Message about forests. What types of forests are there?
A natural community is a collection of organisms of various functional affiliations on certain territory with the same physical and geographical conditions. Further in the article, facts will be provided that will help answer the question of why the forest is natural community.
The community includes shrubs, trees, herbaceous plants, various species of animals and birds. The natural community forest is one of the main types. This is an integral and one of the most important parts of the biosphere. Forest is an element of the geographical landscape.
Forest is understood as a product of nature and its main part. This natural system, which can be considered at different levels, depending on the scale of study.
Forest as part of the biosphere
The concept of forest as an integral and one of the main parts of the biosphere is the broadest and most comprehensive. Forests can be seen on all continents except the southernmost - Antarctica. They occupy about 30% of the land and cover more than 4,000 million hectares. More than half of all forests are subtropical and tropical.
Their formation began in the Devonian, over a long period of time they were subjected to various influences, as a result they acquired their modern appearance.
Types of forests
- Natural forests. Natural community forest of this type occupies the main area. They can be virgin - where no man has gone before. Spontaneously natural forests- are created by nature, the external influence of the elements and man. Natural forests are partially regulated by humans. There may be held various events, for example, cutting down undergrowth, partial catching of animals.
- Artificial forests. Created by man. Certain types of plants are planted that are necessary on the farm or to increase the number of a species. Such forests are especially common in arid areas in some Western European countries.
The forest is a global accumulator of living matter; it affects the level of carbon and oxygen balance. Thus, the most forested regions of the world produce more than 50% of the oxygen that, in turn, enters the atmosphere.
The natural forest community has a unique type of metabolism and energy between all its individual components. As a result of this exchange, organic substances are transformed and accumulated. The result is so-called biomass.
Average annual rainfall productivity tropical forests- 28 tons of organic matter per 1 hectare. U mixed forests this figure is much lower - 10 tons per 1 hectare. Due to the relatively long lifespan of woody plants, the biomass of forests is much higher than the biomass of other natural communities.
Natural-zonal division of forests
In the context of natural zonality and provincial-regional division, the forest makes it possible to approach it as a geographical phenomenon. Forest vegetation depends entirely on climate, primarily on solar radiation.
An example of the division of forests are those allocated to separate biomes coniferous forests, which occupy large areas cold zone, as well as mixed, deciduous, evergreen equatorial.
Within provinces and zones, the forest is divided into subzones and subprovinces. The smallest part is the massifs, which consist of one type of tree.
Forest as woodland
Another concept of a forest sounds like this: it is a separate area with woody, herbaceous and shrubby vegetation. It is also called woodland.
A planting, or forest phytocenosis, is a collection of various plant components growing in a certain environment.
A forest is a group of plants, i.e. separately standing trees are not forest. The main feature of the planting is integrity land plot, which it occupies, and the tree canopy, which is characterized by the closeness and completeness of the tree stand.
The canopy density varies depending on the tree species, age, development of the forest stand, and climatic conditions.
In addition to plants, the natural community of the forest unites animals and birds. In the forest, not only plants adapt to each other, but also plants to animals, and animals to plants.
Forest as a biogeocenosis
Forest biogeocenosis is understood as an area of forest that is sufficiently homogeneous over a certain period in structure, composition, and properties of its components. That is, homogeneous in terms of the plants growing in it, the animals and microorganisms inhabiting it. Also according to microclimatic, hydrological, soil conditions.
Areas of forest biogeocenoses that are similar to each other can be combined into some type of forest. Each type, depending on the conditions, is characterized by the species composition of trees and shrubs.
There is an indigenous type that is not disturbed by man and the elements, for example, aspen forests that grew in place of spruce forests in places of fires or clearings.
Interaction of forests with the environment
All numerous environmental factors determine the living conditions of the forest. The following groups are distinguished:
- Climatic factors. These are the influence of light, heat, precipitation, air movement and others.
- Edaphic factors. Soil composition, its physical and Chemical properties, slope exposure, relief features and others.
- Biotic factors. Animals, microorganisms and plants.
- Anthropogenic factors. All human actions aimed at changing conditions: deforestation, drainage, uprooting and others.
In nature, there is a complex influence of environmental factors, manifested in various combinations. For example, the northern taiga and steppe regions receive the same amount of precipitation. But in the first case it prevails low temperature, high humidity soil and air. In the second case - the opposite combination.
A change in one factor always entails a change in another. For example, a change in exposure, terrain height, or slope steepness will cause a change in climate, and therefore in soil and vegetation.
Natural rainforest community
A tropical forest- this is a type of biotome that is common in equatorial latitudes, as well as in subequatorial and tropical latitudes. The main conditions that influenced the formation of this vegetation are excess moisture and increased solar radiation.
Rainforest species
There are two formations:
1. Rain forest. It is also called Hylea, a natural community of tropical rainforests. This is the most species-rich plant formation on the planet. The forest flora is considered the center of evolution. Prevail woody species- about 70% higher plants. The species diversity is exceptionally high - from 50 to 100 per hectare. The tree stand of tropical rainforests is dominated by representatives of the dipterocarp, myrtle, legume, and palm families. A large number of tree ferns.
In this biome there is a division according to growth intensity:
A. Fast-growing species, but short-lived (balsa tree).
B. Relatively fast-growing and long-living (entandrophragms, kayas).
B. Slow-growing and long-lived shade species (Gabonian mahogany, ocumea).
2. Seasonal rainforest. These forests grow in an area with big amount precipitation, but there are dry periods. Depending on duration dry period, precipitation amount, the following formations are distinguished:
A. Evergreens. Eucalyptus forests in Australia.
B. Semi-evergreen. Typically, deciduous trees grow in the upper tier, and evergreen species grow in the lower tier.
B. Light sparse forests with a fairly poor species composition.
The natural community of the tropical forest is monsoonal and savannah.
With a decrease in precipitation, sparse forest stands with cereals or thorny xerophilous forests appear in the growing area.
Rainforest fauna
The natural community of the forest has a rich fauna. Its description consists of presenting species living in the upper tier (in the crown of trees). These are different apes, monkeys, woolly wings and others.
Seasonal forests are home to large animals - giraffes, elephants, buffalos. The species composition of small invertebrates is extremely diverse.
Tiering
Tiering is the vertical division of a phytocenosis into distinct layers or tiers. This phenomenon- this is the result of the selection of species that are able to grow together; they use different environmental horizons.
Layering can be observed in various phytocenoses, but it is most clearly visible in forest ones. Highlight:
- Tree stand - can have 2 or 3 tiers.
- Undergrowth.
- Grass cover.
- Moss-lichen cover.
It is worth noting that in tropical forests, where the cover is quite dense and there is a large vertical density, it can be difficult to distinguish tiers.
The Meaning of Rainforests
Humans and natural communities are closely interconnected. The importance of forests for humanity is enormous: the forest creates oxygen and destroys carbon dioxide, it is a resource base.
Primary tropical forests have replaced almost 50% of their range with secondary forests or herbaceous plants, which are at risk of desertification.
The main reasons for the removal of tropical forests:
1. Slash-and-burn agriculture, burning of forests to create fields for economic activities.
2. Forestry. Export valuable species wood
Currently, more than 16 million hectares of tropical forest are destroyed every year.
Observation and action are needed to protect a biome such as a natural forest community. The environmental message, laws being prepared by various "green" organizations, are aimed at reducing the deforestation of tropical forests and partially restoring them. Humanity needs to stop deforestation and begin restoring species diversity.
Natural communities of forests, meadows, and reservoirs are continuously exposed to human activity.
A forest is a complex combination of many different plants that vary greatly in size, structure, reproduction, type of nutrition, etc. It is like a kind of living mechanism, large and very complex, and individual plants are its parts, details. Trees and all other plants in the forest are closely related to each other in their life activities and influence each other. That's why the forest is called vegetative community or phytocenosis. This is truly something holistic, harmonious, with its own internal connections, and not a random collection of individual plants.
Modern natural forests are gone long haul formation and development. Over the course of many centuries, a certain composition of plants capable of coexistence was selected in the forest. From time to time, new plants penetrated under the forest canopy in one way or another, but not all of them survived or were preserved. Only the most resilient and most adapted to life in the given conditions became full members of the plant community. The forest plant community is formed only by those plants that are able to successfully resist the influence of their neighbors.
Our forests were formed in different parts countries, in different soil and climatic conditions - in the north and south, on plains and in the mountains, on sand and loam, on watersheds and floodplains. Under different conditions arose Various types forests, since vegetation is closely related to environment, V to a large extent depends on climate and soil. In each type of forest we find a certain set of forest plants corresponding to the given natural conditions. Consequently, the composition of the forest includes plants that are adapted not only to coexistence, so to speak, to internal environment forests, but also to certain soil and climatic conditions, i.e. to the external environment.
Dependence is especially clear plant population forests from soil conditions in a small flat area, for example, on the territory of some forestry. In the middle zone of the European part of the country, on nutrient-poor and dry sandy soil, we usually find Pine forest with a cover of lichens and a meager selection of other plants. On loamy soil, quite moist and fully supplied with nutrients, you will find a completely different type of forest - most likely a spruce forest with a cover of oxalis. The composition of plants here will be different than in the pine forest, and species diversity much more.
In every forest phytocenosis, many plants develop together. But this is not a peaceful existence. The influence of plants on each other often comes down to competition for the goods of life: light, water, nutrients etc. More strong plants capable of oppressing the weaker. Very noticeable, intense competition for light among trees in a dense chalk forest. Those spruces that grow faster survive. And those that lag behind their closest neighbors in growth find themselves in conditions of severe shading and after some time die from lack of light.
In the forest there is also competition between plants for nutrients contained in the soil. Tree roots absorb these substances more vigorously than grass roots, as a result of which trees can suppress the development of herbaceous plants.
But the relationship between plants in the forest does not lead only to competition, to the oppression of some by others. There are other forms of interaction. Especially important in the life of the forest there is a symbiosis between the roots of higher plants (trees, shrubs, grasses) and microorganisms (bacteria, fungi). The best studied symbiosis of roots and microscopic fungi, which is known as mycorrhiza. The thread-like hyphae of the fungus completely entwine the tips of the roots, forming a kind of loose case, and help the roots extract some hard-to-reach nutrients from the soil. In turn, the fungus receives nutrition from the root - organic products secreted by the outer cells of the root.
Mycorrhiza is very widespread among forest plants. Suffice it to say that about 80% tree species, which are part of the forests of our country, have mycorrhizae. In other words, the vast majority of our trees cannot manage their nutrition without the help of soil fungi. Many forest herbs also have mycorrhizae.
Thus, two opposing processes are continuously going on in the forest: the creation of organic matter and its destruction. One process is carried out by green, autotrophic plants, the other by saprophytes.
In the forest it is usually not difficult to see the peculiar layers of vegetation - tiers. The upper, dominant tier is always formed by trees. These large, powerful plants are the basis of the forest plant community. Under their canopy a specific forest environment, very different from what we find in an open, treeless space.
In forests, trees grow quite close and therefore have a strong influence on each other. As a result, their trunks are very elongated, their crowns are very narrow, and their living branches begin high from the ground. It is in the forest that the trees stretch strongly upward and none of them can freely grow in width. The interaction of trees, fierce competition between them is the most characteristic feature of the forest.
Under the canopy of trees there are usually more low tiers vegetation: undergrowth (shrubs), grass and moss cover.
In a forest, not only individual plants are interconnected, but also entire structural units of forest vegetation - different tiers. The denser the tree canopy, the less developed the underlying layers are usually and the more depressed the individual plants that form them. Suppression of plants is manifested in the fact that they grow poorly, do not bloom, and show other signs of suppressed development.
Which of our trees are light-loving and which are shade-tolerant? The first include larch, birch, and pine. Their love of light can be judged by their appearance: the crowns of these trees are very loose, openwork, they let in a lot of light. Shade-tolerant trees, on the contrary, have thick, dense crowns that create strong shading. Examples of such trees include spruce, fir, and linden. Oak occupies an intermediate position; it cannot be classified as either a typical light-loving or a typical shade-tolerant tree species.
Most plants that are found in the forest can be classified into a certain layer. However, there are also such forest plants, which are not included in any tier and represent special, extra-tiered vegetation. One example of this kind is creepers. The weak, thin stems of these peculiar forest inhabitants use trees as support and rise from the ground to the very tops of the crowns, and are thrown from one tree to another. Different vines climb trees in different ways. Some of them wrap around the trunk like a spiral, others crawl along the bark, attaching themselves by means of special roots-trailers. There are also those that cling to a tree with the help of strong tendrils or sharp spikes that resemble hooks. Lianas are well adapted to life in the forest; here they find quite suitable favorable conditions existence. There are very few vines in the forests of the central zone of our country. There are several more of them in the forests of the Caucasus and Far East.
Old trees growing in the forest, as a rule, bear seeds, and these, in turn, give rise to new small trees. This young generation of the forest is called self-seeding and undergrowth. Self-seeding- very young trees no more than half a meter high. Teenager- trees are larger, but not exceeding half the height of adult, mother trees.
Neither self-seeding nor undergrowth are considered separate layers of forest vegetation. This is explained by the fact that young trees do not remain the same in height all the time and do not form a permanent layer in the forest. The distribution of self-seeding and undergrowth in the forest is usually uneven. In the forest, the distribution of individual herbaceous plants over the area is usually uneven and spotty. They also often grow in patches and clumps.
Uneven, patchy distribution of plants - characteristic feature forests. This is a manifestation of the horizontal heterogeneity of the forest phytocenosis, its mosaic nature.
Among the diverse forest plant communities, primary and derived forest types are distinguished. Many of our pine, oak, and spruce forests are indigenous types of forest. These are stable, long-lasting plant communities.
Derivative forest types - birch and aspen forests - usually appear on the site of cleared-out primary forests; they owe their existence to human activity. The replacement of primary forests with derivatives is a widespread phenomenon.
The ability of a tree to produce shoots from a stump after cutting is useful biological property, this is a kind of natural protection from destruction by humans. In forestry, growth regeneration of tree species is not always desirable. The fact is that a tree that grows from a stump has much worse technical properties of wood than a tree that grows from a seed. Copper trunks are always more or less curved like a saber, the wood has wide and loose annual layers, and the width of the layer around the trunk circumference is not the same.
In addition to plants, the forest is home to various representatives of the animal world: animals, birds, numerous insects, etc. They inhabit the forest from top to bottom - from the top of tree crowns to the ends of their roots. Even the forest soil does not remain uninhabited: mouse-like rodents, moles, larvae of various insects, and earthworms live here.
All living creatures living in the forest are closely related to the forest phytocenosis: they find shelter, food, and breeding conditions here. Between them, as well as between plants, there are close connections and various kinds of interactions. In the animal world there are also strong and weak, competition and cooperation. But the forms of interaction between animals are, of course, completely different than between plants. Here, for example, there are predators and their prey, some living beings serve as food for others, which is not the case with plants.
The animal population of the forest has strong influence on vegetation, on phytocenosis. Some insects (caterpillars certain types butterflies, larvae of a number of beetles) cause great harm to the forest, destroying the foliage of trees, damaging their fruits and seeds. Oak trees especially suffer from such pests. Forest mice and voles destroy a large number of seeds of tree species that have fallen to the ground, especially oak acorns, and thereby complicate the seed regeneration of trees.
However, in the forest there is also a kind of counterbalance to this harmful activity: insect pests are destroyed en masse by forest birds, and voles are exterminated in large numbers forest predators. Some living creatures inhabiting the forest have a beneficial effect on the forest phytocenosis. These are earthworms, which improve the properties of forest soil, and forest ants, which destroy harmful insects. The activity of some birds that help spread seeds is also beneficial. forest trees and bushes. It is impossible to list here all the interactions and connections that exist between the animal and plant populations of the forest; they are very diverse and complex.
Forest vegetation is in close interaction with the environment. Each forest phytocenosis develops in one area or another earth's surface, in certain soil and climatic conditions. It largely depends on the environment and is strongly influenced external factors. Composition of tree species and plants lower tiers forests. Many other features of the forest phytocenosis are largely determined by the nature of the climate and soil properties.
However, silt vegetation affects the habitat, modifies and transforms it. Forest phytocenosis and the environment influence each other and interact.
Forest vegetation is closely related, in particular, to the soil on which it develops. One example of such a connection is nutrient cycling in forests. These substances necessary for plant life (nitrogen salts, phosphorus, potassium, etc.) are contained in forest soil and are extracted from there by roots. From the roots they enter the above-ground part - stems and leaves. However, their stay here is limited. Sooner or later, the stems and leaves die, fall to the ground, decompose, and the nutrients return to the soil layer. There is a continuous exchange of nutrients between the forest phytocenosis and the soil environment; there is a constant movement of nutrients from the soil to the plants and back.
Plays an important role in this process forest floor- a layer of fallen leaves or pine needles on the soil surface. Litter contains many nutrients, but almost all of them are part of complex organic compounds and for green plants not available. However, in the process of natural decomposition of litter, simpler, available forms nutrients that gradually, in small portions, enter the soil.
The forest phytocenosis is in close interaction not only with the bud, but also with the atmosphere. The manifestations of this interaction are very diverse. Many forest phytocenoses receive the water necessary for plant life from the atmosphere through precipitation (water enters the soil and is absorbed by the roots from there). The atmospheric factor has big influence to the forest. Moreover, it often determines the type of forest itself.
However, the forest, in turn, also affects the atmosphere. It not only absorbs water, but also returns some of it back in the form of water vapor, moistening the atmosphere. The air humidification above the forest is very significant. It occurs as a result of transpiration - the release of water vapor from the internal tissues of leaves and needles through stomata, as well as due to the physical evaporation of water from the surface of the aboveground organs of plants, especially leaves, wetted by rain. The main air humidifiers above the forest are trees: they have immeasurable large mass and foliage surface than other forest plants. On one hectare deciduous forest the total area of all tree leaves is tens of hectares, it is many times larger than the area occupied by the forest itself.
"What is a forest"
Sementsova Anastasia
7 "B" school No. 390
December 2002
the total area of all tree leaves is tens of hectares, it is many times larger than
In ancient times, forests occupied almost the entire land area of our planet. invaluable. From time immemorial, the forest sheltered people from bad weather, saved people from natural disasters, warmed them and fed them. The gifts of forests were the main source of subsistence for our distant ancestors . And today, with a high level of development of civilization, there is no sector of the economy that does not consume plant raw materials. to a person? Forests are a climate regulator, they purify air and water from pollution and toxins, protect rivers and fields from wind and water erosion, they humidify the air many times more than the water surface, helping to increase crop yields. Forests and public gardens planted around cities and in the cities themselves are the main supplier of oxygen for people. It is known that
one hectare of forest in one hour produces as much oxygen as is required for the breathing of two hundred people
. The truth that forests are the “lungs” of our planet is well known. Forest is a self-regulating bioecological system But not many people think about the fact that forest is complex self-regulating bioecological system , which a person can easily violate. Trees and other plants convert inorganic substances into organic ones. Herbivorous animals receive the energy necessary for their existence along with food. Predators, by eating herbivorous animals, regulate their numbers. The number of predators themselves is determined by the number of herbivores. A large harvest of seeds and fruits allows rodents to multiply greatly, which, being the main food of foxes, ferrets, weasels and martens, contribute to the increase in the offspring of these predators. Predators, having destroyed the bulk of rodents, begin to die out, and their birth rate decreases. Animals whose existence depends on the forest actively participate in its life. Rodents and moles bring lower, low-nutrient soil layers to the surface, thereby increasing the depth of the fertile layer and air exchange processes in the soil. Wild boars, rummaging in the ground, bury some of the seeds of wild fruits into it and create conditions for their germination. The seeds of many berries and fruits eaten by animals are not killed by gastric juice, but on the contrary, their germination capacity increases. Thus, animals contribute to the restoration of the forest and increase its area. Forest birds perform important role protectors of the forest from all kinds of harmful insects - destroyers of trees and shrubs. the existing equilibrium in the ecological system of the forest, with , can cause very undesirable consequences. Therefore, when using forest storehouses, it is necessary to treat their true owners with care - plants and animals.
Man in the lap of nature
Human, being in the lap of nature must take care of everything that surrounds him. Only a person devoid of common sense would set fire to a forest, destroy bird nests or anthills, break trees or bushes. For such “amateurs” there is environmental legislation, which includes various penalties, including criminal liability. Many admirers of the forest can unwittingly bring harm to it. The tourists lit a fire in a clearing, and nothing will grow in this place for five to seven years. The owner of the car drove into a green clearing, compacted the soil with the wheels, and the grass on the rut would die and the roots of the trees would begin to be suppressed.The sharp and piercing screams of the human voice frighten the forest inhabitants. They leave their familiar secluded places, and their cubs, not adapted to stressful situations, either die themselves or become easy prey for predators. It has been noticed that foxes and ferrets often observe human behavior in the hope of profiting from something. And people sometimes live up to their expectations. A tourist saw a chick that had fallen from its nest in the bushes, wanted to help it and... showed it to the predator; admired the carefully camouflaged nest - and doomed its inhabitants to death. Curiosity can turn out to be disastrous both for the inhabitants of the forest and for the curious one himself. If you ask who might live in a small round hole, sticking a stick in it can wake up a hive of bees or wasps. You should not pick up young wild animals, as their parents, who are most likely somewhere nearby, may misunderstand your good intentions and rush to protect their children. And you are unlikely to be able to explain to a wild boar that you just wanted to play with his striped descendant, or convince a fox that you have never held a fox cub in your hands and, as a kind and humane person, will not harm him. It must also be kept in mind that wild animals and humans have about 150 common diseases.
The forest inspires people
Man cannot exist without living nature, either physically or spiritually, the forest inspires people. Brilliant ancient architectural complexes were built “in collaboration” with nature. The domes of the cathedral in Kizhi are shaped like onions covered with scales, like pine cones; as if living plants are developing from the center to the periphery of the dome of St. Basil's Cathedral and the church in Fili. Communication between a person and nature is absolutely necessary for his normal mental activity. The city dweller is oppressed by the monotony of everyday life, constantly “pressuring” him with noise and dust - an indispensable cost of urbanization. Contact with living nature relieves psychological stress and has a beneficial effect on the body as a whole.. Mixed forest has a particularly beneficial effect on humans.. Here you can hide from the heat, listen to amazing sounds: the creaking of an oldForests are the “lungs” of our planet: if there were no forests on Earth, humanity would have long ago suffocated from harmful emissions. However, the benefit of the forest is not only in purifying the air - it is also a real breadwinner, giving us mushrooms, berries and medicinal plants. Speaking about the benefits the forest brings, we must not forget that until recently wood was the main building material, and even now wood is used to build environmentally friendly buildings. How trees grow in the forest, what kinds of forests there are, and much more interesting information You will learn about forest plantations on this page.
Biologists have a clear definition of what a forest is: a forest is a type of green space consisting of plants of one or more species. But not everything is so simple: two strong links “forest and animals” and “forest and plants” form a single community - an ecological system. Plants produce oxygen and sugar, herbivores eat plants and distribute their seeds, and predators eat herbivores. This is how plants provide food for wild animals. And here the third connection comes into play - “forest and man” - when the “king of nature” goes hunting and reduces the population of a particular species.
What forests are there: types and tiers of forests
Forests grow in both cold and hot countries. When talking about what types of forests there are, coniferous, mixed, deciduous and evergreen are most often mentioned. In fact, the answer to the question “what kind of forests are there” is much broader: forests include the jungle, taiga, selva and many other groups of green spaces.
Forests occupy about a third of the land, but in ancient times this area was much larger. Man has always mined wood, collected mushrooms, berries and honey, and also cut down and burned forests in order to sow bread in their place, plant gardens and build cities. Every year there are fewer and fewer forests, but they bring us so much essential oxygen and wood. Therefore, it is very important to protect this wealth, whenever possible, planting new forests to replace disappearing ones.
Among the types of forests, a distinction is made between natural ones, created by nature, and artificial ones, planted by humans. But in any case, plants and animals in the forest occupy their own floors - tiers formed by the foliage of plants of different heights.
Look at the photo of the forest above: the first tier, or canopy, is the crowns of the tallest trees; the forest layer, consisting of bushes and low-growing trees, is called the “undergrowth”; it is followed by a grass and ground layer formed by mosses, forest litter and underground layers.
The understory consists of plants that grow in the shade of the trees that form the forest canopy. The undergrowth consists of both shrubs and low trees. In broad-leaved and mixed forests, raspberries, hazel, euonymus, buckthorn, juniper, rowan grow in it, and in coniferous and light coniferous forests- alder, dwarf birch and willow.
How plants and trees grow in the forest
Talking about how the forest grows on the lower tiers, it is immediately worth noting that the forest has several lower tiers: one is formed from grass and shrubs, the other from mosses and lichens. The third is the forest floor, consisting of organic residues on the soil surface, and the fourth, underground, includes the root system of plants, fungi and microorganisms. It is the soil that nourishes both the undergrowth and the trees that make up the forest canopy. All these layers are extremely important for the life of the forest.
The forest floor is created by fallen leaves and fruits, bark and branches, and the shells of insect pupae and larvae. Life there is simply in full swing - for every 1 m2 there are several million different inhabitants. These are not only bacteria and protozoa, but also small mammals, such as rodents. The value of litter is very great - it enriches the soil with humus, protects it from external influence and regulates the oxygen content in it.
Speaking about how plants grow in the forest, we must not forget about the underground tier - here, too, there are several floors, located depending on the depth of different roots - herbs, shrubs, etc. The roots forming the upper underground tier can intercept rainwater those that lie deeper. And far-reaching roots manage to get underground water earlier.
Deadwood - parts upper tiers forests that ended up on the lower ones, that is, branches, twigs and tree trunks that fell to the ground. It is both dangerous and useful: fungus multiplies in fresh dead wood and can spread to healthy trees. It can also cause a fire, so they try to remove it from the forest, but not all of it. After all, when the dead wood rots, it turns out beautiful.
Causes of forest fires
Forest fires can be so large that they can be seen even from space. Natural cause their occurrence is usually lightning. Most often they appear where there are a lot of sick and dry trees. By destroying them, fire contributes to the renewal of the forest. Nowadays, the share of natural fires is only 7-8%. In most cases, the main cause of fires is human activity: due to unextinguished cigarette butts or fires, as well as due to the burning of dry grass or leaves in agricultural land, fire can spread over vast areas. Such fires destroy vegetation over vast areas and threaten villages and entire cities. And the fight against them does not stop.
Ground fires are easier to extinguish. Terrible crown fires are especially dangerous. They rush along the treetops and spread through the forest at tremendous speed.
Animals and plants of the forest
One of the millions of inhabitants of the lower tiers of the forest is the common shrew. This small animal weighing no more than 16 g lives in the litter, in the grass, among mosses and even underground. He digs holes, improving the soil and thus contributing to the life of a giant community of plants and animals - the forest.
Many birds and animals find home and food in the undergrowth. Forest animals such as tigers, once widespread across Eurasia, hunted among small trees and shrubs. Amur tigers and today they rule in the undergrowth of the Ussuri taiga.
The forest canopy allows little light to pass through, so the plants that make up the understory are shade-loving. In addition, in the shade the temperature of the earth's surface is not very high, as is evaporation. Consequently, high humidity is created, allowing mushrooms to grow and enriching the soil. Undergrowth influences the formation of tall tree trunks, strengthens the soil, and protects the shores of forests and lakes from erosion.
Honeysuckle is a shrub famous for its large beautiful flowers, which are fragrant for a whole month, attracting insects with their aroma. Because of this, it is grown in gardens, and in forests it forms part of the undergrowth. Depending on its type, honeysuckle berries can be edible or inedible. The edible bush grows only in Eastern Siberia and in the Far East, and its berries taste similar to blueberries.
Another forest plant is euonymus; its beautiful fruits are actually poisonous, but are still used in medicine. After all, as you know, drugs in large doses become poison. The euonymus itself is a typical understory shrub. People have long cultivated it and bred it as an ornamental plant, growing on its own or entwining metal fences.
Not all small trees in the forest are undergrowth. It does not include young trees, which later form the canopy and are called undergrowth. The long-extinct Caspian tiger once lived in such dense thickets. He even had to stand on hind legs to inspect the area.
Mixed forests and northern taiga forest
In a mixed forest both conifers and deciduous trees. Moreover, it can be called mixed only when deciduous trees make up more than 5% (or 1/20) of total number. The further north you go, the more coniferous trees and fewer deciduous trees. Such forests grow in the temperate zone, south of the taiga, as well as in Eurasia and North America.
In mixed forests, rowan trees and, of course, also grow. They provide many animals not only with food and shelter, but also with building material for their homes. AND we're talking about not just about birds' nests. On forest streams, rivers and lakes you can often see beaver dams, or dams. Thanks to such structures, these animals regulate the water level in the reservoir so that predators do not reach their huts. Usually the length of the dam is 20-30 m, but there are also records reaching 700 m and even 1200 m.
When building a dam, beavers place branches and trunks vertically in the bottom, reinforce the gaps with branches and reeds, and then fill the voids with silt, clay and stones. For support, they often use a tree that has fallen into the river, covering it with building material. Sometimes branches in beaver dams take root, giving them extra strength.
Beavers chew through tree trunks not only to build a dam, but also to knock them down and get to the tasty leaves.
The northern taiga forest is a closed dark coniferous forest located in northern Eurasia. However, it must be remembered that Pinery temperate latitudes are not taiga. And the taiga, like mixed forests, covers the vast expanses of Siberia, as well as the north of the European part of Russia and Canada. Due to the harsh climate, broad-leaved tree species such as linden, maple, ash and oak cannot grow in it. During the short summer, they do not have time to develop leaves, flowers and seeds. Only in clearings can you find birch and aspen. That's why they reign in the taiga coniferous trees- fur tree, pine tree, Siberian cedar and larch. All of them, except larch, are evergreen and change needles gradually and imperceptibly.
The brown bear is one of the strongest, largest and dangerous predators. Although he never refuses berries and honey from wild bees, meeting him does not bode well. It lives not only in the taiga, but also in mixed forests.
What benefits does the taiga forest bring?
The taiga of Eurasia is called green lungs planets. The oxygen content and carbon dioxide in the air we breathe. Speaking about the benefits that the taiga brings, it is impossible not to note that it is in these forests that the largest reserves of timber, minerals, and animals live, without which our world would become poorer.
Siberia is the most forested place in Russia. The area of Siberia, not counting the Far East, is more than 12 million km2, and almost two-thirds of it is occupied by forests. 1 hectare of taiga absorbs in 1 hour the amount of carbon dioxide that 200 people exhale during this time.
People have been living in the taiga for a long time. Since ancient times, local residents have been hunting fur-bearing animals, collecting medicinal herbs, and fishing. In the 20th century, geologists came to the taiga, and since then oil and gas have been extracted there. And also the taiga for its animals and flora attracts “hunters” with cameras and cameras that film all its diversity.
Deciduous forests and Belovezhskaya Pushcha
Deciduous forests consist of deciduous trees and shrubs and grow in temperate climates. It is interesting that in such forests the diversity of grasses is much greater than the diversity of trees, which branch strongly and form a dense crown. Their leaf blades are thin, sensitive to drought and cold. All trees shed their leaves for the winter, which is why they are also called deciduous.
Grows in temperate and cold climates in small-leaved forests. This tree reaches 35 m in height and has a trunk with a diameter of about 1 m. Aspen leaves have very thin petioles, so they are sensitive to even the slightest breath of wind. This is where the saying “tremble like aspen leaf" Aspen flowers are collected in long hanging earrings.
And roe deer live in mixed forests. The favorite treat of these little deer is aspen leaves. In the distant past, roe deer were found in the forest-steppe, but people who built cities there and plowed the land for fields and gardens forced them to retreat into the forests.
Roe deer live in them now, feeding on leaves, berries, fruits, seeds, grass, but sometimes animals also appear in the meadows.
In myths Ancient Greece forests and forest deities - satyrs and dryads - are often mentioned. But then almost all the forests were destroyed by people and goats, which local residents They began to breed in ancient times. Herds of goats ate and trampled the young shoots of trees, so the expression appeared: “The goats ate Greece.” True, new forests did grow in the country over time, but now their area occupies about a fifth of the entire territory, which is much less than in antiquity.
Belovezhskaya Pushcha, which is located on the territories of Belarus and Poland, is the largest area of relict mixed forest in Europe. It was rightfully made a protected area and included in the list World Heritage UNESCO. In some areas of the Pushcha there are trees that are 250-350 years old. There are 400-600-year-old oaks, 300-year-old pines up to 50 m high, and 250-year-old spruce trees. The ground in the Pushcha is covered with fluffy mosses, there are a lot of blueberries, raspberries and mushrooms. The same ancient animals live in it - the mighty bison.
Relict forest, or forest, is the remnant ancient forest, which has survived to this day as it existed many thousands of years ago. Then it grew on vast territories and has not been affected by human activity. Over the centuries, many forests have been cut down, so the areas that have survived to this day are carefully protected. The same trees grow in them and the same animals live as before.
Impenetrable rainforest jungle
Rainforests around the world are called jungles. However, with scientific point view wet equatorial forest- this is hylea, and “real” jungles are found only in Asia. The word “jungle” comes from “jangal,” which translated from Sanskrit, one of the languages of Ancient India, means “impenetrable thickets.” Thus, the jungle forest is a thicket of trees and shrubs entwined with woody vines. But people get to them too.
The jungle flora is extremely diverse. The plants here are evergreen, bloom, and produce juicy, tasty fruits all year round. The trees have thin bark, and many have projections at the base of their trunks. It is believed that water with nutrients dissolved in it flows down these protrusions to the roots. But main feature In the tropical forest, the jungle consists of numerous vines and epiphytic plants that live on tree trunks. They make the jungle impenetrable. However, this obstruction is also overcome by people.
The jungle, as befits a forest, has tiers - usually four. But, characteristically, they also have a lot of extra-tiered vegetation, such as lianas. Plants in the lower layers of the jungle have wide leaves that catch light better. However, the taller the tree, the smaller area his sheet. At the very top of the last tier, at a height of 60 m, a kind of canopy is formed. The leaves here are small and rugged to better resist winds. The tops of trees are often interconnected by vines and other plants that are attached to the trunks.
Durian fruits reach a diameter of 20 cm and a weight of up to 4 kg. They have a hard shell and are covered with powerful spines that protect the fruit from animals. Durian smells bad, but its flesh is very tasty.
Rainforest selva
Amazon is considered the most long river in the world and has a length of about 7000 km. And this pool great river- the largest on Earth, it occupies 70,000 km2. More than a million people live in the Amazon rainforest - the jungle. various types animals and plants. And it's only about known species! Many are simply not open yet. This is the largest tropical rainforest in the world, covering half total area remaining tropical forests on the planet.
Rainforests from Mexico to Amazonian jungle decorated with macaws. These birds have the strongest beak in the world.
The wild mango, or python tree, which reaches a height of up to 30 m, is not related to the ordinary mango, and does not even look like it. Flowers and edible tasty fruits of this tree grow directly on the trunk, which is typical
Selva is a tropical forest in which there are from three to five layers of plants. The trees are usually straight, column-like and branch only at the very top, where there is access to sunlight. They bloom and bear fruit all year round, and sometimes you can see young leaves, flowers, and fruits on one tree. The trees of the selva are very diverse - there are at least 2,500 species. From above, the closed crowns look uneven and spotty - after all, all the trees are different both in height and in the shade of green leaves. Melon trees, cocoa trees, hevea trees, and the largest water lily in the world, Victoria religios, grow in the jungle.
The fruits of the tropical guava plant are very tasty. Jams, jellies, and juices are made from them. One such fruit contains ten times more vitamin C, which is beneficial for the human body, than a lemon, which is considered a storehouse of this substance.
Or the melon tree, native to southern Mexico and northern South America. Today it is grown in the tropics throughout the world. Raw fruits are suitable for food, as well as baked ones, which smell like fresh bread. That’s why papaya is also called “breadfruit”. However, when collecting papaya, you need to be careful: the milky sap of this tree can cause irritation to the skin.
Local Indian tribes live in harmony with the forest without harming it. They clear a small area called a “garden in the forest” and grow a variety of vegetables and fruits there. And a few years later they leave this area and clear a new one for themselves, but the old one is again overgrown with forest.
On the shores of the seas and oceans, ebbs and flows occur daily. And in the rich tidal zone, which alternately becomes seabed, then on land, their plants live - mangroves, or mangroves. They are found mainly in the tropics and also in temperate latitudes With warm currents. These plants have adapted to live in salt water, on soils with poor oxygen content. Mangroves enrich these soils with nutrients.
Mangroves successfully survive where other plants would die. Their seeds are buoyant and can spread through water. In many mangroves, the seeds germinate without being separated from the trunk. And when a seedling is formed from a seed, it falls into the water and is transported over long distances. If he finds himself in unfavorable conditions, he “falls asleep” for weeks and even months. Having waited its time, the seedling changes its density and stands vertically in the water to take root. It goes on like this
The mangroves are home to many animals. These are, of course, sloths who live in trees, practically cannot walk, but swim perfectly. Although sloths do not possess sports styles, but swim by raking with their paws like a rake, they still develop a speed that is quite decent for themselves - 4 km/h.
Mangroves are by no means safe - the mangrove snake, or ulenburong, lives on their branches. She is poisonous and very aggressive. It is easy to notice by its bright, beautiful color.
Supporting, or stilted, roots grow from the stem and only then penetrate the ground, which is constantly under water. The roots receive oxygen from the atmosphere and nutrients from the soil. Sometimes they store oxygen so that they can get it under water. This way the plants gain the opportunity to feed and additional reliable support during high tide. Moreover, powerful roots hold back waves and prevent them from eroding the shores.
Mangroves exist not only in the tidal zone, but also along the banks of tropical rivers. There are also dry seasons in the tropics.
Not only plants, but also animals are quite capable of surviving them. Mangrove rivulus fish store water in their gills, which they find in certain wet places. And on land they move by jumping, pushing off with their tail. This way they can live for more than two months.
A forest is a complex combination of many different plants, which vary greatly in size, structure, reproduction, type of nutrition, etc. It is like a kind of living mechanism, large and very complex, and individual plants are its parts, details. Trees and all other plants in the forest are closely related to each other in their life activities and influence each other. That is why the forest is called a plant community or phytocenosis. This is truly something holistic, harmonious, with its own internal connections, and not a random collection of individual plants.
Modern natural forests have come a long way in their formation and development. Over the course of many centuries, a certain composition of plants capable of coexistence was selected in the forest. From time to time, new plants penetrated under the forest canopy in one way or another, but not all of them survived or were preserved. Only the most resilient and most adapted to life in these conditions became full members of the plant community. The forest plant community is formed only by those plants that are able to successfully resist the influence of their neighbors.
Forests were formed in different parts of the country, in different soil and climatic conditions - in the north and south, on plains and in the mountains, on sand and loam, on watersheds and in floodplains. Different types of forests have arisen in different environments because vegetation is closely related to the environment and is highly dependent on climate and soil. In each type of forest we find a certain set of forest plants corresponding to the given natural conditions. Consequently, the forest includes plants that are adapted not only to coexistence, so to speak, to the internal environment of the forest, but also to certain soil and climatic conditions, i.e. to the external environment.
The dependence of the plant population of a forest on soil conditions in a small flat area, for example, on the territory of a forest district, is especially clearly manifested. In the middle zone of the European part of the country, on nutrient-poor and dry sandy soil, we usually find a pine forest with a cover of lichens and a sparse selection of other plants. On loamy soil, sufficiently moist and well supplied with nutrients, a completely different type of forest will be found - most likely a spruce forest with a cover of oxalis. The composition of plants here will be different than in a pine forest, and the species diversity is much greater.
In each forest phytocenosis, many plants develop together. But this is not a peaceful existence. The influence of plants on each other often comes down to competition for the benefits of life: light, water, nutrients, etc. Stronger plants are able to suppress weaker ones. Very noticeable, intense competition for light among trees in a dense spruce forest. Those spruces that grow faster survive. And those that lag behind their closest neighbors in growth find themselves in conditions of severe shading and after some time die from lack of light.
In the forest there is also competition between plants for nutrients contained in the soil. Tree roots absorb these substances more vigorously than grass roots, as a result of which trees can suppress the development of herbaceous plants.
But the relationship between plants in the forest does not lead only to competition, to the oppression of some by others. There are other forms of interaction. Particularly important in the life of a forest is the symbiosis between the roots of higher plants (trees, shrubs, grasses) and microorganisms (bacteria, fungi). The best studied symbiosis of roots and microscopic fungi, which is known as mycorrhiza. The thread-like hyphae of the fungus completely entwine the tips of the roots, forming a kind of loose case, and help the roots extract some hard-to-reach nutrients from the soil. In turn, the fungus receives nutrition from the root - organic products secreted by the outer cells of the root.
Mycorrhiza is very widespread among forest plants. Suffice it to say that about 80% of the tree species that make up the forests of our country have mycorrhizae. In other words, the vast majority of our trees cannot survive in their nutrition without the help of soil fungi. Many forest herbs also have mycorrhizae.
Thus, two opposing processes continuously occur in the forest: the creation of organic matter and its destruction. One process is carried out by green, autotrophic plants, the other by saprophytes.
In a forest, it is usually not difficult to see the peculiar floors of vegetation - tiers. The upper, dominant tier is always formed by trees. These large, powerful plants are the basis of the forest plant community. Under their canopy a specific forest environment is created, very different from what we find in open, treeless space.
In a forest, trees grow quite close and therefore have a strong influence on each other. As a result of this, their trunks are very elongated, their crowns are very narrow, and living branches begin high from the ground. It is in the forest that the trees stretch strongly upward and none of them can freely grow in width. The interaction of trees and fierce competition between them is the most characteristic feature of the forest.
Under the canopy of trees there are usually lower layers of vegetation: undergrowth (shrubs), grass and moss cover.
In the forest, not only individual plants are interconnected, but also whole plants. structural units forest vegetation - different tiers. The denser the tree canopy, the less developed the underlying layers are usually and the more depressed the individual plants that form them. The depression of plants is manifested in the fact that they grow poorly, do not bloom, and show other signs of suppressed development.
Which of our trees are light-loving and which are shade-tolerant? The first include larch, birch, and pine. Their love of light can be judged by their appearance: the crowns of these trees are very loose, openwork, they let in a lot of light. Shade-tolerant trees, on the contrary, have thick, dense crowns that create strong shading. Examples of such trees are spruce, fir, linden. Oak occupies an intermediate position; it cannot be classified as either a typical light-loving or a typical shade-tolerant tree species.
Most plants that are found in the forest can be classified into a certain layer. However, there are also forest plants that are not included in any layer and represent special, extra-tier vegetation. One example of this kind is creepers. The weak, thin stems of these peculiar forest inhabitants use trees as support and rise from the ground to the very tops of the crowns, and are thrown from one tree to another. Different vines climb trees in different ways. Some of them wrap around the trunk like a spiral, others crawl along the bark, attaching themselves by means of special roots-trailers. There are also those that cling to the tree with the help of strong tendrils or sharp spines that resemble hooks. Lianas are well adapted to life in the forest; here they find quite favorable living conditions for themselves. In forests middle zone There are very few vines in our country. There are somewhat more of them in the forests of the Caucasus and the Far East.