An ecological forest tending method for controlling stubborn layer plants in undergrowth

Abstract

The application discloses an ecological forest cultivation method for controlling stubborn layer plants of forest understory, and steps are as follows: keeping and cultivating native dominant tree species such as Schima superba, Castanopsis carlesii, Castanopsis fargesii, Phoebe sheareri and Loropetalum chinense in an arbor layer, the density is 850-1150 trees / hm2, keeping and cultivating dominant tree species such as Neolitsea zhejiangensis, Litsea zhejiangensis, Symplocos glomerata and Phoebe sheareri in a shrub layer, the density is greater than or equal to 1800 trees / hm2, and the species composition and structure of the stubborn layer low-quality forest of forest understory are supplemented and reconstructed in a forest gap; through the measures of Li Bai removal, sanitary cutting, target tree cultivation and stand management, the low-quality forest is converted into a stable, high-quality and relatively complete structure mixed forest of different ages. The application utilizes the chemical mutual-sensing characteristics of native tree species, selects tree species which are not directly affected by secondary metabolites of Li Bai, reconstructs the species composition and structure of the community, rejuvenates dominant species, increases ground surface light and ventilation, improves the light resources of arbor seedlings in the forest understory, reduces the density and coverage of Li Bai, relieves the underground competition, and promotes the growth of forest trees and the stability of the community.

Description

Technical Field

[0001] This invention belongs to the field of forest pest control technology, and specifically relates to an ecological afforestation method for controlling stubborn white vegetation in the understory. Background Technology

[0002] Before the 1990s, large areas of mixed pine and broadleaf forests existed in the hilly areas of eastern Zhejiang. Subsequently, an outbreak of pine wilt disease led to the rapid decline of coniferous species (mainly Masson pine) within the forests. Furthermore, ineffective long-term forest protection and restoration measures, including forest closure and tending, resulted in a low proportion of native tree species within the pine and broadleaf forests. This led to the invasion of large numbers of ferns, forming a large-scale, high-coverage, single-dominant, shrub-like, persistent layered structure. The extremely dense understory of ferns resulted in insufficient sunlight, poor ventilation, intense competition, and soil degradation within the forest. Consequently, after the broadleaf forests matured, they exhibited high tree mortality, slow growth, structural deficiencies, difficulty in stand regeneration, and low timber yields.

[0003] Li Bai ( Diplopterygium glaucum *Pteris vittata* is a large fern belonging to the family Gynostemmaceae, reaching a height of up to 1.8 meters. Its widespread outbreaks are due to several factors. Firstly, its strong asexual reproductive capacity allows it to rapidly invade suitable habitats and form large monotypic layers. More importantly, research has revealed that *Pteris vittata* secretes two allelochemicals that inhibit the growth of roots and shoots in some plants, hindering the growth and regeneration of surrounding plants and reducing timber quality and yield. These allelochemicals are secreted into the soil through the roots and remain there for a long period, exerting a continuous chemical interaction with other plants. *Pteris vittata*'s persistence is also due to its well-developed rhizomes, which store abundant nutrients such as starch, allowing it to quickly regrow even after being cut down. However, given the severe damage caused by forest pests, current measures are insufficient to meet regional control needs and alleviate the significant control pressure. Therefore, effectively controlling the persistent *Pteris vittata* layer using ecological principles and cultivating healthy zonal evergreen broad-leaved forests is a pressing problem that needs to be solved in forestry management.

[0004] A search revealed that CN106234136A has published an ecological restoration and tending method for high-density degraded evergreen broad-leaved forests of Libai, but it does not involve the ecological control technology of dense Libai shrubs based on forest stand species composition and structure. Years later, it may still cause the ecological risk of Libai regeneration due to the large-scale invasion of Libai. Therefore, there are deficiencies in the control technology of invasive plants. Thus, there is an urgent need to develop a new technology that is highly applicable, effective, and safe. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the above-mentioned production by proposing an ecological afforestation method for controlling the stubborn white shrub layer under forest canopy. Through white shrub clearing, sanitary felling and tending, and targeted tree management, this method targets the chemical interaction between white shrubs and *Symplocos edulis* forest trees. It selects species whose white shrubs have no significant direct impact on the allelopathic interaction between dominant tree and shrub species, constructs a community structure, and reorganizes and remodels the vegetation by referring to the dominant species composition and structure of the local "top forest". Then, it adopts targeted tree management for afforestation to alleviate the harm of selected tree species to white shrubs, improve the stability and health of the forest stand, promote tree growth, accelerate the positive process of community succession, increase the economic benefits of the forest stand, and achieve the control of dense white shrub layer by the entire forest community.

[0006] The specific technical solution for achieving the objective of this invention is as follows:

[0007] An ecological afforestation method for controlling stubborn white vegetation in the forest understory includes the following steps:

[0008] (1) Tree species selection: The dominant native tree species to be retained are Schima superba, Castanopsis fargesii, Castanopsis fargesii, Machilus thunbergii, and Sassafras japonica; the tree height of the tree layer is ≥ 10 m and the density is 850-1150 trees / hm. 2 ;

[0009] (2) Species selection for the shrub layer: The main shrub species to be retained in the shrub layer are Litsea zeylanica, Litsea huangdanensis, Camellia pubescens, Machilus thunbergii, and Symplocos chinensis, with a tree height ≤ 4 m and a density ≥ 1800 trees / hm. 2 ;

[0010] (3) Reconstruction method: Through thinning and tending, the sum of the dominance of 2 or 3 species selected in the tree layer is ≥80%; and the sum of the dominance of 3 or 4 species selected in the shrub layer is ≥60%, thereby reconstructing the species composition and structure of the forest community;

[0011] (4) Forest clearing: removing barnyard grass and sanitary felling;

[0012] (5) Replanting and tending: In winter, prepare the land and dig holes in forest gaps or open spaces, with a size of 0.4 m × 0.4 m × 0.3 m. Replant 2-year-old container seedlings of Zhejiang Nanmu and Red Bark Qinggang in March of the following year. After planting, clear the newly grown weeds within 0.5 m around the seedlings in May and September of the same year, and tend them continuously for 4 years.

[0013] (6) Rejuvenation of dominant species: Prune and nurture the dominant trees in the arbor layer, remove dead branches and twigs; select target trees; cover the area under the canopy projection of the target trees with fresh grass and mulch residue for organic matter and soil;

[0014] (7) Forest stand management: Implement continuous and comprehensive management of forest land, control forest stand density and shrub density, establish observation plots, monitor the dynamics of shrub growth and decline, control shrub recurrence and reduce ecological risks.

[0015] The selected tree and shrub species are not directly affected by the persistent metabolic products of the lower layers of the plant; the target trees are superior individuals that are seed-grown, robust, with straight trunks, long and rounded branches, and large crowns; their density is 150-180 trees / hm². 2 The replanted seedlings are robust, highly lignified 2-3 year old container seedlings of local seed source, with a height of 0.6-0.9 m. The replanted seedling species are Zhejiang Nanmu and Red Bark Oak. The spacing between the replanted seedlings is 2.2 m and the row spacing is 2 m.

[0016] The selected tree and shrub species are not directly affected by the secondary metabolites formed by the stubborn white layer; the replanted seedlings are robust, highly lignified 2-3 year old container seedlings of local origin, 0.6-0.9 m tall, with a plant spacing of 2.2 m and a row spacing of 2 m; the target trees are superior individuals grown from seed, robust, with straight trunks, long and rounded branches, and large crowns; the density is 150-180 trees / hm². 2 The organic matter cover and soil covering ratio under the target tree canopy projection area is 100 kg of white residue and 100 kg of fresh grass per tree; the soil covering thickness is 2-3 cm. Beneficial effects

[0017] 1) This invention utilizes plant chemical interaction to select dominant tree and shrub species that have no direct impact on the chemosensory effect of existing forest trees for vegetation recombination. It is an ecological control technology of "controlling grass with trees", which is safe, economical, and can both prevent and control the harm of large-scale chemosensory in the long term and maintain the stability of forest ecology.

[0018] 2) This invention adopts the plant species composition and structure reference of typical local "top forests", selects native dominant tree species to reconstruct and transform vegetation, makes full use of the natural laws and natural forces of forests, improves forest stand structure and forest stand environment, enhances the stability and health of forest ecosystem, promotes tree growth, accelerates community succession process, vegetation recovery is fast, input is low, results are good, management is simple, and applicability is high.

[0019] 3) This invention increases soil fertility, reduces water evaporation, and reduces the loss of soil nutrients due to direct rainwater runoff by covering the target tree canopy with fresh grass, white residue, and fallen organic matter and covering it with soil. It also improves soil structure and quality, effectively maintains soil fertility, promotes tree growth, and is convenient to use locally sourced materials.

[0020] 4) This invention utilizes highly adaptable species that rapidly occupy the shrub layer habitat, reducing the area and quantity of forest land occupied by Libai shrubs, decreasing the regeneration capacity of Libai, and increasing the diversity of shrub species. At the same time, it cultivates second-generation high-value tree species as backup trees, resulting in high economic benefits, simple management, and affordability. Attached Figure Description

[0021] Figure 1 This is a comparison chart of the relative growth rates of trees in the target tree management and transformation area (after 6 years of clearing, sanitation felling and target tree management), the comprehensive tending and transformation area (clearing, sanitation felling and tending and replanting), and the extensive management and transformation area (only clearing and sanitation felling and tending) in Embodiment 1 of the present invention. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Example

[0023] The implementation site is located in Linglongyan, Tiantong Forest Farm, Yinzhou District, Ningbo, Zhejiang Province. It is a natural forest of *Symplocos edulis* with an altitude of 200-300m, a southeast-facing slope of about 18°, and a shrub height of 1.2-1.5m with a coverage of about 98%.

[0024] (1) Species selection for the tree and shrub layers. Based on the existing forest stand conditions, native tree species that are not directly affected by the secondary metabolites formed by the stubborn white layer were selected for the tree layer. The tree layer consisted of *Symplocos macrantha*, *Castanopsis fargesii*, and *Castanopsis chinensis*, with a tree height of 12 m and a density of 900 trees / hm². 2 The shrubs retained for cultivation are mainly *Litsea cubeba*, *Camellia pubescens*, *Machilus thunbergii*, and *Symplocos chinensis*, with a tree height of approximately 2.8 m and a density of ≥2100 trees / hm². 2 ;

[0025] (2) Stand reconstruction. In June 2014, thinning was carried out to make the sum of species dominance in the tree layer ≥80% and the sum of species dominance in the shrub layer ≥60%, thereby reconstructing the species composition and structure of the forest community;

[0026] (3) Forest land clearing. Remove barnyard grass and sanitary felling, and cut down dead, fallen, weak, and diseased trees with no future growth.

[0027] (4) Replanting and tending: In December 2014, prepare the land and dig holes in forest gaps or open spaces, with a size of 0.4 m × 0.4 m × 0.3 m. In March of the following year, replant 2-year-old container seedlings of Zhejiang Nanmu and Red Bark Oak. The seedling height is 0.6-0.9 m. The spacing between replanted seedlings is 2.2 m and the row spacing is 2 m. After planting, in May and September of the same year, clear the newly grown weeds within 0.5 m around the seedlings. Continue tending for 4 years.

[0028] (5) Rejuvenation of dominant species: Prune and nurture the dominant trees in the arbor layer, remove dead branches and twigs; select target trees; cover the target tree canopy projection area with fresh grass and mulberry residue for organic matter covering and soil covering; the organic matter covering and soil covering quality ratio is 100kg of mulberry residue and 100kg of fresh grass / tree, and the soil covering thickness is 2-3cm.

[0029] (6) Forest stand management: Implement continuous and comprehensive management of forest land, control forest stand density and shrub density, establish observation plots, monitor the dynamics of shrub growth and decline, control shrub recurrence and reduce ecological risks.

[0030] See Figure 1 In June 2014, on Tiantong Mountain with the same site conditions, initial tree species composition, and stand age, a survey was conducted on three different management methods for *Michelia macclurei* forests: extensive management (clearing the inner slope and scattering it across the forest floor), comprehensive tending management (clearing the inner slope and stacking it in horizontal strips with a width of 1.8m, with 2m intervals for regeneration strips and sanitary felling), and a target tree management transformation area (implementing target tree cultivation measures based on comprehensive tending management). The survey covered stand species, density, average diameter at breast height (DBH), tree height, and forest health. Three 20m × 20m plots were set up in each management area. Statistical tests were used for comparison, and the Presler formula was applied to calculate the forest volume growth rate for each management area. The results showed that the annual growth rates of forest stand volume under extensive management, integrated tending management, and target tree management were 7.2%, 7.7%, and 9.5%, respectively. The growth rate of target tree management was 1.23 times that of integrated tending management and 1.32 times that of extensive management. The annual growth rate of basal area at breast height (BHH) under target tree management was also higher than that under extensive and integrated tending management. This indicates that the technology of this invention significantly promotes forest growth. Simultaneously, the regeneration of dominant species such as Camellia pubescens, Zingiber officinale, and Machilus thunbergii in the shrub layer reached heights of up to 2.2 meters, with a canopy coverage of 20%, rapidly restoring the shrub structure, effectively controlling the density of shrubs and recurrence, improving forest stability, and reducing ecological risks and hazards. Example

[0031] In March 2014, in areas with numerous "forest gaps" in the *Michelia champaca* forest, container seedlings of 2-3 years old (0.6 meters tall) of *Quercus variabilis* and *Machilus chinensis* were replanted in these gaps, following the steps outlined in the previous embodiment. The seedlings were randomly mixed at a 1:1 ratio, with a plant spacing of 2.2 meters and a row spacing of 2 meters, while other steps remained unchanged. Five years after replanting, the *Quercus variabilis* and *Machilus chinensis* trees in the forest reached heights of 1.8 meters and 2.2 meters, respectively, with crown widths of 0.9m × 0.9m and 1.1m × 1.1m. The average height of the herbaceous layer was 0.4 meters, with a canopy coverage of 30%. No clumps of white shrubs were observed on the forest floor. While controlling the damage from white shrubs, the replanted seedlings rapidly restored the structure of the right shrub layer, increased plant diversity, improved forest community stability, and effectively controlled the recurrence of white shrub damage.

Claims

1. A method of ecological forestation for controlling the forest floor of the stubborn layer of the larch, characterized in that, It comprises the following steps: (1) Species selection in arbor layer: the native dominant tree species, such as Schima superba, Castanopsis carlesii, Castanopsis fargesii, Phoebe sheareri and Machilus zuihoensis, were kept; the tree height was greater than or equal to 10 m, and the density was 850-1150 trees / hm 2 ; (2) Shrub layer species selection: the shrub layer tree species to be preserved are Neolitsea zhejiangensis, Litsea zhangii, Symplocos glauca, Machilus thunbergii and Symplocos paniculata, with a tree height of ≤ 4 m and a density of ≥ 1800 plants / hm 2 ; (3) Reconstruction mode: through tending, the sum of the dominance of 2 or 3 species selected in the arbor layer is ≥80%; the sum of the dominance of 3 or 4 species selected in the shrub layer is ≥60%, the species composition and structure of the forest community are reconstructed; (4) Forest cleaning: remove the li Bai and sanitary cutting; (5) Supplementary planting and tending: in winter, reclamation and rearing are carried out in the forest gap or empty land, the specification is 0.4 m x 0.4 m x 0.3 m, Zhejiang nan and chiqi qinggang 2-year-old container seedlings are supplemented and planted in March of the next year; after planting, the weeds newly grown within 0.5 m around the seedlings are cleaned in May and September of the same year respectively, and continuous tending is carried out for 4 years; (6) Dominant species rejuvenation: pruning and tending are carried out on the dominant trees in the arbor layer, and the dead branches and twigs are removed; target trees are selected; fresh grass and li Bai residues are used for organic mulching and soil covering under the projection area of the target tree crown; (7) Stand management: the forest land is implemented with continuous comprehensive management, the stand density and li Bai shrub layer density are controlled, observation sample plots are established, the dynamic of li Bai growth and decline is monitored, and the recurrence of li Bai and the reduction of ecological risk are controlled; The growth and reproduction of the selected arbor and shrub layer tree species are not directly affected by the secondary metabolites of the stubborn layer formed by li Bai; The mass ratio of the organic mulching and soil covering is 100 kg of li Bai residues and 100 kg of fresh grass per plant; the soil covering thickness is 2-3 cm.

2. The method for controlling the undergrowth of the Liriope spicata in the forest according to claim 1, wherein, The seedlings are healthy, 2-3-year-old container seedlings with high degree of lignification, 0.6-0.9 m in height, and the distance between the seedlings is 2.2 m, and the row spacing is 2 m.

3. The method for controlling the undergrowth of the Liriope spicata according to claim 1, wherein, The target trees are healthy, straight, round and complete, with high height and large crown. Density 150-180 plants per ha 2 .

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