What effect does afforestation density have on landscape engineering?

The same is true of the effect of afforestation density on tree height, and researchers have drawn different conclusions about this effect during the research process. Based on the comprehensive experimental results, the following conclusions are drawn: First, different geographical conditions in different regions make local trees absorb soil moisture to different degrees, so their responses to tree density are different. Secondly, according to the different biological characteristics of trees, such as sunshine, branching and apical dominance, there are different responses to density. Only shade-tolerant tree species and stout top branches can promote growth in a certain density range. Thirdly, the effect of density on the growth of tree height is much weaker than the growth index, no matter under the condition of wood-like. In the range of medium density, density has no effect on tree height growth.

The influence of afforestation density on tree diameter is also found in the survey data, and the specific analysis is as follows: trees have a competitive role in the growth process, so the greater the density, the smaller the diameter growth, and its role in this respect is very significant. At the same time, density is of special significance to the growth of diameter, which is a basis for tree yield and an important factor for tree growth. On the other hand, the diameter growth is also reflected in the diameter distribution, which is an important factor in studying the growth and structure of forest trees and plays an important role in determining the yield and growth quality. Therefore, among these important factors, the density of trees is the embodiment of diameter to economic benefits.

The effect of density on the growth of individual volume is determined by the forest itself. When growing, the height of the tree, the cross-sectional area at breast height and the number of trunk shapes play a certain role in the density. Generally speaking, the number of trees changes with the change of density, but the difference does not change much. The effect of density on individual plant growth is the same as that of tree diameter growth. The greater the stand density, the smaller the average volume per plant, which leads to the more reduction of the average DBH.

Effect of density on tree species In the same growth environment, different varieties have different standards for planting density. For example, trees with the pursuit of yield as charcoal or short-cutting as pulp are mostly as dense as possible. Trees planted as dry firewood must be planted at a suitable density, not too close. The planted fruit trees are mainly used to produce fruits. In order to prevent the interaction between crowns and ensure adequate ventilation and sunshine, most of them are sparse. It is also a timber forest industry. If the planting density of smaller trunk is denser, the planting density of thicker trunk is thinner.

There are two ways to calculate the total output of dry wood per unit area. In non-thinning forest, it is divided into the sum of dead loss and standing stock, and in thinning forest, it is divided into the sum of thinning and standing stock. The volume of a stand is equal to the average volume of each tree multiplied by the density of trees. These two factors restrict each other. The product value depends on which factor is dominant. In the range of sparse density, the greater the stand density. The greater the output of dry wood. When the density increases to a certain extent, the increase of the number of trees and the decrease of the volume reach a balance, and the dry wood yield of the stand is not affected by the density.

Effect of density on wood quality If the planting density is appropriate, the trunk will be straight and thick, with fewer side branches, and the quality of trees will be better. If the density is too high, trees will crowd out each other to get more nutrients, and the trees will grow faster, but the trunk will be thinner, and the quality of the trees will not be good enough to meet the wood standards. Planting density cannot be expressed by numbers and concepts. It is necessary to ensure that afforestation achieves the goal of high efficiency, high yield and high quality. We must pay more attention to afforestation. According to the local actual situation and local conditions, we should not only plant forests well, but also achieve their goals, and choose appropriate planting density in order to obtain more economic profits.

The effect of planting density on root growth is also related to density. In general, the higher the density, the larger the root system of trees, which absorbs a lot of water and nutrients in the soil, resulting in uneven quality level of trees. If the density is smaller, the roots of trees will fully stretch in the soil, absorb a lot of water and nutrients, and improve the growth rate of trees.

The effect of planting density on biodiversity is almost proportional to the diversity of plant species. The planting density is too low and there are not many kinds of plants. With the increase of density, the diversity of plants gradually increased. After a certain effect is achieved, increasing the density will be counterproductive.

Determine the suitable afforestation density

In addition to growth, other factors should be considered when determining afforestation density:

According to the management purpose and biological characteristics of afforestation tree species, different management purposes require different afforestation density in forestry production, and the density of shelter forest should be larger. Generally, smaller plant spacing can be used. For example, the density of 1m× 1.5m or 1m× 1m is enough, which can accelerate the formation of closing hillsides to facilitate afforestation and increase the protection effect. Cultivate timber forests with large diameter and lower density. According to the experience, the planting density of 2m×2m or 1.5m×2m can be generally adopted to cultivate small-diameter timber forests. The afforestation density can be 1m× 1m or 1m×2m. Trees that mainly harvest fruits should keep a large spacing between trees to facilitate ventilation and light transmission, and ensure tree growth and fruit maturity. The afforestation density can be 3m×4m or 2m×5m. In addition, the planting density of different timber species produced by timber forest is different, and the light-loving tree species should be planted thinly, while the slow-growing tree species with shade tolerance should be planted densely. If the trunk is straight, it should be planted thinly, and if the trunk is not in good shape, it should be planted densely. Wide crowns should be planted sparsely.

According to the site conditions, the influence of soil conditions on the growth rate of trees in the planting area is determined. From the biological point of view, the planting density of good soil in the planting area can be correspondingly larger, and the planting density of poor soil in the planting area is better to be smaller; Especially in places with insufficient rainfall, afforestation is not for the purpose of canopy covering the ground, and the planting density is better to be thinner. Planting density is higher in areas with good soil quality, which can improve its coverage. Considering the economic benefit, it is best to plant trees with large trunk diameter in areas with good soil quality, in which case the planting density should be denser.

According to the cultivation techniques, it is determined that in the process of plantation construction, if the afforestation technicians are experienced. Good technology, high survival rate of planted trees, and sparse planting. High-tech intensive cultivation should be sparse.

At present, the forest density in China has undergone a qualitative change in the overall output of forestry. The forest economy is an important foundation of China's economic development, so the emphasis on output is getting higher and higher, and the forest planting density has a direct impact on output. Therefore, the planting density of forest land in China is also changing according to the site conditions in various places, so that it is suitable for the growth conditions of density in all aspects, producing high-quality tree species and efficient output, and increasing the use of forestry in product development.

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