Chapter I FOREST STRUCTURE AND LIFE

The forest is a very complex plant community. It includes a wide variety of plants - from large trees, raising their crowns many meters above the ground, to small mosses, barely visible to the naked eye. In addition to trees and mosses, various other groups of plants can also be found in the forest - shrubs and shrubs, grasses and lichens. There are even creepers in the forests of the Caucasus and the Far East. All these inhabitants of the forest vary greatly in size, appearance, structure, reproduction, and vital activity. But they are all closely related, one way or another affect each other. And each occupies its own specific place in the forest, plays a particular role in the life of the forest.

The most important component of the forest plant community is green plants, primarily trees. It is they who serve as a giant "factory" of organic matter, which forms the very basis of the forest. These plants use water, carbon dioxide, mineral salts as raw materials, and light as an energy source. The scale of the creative activity of green plants in the forest is enormous. Suffice it to say that only some trees accumulate in their above-ground part - in the trunk and crown - many tons of organic matter per hectare.

By creating organic matter from primary mineral products, green plants provide food for many different living creatures that live in the forest. One of these creatures needs living parts of plants for nutrition, while others, on the contrary, are content only with dead plant remains. The green population of the forest creates the necessary conditions for the existence of a wide variety of living organisms - from animals and birds to fungi and bacteria. All of them successfully breed in the forest and develop normally.

Without the green "factory" their life would be impossible. In a forest plant community, several tiers of plants can usually be distinguished. The upper tier is formed by trees, lower is the tier of shrubs, even lower is the grass-shrub tier and, finally, the moss-lichen cover.

In the forest there are also such plants that are not included in any tier - for example, creepers climbing up trees, mosses and lichens covering tree trunks. This is the so-called extra-tiered vegetation.

Let us consider in more detail the individual tiers of the forest and the main groups of forest plants.

Tree layer (tree stand). Among the green population of the forest, the leading role undoubtedly belongs to trees. It is they who first of all create the forest, without them there can be no forest itself. The dominant role of woody plants is manifested in many ways.

Trees have a huge plant mass. In this respect, they are far superior to all other green plants in the forest - shrubs, shrubs, grasses, mosses. Trees account for the vast majority of organic matter. This is the basis of the forest in terms of plant mass.

It is important to note something else. Trees create a very special forest environment under their crowns - strong shading, high humidity, etc. The whole situation under the forest canopy differs sharply from what we find nearby in the open. This is especially noticeable in the summer on a hot, sunny day. The specific forest environment is not suitable for life for all plants. Under the dense canopy of the forest, for example, light-loving grasses and shrubs cannot develop. But shade-tolerant ones grow quite well. In a word, trees determine the possibility of the existence of certain plants under their canopy, as if they produce a kind of selection. This also shows their dominant role.

The influence of forest giants on the lower tiers of the forest is not only in shading. Of great importance is the "interception" of water by the roots of trees, and especially nutrients in the soil layer. Trees “take away” these vital goods from other, weaker forest plants, making it difficult for them to feed from the soil. But that's not all. Falling leaves of trees contain some substances that adversely affect the smallest forest plants, especially mosses. The fall of a large mass of foliage in autumn can inhibit even low-growing forest grasses located near the ground itself (for example, oxalis). Foliage acts both purely mechanically, falling asleep and pressing down on plants, and biochemically, being a source of toxic substances.

Trees form the uppermost, dominant tier in the forest. It is commonly referred to as a tree stand. It must be said that in different parts of a sufficiently mature forest, the forest stand has an unequal density. In some places it is relatively dense, the gaps between the crowns are small. In other places, trees, on the contrary, stand quite rarely, the gaps between the crowns are significant.

What is the reason for such differences? In a forest not affected by logging, sparse stands are usually found where the soil conditions for tree growth are especially unfavorable. An example would be pine forests developing on sand dunes. The soil here is very dry, the water "ration" is extremely scarce, and there is not enough water for the development of a dense forest. Where the forest develops under normal soil conditions and receives enough moisture, it is usually dense and closed.

The density of tree placement is most often expressed as the number of trunks per 1 ha. If we calculate this number in a pine forest and spruce forest of the same age untouched by felling, the result will be different. In a pine forest, there will be somewhat fewer trunks than in a spruce forest. Consequently, the pine forest is, by its very nature, rarer than the spruce forest. This is due to the different relation to the light of those tree species that form the forest. Pine is photophilous and cannot grow as densely as shade-tolerant spruce. As you can see, the density of the forest stand is determined not only by the soil conditions of tree growth, but also by the nature of the trees themselves, their relationship to light. In a natural forest, trees, even in a small space, are never distributed evenly over the area. In some places they seem to be crowded, in others, on the contrary, they are sparse. In addition, in the canopy of trees there are almost always breaks of a larger or smaller size - the so-called "windows". These gaps are especially characteristic of the old forest, where individual large trees, for one reason or another, die off from time to time. Trees can die in the forest from old age, wind breakage, and insect damage, etc. After the death of a large tree, a large clearing remains, which does not overgrow for quite some time. "Windows" in the tree canopy are the most common, widespread phenomenon.

It is necessary to say a little about the composition of tree species that form our forests. Different trees grow in different parts of the country. The number of tree species found in the forest also varies. Walking through the taiga, we can rarely count more than two or three tree species. Our Central Russian oak forests are richer in this respect. Here you can find up to a dozen different trees (oak, linden, ash, several types of maple, elm, elm, etc.). All this has its reasons. The number of tree species in the forest is directly dependent on how favorable the natural conditions of the territory are - climatic and soil. The better these conditions, the richer the species composition of trees. Northern coniferous forests have few tree species because they develop in harsh natural conditions - in a cold climate and on relatively poor soils. Oak forests, on the contrary, are common in areas with a fairly warm climate and on rich soils. It is because of this that the set of trees here is much larger.

In nature, one can often find such areas of the forest where the forest stand is formed by only one tree species, for example, spruce, pine, birch. In this case, the trees usually have more or less the same height and form a single tier.

When there are several tree species, some of them sometimes grow clearly higher than others and form their own special tier. The tree stand becomes two-tiered. A good example of this kind is a widespread type of forest called compound boron. The first tier here is formed by pine, reaching 30 m in height. In the second tier, oak and linden usually grow, which are much lower - up to 15-18 m. Broad-leaved trees cannot grow tall under these conditions, since they are demanding on soil fertility, and the soil under complex forest is not very rich in nutrients. Oak and linden grow here, so to speak, below their capabilities. In favorable conditions, on sufficiently rich soils, these trees reach a much greater height.

Other examples of bunk stands could be given. Sometimes even three tiers of trees are distinguished in the forest.

It is necessary to note one more circumstance. The composition of the lower tiers of the forest stand always includes trees that are more or less shade-tolerant. The most common species here are spruce and linden, tree species that can tolerate strong shading. However, you will never see either pine or birch in the lower tiers of the forest stand. These tree species are very photophilous and absolutely cannot tolerate the lack of light.

To judge whether a tree is photophilous or shade-tolerant, one can, of course, not only by the position that it occupies in the forest stand. This is also indicated by his appearance. Shade-tolerant tree species have dense, dense crowns that let in little light. In light-loving crowns, on the contrary, they are very loose, openwork.

Shrub layer (undergrowth). A variety of shrubs usually develop under the trees in the forest. They form their own special layer - the so-called undergrowth. In some areas of the forest, the undergrowth is lush, dense, in others - rare, poorly developed. Such differences are most often explained by the fact that different forest areas have unevenly dense tree canopies. Where trees rarely stand, shrubs receive a lot of light and grow strongly. A good example of this is our oak forests. See how a hazel (hazel) grows in an old oak forest, where the trees are quite far apart. Its bushes are powerfully developed, they form dense thickets. And in a younger forest, the trees stand close to each other, create strong shading and hazel bushes are low, oppressed, there are few of them. If the oak forest is dense enough, the undergrowth is almost always poorly developed.

None of the forest shrubs, even if it develops in the most favorable conditions, can "catch up" with mature trees in height. Forest shrubs always remain under the canopy of trees, as if "under the forest." That is why they are called undergrowth.

There are not so many types of shrubs in our forests. All of them are more or less shade-tolerant and develop normally in shading conditions under trees. Many of them bloom and bear fruit. However, shading and forest conditions in general are not a necessary condition for their existence. Forest shrubs also grow well outside the forest, in an open area. Here they develop even more magnificently than in the forest, bloom and bear fruit more abundantly. And this is quite natural. In the forest, they are more or less oppressed by trees, but in the open they are not constrained by anything. If you transplant any shrub from the forest to a flower bed, it will grow strongly and begin to bloom profusely. Of course, this will not be noticeable immediately, but only a few years after the transplant.

We have already talked about the fact that the stand is called the dominant layer in the forest. All other tiers of vegetation located below are called subordinate. The undergrowth also belongs to these tiers. It really occupies a subordinate position in relation to the forest stand, experiencing a strong depressing influence from the trees.

In different types of forests, the species composition of shrubs is different. In the blueberry pine forest, for example, there are few types of shrubs - most often only juniper and brittle buckthorn. In the oak forest, the set of shrubs is much richer: hazel, warty euonymus, forest honeysuckle, wolf's bast, wild rose and some others. Each type of forest has its own set of shrub plants. And this is due to the fact that shrubs are by no means indifferent to the properties of the soil on which they grow. Some of them, like juniper, are content with soil poor in nutrients, others, like hazel, can grow only on sufficiently rich soil. And since soil properties are different in different types of forest, the species composition of shrubs is not the same.

The undergrowth plays an important role in the life of the forest. It serves primarily as a nesting site for various birds. And many birds are very useful for the forest, as they exterminate a large number of harmful insects. Where the undergrowth is destroyed or it is poorly developed, few birds nest, here the trees are poorly protected from pest attacks. From this it is clear that the undergrowth must be preserved and protected. It is necessary for the existence of the forest.

The useful role of the undergrowth also lies in the fact that the fruits of forest shrubs serve as food for the most diverse animals and birds that live in the forest. Almost all forest shrubs have juicy fruits, and representatives of the fauna willingly eat them. There are many examples of such shrubs: honeysuckle, euonymus, wolf's bast, elderberry, buckthorn, viburnum, raspberry, etc. Hazel is an exception, its fruits are dry. But they also feed on various forest dwellers, such as squirrels, forest mice.

grass-shrub cover. On the soil in the forest, as a rule, various herbaceous plants and shrubs develop. They also form their own special tier. A characteristic feature of herbs is more or less soft, never woody stems. And shrubs are small plants, similar in structure to ordinary large shrubs, but only much inferior to them in size. The grass-shrub cover is very different in different types of forest. Sometimes only grasses can be seen on the soil, sometimes they grow together with shrubs, sometimes the latter dominate. The predominance of shrubs, especially blueberries and lingonberries, is typical for coniferous forests. Here, these plants often grow very luxuriantly, completely covering the soil over a large area. A dense cover of blueberries and lingonberries can be found, for example, in some pine forests. In broad-leaved forests, oak forests, shrubs, on the contrary, are rare and never form a continuous cover. Tug they are most often not at all.

Grass-shrub cover - a subordinate layer of vegetation in the forest. The degree of its development largely depends on how close the tree canopy is. As an example, you can again take the oak forest. When the trees in an oak forest closely interlock with their crowns and create strong shading, the grass cover develops poorly: only individual oppressed plants are found on the soil. The situation is quite different in a rare oak forest, where there is a lot of light under the trees. Here the grass cover is continuous, dense, and the grasses themselves are taller and larger.

Living conditions in the forest, under the canopy of trees, do not prevent many herbs and shrubs from blooming and bearing fruit. All these plants are quite shade-tolerant, well adapted to shading. Their flowers often have a white color (lingonberries, oxalis, septenary, etc.). This is especially true for spruce forests. It is these flowers that are best seen in the shade of the forest, they are more easily found by pollinating insects.

Among the forest grasses and shrubs, there are many that develop juicy fruits that attract animals and birds (lingonberries, blueberries, stone berries, maynik, lily of the valley, etc.). The dispersal of seeds with the help of representatives of the animal world is a common occurrence in forest plants. Just as common is another way to transfer seeds - with the help of air currents. This is how the smallest, almost invisible to the naked eye, seeds of all our forest orchids, wintergreens, and spices spread. They are carried through the air due to the fact that they are extremely small and light, like dust particles. Even the faintest breath of the breeze picks them up. Dust-like seeds are also one of the adaptations of plants to life in the forest. After all, under the canopy of trees there is no strong wind. Under these conditions, only microscopically small, almost weightless seeds can spread through the air.

Interestingly, among the forest plants there are almost no plants in which the seeds would be equipped with special adaptations for flight (tuft of hairs, etc.). Seeds of this kind are found mainly in plants in open places where more or less strong winds blow.

Finally, the seeds of some forest grasses, especially various sedges, violets, corydalis, are spread by ants. Transferring seeds to an anthill, insects often lose them along the way and thus make "sowing".

Many forest grasses and shrubs can grow quickly to the sides, capturing new territory. The “mobility” of these plants is explained by the fact that they have long creeping rhizomes located not deep in the soil layer, or above-ground shoots spreading over the soil surface. They grow rapidly with the help of creeping rhizomes, for example, lily of the valley, minik, various wintergreens, through above-ground shoots - drupe, zelenchuk, tenacity. Often in the forest there are whole thickets formed by any one plant (for example, the same lily of the valley). This is a consequence of the strong growth of creeping shoots.

Almost all forest grasses are perennials. For many years they keep their place in the forest, and some even expand their territory, “spread” to the sides. However, among the forest grasses there are also “fixed” ones. These plants remain in the same place all their lives. An example is the Kashubian ranunculus, common in oak forests.

One of the most characteristic features of many forest grasses and shrubs is shallow rooting. The roots and rhizomes of these plants are often located in the uppermost layer of the soil, and sometimes even in the litter. They do not go deep into the soil any significantly.

The species composition of herbs and shrubs in different types of forest varies. In a coniferous forest, some plants are found, in an oak forest - completely different. This is due to the fact that each plant has its own requirements for the soil. Some, like the cat's paw, tolerate nutrient-poor soils well. Others, like Corydalis, on the contrary, are very demanding on soil fertility. Each type of forest develops in certain soil conditions and, in accordance with this, one or another composition of plants is “selected”.

Different types of forest grasses and shrubs vary greatly in height. Among them there are both high and low. Some forest cereals, for example, almost reach the height of human growth, and oxalis, linnaeus, on the contrary, barely rise above the soil surface. Sometimes the grass-shrub cover can be subdivided into well-separated plant layers. For example, in some types of coniferous forest, dense thickets of blueberries develop under the trees, and below, on the soil itself, a continuous carpet of oxalis. In this case, the grass-shrub cover has, as it were, two tiers - a higher and a lower one (however, it is more correct to call them not tiers, but sub-tiers).

A characteristic feature of the grass-shrub cover in the forest is its spotting, mosaic. In some places there are very few plants, almost none, in others, on the contrary, whole clusters. Often these thickets are formed by only one species. So, in a spruce forest, we can find separate, more or less large patches of mainnik, sorrel, oxalis, and other plants.

The spotting of the grass-shrub cover in the forest has its own reasons. One of the most important is the heterogeneity of environmental conditions under the forest canopy. This applies primarily to illumination at the level of the soil surface. The access of light is especially great in the "windows". Favorable conditions are created here for the growth of grasses and shrubs. It is in the "windows" that we usually find a lush ground cover. A completely different picture is where the tree canopy is closed and the soil is very strongly shaded. Here grasses and shrubs develop weakly, grow as separate oppressed specimens.

But there is another reason for the mosaic. It is related to the characteristics of the growth of the plants themselves. We have already said that many forest grasses and shrubs are able to quickly "spread" to the sides due to the growth of horizontal rhizomes and creeping above-ground shoots. This is what causes stains. The species, once settling at some point in the forest, then begins to spread in different directions and finally forms a spot of greater or lesser size. This does not necessarily happen in the "window".

The role of grass and shrub cover in the life of the forest is quite significant. The most common shrubs of our coniferous forests - lingonberries and blueberries - form juicy fruits, and they serve as the main food for some forest animals and birds. Large forest animals (for example, elk, roe deer) and even small ones (forest mice, voles) feed on the green mass of many herbs. Suitable for forest fauna and juicy fruits of some herbs (strawberries, stone fruits, lily of the valley, mainika, etc.). In other words, grass-shrub cover is important for many living creatures living in the forest as a source of food.

Moss-lichen cover. The lowest tier of the forest plant community is the moss-lichen cover. Mosses and lichens are very stunted, they barely rise above the soil surface.

Moss cover is quite common in forests. It is well developed in many types of coniferous forests, common in our pine and spruce forests. This green carpet is often spread over a large area, completely covering the soil.

Mosses in the forest develop in conditions of especially strong shading. They get very little light. They are shaded not only by trees, but also by all other forest plants. However, they are very shade tolerant and tolerate extremely poor lighting well. In some areas of the spruce forest on the soil, due to lack of light, no plants develop at all, except for mosses. And mosses form a continuous cover here.

But the shade tolerance of these little inhabitants of the forest is still not unlimited. Where it is especially dark under the canopy of the spruce forest, mosses also disappear, only a layer of dry fallen needles remains on the soil - the litter. Such a picture can be seen, for example, in very dense young spruce forests. Here the shading is so strong that no plants can grow at all.

Mosses also tolerate falling asleep with dry needles falling from trees. They don't suffer from it at all. Needles do not have an adverse effect on them. However, falling leaves act on mosses in a depressing way. Small plants do not tolerate well when they fall asleep leaves. It is not difficult to notice this in the forest. Imagine that you are walking through a dense old spruce forest, where a solid moss carpet is spread under your feet. But suddenly a large group of birches appeared on your way. The moss cover on the soil immediately disappears.

Now it will be clear to us why in some types of forests mosses form a continuous cover on the soil, while in others they are very rare. The point here is, first of all, what is the nature of the litter in the forest, what falls to the ground - dry needles or foliage. In a coniferous forest, mosses tend to develop very well. In deciduous forests, they usually do not form a continuous cover and are scattered. There are especially few mosses in the oak forest. They are occasionally found here in small spots, and, moreover, in special conditions - only on heaps of earth thrown out by the mole. Yes, and the mosses themselves are special - not at all those that form a cover in a coniferous forest.

The moss carpet plays a significant role in the life of the forest, especially when it completely covers the soil. In this case, mosses growing in large masses prevent the germination of falling seeds of pine, spruce and other trees. Seeds, as it were, hang among the moss stalks, do not have the opportunity to germinate normally. Where the moss cover is continuous, tree shoots almost do not appear, there are very few of them here.

But the role of mosses is not limited to this. A powerful and dense cover of some mosses absorbs a lot of moisture. It absorbs water like a sponge and causes waterlogging of the soil. And this leads to a sharp depletion of the soil layer with oxygen and creates unfavorable conditions for the development of tree roots and other forest plants.

The composition of the moss cover includes many types of mosses. And at the same time, different species are found in different parts of the forest. It depends on differences in soil conditions. Where the soil is more humid, some mosses develop, where it is drier, others. Mosses are also sensitive to soil fertility. Some of them grow only on richer soils, others are content with poorer ones. According to the species composition of mosses in a particular part of the forest, one can judge the properties of the soil. Mosses are just as indicative in this respect as other inhabitants of the forest - trees, shrubs, shrubs, grasses. Each forest plant has its own requirements for the environment and can be an indicator of soil and other conditions.

Lichen cover develops quite rarely in the forest and only where the forest grows on very dry and poor sandy soil. A continuous cover of white fruticose lichens can be seen, for example, in pine forests growing on sand dunes. This type of forest has received a special name - "pine forest". When you walk through such a forest in dry weather, small lichen bushes crunch under your feet - they are very fragile and break easily.

Lichens that form a cover on the soil are rather photophilous plants. They cannot grow, for example, under the canopy of a shady spruce forest - it is too dark for them here. But in the pine forest we just talked about, there is a lot of light, and they are developing well. There is another reason why lichens are rarely found in the living ground cover of the forest: they do not tolerate the presence of neighboring plants, in particular grasses and shrubs. In the forest, which grows on sand, there are few plants that inhibit lichens. That is why they grow so luxuriantly here.

Lichens can be found on the soil not only in white moss forest, but also in some other types of forest. However, their role here is insignificant. They never form a continuous cover under these conditions. And their views are completely different than in the pine forest.

So, we got acquainted with the individual tiers of the forest plant community, with the plants that form them. In a fairly old, fully formed forest, all these tiers are usually well expressed. However, some of them, except, of course, the forest stand, may be absent.

undergrowth. Not every plant found in the forest can be assigned to one or another tier. There are plants that do not belong to any forest "floor". As an example, we can point to undergrowth - young trees that have appeared under the forest canopy in a natural way. At first, future trees are very small and are located in the same tier as grasses and shrubs. Then they get taller and emerge into the undergrowth layer. Large undergrowth can rise even higher and be above the bushes. In a word, young trees in the process of their growth change their height all the time and find themselves in one or another tier. They do not form their own, separate tier.

Undergrowth is an important component of the forest plant community. Young trees, under certain conditions, can replace the old, mother trees, they provide a natural restoration of the forest. In a word, undergrowth is, as it were, the future of the forest. But at the same time, it is also an indicator of his well-being, a normal state. If there is undergrowth under the canopy of trees, then the forest can support its existence, it is quite viable. The presence of undergrowth indicates that mature trees form seeds in sufficient quantities, these seeds germinate well, and seedlings find favorable conditions for their further development.

In the forest, undergrowth is usually distributed unevenly, in clumps. Most often, such curtains are located in the "windows". This is especially noticeable in the old spruce forest. When you walk through such a forest, there is little spruce undergrowth. But suddenly you come across whole thickets of young Christmas trees. Looking up, you notice that there is a large gap in the canopy of trees in this place. Undergrowth is confined to windows for the reason that favorable conditions are created here for the emergence of seedlings and their growth. It is especially favorable that there is a lot of light in the windows. The undergrowth is most abundant in those areas of the forest where the tree layer is sparse, more or less sparse (for example, the so-called thinnings). There is enough light in such a forest, and this, as we already know, contributes to the emergence of a young generation of trees. When the stand is sparse, the undergrowth is usually located not in clumps, but more or less evenly over the area. In the forest, we often encounter such a phenomenon when one tree species dominates in the upper tier, and another in the undergrowth. Many of our pine forests of a fairly old age can be an example. There is no pine undergrowth under their canopy, and spruce undergrowth is very plentiful. In this case, the old trees are replaced by the young generation of not the same tree species, but a completely different one. Significant changes may occur in such a forest in the future: the composition of the stand may change dramatically. There will be a so-called change of breeds.

Lianas and epiphytes. In our forests, there are other plants that are not included in any tier of the forest plant community - creepers and epiphytes. This is the so-called extra-tiered vegetation.

Lianas have thin, weak stems, which in one way or another climb up the trees, bringing leaves to the light. The roots of these plants are in the soil, extracting water and necessary nutrients from there. Few species of vines are found in the forests of the middle zone of the country; they have a slight distribution here. In the northern coniferous forests, in the taiga, most often you can find only one liana - the Siberian prince. There are much more lianas in the forests of the Caucasus, the Far East.

Extra-tiered vegetation also includes epiphytes - plants that settle on the trunks and branches of trees. In our forests, they are represented almost exclusively by mosses and lichens. These small plants sometimes completely cover the trunks of trees, and often over a considerable distance. Some of them hang down from the branches like braids. Epiphytic plants use the tree only as a place of their settlement, but not as a source of food. They develop on the cortex and live their own special life. These unpretentious plants, using mineral "raw materials", themselves produce organic substances necessary for nutrition. As epiphytes on trees, we meet completely different types of mosses and lichens than on the soil in the forest.

Lichens usually form the basis of the epiphytic population on trees in our forests. They play a much larger role than mosses. Epiphytic lichens, even if they completely cover the tree trunk, do not cause much harm to the tree itself, do not prevent it from growing. However, many have probably noticed that lichens develop especially luxuriantly on oppressed, weak trees. The trunks of such trees and even their thin branches are sometimes completely covered with small uninvited settlers. But lichens are not at all to blame for the poor growth of trees. The point here is quite different. Oppressed trees themselves create favorable conditions for the settlement of "lodgers". Their bark is slowly renewed, its old outer layers do not fall off for a long time, and lichens have enough time to grow here. In a strong tree that grows well, the bark is updated quickly and lichens simply cannot gain a foothold here. The tree discards them along with particles of the old bark.

fungi and bacteria. An important component of the forest are non-green, chlorophyll-free plants - fungi and bacteria. As you know, all of them are unable to create organic substances from mineral "raw materials". These plants need ready-made organic compounds for nutrition.

The world of forest mushrooms is exceptionally rich and diverse. And the role of mushrooms in the life of the forest is extremely great. They are important primarily because they do a great and useful job of decomposing dead plant residues that accumulate on the surface of the soil and in its upper layers. But mushrooms are useful in other ways as well. The hyphae of fungi that develop in the soil, like a web, braid the ends of the living roots of green forest plants, forming mycorrhiza. Such a commonwealth of a green plant and a fungus is beneficial for one and the other partner, allowing each of them to develop better. Fungal hyphae, for example, facilitate the absorption of phosphorus from the soil by roots, which is important in plant nutrition. Mycorrhiza is found in most of our trees, in many forest shrubs, shrubs and herbs. The role of mushrooms in the forest, of course, is not limited to what we mentioned above, it is much wider and more diverse. Forest mushrooms are an important part of the forest.

The bacterial population is quite numerous in the forest, concentrated mainly in the litter and in the upper part. mineral horizons of the soil. Soil bacteria in the forest are represented by many species, and the total number of bacteria is huge - billions of cells per 1 g of soil. All this mass of the smallest organisms performs a great and important job of decomposing the dead remains of plants and animals. Bacteria, like fungi, do not allow dead organic matter to accumulate in the forest, and quickly decompose it. It's like a kind of forest "gravediggers". Under the influence of soil bacteria and fungi, complex organic substances of plant and animal remains are converted into simpler compounds up to carbon dioxide and mineral salts. And these substances are available to green plants and are widely used by them.

Both bacteria and fungi that live in forest soil do a similar job. However, they have different requirements for the soil environment and develop in different conditions. Fungi prefer more acidic soils, such as we usually find in coniferous forests; bacteria, on the contrary, are confined to less acidic soils, which are found in deciduous forests.

So, the forest is primarily a plant community. However, the concept of "forest" is usually invested not only in the totality of plants. This is a more complex natural formation. It also includes various representatives of the animal world, the habitat of living organisms - the soil and the atmospheric layer. This whole set of individual components of animate and inanimate nature, closely related to each other, was called "biogeocenosis".

The animal population of the forest. The totality of living beings is an important part of the forest. It is difficult to imagine a forest without animals, birds, insects, earthworms, etc. They are found everywhere and are an indispensable part of forest biogeocenoses. There are quite a few species of these living creatures, especially insects. Their activity is very diverse and has a great influence on the life of the forest.

In our forests, large mammals (moose, deer, etc.) are primarily distributed. However, their influence on the life of the forest as a whole is less significant in comparison with small mammals (forest mouse-like rodents).

Large herbivorous animals gnaw branches, bark and leaves of trees, causing them certain damage. Small animals harm trees more strongly: they destroy the seeds of these plants that have fallen to the ground and thus do not allow seedlings to appear. The scale of destruction of acorns by mouse-like rodents, in particular the yellow-throated mouse, is especially large.

Protein has a significant impact on the forest. It feeds on the seeds of coniferous trees, and in lean years - on their buds, which causes certain harm. Walking through the forest in winter, you can often see many short spruce branches with living needles under large fir trees. They did not fall from the tree by themselves. This is the “work” of a squirrel that gnawed on spruce buds.

There are many kinds of birds in the forest. The feathered population of the forest numbers many dozens of species. The influence of birds on the forest is manifold. Their most important role is in the destruction of harmful insects, including such dangerous ones that cause enormous damage to the forest, such as gypsy moth, oak leafworm. Destroying pests, feathered "forest orderlies" are of great benefit. The role of birds is also significant in the distribution of seeds of forest shrubs, shrubs and herbs that have juicy fruits.

The forest fauna should also include small invertebrates (earthworms, mollusks, insects, arachnids, etc.). Some of these creatures spend their entire lives above the ground (many butterflies), while some, on the contrary, remain in the soil almost all the time (earthworms). There are also those whose life takes place both in the soil and above the ground (ants). The forest is inhabited by living beings at all its levels - from the tops of the trees to the ends of their roots.

The role of earthworms in the forest is very great, and it is entirely positive. Worms bring great benefits to the forest, processing dead organic residues, loosening and “ventilating” the soil, fertilizing it with their excrement, etc.

The role of insects in the forest is also very important, but it is far from always positive. The most useful forest insects are ants. This, like many birds, is a kind of "orderlies of the forest." Ants destroy many harmful insects, especially caterpillars that eat leaves, beetle larvae, etc. They also play a certain role in the distribution of seeds of forest herbaceous plants, in their settlement.

Useful in the forest are also those insects that visit the flowers of forest plants and carry out pollination (mainly bees, butterflies, bumblebees, and also some beetles). In this way, they contribute to a better formation of seeds and fruits.

However, there are many insects in the forest that cause damage to plants. This includes all kinds of pests that feed on leaves and roots - caterpillars of some butterflies, beetle larvae, beetles themselves, etc.

Finally, insects harm plants in another respect - they damage flowers and unripe fruits, preventing seeds from ripening. A good example of this kind is damage to oak acorns in the crown of a tree, before they fall to the ground. Such damage is caused, in particular, by the larvae of the acorn weevil beetle and the caterpillar of the acorn moth butterfly. Damaged acorns die, do not ripen. In some years, pests destroy a significant proportion of the acorn crop, and sometimes the entire crop.

From what has been said, it is clear how large a role in the life of the forest is played by its numerous and diverse animal population. Some representatives of the fauna harm forest plants, while others, on the contrary, are beneficial. But one way or another, all these living beings live in the forest, influence it and constitute its indispensable component. There are no such forests, wherever they are. This is an important and indispensable element of the forest, which, along with others, is also included in the concept of "forest".

So far, we have only talked about the living organisms that inhabit the forest. But they cannot be imagined outside the environment - soil and atmosphere. No representatives of flora and fauna can exist outside the habitat, in isolation from it. Living and non-living matter constitute an inseparable unity.

Let us now turn to the habitat of forest plants and animals.

Soil layer. The role of the soil layer in the life of the forest is very large and diverse. It is most noticeable in relation to the green inhabitants of the forest.

The roots of forest plants, penetrating into the soil, take water and necessary nutrients from there.

The main mass of the roots is concentrated in the uppermost spruce of the soil, i.e., in the soil itself. The soil near the surface is most saturated with roots, since it is here that the most nutrients are contained. With depth, the number of roots sharply decreases. The soil layer serves not only as a supplier of water and mineral nutrients for green plants. The decomposition products of dead plant residues accumulating on the soil surface also come here. Consequently, the soil layer not only gives, but also receives. Between this layer and plants there is a continuous exchange of substances.

The importance of the soil in the life of forest fungi, soil microorganisms, and many representatives of the forest fauna is also great. This layer is necessary for earthworms, mouse-like rodents, moles, numerous insects, etc. Various mammals dig holes in the soil layer - fox, badger, etc.

A very important role in the life of the forest as a whole is played by the uppermost soil horizon - the layer of fallen leaves or needles, that is, the forest floor. Many processes occurring in the forest are somehow connected with the litter. It affects the life of plants and small animals, the water regime and the nutritional properties of the soil, etc. Formally, the litter refers to the soil. But in fact, this is a very special formation, which is, as it were, a link between living green plants and mineral soil.

The significance of the litter in the life of the forest lies primarily in the fact that it is a kind of treasury of nutrients for green plants. The leaves and needles that fall from the trees contain compounds of nitrogen, phosphorus, potassium, calcium and other elements necessary for the life of green plants. Fallen leaves and needles bring these nutrients with them.

The litter is relatively rich in plant nutrients; there are incomparably more of them here than in the underlying mineral soil horizons. However, nutrients are in a bound state, they are part of complex organic compounds and are almost inaccessible to green plants. In the process of decay of the litter, the nutrients become available, they go to the roots. The decomposition of the litter is relatively slow, and nutrients are released gradually, in small quantities. This allows plants to make the most of their nutrient resources.

The litter in the forest serves as the layer in which many thin suction roots of various forest plants are concentrated. In some types of forest, the litter serves as a place for the concentration of tree roots (for example, when the permafrost is close). In this case, it becomes especially important in the life of the forest.

The role of litter in the forest is very diverse and not always positive. Thus, the litter layer serves, for example, as an obstacle to the germination of fallen seeds of pine, spruce, and some other trees with small seeds. Where the soil is completely covered with litter, there is very little undergrowth of coniferous trees. When this, there is no obstacle, undergrowth appears in large numbers. Many, probably, paid attention to the fact that under the canopy of a spruce forest, small Christmas trees are found mainly on rotten tree trunks lying on the ground, on rotten stumps - that is, where the litter does not accumulate.

All that has been said about the soil layer allows us to imagine how important this layer is for the forest. Without it, the existence of the forest flora and fauna is impossible.

Air environment. For the existence of the forest, the layer of the atmosphere in which forest plants and other living organisms develop is also necessary. Outside this layer of air, forests cannot be imagined. The atmosphere contains carbon dioxide, without which the life of the green inhabitants of the forest is impossible. It is also a source of oxygen, which is necessary for the respiration of all living organisms inhabiting the forest, including green plants.

Of course, the atmosphere not only gives, but also receives. It is replenished with oxygen released by green plants and carbon dioxide formed during respiration. In a word, the layer of the atmosphere is a kind of air reservoir into which substances vital for the inhabitants of the forest enter and from which these substances are again absorbed by plants and animals. There is a close interaction between the inhabitants of the forest and the air around them, there is an exchange of substances. Without atmosphere, as well as without soil, there can be no forest.

Let us return once again to the question of what a forest is and what is included in its composition.

A forest is, first of all, a collection of many of the most diverse representatives of flora and fauna, i.e., plant and animal populations.

All these organisms are a living component of the forest, its main element. Without them there can be no forest. However, all these representatives of wildlife cannot be separated from the environment - the layer of the atmosphere and the soil in which they develop. Living organisms in the forest are inextricably linked with what surrounds them, it is a single whole.

Forest biogeocenosis, which is not strongly influenced by humans, is quite stable, it develops according to its natural laws. However, human activity makes great changes in the "work" of this complex natural "mechanism", in one way or another violates it.