Physiological and ecological basis and methods of crown thinning?

decibel

Beijing local standard

DB 1 1/290-2005

Technical specification for tending of ecological public welfare forest in mountainous areas

Released on June 28th, 2005 and implemented on August 8th, 2005 -0 1.

Issued by Beijing Municipal Bureau of Quality and Technical Supervision

DB 1 1/290-2005

order

Preface 1

Introduction II

1 range 1

2 terms and definitions 1

3 Tending principle 6

4 cultivating objects 8

5 Forest classification 9

6 Tending method 10

7 Forest Tending Survey Design and Construction 13

8 Tending quality inspection 16

Appendix A 18

Appendix B 19

Appendix C 20

Reference 2 1

DB 1 1/290-2005

order

This standard is formulated to meet the needs of tending ecological public welfare forests in mountainous areas of Beijing and improve the quality and benefit of forest tending. This standard is based on the national standard GB/T15781-1995, combined with the actual cultivation of ecological public welfare forests in mountainous areas of Beijing. The main definition adopts the national standard GB/T15781-1995.

Appendices A, B and C of this standard are appendices of this standard.

This standard is put forward by Beijing Forestry Bureau and is responsible for centralized interpretation.

Drafting unit of this standard: Beijing Forestry Bureau.

Main drafters of this standard: Gan Jing, Du Pengzhi, Xu Chengyang, Cai Baojun and Wang Jixing.

Yan Xueqiang.

DB 1 1/290-2005

introduce

Among the ecological public welfare forests in Beijing, the area of young and middle-aged forests is 372,000 hectares, accounting for more than 8 1.8% of the total existing forest area, and it is still expanding gradually. These forests are at a critical stage of growth and development. Timely and reasonable tending is the main measure to improve the forest environment, which plays an irreplaceable role in improving the afforestation preservation rate, promoting the growth of trees, improving the ecological environment of the capital, providing a beautiful living environment for citizens and giving full play to the ecological, social and economic benefits of forests. Tending of ecological public welfare forests in mountainous areas is a key project in forestry construction. It is necessary to unify technical standards and strictly follow the standardized management of engineering projects to ensure the quality of tending work. In order to make the tending work of ecological public welfare forests in mountainous areas of our city scientific, healthy and orderly, it is particularly urgent and important to compile local standards for tending ecological public welfare forests in mountainous areas of Beijing.

DB 1 1/290-2005

Technical specification for tending of ecological public welfare forest in mountainous areas

1 range

This standard specifies the technical requirements for tending objects, tending methods, investigation, design, construction and verification of ecological public welfare forests in mountainous areas of Beijing.

This standard is applicable to tending management of ecological public welfare forests in mountainous areas of Beijing.

2 Terms and definitions

The following terms and definitions apply to this standard.

2. 1

Public welfare forest (ecological) public welfare forest

In order to maintain and improve the ecological environment, protect the ecological balance, protect biodiversity and other forests, trees and woodlands that mainly provide public welfare and social products or services to meet the ecological and social needs of human society and sustainable development.

[GB/T18337.1—2006.5438+0, definition 2. 1]

2.2

Natural secondary forest

Primitive forest or artificial forest refers to a kind of natural forest that is restored by natural forces after being destroyed by human or natural factors without reasonable human management.

2.3

Aerial seeding forest

Forests formed by air seeding.

2.4

colonize

Forests cultivated by planting seedlings, sowing, logging and other artificial methods.

[GB/T15781-1995, Article 2.3]

2.5

scenic/landscape forest

Forests distributed in scenic spots, forest parks, resorts, ski resorts, hunting grounds, city parks, country parks and tourist attractions with the main purpose of meeting human ecological requirements and beautifying the environment. There are all kinds of scenic facilities.

2.6

mingled forest

A stand consisting of two or more tree species. The proportion of any tree species in the forest is less than 65%, and it can form a stable stand for a long time.

2.7

Young and middle-aged forest

Young forest and middle-aged forest are collectively referred to. Young forest is the juvenile stage of forest growth and development, which usually refers to the first or second age forest; Middle-aged forest, also known as strong-aged forest, refers to the forest below grade III to IV.

2.8

Main tree species and main categories

Dominant tree species in the mixed forest meeting the management requirements.

2.9

Associated tree species

The subordinate tree species accompany and promote the growth of the main tree species in the mixed forest.

2. 10

Free tree

In natural forests, trees with huge crowns are scattered on the forest floor.

2. 1 1

Stand up, stand up.

Forests with the same internal characteristics such as forest origin, forest phase, tree species composition, age, status class, density and forest type, but different from adjacent communities.

2. 12

Forest age

Average age of trees in a stand.

2. 13

Site site

Synthesis of natural environmental factors affecting the growth and development of forest land.

2. 14

Cumulative quantity

The total volume of all standing trees on the forest land per unit area, in m3.

2. 15

crown density

The degree to which the crown of a stand is interconnected. It is expressed by the ratio of the vertical projection area of the whole crown to the total area of the forest land.

2. 16

stand density

Number of stumps per unit area of forest land.

2. 17

Gap of forest window

Just below the canopy gap, the open space area with an area of more than 25m2 still maintains the characteristics of forest environment.

[GB/T18337.1-2006.5438+0, definition 2. 18]

2. 18

Forest layer

In a stand, the hierarchy of trees.

2. 19

Difference of tree differentiation of stand of the same age

With the growth and development of forests, the height, thickness and vitality of trees are different in areas with the same tree species, the same age and the same site conditions. If the average tree height of a section is 1, the highest is 1.2 and the shortest is 0.8; Similarly, if the average diameter of trunk height at DBH is 1, the maximum is 1.7 and the minimum is 0.5. The degree of forest differentiation varies with its own genetic and environmental characteristics.

2.20

growing season

The time of year when a certain area is suitable for plant growth.

2.2 1

ecotone

Ecological ecotone, also known as community ecotone or ecological ecotone, is a transitional area between two or more ecological areas (or communities). For example, there is a forest-grassland belt between forest and grassland, and there are also interlaced areas between two different forest types or between two herb communities. The shapes and sizes of interlaced zones are different. The transition zone is wide and narrow; Some are gradual changes, and some are abrupt changes. Some edges of the community are persistent, while others are constantly changing.

2.22

biodiversity

Diversity of biological species in unit space or lots. All species, including plants, animals and microorganisms, can be expressed by the number of all species in a unit survey space or lot.

2.23

food chain

The chain relationship between species through mutual predation.

2.24

Young and middle-aged forest tending

In the middle and young forest stage, according to the forest development, natural thinning law and forest cultivation objectives, timely take artificial intervention measures such as cutting, expanding irrigation (grass), planting, thinning, pruning, etc., adjust tree species composition and stand density, improve forest growth environmental conditions, and promote the growth of reserved trees.

2.25

Ding Zhu promotes the division

In the young forest, a certain number of trees should be kept for tending at a reasonable density.

2.26

Trim trim

Also known as manual pruning. Manually cut off the dead branches and some live branches at the lower part of the crown. The measure of cutting off some living branches on the trunk is called green branch pruning; The measure of cutting off the dead branches at the lower part of the trunk is called dry repair.

2.27

Sanitary cutting

Cutting to improve the sanitary conditions of forests and promote the healthy growth of trees.

2.28

Ecological thinning

In order to make the forest canopy step closed, the large, medium and small trees in the forest can directly receive sunlight, induce the formation of multi-layer uneven-aged forests, and enhance the ecological protection function of the forest ecosystem, comprehensive tending methods were carried out.

[GB/18337.1—20065438+0, definition 2.20]

2.29

Landscape thinning in landscape improvement

According to the principle of forest aesthetics, transform or shape the landscape forest and create the heterogeneity of natural landscape.

[GB/18337.1-2006.5438+0, definition 2.2 1]

2.30

Tending and cutting standard land for thinning plots.

A certain area of forest area that provides a basis for the design of tending and cutting operations or scientific research and inspection of tending effect. It can reflect the average index of the forest land to be tested, and it is the epitome of the whole stand, through which various quantitative and quality indicators of the stand can be obtained. There are temporary standard land and fixed standard land. The latter has a controlled area without logging.

2.3 1

Thinning strength

The extent to which trees are cut down and preserved. It expresses the percentage of the volume (or number of trees) of common cut trees to the volume (or total number of trees) of small classes. Reasonable intensity depends on commercial purpose, biological characteristics of tree species and economic conditions. Generally, according to the quantitative relationship between forest growth and standing trees, the reasonable density is determined at different growth stages. Reasonable strength can be determined by accumulation, optimum number of plants and canopy density.

3 tending principle

The general principle is "survival of the fittest, strong retention of the weak, uniform distribution and moderate density".

3. 1 Principles of biodiversity conservation

3. 1. 1 Keep the trees, shrubs and grasses in the stand that will not affect the growth of main tree species, promote the development of the stand into a multi-layer forest, keep the forest close to nature, and provide places for birds and animals in the forest to live and reproduce; Protect trees and shrubs, such as mulberry, Broussonetia papyrifera, Prunus humilis, raspberry, hawthorn, pear and oak, to maintain the food chain of birds and small mammals;

3. 1.2 Protect the precious animal and plant resources in the forest and maintain the ecological balance;

3. 1.3 Protect natural regeneration seedlings and promote the development of stand to uneven-aged forest;

3. 1.4 The open spaces and gaps in the forest are important ecotones, and their natural vegetation should be preserved as much as possible.

3.2 Pay attention to the principle of landscape effect

3.2. 1 Preserve trees and shrubs with ornamental value, such as Prunus armeniaca, Prunus armeniaca, Cotinus coggygria and Rhododendron;

3.2.2 Under the condition of ensuring the health of the stand, free trees with high ornamental value and special trees with strange growth, such as multi-headed trees, deformed trees, parasitic trees, etc., are reserved to make them become forest landscapes.

3.3 Pay attention to the principle of tree species configuration

Artificial pure forest should retain natural secondary tree species as much as possible, and mixed forest should not be cut into pure forest.

4 tending object

4. 1 Shelterbelt

There are many tree species, which will not cause soil erosion and desertification. Those who meet one of the following conditions are listed as tending objects.

-Stand with canopy density above 0.8, obvious tree differentiation, and understory vegetation not easily exposed to light;

-Suffering from serious natural disasters such as diseases, insects, fires, snow pressure, wind bending, etc., and the damaged trees exceed 10% of the stands;

4.2 Special purpose forest

Tending will not reduce the special function, and those who meet one of the following conditions are listed as tending objects.

-The stand density is too high, the competition is fierce, and the tree differentiation is obvious, which affects people's aesthetic and scenic recreation needs;

-Stand with poor growth and development that does not meet the specific dominant function;

-Stand suffering from serious natural disasters such as diseases and insect pests, fire, snow pressure and wind bending, with more than 5% of trees damaged;

-Forests that need to change their community structure and composition for viewing.

4.3 temporary or limited to tending forests.

4.3. 1 Tending in any form is strictly prohibited in the forest in the core area of nature reserve, and tending is not carried out in the buffer area in principle. The forest in the experimental area is only harvested in health, and tending is carried out according to the experimental design of the experimental area.

4.3.2 Tending and thinning are generally not carried out for stands with slope greater than 36 or barren soil, exposed rocks and extremely fragile ecological environment;

4.3.3 State-level forest parks generally do not carry out tending and thinning, except for over-dense forests and landscape transformation;

4.3.4 National defense forests and environmental protection forests are only cut for health purposes.

5 forest classification

5. 1 Single-layer pure forest trees of the same age in artificial forest and natural secondary forest are divided into five grades:

Forest classification is an important basis for determining thinning. Trees are divided into five grades according to their growth, light and position in the stand.

First-class wood-dominant wood. The height of the tree is the highest, the diameter at breast height is the largest, and the crown is above the main forest layer, which is hardly squeezed.

Grade Ⅱ timber-sub-dominant timber. DBH and tree height are second only to the dominant trees, and the crown forms the average height of the crown, and the side will be squeezed.

Grade ⅲ wood-medium wood. Both DBH and tree height are medium, and the crown can reach the main forest layer, but it is squeezed laterally.

Grade Ⅳ wood-pressed wood. The trunk is slender, the crown is narrow and slant, and it can reach the main forest layer below the main forest layer or only the treetops.

Grade ⅴ wood-dying wood and dead wood. Below the main forest layer, it is weak and close to death or death.

5.2 Trees in natural mixed forest or multi-layer forest are divided into three grades:

Excellent tree-a tree with straight trunk, good natural pruning, normal crown development, vigorous growth and promising cultivation.

Auxiliary trees-trees that are conducive to the natural pruning of excellent trees and the formation of good trunk shapes, and have the function of protecting and improving soil, and there may be gaps or open spaces in the forest after logging.

Harmful trees-dead trees, dying trees, dead trees, crushed trees and trees that hinder the growth of excellent trees and auxiliary trees.

6 tending method

6. Main contents of1

Young forest tending can be divided into management measures such as cutting irrigation (expanding grass), fixing plants (thinning seedlings), pruning and replanting; Forest thinning refers to forest management measures based on ecological thinning and landscape thinning. The division standard of forest age groups shall be implemented according to Appendix A. ..

6.2 Tending measures

6.2. 1 cut irrigation (grass) expansion

When the growth of young trees is affected by the surrounding shrubs and grass covers, it is necessary to prune the shrubs and weeds around the young trees in the range of about 1 m2. In order to facilitate water collection, at the same time, it is necessary to cultivate and expand the ridges to promote the normal growth and development of young trees. Suitable for young forests.

Planting and tending

Afforestation and tending should be carried out before young forests have obvious competition for nutrient space. Cut off too dense young trees and replant target trees in sparse areas. Plant fixation is generally carried out in 2~3 times. Young forests formed by closing hillsides to facilitate afforestation and aerial seeding afforestation must be planted and tended.

The planting density (number of plants/unit area) is reasonable, and if there are many young trees in each planting point (hole), planting should be carried out according to the growth status of trees, and 1 plant should be reserved in each planting point (hole); If the plant spacing is too small, the plants should be fixed according to the reasonable density, and 70 ~ 150 plants should be reserved every 667m2 according to the specific situation, and the distribution should be uniform.

In the natural secondary forest, if the DBH of broad-leaved trees is greater than or equal to 6cm, 70 ~ 150 trees should be reserved every 667m2 according to the specific situation, and the distribution should be uniform; For broadleaf trees with DBH less than 6cm, more than 150 trees should be reserved every 667m2 according to the specific situation, and the distribution should be uniform.

According to the specific situation, more than 440 seedlings with tree height less than 2m should be reserved every 667m2150, and more than 70 seedlings with tree height more than 2m should be reserved every 667m2, which are evenly distributed.

Replanting

It is mainly suitable for stands with broken forest phases. According to the size and distribution characteristics of gaps in the stand, unified replanting or local replanting is adopted, and after replanting, mixed communities of different tree species or mosaic distribution of different origins are formed. Pure coniferous forest or stand dominated by conifers, replanting broad-leaved species; Pure broad-leaved forest, replanting coniferous trees or different broad-leaved trees to form a mixed forest of different trees. After replanting, there shall be at least two tree species, and the proportion of one tree species shall not exceed 65%. See appendix b for planting density.

prune

Cut off dead branches and dying branches at the lower part of the crown. Pruning measures are mainly suitable for middle-aged forests.

1 purpose

Eliminate dead joints, reduce live joints, increase trunk fullness, and improve ornamental and protective functions; Improve the ventilation and lighting conditions in the forest, promote the growth of trees, reduce the occurrence of trunk fire, snow pressure and wind damage, and prevent the occurrence of pests and diseases.

6.2.4.2's initial period

The stand began to close after dead branches appeared at the lower part of the trunk.

6.2.4.3 interval

Prune conifers when there are two rounds of dead branches after the previous pruning; The interval between broad-leaved trees is generally 3 years.

6.2.4.4 season

Generally suitable for tree species in late winter and early spring. Some tree species with strong germination will cause serious bleeding when pruning in winter and spring, so pruning should be carried out in the prosperous season of trees.

6.2.4.5 method

Pruning is divided into dry pruning and green pruning; Most conifers are pruned dry, and most broadleaf trees are pruned green.

Pruning adopts flat cutting method (close to trunk pruning), which requires the incision to be smooth and not to tear the bark.

6.2.4.6 strength

Young broad-leaved trees and conifers do not exceed one-third of the tree height; Middle-aged broad-leaved trees should not exceed half the height of trees.

Ecological thinning

Applicable conditions

Stand with slope less than 25 degrees, deep soil layer, good site conditions, high canopy density or high density.

The Choice of Cutting Trees in 6.2.5.2

Generally, fallen trees, dying trees (grade V) and crushed trees (grade V) should be cut down, and dominant trees, secondary dominant trees, medium trees and appropriate shrubs, vines and herbs should be retained; For over-dense stands, we should also consider cutting down some medium-sized trees (third-class trees). At the same time, attention should be paid to retaining forest edge trees, forest edge trees and isolated trees. According to the biological characteristics of multi-layer forest, pay attention to the reasonable distribution of each forest layer.

6.2.5.3 sparsity intensity

The intensity of primary ecological thinning should not exceed 15 ~ 20% of the stock (or the total number of trees), and the canopy density should be kept at 0.6 ~ 0.7 after cutting. The canopy density of aerial seeding forest after the first thinning should be controlled at 0.7 ~ 0.8.

The ecological thinning intensity of natural secondary forest is controlled by the number of trees per unit area. In areas with good site conditions, the number of reserved plants should be appropriately less, and vice versa. Appropriate retention density shall be implemented in Appendix C..

Landscape thinning

According to the principle of forest aesthetics and different landscape characteristics, landscape thinning, transformation or shaping of new landscape, creating the heterogeneity of natural landscape, improving the accessibility of stands, maintaining biodiversity, and improving tourism and ornamental value.

Sanitary felling

Scenic forests with a slope less than 25 degrees can be cut down hygienically, and trees that seriously affect the purpose of forest cultivation, such as rotten trees and dead trees, can be cut down.

7. Design and construction of forest tending survey

7. 1 Tending design qualification

Tending operation design should be undertaken by units with forestry survey and design qualifications or grass-roots units authorized by forestry authorities.

7.2 Preparation of design documents

To the municipal state-owned forest farms, nature reserves, forest parks, towns (county-level state-owned forest farms) and other units.

Tending of young and middle-aged forests should be carried out in a planned and step-by-step manner, and priority should be given to the stands in key areas where tending management is most urgently needed.

7.3 Investigate design content and construction

7.3. 1 division of work area

According to the business purpose, tree species, origin, forest age, site and other factors, the operation division is divided into different types of small classes, and the summary area is calculated.

Standard setting

7.3.2. 1 Set standards in small classes.

Number, size and shape of 7.3.2.2 standards

Each subclass has 1 ~ 3 typical standard sites. Each standard land area is not less than 300 square meters; . The standard chart should be evenly distributed in the operation class, which should fully represent the different situations of the Nehrig score of the class; The shape of the standard plot is generally designed as a rectangle or a square to facilitate the production operation;

7.3.2.3 drawings and labels.

Draw the position of each tree on the standard plot on the coordinate paper, number the trees and measure each tree to determine the height (h) and diameter at breast height (d).

Calculation of forest tending in 7.3.2.4

Calculate the canopy density of standard plots before and after logging; According to the principle of tree classification and thinning selection, combined with the field investigation of each tree, the cut trees are determined on the tree map of the standard plot, and the number and volume of trees are calculated. The thinning intensity (number of trees after cutting, storage intensity and canopy density) is calculated by using the data before and after cutting.

Intensity of plant number:

D=a÷A× 100%

Density of plant number

A-the number of thinning trees

A —— Total number of plants in standard plot.

Accumulation intensity:

G=v÷u× 100%

G- cumulative strength

Volume of thinning trees

U- the total volume of trees in the standard plot.

Intensity of canopy density:

q = p÷

Q- canopy density after cutting

P- reserved crown projection area

S- standard land area

7.4 preparation of survey, design and construction instructions

The main contents of the survey and design instructions include: design basis and principles, basic situation of operation design area, standard plot questionnaire, tree position map, tending and thinning operation zoning map, tending technical measures, tending operation construction arrangement and personnel organization. For tending and thinning of pine stands, the district and county forest pest control departments shall put forward preventive opinions and strengthen the monitoring of dangerous pests and diseases.

7.5 Construction technical requirements

7.5. 1 Label it before cutting it.

Designers and technicians will double-label thinning trees (also known as thinning trees), that is, breast number and land number, and then construction workers will cut them according to the labels.

7.5.2 Matters needing attention in thinning operation

Thinning operations are carried out in the order from mountain to mountain;

The height of pile cutting shall not exceed 5 cm;

Don't damage the reserved wood.

7.5.3 Cleaning of tending residues and pile cutting treatment

The cleaning methods of tending residues can be diversified. The main scenic spots should clear the thinning and branches out of the forest land in time, keep the thinning land clean and tidy, and advocate scattering the residue after mechanical crushing in the forest to speed up its decay when conditions permit; The main protected stands can be piled up and allowed to rot.

Cover the roots of pine stands with soil to avoid the smell of turpentine attracting Dendroctonus valens, which is harmful to healthy trees.

7.5.4 Supervision and inspection of tending and thinning

Technicians should be responsible for on-site work and work in strict accordance with the approved design scheme of tending and thinning.

8 tending quality verification

8. 1 verification requirements

The competent forestry departments at all levels shall organize special personnel to conduct sampling inspection and acceptance on the tending design and construction quality approved and audited by them. Units that pass the inspection will be issued with inspection certificates, and units that fail the inspection will be reworked within a time limit until they pass the inspection.

The sampling proportion of design quality inspection is 5 ~ 10% of the original standard plot and 1 ~ 5% of the sub-class area. On-the-spot verification of tree measuring factors, tending operation design and other projects in standard plots.

Construction quality inspection and acceptance shall be carried out in accordance with the operation design category. Stand factors were measured in situ by mechanical sampling. The minimum area of actually measured plots shall not be less than 200m2, and the number of each type of actually measured plots shall not be less than 3. The accumulated area of the sample plot shall not be less than 1% of the working area.

8.2 Verification of Intermediate Forest Cutting

8.2. 1 Stand canopy density decreased, not less than 0.2.

The canopy density after tending is between 0.6 and 0.7; Or not less than 0.7.

8.2.2 Cut down trees of Grade IV and V according to the principle of "keeping the superior and eliminating the inferior, keeping the strong and eliminating the weak, evenly distributing and moderately dense".

8.2.3 Mixed forest can maintain the original composition of mixed tree species after cutting.

8.2.4 Pure forest and mixed forest can retain natural invasive species and characteristic shrubs and herbs after cutting.

8.2.5 The stump cut is less than 5cm, and the stump should be marked with the ground number.

8.2.6 Tending residues shall be properly cleaned (crushed, tiled and stacked), and the roots of pine trees shall be cut off and covered with soil.

8.3 pruning verification

8.3. 1 Trimming strength meets the standard.

The pruning of young broad-leaved trees and conifers shall not exceed 0/3 of the tree height; The pruning of middle-aged broad-leaved forest dominated by broad-leaved trees shall not exceed1/2 of the tree height; The scenic forest should cut off all the dead branches under the crown.

8.3.2 Pruning incision is smooth, and there is no phenomenon of tearing bark.

8.3.3 Pruning season is appropriate, without bleeding.

8.4 Verification of Cutting and Irrigation (Grass) Extension

Young trees are not covered with grass, ventilated and transparent, the surrounding environment of young trees is clean, and the grass is irrigated within 1 m2; Embankment should be compacted and widened, and the opening should be upward to facilitate water collection.

8.5 Verification of Young Tree Planting

8.5. 1 All kinds of stands are fixed according to the reserved density.

70 ~ 150 plants/667m2 are reserved in the plantation; Natural secondary forest reserves 150 ~ 330 trees /667m2.

8.5.2 Leave 1 young tree in each planting hole; The planting of aerial seeding forest shall be carried out according to the standard of reserving 150 ~ 440 plants per 667m2 when the seedling height is less than 2m, and reserving more than 70 plants per 667m2 when the seedling height is more than 2m.

Appendix a

(normative appendix)

Standard table of forest age class and age group division

Unit: year

Division of forest age groups of main cutting age of tree species in origin age class

Young forest, middle-aged forest, near-mature forest, mature forest and over-mature forest

Platycladus orientalis natural 20 years1-6061-1-1-1-kloc-0/665448.

Worked for 20 years1-4041-6061-8081-kloc-0/20 ≥121year ≥8 1.

Deciduous pine has been natural for 20 years,1-4041-6061-808120 ≥141year ≥ 8/kloc-.

Labor 10 year1-2021-3031-4041-60 ≥ 61year ≥4 1 year.

Korean pine is natural 10 year1-3031-5051-6061-80 ≥ 81year ≥6 1 year.

Labor 10 year1-2021-3031-4041-60 ≥ 61year ≥4 1 year.

Broad-leaved trees such as oak and Juglans mandshurica have been natural for 20 years,1-4041-6061-8081-kloc-0/20 ≥1year ≥ 8/kloc.

Labor 10 year1-2021-4041-5051-70 ≥ 71year ≥5 1 year.

Populus davidiana, Betula platyphylla, Tilia amurensis, Ulmus pumila and Sophora japonica are naturally101-3031-6061-80 ≥ 81year ≥ 665438+

Labor 10 year1-2021-3031-4041-60 ≥ 61year ≥4 1 year.

Poplar, willow, Robinia pseudoacacia, paulownia and other fast-growing trees have been planted artificially for 5 years,1-1-kloc-0/6-2021-30 ≥ 31year.

Appendix b

(normative appendix)

Density unit of ecological public welfare forest after replanting: plant /667m2.

Number of trees (group)

Chinese pine 80~267

Larch 70~ 167

Platycladus orientalis 100~233

Robinia pseudoacacia 70~ 167

Yushu 53~ 107

Quercus mongolica and Quercus liaotungensis 100~ 133

Quercus acutissima and Quercus variabilis 42-80

Acer truncatum and Acer truncatum 42-80.