Mixed forest

Mixed forest canopy by means of two or more dominant tree species or different Life type The composition of the forest trees. Mixed forest can form a multi-level or thick canopy Stand structure That has an important role to improve the protection efficiency and stability.
Mixed forest

Mixed forest Definition

The mixed forest is composed of two or more than two species
Forest。 According to the Convention, other species of main tree species in the outside, number of trees, basal area or volume meter, shall not be less than 20%. Mixed forest can form a multi-level or thick canopy stand The structure, has an important role to improve the protection efficiency and stability.

Mixed forest Advantage

From the ecological perspective, mixed forest has the following advantages:
Make full use of the space and nutrition area
adopt Shade tolerance (light and shade), root type (deep root and shallow root, root and root absorption absorption intensive dispersion type), growth characteristics (fast-growing and slow growing deciduous, and sooner or later, the early germination of different Growth type With the growth of fertilizer (type) and eosinophils like nitrogen and phosphorus and the like, the time of absorption and utilization of different tree species) collocation, can make full use of underground space on the ground, is conducive to the use of light, water and nutrients in different time and different levels of scope.
Can play a better protective effect
Protective effect of forest depends largely on Stand structure . Mixed forest and thick crown, root depth, litter rich, ground and underground parts in complex structure than the pure forests, water and soil conservation, windbreak and sand fixation, and other protective benefits are better than the pure forests.
Can enhance the ability to resist natural disasters
Comparison of mixed forest and pure forest, due to multiple tree species, habitat The condition is good, the ecological conditions of some pest or pathogen lose blooms, while in a complex environment, parasitic insects, fungi and other natural enemies increased, and a variety of Class Useful animal, so pest mixed forest is not like three so serious harm. Mixed forest with low temperature, humidity, wind speed, various combustible materials are not easy to fire, so the fire is small. Coniferous and broad-leaved mixed forest Yes Broadleaf tree The vibration resistance, can prevent Crown fire and Surface fire The spread and development, not like Conifer Three that once the fire has become Liaoyuanzhishi, difficult to fight. The mixed forest of bad Meteorological factors Strong resistance. Such as trees with deep roots and shallow rooted species mixed, can reduce The wind Evergreen conifer and deciduous broad-leaved trees; mixed, can reduce the snow snow fall etc..
The improvement of site conditions
Compared with the pure forest mixed forest, forest light weakened, air temperature The temperature is slightly lower, while the amplitude is small, the decrease of wind, Evaporation Reduce, air humidity Increase, is conducive to improving the microclimate. The thick mixed forest canopy, leaf area index Larger, more litter, composition is complicated, can improve more than three soil fertility .
To improve the quantity and quality of forest products
Mixed forest can make full use of the favorable interaction between the external environment and promote tree species, photosynthesis efficiency, organic matter accumulation more at the same time, the total volume and Biomass Compared to the pure forest. The main tree species in mixed forest Associated tree species With the help of the main, long straight, perfect, Natural pruning Quickly, dry wood is good quality pure forest.

Mixed forest Mixed type

Select the appropriate mixed species is regulated The relationship between species The important means is to ensure Artificial forest Smooth forest, enhance stand Stability is an important measure to realize the fast growing. Therefore, you should try to make the mixed tree species and main species in the coordinated growth characteristics and ecological requirements, while also taking into account the species itself Suitable tree The problem. China practice in the construction of mixed forests, the tree species collocation has accumulated certain experience. as Northeast , Korean pine and Juglans mandshurica Korean pine and A Manchurian Ash Mixed; Southern China area, Fir wood With the Chinese fir and Masson pine, Acacia confusa Masson, and He Mu Masson, and Glauca wood So mixed, have successful cases. In determining the species collocation, first of all should be aimed at Afforestation The main purpose of the selection of tree species and afforestation site conditions, and then the configuration Associated tree species Or shrub.
According to the status of species in the mixed forest, biological characteristics and growth types, artificially collocation into different combinations, called mixed type. Are as follows: (1) tree mixed types: the more than two tree species mixed. When more than two tree species are the main species, it can make full use of land, access to a variety of wood, give full play to the effectiveness of other. When mixed with positive species (such as tree species. Chinese pine And the oak), a contradiction between the early and the sharp competition, the rapid development of the process. such stand The contradiction between the more difficult to adjust. Negative and negative species mixed species (e.g. Spruce and Fir ), interspecific conflicts occur late and mild, favorable effect between tree species lasts for a long time. This Artificial forest But, at a later stage of growth and development, the contradiction was intensified, but were relatively stable, The relationship between species Easy to adjust. Mixed tree species and tree species (such as negative and positive larch And, the relationship between the species of spruce) between the two, the favorable effect for a long period of time is the main. When mixed with the main tree species in secondary species, multi form Multi storied The main tree species in the upper, lower, minor species in. The contradiction between tree species in mixed type mild, stand Higher productivity, better protection efficiency, strong stability. For the minor species of shade trees (such as maple Linden, medium, Carpinus Etc.), generally do not pose a serious threat to the main tree species, even between the contradictions, is also relatively easy to adjust. (2) Shrubs Mixed type: that is the main species of tree and shrub. This kind of mixed type contradiction between mild and stable stand. Mixed initial shrubs can create lateral shelter for trees, soil and soil improvement. stand Canopy After the light under the canopy, shrub tends to aging, then gradually died. But when the forest canopy closure dispersal, and will appear in the forest shrub. Bush death in some mixed forest, and can make a greater space of tree nutrition, to adjust the stand density effect. Easy to adjust the main tree species and shrubs sharp contradiction, and can be cut out part of shrub, the re germination. (3) comprehensive mixed type: main species, trees and shrubs mixed secondary. Both of the characteristics of mixed type mixed type.

Mixed forest Mixed forest tree species

Wang Huai Sen, Papilionaceae genus of deciduous trees, flowers, bark, leaves are widely used. It grows quickly, a straight trunk, narrow crown, stipules small puncture and soft thorns before 2 years, 3 years after the assassination of basic shedding, green leaf color, white color, pleasant fragrance, is a great market potential of the fast-growing tree species.
Wang Huai Sen has certain drought resistance, dust, salt effect. Is suitable for a wide range, soil improvement, soil and water conservation, protection forest, all around the excellent planting multipurpose tree species. Can be used as street trees, residential district greening tree species, tree species for soil conservation, afforestation pioneer species etc..
Now the national afforestation single species, soil fertility decline seriously, and create Hongsen Huai mixed forest can greatly improve the soil, Rhizobia Nitrogen fixation, leaves can be loam. With the elm, poplar and willow forests, growth will be better. Wang Huai Sen developed root system, its root nodule can improve soil fertility, nitrogen fixation, the barren, drought resistance is better than that of Salicaceae species, in poor soil, can also be compared to the normal growth. Nitrogen fixation characteristics of Hongsen Huai, is a very good mixed forest tree species, can improve soil, improve soil fertility, promote the rapid growth of other mixed forest tree species.

Mixed forest Mixed proportion

Refers to the number of species percentage of the total number of mixed forest. The change in the number of mixed ratio, and the mixed tree species The relationship between species There is a close relationship between the development direction and the mixed effect. The proportion of mixed species, should be conducive to the growth of main tree species should be according to the principle of mixed type and site conditions, and different species. Competitive species, mixed ratio should not be too large, so as not to suppress the main tree species; on the other hand, it may be appropriate to increase. The site conditions where the species proportion is small, which should be more than companion species shrubs; site of local conditions, can not or less use of associated species, and the proper increase of the proportion of shrubs. In the early days of afforestation, Associated tree species The total number of forest or shrub should be 25 ~ 50%. But the individual mixed method or special site conditions, the proportion of mixed tree species on the.

Mixed forest Mixed method

Refers to the configuration method of different species plants in mixed forests. Different configuration method, The relationship between species And the tree growth will also cause a change. There are several mixed methods: (1) strains mixed: also known in mixed. More than two species among the separated strains were mixed or separated by a few. This mixed method for different tree species grown close, species interact and affect each other earlier. If the tree configuration properly, the relationship between species showed favorable; otherwise, a sharp contradiction between. This method is generally used for afforestation construction problems Shrubs Mixed. (2) planting: also known as interlaced mixed. More than two species separated by mixed. This mixed method, a beneficial or harmful, and more generally in the stand Canopy Later appeared obviously. A contradiction between the ratio between strains mixed easily, the construction is simple, is a mixed method commonly used, suitable for mixed trees or shrubs mixed Yin and yang. (3): strip mixed is a species of continuous planting of more than 3 lines form a band with another species with mixed methods successively arranged. Strip mixed can buffer Interspecific competition And even in the two adjacent trees there are contradictions, but also by Tending Felling To adjust. The planting and management is more convenient, more for the kind of contradiction between the relatively sharp, initial growth speed between the mixed tree species. Sub trees, trees and slow growing shade tolerant species can be mixed. Associated tree species Instead of single plant. This is a transitional type between the strip and planting, called mixed zone. With the advantages of ensuring the main species of mixed advantages, weaken the strong competition ability associated species. (4) mixed block: also known as dough mixed. It is a tree planting into regular or irregular block, and the block to another species in mixed configuration method. Like mixed rules, is flat or slope and afforestation, is zoned to block square or rectangular, then in each block on the ground according to certain Plant spacing Planting the same species, adjacent to another massive planting tree species. Block the area of not less than the average area per plant trees accounted for the mature forest, generally 25 ~ 50 square meters. Land is not too large, too large a mixed forest, it is not the meaning of. Mixed block irregular, is in the mountain afforestation by small changes in the terrain into blocks of different tree species planted respectively. It can achieve the purpose of mixed, and local afforestation. Mixed block can effectively use the favorable relationship between intraspecific and interspecific, can meet the young period like clusters of some conifer species, trees grow up, each species also produce good The relationship between species . The massive afforestation construction more convenient, suitable for mixed in the larger conflict of main tree species, can also be used for young Dan Chunlin transformation, or low value stand Reform。 The vegetation group is mixed: planting configuration shape of mixed form groups. In a small piece of land on the intensive cultivation of the same species, is mixed with another species of small dense planting of the adjacent. Due to massive larger space interaction between late. Block were in the same species, has the advantages of cluster configuration. Vegetation group mixed interspecific relationship is easy to be adjusted, but the afforestation of complicated construction, mainly used in artificial regeneration forest, secondary forest The transformation and afforestation etc..
In order to correctly handle The relationship between species The main tree species, as much as possible to benefit less harm, need to be artificially adjusted to take Stubble , pruning, thinning and girdling, go to the top, cutting and other technical measures to weaken the secondary species growth, meet the growth requirements of main tree species.

Mixed forest Development trend

The contemporary world forestry development trend, gradually from the pure forests to create mixed forest. However, how to build mixed forest, the China is still in the experimental stage, both in theory and practice are not mature, further discussion and research.