How to scientifically cultivate mixed forests and what are the limitations of creating mixed forests

Tree and shrub matching, planting dominant tree species to enhance resistance.

The selection of suitable mixed tree species is an important means to regulate the interspecific relationship, and it is an important measure to ensure the smooth formation of plantations, enhance the stability of stands, and achieve rapid growth and high yield. Therefore, it is necessary to harmonize the growth characteristics and ecological requirements of the mixed tree species with the main tree species as much as possible, and at the same time, the problem of the right place and suitable tree for the mixed tree species itself should also be considered. In the practice of creating mixed forests, China has accumulated some experience in the combination of tree species.

For example, in Northeast China, Korean pine and walnut are mixed, Korean pine and ash; In South China, there are successful cases of Chinese fir and masson pine, fir and Taiwan acacia, masson pine and lotus, and masson pine and alder. When determining the combination of tree species, the main tree species should be selected according to the site conditions and afforestation purpose of the afforestation site, and then the associated tree species or shrubs should be allocated.

According to the status of tree species in the mixed forest, biological characteristics and growth types, etc., artificially matched into different combinations, called mixed type. There are the following types: (1) Arbor mixed types:

That is, two or more tree species are mixed. When more than two tree species are the main tree species, it can make full use of the soil fertility to obtain a variety of timber and give full play to other benefits. When positive species are mixed with positive species (such as Pinus tabuliformis and Quercus tabuliformis), the interspecific contradictions appear early and sharp, and the competition process develops rapidly.

It is difficult to adjust the interspecific contradiction of this kind of stand. Negative and negative tree species were mixed (such as spruce and fir), and the interspecific conflict appeared later and moderated, and the favorable effect between tree species lasted longer. This kind of plantation is only in the late stage of growth and development, the contradiction is intensified, but the stand is relatively stable, and the interspecific relationship is easier to adjust.

Positive and negative species are mixed (e.g., larch and spruce), and the relationship between the tree species is between the above two, and the favorable effect is the main one for a long time. When the main tree species are mixed with the secondary tree species, most of them form a multi-layered forest, with the main tree species in the upper layer and the secondary tree species in the lower layer. The contradictions between the mixed tree species were relatively relaxed, and the stand productivity was higher, the protection efficiency was better, and the stability was stronger.

Most of the minor tree species are shade-tolerant medium trees (such as linde, maple, hornbeam, etc.), which generally do not pose a serious threat to the main tree species, and are relatively easy to adjust even when the interspecific contradictions are acute. (2) Mixed type of tree and shrub: that is, the main tree species are mixed with shrubs.

The interspecific contradictions of this mixed type were relatively alleviated, and the stand was stable. Mixed early shrubs can create lateral shade, soil protection and soil improvement for tree species. After the canopy closure of the stand, due to the lack of light under the canopy, the shrubs tend to senescence and gradually die.

However, when the canopy canopy is thinned, shrubs reappear in the forest. In some mixed forests, shrub death can free up a large nutrient space for tree species and play a role in regulating stand density. When there is a sharp contradiction between the main tree species and the shrub, it is easy to adjust, and the aboveground part of the shrub can be removed to make it re-germinate.

3) Comprehensive mixed type: that is, the mixing of major tree species, minor tree species and shrubs. The comprehensive hybrid type has the characteristics of the above-mentioned hybrid types.

From an ecological point of view, the creation of mixed forests has the following advantages: making full use of space and nutrient area, giving full play to the protection benefits, enhancing the ability to resist natural disasters, improving site conditions, and improving the quantity and quality of forest products.

At present, the national afforestation tree species are single, and the soil fertility is seriously declining, and the construction of Hongsen Acacia mixed forest can greatly improve the soil, rhizobia, nitrogen fixation, and leaf litter can fertilize the soil. If you mix elm, poplar, willow, etc., the growth will be better. The root system of Acacia hongsensen is well developed, with root nodules, which can fix nitrogen and improve soil fertility, so its resistance to hidden sensitivity and barrenness, drought tolerance is better than that of Salix varieties, and it can also grow more normally in poor soil.

The nitrogen-fixing characteristics of Acacia hongensis are a good mixed forest tree species, which can improve the soil, improve soil fertility, and promote the rapid growth of other mixed forest tree species.

The limitations of mixed forest construction are mainly as follows:

1.Limitations of tree species selection: Mixed forests need to choose tree species that are coordinated with each other and have different growth habits, but the selection of tree species will be limited by factors such as climate, soil, and ground slippery shape.

2.Limitations of stand structure: The proportion and distribution of different tree species need to be controlled in mixed forests, but with the passage of time, the growth rate and competitiveness of different tree species will change, which may lead to the disorder of stand structure and affect the benefits of mixed forests.

3.Limitations of management techniques: Mixed forests need to adopt appropriate management techniques, such as thinning and pruning, but these management techniques require a high level of technology and cost investment and branch concession, which is difficult to achieve in some resource-scarce areas.

4.Limitations of economic benefits: Mixed forests need to be operated and managed for a long time, and it is difficult to obtain economic returns for some areas where short-term benefits are pursued.

In summary, the construction of mixed forest needs to consider many factors, and it is necessary to consider the selection of tree species, stand structure, management technology, economic benefits and other aspects to effectively solve its limitations.

The structure of a mixed forest is as follows: mixed (left and right structure) cross (upper and lower structure) forest (left and right structure).

The structure of a mixed forest is as follows: mixed (left and right structure) cross (upper and lower structure) forest (left and right structure). The phonetic pronunciation is: one by one. Pinyin is: hùn jiāo lín.

What is the specific explanation of mixed forests, we will introduce you through the following aspects:

1. Explanation of terms [click here to view the details of the plan].

2. Network Explanation.

Mixed ForestA mixed forest is a stand composed of two or more tree species. Each type of tree accounts for no less than 10% of the forest. If the tree species in the forest are properly matched, the productivity and stability of the stand can be improved, the forest can make full use of light energy and the water and nutrients in the soil, the growth is relatively rapid, the occurrence and spread of pests and diseases, fires are lighter, and can provide a variety of wood and other forest products, and the protective effect of hidden withering is stronger.

However, the cultivation technology is more complex and requires high land conditions, such as improper allocation of tree species, which often fails to achieve the expected results. Mixed forests are the main targets of forest fire insurance.

Idioms about mixed forests.

Chaos is natural, fishing in chaotic waters, chaos is chaotic, chaos is chaotic, the demon king is chaotic, and there are all kinds of chaos, and there are always chaos, and there are always forests.

Words about mixed forests.

Confused, confused, mixed with the eyes of the fish, mixed with the demon king, chaotic as one, chaotic without distinction, chaotic nature, confused, black and white.

Sentence formation about mixed forest.

1. The difficulties in the growth simulation of mixed forests mainly include the expression of multiple tree species, stand age, site index and competition effect.

2. The spatial structure of biomass in the pure P. massoniana forest and its interplanted mixed forest was analyzed by grading sampling method.

3. The root system of the mixed forest tends to be uniformly distributed vertically in the soil profile.

4. From the aspects of the size and structure of the forest stove gap, the formation mode and the number of trees formed, the disturbance status of the forest gap between the pure and mixed forests of P. long-bract and hemlock was compared.

5. The construction of mixed forests of broad-leaved trees in sandy grassland has played a role in protecting grass and promoting animal husbandry with forests, which is conducive to the establishment of a forest-grass composite management model.

It refers to the percentage of the number of trees of each tree species to the total number of trees in the mixed forest. The quantitative change of the mixed ratio was closely related to the development direction and the mixed effect of the relationship between the mixed tree species. The proportion of mixed tree species should be conducive to the growth of the main tree species, and should be different according to the tree species, mixed type and site conditions.

For competitive tree species, the mixed proportion should not be too large, so as not to suppress the main tree species; Otherwise, it can be appropriately increased. In places with superior site conditions, the proportion of mixed tree species should be small, and there should be more associated tree species than shrubs. In places with poor site conditions, the proportion of shrubs can be appropriately increased without or less associated tree species. In general, in the early stage of afforestation, associated tree species or shrubs should account for 25 to 50% of the total number of trees in the whole forest.

However, the proportion of mixed tree species is not limited by individual mixed methods or special site conditions.