"Northern China Larch Pine Fast-growing and High-yielding Forest Cultivation Technique"

First, the impact of thinning on the growth of stands

(I) Impact of high growth

In the production practice, it is observed that the effect of tending on the average tree height growth of artificial larch forest is not very obvious (5-9). The growth of tree height depends on the site conditions and the age range of the stand. Generally, high growth is faster under better site conditions; in the young forest stage, the high growth rate is faster than that in the medium and near mature forests. However, in the conversion of the mixed forest to a fast-growing and high-yield forest, the removal of some broad-leaved dominating trees has a certain role in promoting the high growth of larch. For example, the two small classes of the 6/19–1 and 6/19–2 Da Zhou Jia Nan Ditch in the Liujiaying Forest Park of Taoshan Forest Farm are all reforested in the 75-year-old broad-leaved cutting land. The small class carried out an intense light cut, which reduced the number of broadleaf trees from 40% to 20%, and the 6/19-2 small class did not have any work at that time. At the time of the 1999 survey, 6/19-1 small class larch became the dominant species with an average of 11.3m, while the 6/19-2 small class of larch was pressed and did not dominate in the stand. The average tree height was only 9.7m.

Table 5-9 Effect of thinning on the height growth and diameter growth of larch forest

Location of investigation: Shirenliang Forest Park, Taoshan Forest Farm

(b) Impact on growth

The impact of thinning on the diameter of the forest breast is very obvious. It is mainly through tending thinning, reducing the number of reserved plants per unit area, expanding the nutrient space of preserved wood, and promoting the growth of the diameter of individual trees, thereby increasing the overall average diameter of the forest. The thinning of forests with different densities has different impacts on the diameter growth of the DBH. Generally, the forests with higher density before cutting have weak effects on the growth of DBH, and the effects of strength tending are obvious. The density of the stand with lower density has obvious effect. The data in Table 5-10 shows that the influence of thinning on the stand diameter is proportional to the cutting intensity within a certain range, that is, the greater the harvest intensity, the greater the impact on the diameter growth of the DBH. However, when the number of trees per unit area reached a certain value, the growth of DBH remained basically unchanged.

Effect of different tending intensity on diameter growth of larch stands

Schedule 5-10

Second, the impact of thinning on forest quality

Raising thinning can improve the quality of trees because the trees preserved by tending are mostly fine trees of the main tree species. They are naturally pruned, dry and straight, and some of the defective trees have been cut during the tending process.

1. Impact on the wood species of forest products Table 5-11 shows that tending can also increase the proportion of wood species and quality of the stand and the percentage of commercial materials. Nearly 182.2%, the proportion of the specification material is 201% of the control, indicating that tending can improve the economic output rate of forest stand.

Table 5-11 Impact of Thinning on Forest Quality

2. Impact on Annual Rings According to Ando et al.'s research, the densely planted and weakly cultivated forest stands have small changes in width and width of annual rings; the medium-density management stands increase in the width of annual rings, and their changes are smaller; The management forest stand has the largest annual ring width; at the same time, there are data showing that tending can increase the proportion of autumn wood in the forest, thereby increasing the proportion and hardness of the wood; the length of tracheids and conduits increases, and the conducting tissue strengthens, which increases the strength of the wood. .

3. The influence of dry shape on the dry shape is mainly the effect on the completeness of the trunk. Generally, the greater the density of the stand, the smaller the sharpness of the forest; the lower the stand density, the greater the sharpness of the tree. Therefore, excessive tending will affect the shape of the trunk, thus reducing the quality of the forest. Table 5-12 shows that with the increase in the intensity of tending in spruce forests, the number of trunks decreases, and the sharpness increases. Larix principis-rupprechtii also conforms to this rule.

Table 5-12 Changes in trunk shape and sharpness of spruce forests with different tending intensity

Raising intensity

Tree height m

Breast diameter cm

Number of trunks

Millimeters per meter

Control

13.1

11.7

0.731

5.3

Weakness

14.4

14.8

0.732

6.2

Moderate

15.2

17.2

0.739

6.4

strength

15.9

19.5

0.709

7.8

Extreme strength

17.3

23.7

0.709

8.6

4. Effect of thinning on forest festivals

The size and number of knots are affected by the stand density to a certain extent.

In the denser larch stands, the natural pruning is strong, the branches gradually wither upward, and the branch diameter is small, and the number of nodes is also small, which can produce high-quality wood. However, the smaller the density of the stands, the poorer the natural pruning, the height of the branches, and the easy formation of thick branches, so the number of knots is large. Therefore, pruning operations should be carried out in time after the larch forest is tended to improve the quality of the wood.

Third, raise the economic benefits of thinning

The timely and moderate tending of larch plantations in North China can shorten the cultivation cycle of forests and advance the age of the main cutting. Tending can improve the quality of forest trees and the ratio of commercial materials. These are the long-term economic benefits of tending and cutting. Can raising thinning increase the economic income of production units? From Table 5-13, it can be seen that in the year 87, the 20-year-old Larix principis-rupprechtii plantation for the first time was intercropped with a total income of 36.2 yuan per mu, the total expenditure was 16.05 yuan, and the total income per mu was 20.1 yuan; in 1991, The second time, the total income per acre was 175.5 yuan, the total expenditure per mu was 39.7 yuan, and the total revenue per mu was 135.8 yuan.

Table 5-13 Income and Expenditure of Larix principis-rupprechtii Raking

Note: Survey Site Beigou Forest Farm Dagouzigou, Beigouyinglin District, Site Type Semi-sunny slope

Therefore, the Mengzi Forestry Bureau tends to fortify the larch of North China larch. Although the level of income varies depending on economic conditions, stand status, specific operating conditions of small classes, and differences in tending intensity, it can be achieved on the whole. Certain economic benefits. At the same time, as a result of the tending practice, various forest by-products were provided to the society, which in turn promoted the development of wood-related industries such as timber processing and timber transportation. Second, it also provided local people with opportunities to participate in labor and increased their income. There is a lack of fuel in the forest area where the Mengzi Forest Management Bureau is located. It is also possible for the local people to solve some of the problems of burning wood. Therefore, tending and cutting have certain social and economic benefits.

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