanopsis gilgii and phoebe zhejiangensis mixed forest. The cultivation method comprises the following steps: selecting slightly acidic red soil with a gentle slope at the altitude of 0-250m; cyclobalanopsis rubra, phoebe zhejiangensis and other Lauraceae woody plants are planted, the plant row spacing is 1.6 m * 1.6 m, strip-shaped mixed planting is carried out, and the same-age forest is cultivated into a stable and high-quality precious wood tree species mixed forest through periodic tending management. According to the method, the mycorrhizal tree species of cyclobalanopsis gilgiana and the non-mycorrhizal tree species of phoebe chekiangensis are planted in a mixed mode, the abundance of endophytic mycorrhizal fungi in soil is increased by means of the symbiotic relationship of the cyclobalanopsis gilgiangensis and the ectomycorrhizal fungi, the nutrient absorption efficiency of the root system of phoebe chekiangensis is improved, meanwhile, the advantage that the phoebe chekiangensis trees grow fast is utilized, light resources are reasonably configured, and the yield is increased. Growth of lateral branches of cyclobalanopsis gilgii is slowed down, the growth rate of trunks is increased, and the yield and quality of dry wood are improved. The method has the advantages of being accurate in cultivation technology, vigorous in forest tree growth, low in production cost and easy and convenient to operate, and has wide application prospects.

Description

Technical Field

[0001] This invention relates to the field of artificial afforestation, and in particular to a method for cultivating a mixed forest of *Quercus variabilis* and *Machilus chinensis*. Background Technology

[0002] Cyclobalanopsis gilva and Phoebe chekiangensis, as evergreen broad-leaved trees, are among the excellent timber species in subtropical regions and are also precious timber species. Historically, camphor, beech, nanmu, and huangu were known as the four famous woods of Jiangnan, especially nanmu and huangu, which were loved and widely used for their hard, strong, beautiful color and grain, durability, and resistance to decay.

[0003] With the transformation of forestry development methods, strengthening forest management and improving forest quality have become the core tasks and main directions of forestry construction. However, the following technical problems currently exist in the afforestation of precious tree species, cultivation of large-diameter trees, and construction of reserve forests: There is a lack of knowledge and technology regarding the rational allocation of tree species and the biological characteristics of mixed-plant species, especially a lack of research on the synergistic effects of light, water, and nutrients; water and fertilizer management techniques are simplistic and extensive, relying on experience to determine mixed tree species and planting spacing, and blindly planting other tree species, resulting in rapid early lateral branch growth and slow tree height growth in *Quercus glauca*, seriously affecting the volume and quality of timber and resulting in low economic timber yield.

[0004] Compared to natural forests, plantations have advantages such as faster growth, shorter growth cycles, and more stable quality, making them a key focus of timber reserve strategies. However, while the number of plantations has increased, their quality, structure, function, and management and economic indicators have declined. Problems such as poor timber quality, geographical degradation, and weak resilience severely limit stand productivity and sustainable development. The most prominent issue facing plantations is their monoculture and low proportion of native tree species. To address this, forest restoration requires careful consideration of the species composition and structural configuration within the forest area to enhance its ecosystem service functions. It is also crucial to fully utilize the feedback mechanisms between plants and soil in the forest ecosystem, particularly mycorrhizal fungi in the soil. Mycorrhizal fungi accelerate the decomposition of organic matter in the soil, improve the efficiency of nutrient absorption by the roots of surrounding trees, and promote tree growth. Mycorrhizal tree species can naturally accumulate mycorrhizal fungi; therefore, leveraging these characteristics to create new methods for cultivating high-quality trees through mixed planting is increasingly attracting the attention of forestry workers.

[0005] A search revealed that CN 104904560 A discloses a cultivation method for young Phoebe zhennan forests, but this technique is a method for cultivating artificial monoculture forests. CN 106613732 A discloses a cultivation method for large-diameter Quercus glauca, which uses mixed planting of Quercus glauca and Cunninghamia lanceolata. The optimal tree density of Quercus glauca is obtained by using a regression model of stand canopy closure, stand diameter at breast height (DBH), and number of trees. However, it fails to deeply analyze the impact of canopy structure on tree growth. More importantly, it does not provide soil management techniques for cultivating large-diameter trees. Relying solely on stand density control techniques is far from sufficient, and the silvicultural cycle is long, making it difficult to apply. Summary of the Invention

[0006] The purpose of this invention is to address the problems existing in the aforementioned production process by proposing a method for cultivating mixed forests of *Quercus variabilis* and *Machilus chinensis*. Through site and species selection, this method involves interplanting typical ectomycorrhizal species *Quercus variabilis* and *Machilus chinensis*, along with non-mycorrhizal species from the Lauraceae family. This utilizes the high abundance of mycorrhizal fungi in the soil, enriched by *Quercus variabilis*, to accelerate the decomposition rate of organic matter in the soil, improve the nutrient absorption efficiency of surrounding tree roots, improve soil structure, promote tree growth, and enhance timber quality. This method cultivates high-quality, valuable timber species and timber forests, reduces production costs, is easy to operate, and increases the economic benefits of the forest stand by utilizing the positive feedback process between plants and soil.

[0007] The specific technical solution for achieving the objective of this invention is as follows:

[0008] A method for cultivating a mixed forest of *Quercus variabilis* and *Machilus chinensis* includes the following steps:

[0009] (1) Selection of afforestation sites: Select sites with an altitude of 0-250m, semi-sunny slopes, gentle slopes, and slightly acidic red soil in mountainous areas, with deep and moist soil;

[0010] (2) Tree species selection: 2-year-old seedlings of local source red oak and Zhejiang nanmu and other Lauraceae species;

[0011] (3) Planting method: strip mixed planting, with a plant spacing of 1.6m × 1.6m;

[0012] (4) Division of young forest growth stages: First, divide by age, and then use average tree height as the dividing standard to divide into the new afforestation stage, the young forest growth to canopy closure stage and the trunk growth stage; the new afforestation stage is 3 years; the average tree height of the young forest to canopy closure stage is 1.5-3.5m; the average tree height of the young forest to canopy closure stage is 3.5-5m;

[0013] (5) Tending at different stages: including tending during the new afforestation stage, tending during the growth of young forests to the canopy closure stage, and tending during the growth of trunks; forming multi-layered mixed forests;

[0014] Furthermore, the tending during the newly afforested stage described in step (5) specifically includes:

[0015] 1) Nurturing; After planting, the young forest should be nurtured by weeding and loosening the soil for 3 consecutive years;

[0016] 2) Fertilization: Fertilize the young forest for two consecutive years after planting.

[0017] Furthermore, the tending of the young forest to the canopy closure stage described in step (5) specifically includes:

[0018] A) Six years after planting, prune the lateral shoots and dead branches of the young oak trees that compete with the main shoot to ensure that the canopy closure is ≤70%.

[0019] B) Remove allelopathic plants from the forest land to maintain forest soil safety.

[0020] Furthermore, the tending of the stalk growth stage described in step (5) specifically includes:

[0021] a) When the average tree height of *Machilus chinensis* exceeds 4.5m, light-piercing pruning should be carried out on the stand, with a density of 3500-4000 trees per hectare, of which *Quercus acutissima* should account for 40-50%;

[0022] b) When the average tree height of *Machilus chinensis* exceeds 6m, thinning and tending should be carried out on the stand, with a density of 2800-3100 trees per hectare, of which *Quercus acutissima* accounts for 35-45%;

[0023] c) Nurturing the sprouts from the stumps: In winter, select one sprout with the best growth and remove the rest. Cover the stump with 3cm of soil to prevent the sprouts from regrowing.

[0024] d) Protect tree species in the later stages of natural succession, maintain the positive succession process of the community, improve species diversity, and form a sustainable forest management model.

[0025] Beneficial effects:

[0026] 1) This invention uses a mixed planting of typical ectomycorrhizal tree species, such as *Quercus glauca*, with non-mycorrhizal tree species, such as *Phoebe zhennan*. The ectomycorrhizal fungi can accumulate in large quantities during the root growth of the mycorrhizal tree species, which increases the abundance of mycorrhizal fungi in the surrounding soil, accelerates the decomposition rate of soil organic matter, improves the soil microbial environment, thereby improving the nutrient absorption efficiency of the surrounding tree roots and enhancing the stress resistance and productivity of the forest.

[0027] 2) This invention utilizes the biological characteristics of the red oak tree, which grows in both height and diameter less than the Zhejiang magnolia. By intercropping the red oak in strips, a reasonable vertical spatial structure is constructed, making full use of light resources. This not only inhibits the lateral shoots that compete with the main shoot of the red oak tree and promotes its tree height growth, but also allows the denser canopy of the red oak tree to provide shade for the trunk of the Zhejiang magnolia tree, reducing excessive growth of branches and improving the quality of the trunk.

[0028] 3) This invention employs mixed planting of precious native tree species and thinning and tending of forest stands to retain sprouts and protect seedlings and saplings that regenerate naturally, thereby increasing the quantity of understory forest resources, improving forest stand structure and environment, making the community more complex and diverse, enhancing the stability of the forest ecosystem, reducing pest and disease damage, and lowering forest management costs.

[0029] 4) This invention has clear cultivation objectives and precise stage management techniques, avoiding the traditional practice of blindly building mixed forests, reducing production costs, and is simple, easy to master, and economical to operate. Attached Figure Description

[0030] Figure 1 Comparison of growth factors between mixed forests of *Quercus rubrum* and *Machilus thunbergii* and pure forests of *Quercus rubrum*;

[0031] Figure 2 A comparison diagram of growth factors between mixed forests of *Quercus acutissima* and *Machilus thunbergii* and pure *Machilus thunbergii* forests. Detailed Implementation

[0032] The present invention will be further explained and described below with reference to specific embodiments.

[0033] Example 1

[0034] The implementation site is located in Tiantong National Forest Park, Yinzhou District, Ningbo City, Zhejiang Province, on Nanshan Mountain, at an altitude of 80-250m, on a semi-sunny slope with a gradient of 14-16°. The soil is slightly acidic red soil developed on granite and shale, with a soil bulk density of 0.9-1.4g / cm³. 3 Total porosity is 40-62%. The forest history of this area is a mixed forest of Masson pine and Liquidambar formosana, which became a sparse Liquidambar formosana forest after the pine wilt disease; the canopy closure is 0-0.3.

[0035] (1) Site selection for afforestation: Select sites at an altitude of 80-250m, on a semi-sunny slope or gentle slope, with red soil in the mountains and a soil bulk density of 0.9-1.4g / cm³. 3 Total porosity 40-65%, pH value 4.2-4.6;

[0036] (2) Tree species selection: local seed sources and seedlings of red oak, Zhejiang nanmu and fine-leaved cinnamon 2-year-old seedlings;

[0037] (3) Planting method: strip mixed planting, with a plant spacing of 1.6m × 1.6m;

[0038] (4) Division of young forest growth stages: First, age and then average tree height are used as the division criteria to divide the forest into three stages: new afforestation stage, young forest growth to canopy closure stage, and trunk growth stage; the new afforestation stage is 3 years; the average tree height of the young forest to canopy closure stage is 1.5-3.5m; the average tree height of the young forest to canopy closure stage is 3.5-5m.

[0039] (5) Tending at different stages: including tending during the newly planted stage, tending during the growth of young forest to the canopy closure stage, and tending during the growth of trunk;

[0040] The tending method for the newly planted forest stage is as follows:

[0041] 1) Nurturing: In the first year after planting, remove shrubs and weeds and loosen the soil in May and September within a 0.8m radius around the newly planted saplings, and continue nurturing for 3 years;

[0042] 2) Fertilization: In early February of the year following planting, dig a semi-circular shallow trench 0.3m away from the plant on the uphill direction of the young tree. The trench should be 15-20cm wide and 10-15cm deep. Apply 50g of compound fertilizer per tree, and cover it with soil after application. Continue fertilization for 2 years to help the root system of the trees develop and expand.

[0043] The tending method for young forests reaching the canopy closure stage is as follows:

[0044] A) Six years after planting, prune the lateral shoots and dead branches of the young oak trees that compete with the main shoot to ensure that the canopy closure is ≤70%;

[0045] B) Remove allelopathic ferns from the forest floor to maintain forest soil safety.

[0046] The cultivation method for the growth stage of the pole is as follows:

[0047] When the average tree height of *Machilus chinensis* exceeds 4.5m, light-penetrating cutting should be carried out on the stand, with a density of 3500-4000 trees per hectare, of which *Quercus acutissima* should account for 40-50%;

[0048] b. When the average tree height of *Machilus chinensis* in Zhejiang exceeds 6m, thinning and tending should be carried out on the stand, with a density of 2800-3100 trees per hectare, of which *Quercus acutissima* accounts for 35-45%;

[0049] c. Nurturing the sprouts from the stumps: In winter, select one sprout with the best growth and remove the rest. Cover the stump with 3cm of soil to prevent the sprouts from regrowing.

[0050] d. Protect Fagaceae and Lauraceae species in the later stages of natural regeneration succession, maintain positive community succession, improve species diversity, and form a sustainable forest management model.

[0051] Experimental results

[0052] Through a 10-year pilot plantation experiment, a 20m x 20m plot was selected in a typical forest stand to conduct per-tree surveys and soil fungal and microbial surveys of mixed forests. The results showed that the densities of *Quercus variabilis*, *Machilus zhinanensis*, and *Cinnamomum camphora* were 1250, 1225, and 475 trees per hectare, respectively; the average diameter at breast height (DBH) were 4.3 cm, 6.5 cm, and 9.9 cm, respectively; the average tree height was 5.2 m, 6 m, and 7.4 m, respectively; and the standing volume per tree was 0.0045 m³, 0.0113 m³, and 0.0304 m³, respectively. These figures were significantly lower than those of a pure *Quercus variabilis* forest (density, average DBH, tree height, and standing volume per tree were 2900, 3.9 cm, 4.1 m, and 0.0032 m³, respectively). Compared to pure stands (density per hectare, average diameter at breast height (DBH), tree height, and single-tree volume of *Quercus variabilis* increased by 10.3%, 26.8%, and 40%, respectively); compared to pure stands of *Phoebe zhennan* (density per hectare, average DBH, tree height, and single-tree volume were 3000 trees, 4.4 cm, 4.8 m, and 0.0045 m³), ​​the average DBH, tree height, and single-tree volume of *Phoebe zhennan* increased by 47.7%, 25%, and 51%, respectively. Regarding soil microorganisms, the relative abundance of ectomycorrhizal fungi in the mixed forest soil was 20.31%, compared to only 4.48% in pure *Phoebe zhennan* and 31.42% in pure *Quercus variabilis*. This indicates that the technology of this invention effectively increased the abundance of ectomycorrhizal fungi in the soil planting environment of *Phoebe zhennan* through mixed stands of *Quercus variabilis*, accelerated the decomposition rate of soil organic matter, improved the nutrient absorption efficiency of its roots, and significantly promoted tree growth. (See appendix) Figure 1 and appendix Figure 2 .

[0053] Example 2

[0054] In 2015, at Fucui'an in Tiantong Forest Park, Yinzhou District, Ningbo, a 5-mu (approximately 0.33 hectares) area with roughly the same site conditions was selected on a semi-sunny slope with a gradient of 12-15° and slightly acidic soil. A mixed forest planting experiment was conducted using *Quercus variabilis*, *Machilus chinensis*, and *Cinnamomum camphora*. The area's forest history consisted of natural forests of *Pinus massoniana*, *Liquidambar formosana*, and *Cinnamomum camphora*. After being affected by pine wilt disease, it became a degraded sparse *Liquidambar formosana* forest with a canopy closure of 0.2.

[0055] Experimental steps

[0056] In step (3) of Example 1, the red oak, Zhejiang nanmu, and fine-leaved cinnamon were interplanted in strips at a ratio of 5:4:1. The Zhejiang nanmu and cinnamon were randomly mixed and planted. All the seedlings were container seedlings with a height of more than 0.6m. The other steps remained unchanged.

[0057] Experimental results

[0058] On plots with identical site conditions, stand density, and stand age, the stand density, average diameter at breast height (DBH), tree height, and stock volume of mixed forests of *Quercus glauca* and *Machilus thunbergii* (after 10 years of stand tending at different stages) and control areas (pure *Quercus glauca* and *Machilus thunbergii* forests also after 10 years of stand tending at different stages) were investigated. The results showed that the optimal stand density, average DBH, tree height, and stock volume per tree for mixed forest management were 2800 trees / hm². 2 6.2 cm, 5.9 m and 0.012 m 3 Compared with pure stands of *Phoebe zhennan* and *Quercus variabilis*, mixed forest management resulted in an increase of over 20% in average diameter at breast height (DBH), tree height, and single-tree volume. This demonstrates that the technology of this invention effectively improves the growth level of trees in mixed forests.

[0059] Example 3

[0060] In 2015, a mixed forest planting experiment was conducted in a 5-mu (approximately 0.33 hectares) area with roughly the same site conditions in Tiantong Forest Farm, Yinzhou District, Ningbo, at an altitude of 120-140 m. The experimental area was located on a southeast slope with a gradient of 12-16°. The soil was slightly acidic with a pH of over 4.5 and a porosity of 40%-60%. The forest history of the area was a mixed forest of Masson pine and Liquidambar formosana, which became a sparse Liquidambar formosana forest after pine wilt disease.

[0061] Experimental steps

[0062] In step (2) of Example 1, the tree species selected are local seed sources and seedlings of *Quercus acutissima* and *Machilus chinensis*. In step (3), *Machilus chinensis* and *Quercus acutissima* are planted in strips at a ratio of 1:1. The seedlings planted are all container seedlings with a height of 0.6m or more. The other steps remain unchanged.

[0063] Experimental results

[0064] On plots with identical site conditions, stand density, and stand age, the stand density, average diameter at breast height (DBH), tree height, and volume of mixed forests of *Quercus glauca* and *Machilus thunbergii* (after 10 years of stand tending at different stages) and control areas (pure *Quercus glauca* and *Machilus thunbergii* forests also after 10 years of stand tending at different stages) were investigated. The results showed that the optimal stand density, average DBH, tree height, and volume per tree in the mixed forest management were 3100 trees / hm². 2 8.0 cm, 7.7 m and 0.058 m 3 Compared with pure stands of *Phoebe zhennan* and *Quercus acutissima*, the mixed forest management showed that the average diameter at breast height (DBH), tree height, and single-tree volume of trees were all increased by more than 30%. This indicates that the technology of this invention has a more significant effect on improving tree growth after mixing *Phoebe zhennan* and *Quercus acutissima*.

[0065] A tabular summary of the specific technical solutions in the embodiments

Claims

1. A method for cultivating a mixed forest of *Quercus variabilis* and *Machilus chinensis*, characterized in that, Includes the following steps: (1) Selection of afforestation sites: Select sites with an altitude of 0-250m, semi-sunny slopes, gentle slopes, and slightly acidic red soil in mountainous areas, with deep and moist soil; (2) Tree species selection: 2-year-old seedlings of local source red oak and Zhejiang nanmu and other Lauraceae species; (3) Planting method: strip mixed planting, with a plant spacing of 1.6m × 1.6m; (4) Division of young forest growth stages: First, divide by age, and then use average tree height as the dividing standard to divide into the new afforestation stage, the young forest growth to canopy closure stage and the trunk growth stage; the new afforestation stage is 3 years; the average tree height of the young forest to canopy closure stage is 1.5-3.5m; the average tree height of the young forest to canopy closure stage is 3.5-5m; (5) Tending at different stages: including tending during the new afforestation stage, tending during the growth of young forests to the canopy closure stage, and tending during the growth of trunks; forming multi-layered mixed forests.

2. The cultivation method of a mixed forest of *Quercus variabilis* and *Machilus thunbergii* as described in claim 1, characterized in that, The tending of newly planted trees in step (5) specifically includes: 1) Nurturing; After planting, the young forest should be nurtured by weeding and loosening the soil for 3 consecutive years; 2) Fertilization: Fertilize the young forest for two consecutive years after planting.

3. The cultivation method of a mixed forest of *Quercus variabilis* and *Machilus thunbergii* as described in claim 1, characterized in that, The tending of the young forest to the canopy closure stage mentioned in step (5) specifically includes: A) Six years after planting, prune the lateral shoots and dead branches of the young oak trees that compete with the main shoot to ensure that the canopy closure is ≤70%. B) Remove allelopathic plants from the forest land to maintain forest soil safety.

4. The cultivation method of a mixed forest of *Quercus variabilis* and *Machilus thunbergii* as described in claim 1, characterized in that, The tending of the stalks during the growth stage described in step (5) specifically includes: a) When the average tree height of *Machilus chinensis* exceeds 4.5m, light-piercing pruning should be carried out on the stand, with a density of 3500-4000 trees per hectare, of which *Quercus acutissima* should account for 40-50%; b) When the average tree height of *Machilus chinensis* exceeds 6m, thinning and tending should be carried out on the stand, with a density of 2800-3100 trees per hectare, of which *Quercus acutissima* accounts for 35-45%; c) Nurturing the sprouts from the stumps: In winter, select one sprout with the best growth and remove the rest. Cover the stump with 3cm of soil to prevent the sprouts from regrowing. d) Protect tree species in the later stages of natural succession, maintain the positive succession process of the community, improve species diversity, and form a sustainable forest management model.

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