Rainforests. Rainforest climate

Planets. It is estimated that millions of animal and plant species have not yet been described. These forests are sometimes called " jewels of the earth" and " the largest pharmacy in the world"Because a large number of natural remedies have been found here. They are also called “ lungs of the earth”, However, this statement is controversial, because it has no scientific basis, since these forests either do not produce oxygen at all, or produce very little of it. But it should be borne in mind that a humid climate promotes effective air filtration, thanks to the condensation of flags on microparticles of pollution, which has a generally beneficial effect on the atmosphere.

Undergrowth formation in tropical rainforests is severely limited in many places due to the lack of sunlight in the lower tier. This allows humans and animals to move through the forest. If, for any reason, deciduous canopy is missing or weakened, the lower tier is quickly covered with a dense thicket of vines, shrubs and small trees - this formation is called a jungle.

Spreading

Distribution of tropical rainforests in the world.

The largest tropical rain forests exist in the Amazon River basin (Amazon Rainforest), in Nicaragua, in the southern part of the Yucatan Peninsula (Guatemala, Belize), in most of Central America (where they are called "selva"), in equatorial Africa from Cameroon to the Democratic Republic of the Congo, in many parts of Southeast Asia from Myanmar to Indonesia and Papua New Guinea, in the Australian state of Queensland.

general characteristics

For tropical rainforest are characteristic:

• continuous vegetation throughout the year;
• variety of flora, predominance of dicotyledons;
• the presence of 4-5 tree layers, the absence of shrubs, a large number of epiphytes, epiphalls and lianas;
• predominance of evergreen trees with large evergreen leaves, weak developed bark, kidneys, not protected by renal scales, in monsoon forests- deciduous trees;
• the formation of flowers, and then fruit directly on the trunks and thick branches (caulifloria).

Trees

Trees in tropical rainforests share several characteristics that plants in less humid climates do not.

The base of the trunk in many species has wide, woody projections. Previously, it was assumed that these protrusions help the tree to maintain balance, but now it is believed that water with dissolved nutrients flows down these protrusions to the roots of the tree. Broad leaves are also common in trees, shrubs, and grasses in the lower tiers of the forest. Tall young trees that have not yet reached the upper tier also have wider foliage, which then decreases with height. Wide leaves help plants to better absorb sunlight under the forest's tree edges, and they are protected from the wind from above. The top-tier leaves that form the canopy are usually smaller and heavily indented to reduce wind pressure. On the lower floors, the leaves are often tapered at the ends so that this facilitates the rapid flow of water and prevents the growth of microbes and moss on them, which destroy the leaves.

Other characteristics of tropical rainforest are unusually thin (1-2 mm) tree bark, sometimes covered with sharp thorns or thorns; the presence of flowers and fruits growing directly on tree trunks; a wide variety of juicy fruits that attract birds, mammals and even fish that feed on the spray.

Fauna

In humid tropical forests, there are edentulous (families of sloths, anteaters and armadillos), wide-nosed monkeys, a number of families of rodents, bats, llamas, marsupials, several orders of birds, as well as some reptiles, amphibians, fish and invertebrates. Many animals with prehensile tails live on the trees - chain-tailed monkeys, dwarf and four-toed anteaters, possums, chain-tailed porcupines, sloths. There are a lot of insects, especially butterflies, (one of the richest faunas in the world ) and beetles (more than 100 species); many fish (as many as 2000 species are approximately one third of the world's freshwater fauna ).

The soil

Despite the lush vegetation, the quality of the soil in such forests leaves much to be desired. Rapid rotting caused by bacteria interferes with the accumulation of the humus layer. Concentration of iron and aluminum oxides as a result laterization soil (the process of decreasing the content of silica in the soil with a simultaneous increase in iron and aluminum oxides) stains the soil in a bright red color and sometimes forms deposits of minerals (for example, bauxite). On young formations, especially of volcanic origin, the soils can be quite fertile.

Rainforest levels

The rainforest is divided into four main levels, each of which has its own characteristics, has a different flora and fauna.

Topmost level

This layer consists of a small number of very tall trees reaching a height of 45-55 meters ( rare species reach 60 - 70 meters). Most often, the trees are evergreen, but some shed their foliage during the dry season. Such trees must withstand harsh temperatures and strong winds... This level is inhabited by eagles, bats, some types of monkeys and butterflies.

Canopy level

Level canopy form most of the tall trees, usually 30 - 45 meters high. It is the densest level known in all terrestrial biodiversity, a more or less continuous layer of foliage formed by neighboring trees.

According to some estimates, the plants of this layer make up about 40 percent of the species of all plants on the planet - perhaps half of the entire flora of the Earth can be found here. The fauna is similar to the upper level, but more diverse. It is believed that a quarter of all insect species live here.

Scientists have long suspected the diversity of life at this level, but only recently have developed practical methods research. It wasn't until 1917 that an American naturalist William Beade(eng. William beede) stated that "another continent of life remains unexplored, not on Earth, but 200 feet above its surface, spreading over thousands of square miles."

Real exploration of this layer did not begin until the 1980s, when scientists developed methods to reach canopy, such as shooting ropes at treetops with crossbows. Canopy research is still in its early stages. Other research methods include travel balloons or aircraft. The science of treetop access is called dendronautics. Dendronautics).

Average level

Between the edges of the canopy-level trees and the forest floor, there is another level, called the middle or sub-ceiling... It is home to a number of birds, snakes and lizards. The life of insects at this level is also very extensive. The leaves in this layer are much wider than at the canopy level.

Forest litter

This area receives only 2 percent of all sunlight, it is twilight here. Thus, only specially adapted plants can grow here. Far from river banks, swamps and open spaces where dense, low-growing vegetation grows, the forest floor is relatively free of plants. At this level, rotting plants and animal remains can be seen, which quickly disappear thanks to a warm, humid climate that promotes rapid decay.

Human exposure

Contrary to popular belief, tropical rainforests are not large consumers of carbon dioxide and, like other mature forests, are neutral to carbon dioxide. Recent research suggests that most rainforests, on the other hand, produce carbon dioxide. Nevertheless, these forests play a significant role in the circulation of carbon dioxide, as they are its established pools, and the deforestation of such forests leads to an increase in carbon dioxide in the Earth's atmosphere. Rainforests also play a role in cooling the air that passes through them. That's why tropical rainforest- one of the most important ecosystems of the planet, the destruction of forests leads to soil erosion, a reduction in flora and fauna species, shifts in the ecological balance over large areas and on the planet as a whole.

Tropical rainforest often planted under plantations of cinchona and coffee trees, coconut trees, rubber plants. In South America for tropical rainforest also a serious threat is posed by unsustainable extraction of mineral resources.

There is a wide strip at the equator wet forests... It passes through the territory of Central and South America, Central Africa, Southeast Asia and Northern Australia. These forests are the most complex ecosystem on Earth, with the most diverse and abundant resources. However, for all their importance, rainforests are being destroyed and disappear at an alarming rate. Wet forests grow in areas where it is constantly high, and there is a lot of precipitation. Over millions of years, humid forests have become the most populated habitat on our planet. They account for less than 10% of the land area, but they are home to 50 to 70% of all terrestrial plant and animal species. The largest wet forests grow in the Amazon (Brazil). We will tell about them on these pages. Local Indians hunt with special blowpipes. The number of Indians in Brazil over the past 400 years has decreased from 5 million to 200 thousand people. Many of these huge trees put out additional shoots for support, as their own roots are empty and weak inside. The soil in the forests is covered with a layer of fallen leaves several centimeters thick. In this layer, necrophages actively process organic matter, and plant roots quickly absorb minerals... This process is so active that very few minerals remain in the lower soil layer: their bulk is found in all kinds of vegetation. When forests are cleared and burned out, the minerals contained in plants are converted to ash. The root system is destroyed, and the surface layer of the soil is washed away by heavy rains. becomes infertile, and areas where life was still in full swing turn into. It will take many centuries to restore forests on such lands.

Tiers

All wet forests have a similar structure with five main tiers. Each tier has its own plant and animal life. Often the tiers merge. Sometimes one of the tiers (or more) is missing. The upper tier is the most tall trees, rising 10-15 m above the main mass of vegetation. From here, American harpy eagles and other predators hunt down their prey. The second tier (canopy) is a strip about 10 m wide at a height of 30-40 m. It is a solid green roof made of intertwining branches and leaves of tree tops. Most of the plants and animals settle here, attracted by the abundant sunshine. Undergrowth - consists of the tops of small trees that receive less light, such as palms, and young trees that tend to. It is much sparser than the second tier and has its own plant and animal community. Undergrowth is shrubs and small trees that receive scattered sunlight shining through the branches and crowns of the upper tiers. Where the sun hardly passes, shrubs and grasses grow very sparsely. When more sun penetrates through the gaps in the second tier, shrubs and grasses grow faster. Ground vegetation includes ferns and grasses. Live here single species mammals such as tapir; and many insects.

Rainforest model

If you have a large aquarium, you can create a miniature wet forest model. Place a layer of gravel and charcoal at the bottom of the aquarium, and on top of it a few centimeters of fertile compost. Tamp it down a little so that the gravel will show through. Plant a variety of exotic plants. Cover with a glass lid and place in a warm place, not in direct sunlight. Plants will begin to thrive. will be moist and will constantly circulate between the compost, plants, air and the aquarium. Add a little water every few months. Plant exotic plants. You can buy them at the store. Small flowering plants such as orchids provide a colorful variety. Plant the plants at some distance from each other: they need space.

Forest people

Wet forests are home scrap for many natives living in harmony with the world around them. Their experience of life in the forest is very valuable to us if we want to learn how to use forest resources wisely. However, today, the natives are constantly driven out and driven from their lands against their will and fundamental human rights. With the destruction of forests, wild tribes also perish, taking with them their invaluable experience.

The importance of wet forests

Rainforests play vital important role in the regulation of the climate on our planet: they occupy a special position in the cycles of the cycle of oxygen, carbon and water. In addition, tropical forests are a valuable source of raw materials for medicine and one of the main sources of new types of food (about 1650 species of plants growing in them are edible). People have already begun to actively use the enormous resources of humid forests. However, this needs to be done in a more thoughtful way: a balance (balance) must be found between the large-scale use of forest resources - such as wood, rubber and nuts - and the conservation of the forests themselves.

More than 50% of humid forests have already been destroyed on our planet, and their destruction continues. As a result, in the countries where these forests grow, the population is rapidly becoming impoverished, and the vacated land is distributed unequally (see the article ““). The reason for the massive deforestation is the constant demand for timber in developed countries and ineffective reforestation programs. It is necessary to significantly change the approach to solving all these problems.

Tropical forests are the "lungs" of our planet, the most precious treasure, "the big pharmacy of the Earth." For many years, it was believed that they produce colossal volumes of oxygen, but this turned out to be not the case, but the humid climate promotes impeccable air filtration and purification of pollution. A lot of medicinal plants grow in this zone, which have been used in folk and official medicine. Where tropical forests grow, a huge number of birds, predators, artiodactyls, amphibians live, they all somehow get along on the same territory, surprising travelers with their large numbers.

Distribution of tropical forests

It will immediately become clear where the rainforests grow, if we explain that they seem to "encircle" the planet along the Equator. They are located in the humid equatorial, dry tropical, temperate, representing a clear line, interrupted only by mountains and oceans. Vegetation changes depending on the air temperature and the amount of precipitation. Rainy areas are covered with evergreen flora, drier regions are characterized by deciduous plants, followed by savanna forests. In both South America and Africa, there are monsoons in the west, savannas in the east, and equatorial forests.

Forest levels

The description of the rainforest will be clearer if it is divided into tiers. There are four main levels. The topmost one is evergreen trees up to 70 m tall, they have green caps mainly only on top, but below there are bare trunks. These giants can easily withstand hurricanes, temperature drops, sheltering the rest of the tiers from bad weather. The main owners here are eagles, butterflies, the bats... Further there is a forest canopy consisting of 45-meter trees. The level of the crowns is considered the most diverse, about 25% of all insect species live here. Scientists agree that 40% of all plant species on the planet are located on this tier, although it has not been fully studied.

This is followed by the middle level, called the underbrush, where snakes, birds, lizards live, the number of insects is also huge. Remains of animals and decaying plants are found on the layer of the forest floor. This stratification is more common in the humid tropics. For example, selva - the forests of South America - is divided into only three levels. The first is grass, low plants, ferns, the second is reeds, low shrubs, young trees, the third is 40-meter trees.

The dominant species of flora and fauna depend on where tropical forests grow. For example, mangroves are common in equatorial and tropical latitudes in the tidal zones of the sea coasts. Plants grow here that are accustomed to do without oxygen and feel great in salty soil. Their roots create an excellent habitat for oysters, crustaceans, and commercial fish species. On the slopes of the mountains, in the area of ​​fog condensation, moss or fog forests grow, characterized by low night temperatures.

The arid regions are dominated by savannah and rainforest, but dry. The plants here are evergreen, but xeromorphic and undersized. In regions of equatorial and tropical zones with variable climate grow variable wet forests, characterized by deciduous crowns and a small number of lianas and epiphytes. They are found in South America, Africa, Sri Lanka, India and Indochina.

Rainforest climate

In humid tropical forests, the air temperature ranges from 20 ° C to 35 ° C, it rains here almost daily, so the humidity is kept at 80%, and in some regions it reaches 100%. In the subtropics there is no pronounced seasonality, the temperature is characterized by stability. On the slopes of the mountains, where fogs are observed, it is warm during the day, and at night a sharp cooling down to 0 ° C is possible. The climate of the rainforest varies depending on the belt. In the tropics, there is high temperature and low humidity, at the equator there is a lot of moisture and very hot, and in the subequatorial zone, the weather depends on the monsoons.

Trees of the tropics

Trees in tropical rainforest differ significantly from trees in the temperate zone. The peculiarity of their development is influenced by weather, because there is no seasonality at the equator, it rains almost daily, and the air temperature is 25-35 ° С. If in Russia giants grow in several centuries, then 10-15 years are enough there. Each type of tree sheds its leaves in a strictly defined period, it can be once every six months, once every 2-3 years. They also bloom when they want, many representatives of the flora delight with flowers once a decade. The trees have mostly large leathery leaves that are strong enough to withstand powerful streams downpour. More than 600 species of bamboo, chocolate cola, marang, jackfruit, mango, etc. grow in the tropics.

Exotic shrubs

The question of whether there is a shrub layer in tropical forests remains rather controversial. It exists in the subtropical and temperate zones, but not in the equatorial zone. Of course, there are representatives of shrubs there, but there are very few of them and they will not create their own level. Together with them, herbaceous phanerophytes grow, preserving the trunk from one to several years, and undersized trees. This includes representatives of the scitamine, marate, and banana families. Most of the shrubs are dicotyledonous, their leaves are large, but tender.

Rainforest herbs

V virgin forests incredibly beautiful, bright, with an unusual appearance birds live. Each separate part of the world can boast of its own kind of birds. For example, in the tropics of Asia, there are turachi, appearance they resemble partridges, only slightly larger. They run fast, so in case of danger they do not take off, but flee with all their might. Shrub chickens, pheasants, and regal peacocks also live in the forests. In the American tropics, you can find tinama - a poorly flying bird with short but very strong legs. Well, how can you not remember the bright, funny and talkative parrots, without which the tropics are not tropics. In addition, variegated pigeons, trogons, woodpeckers, flycatchers, hornbills live on the equator. In the forests of the Amazon there are hummingbirds, tanagers, rocky cockerels, cotings and many others.

Animals

The fauna of tropical forests is striking in its diversity and richness of species. The largest number is represented by a group of monkeys living high in trees and in impenetrable thickets. The most interesting of them are cebids, marmosets and arachnids of the family. Igruniforms are characterized by a very small size, in length they reach no more than 15 cm, cebids boast a long tail with which they hook onto branches, and arachnid monkeys have flexible and long limbs.

But animal world The rainforest is not limited to monkeys alone, anteaters, sloths, porcupines also live here. Among predators, representatives of felines predominate - jaguars, jaguarundi, ocelots, panthers, from the canine family - bush dogs. There are also ungulates - tapirs, spoke-horned deer. The rainforests are also rich in rodents - opossums, marsupial rats, bats, agouti.

Amphibians of the tropics

Large and reptiles are also characteristic of the rainforest. Photos of exotic snakes, frogs, crocodiles, chameleons, lizards are no longer considered a rarity. Amphibians are found in all parts of the world, but they are most abundant in tropical rainforests, as they are attracted by heat and moisture. At the equator, they live not only in water, but also in trees, in the axils of leaves, in hollows. Salamanders live in the tropics, many poisonous snakes, water anacondas and land boa constrictors became widespread.

Insects

Looking at what animals live in the rainforest, it can be assumed that insects are no less bright, unusual and dangerous here. These small creatures of the tropics are attracted by the warmth, high humidity and a wide variety of food - animal remains, numerous plants. At the equator, you can find bees and wasps that are familiar to us, but here they differ more large size and bright, shiny color. Among them there are representatives with long legs, blue wings and a large body, they are able to tame large beetles and spiders. Bloated trunks are found on many shrubs - these are ant nests. Ants in the tropics protect plants by eating leaf-eating insects.

Beetles do not play a significant role in the life of tropical forests, but every traveler will be fascinated by their diversity and variegation. These insects are a natural decoration of this God-forsaken area. Of course, one cannot help but remember the tropical butterflies, only in South America there are more than 700 species of these beautiful creatures. Animals and plants of tropical forests represent a special world unknown to people. Researchers annually make their way deep into the thickets in order to lift the veil of secrets that this area keeps, to find new representatives of flora and fauna.

Seasonal semi-deciduous forests

Seasonal semi-deciduous forests are very diverse in tropical countries and develop where the dry period lasts about 1 - 2.5 months, and the annual precipitation is 2500 - 3000 mm. Here, taller trees shed all their foliage at once, and epiphytic orchids during the dry season, they fall into a state of rest. With an increase in the humidity of the climate, only emergent species remain deciduous, and under their canopy, all tree species retain their foliage throughout the whole season.

Seasonal semi-deciduous forests can exist with a dry period of up to 5 months with rainfall of less than 100 mm in each of the months of this period. Such forests have some of the features characteristic of a humid tropical forest - plank-like tree roots, the presence of tall emergent trees.

The layering in seasonal semi-deciduous forests, as well as in rain forests, is poorly expressed. There is no layer of shrubs at all.

In terms of the animal population and the composition of the fauna, forests of this type show a certain similarity with tropical (rain) forests. Termite structures are observed everywhere, towering above the soil surface. Their number ranges from 1 - 2 to 2000 per hectare. Aboveground buildings usually occupy 0.5 - 1% of the soil surface. The number of land-based molluscs, locusts, rodents, ungulates, and in Australia - kangaroo and wallaby... The seasonal aspects of the animal population are expressed with the domination of one or the other groups. Of birds, a large ecological role belongs to granivorous forms - weavers in Africa, oatmeal- In South America.

Wet (rain) rainforests

Wet (rain) rainforests grow in optimal moisture conditions and temperature regime... These conditions ensure the maximum production of the vegetation cover, and, consequently, the total biological production.

The climate of the area of ​​distribution of these forests is characterized by an even annual temperature variation. Average monthly temperatures range from 1 to 2 ° C. At the same time, the daily temperature range is much greater than the differences between the average monthly and can reach 9 ° C. For example, the absolute maximum temperatures in the forests of the Congo Basin are 36 ° C, the minimum is 18 ° C; the absolute amplitude is 18 ° C. The monthly average amplitudes of daily temperatures are often 7 - 12 ° C. Under the forest canopy, especially on the soil surface, these differences decrease.

Annual precipitation is large and reaches 1000 - 5000 mm. In some areas, there may be periods when less precipitation occurs. Relative humidity ranges from 40 to 100%. High air humidity and large clouds prevent penetration sun rays to the soil surface.

The length of the day within the equatorial and tropical zones varies little. Even at the southern and northern borders of the tropical belt, it changes only from 13.5 to 10.5 hours. This constancy is of great importance for photosynthesis. In the tropics, increased evaporation in the first half of the day leads to the accumulation of vapors in the atmosphere and rainfall in the afternoon. Cyclonic activity in the area of ​​tropical rainforests is characterized by a significant frequency of hurricanes, sometimes quite powerful. They can cut down huge trees, creating windows in the stand, which is the main reason for the mosaic nature of the vegetation cover. In a humid rainforest, there are two groups of trees:

- shade-loving dryads,

-nomads that endure significant lightening.

The former develop under the undisturbed forest canopy. When lightened as a result of hurricanes, they cannot develop and are replaced by species that endure significant lightening. When nomads reach a significant size and close the crowns, shade-loving begin to develop under their canopy dryads.

The soils of the tropical rainforest (red, red-yellow and yellow ferralite) are insufficiently provided with nitrogen, potassium, phosphorus and many microelements. The litter of woody leaves here is no more than 1 - 2 cm; it is often absent altogether. A paradoxical feature of a humid tropical forest is the poverty of soils in water-soluble mineral compounds.

The tropical rainforest is characterized by a huge number of tree species. With different counts (often including only trees with a diameter exceeding 10 cm, or a girth of at least 30 cm), the number of their species ranges from 40 (on the islands) to 170 (on the mainland). A significantly smaller number of grass species - from 1-2 on the islands to 20 on the mainland. Thus, the ratio between the number of tree and grass species is inverse compared to temperate forests.

Of the interlayer plants in tropical rainforests, there are many lianas, epiphytes, there are strangler trees... The number of lianas is several dozen species, epiphytes - more than 100 species, and strangler trees - several species. In total, there are about 200-300 species of interlayer plants, along with trees and grasses.

The vertical structure of tropical rainforest is characterized by the following features:

1. Higher emergent trees are rare... The trees that form the main canopy give gradual elevation changes. That is why the canopy is solid, not divided into tiers. Thus, the layering of the stand of the humid tropical forest is not clearly expressed. The following are also important reasons for the poor expressiveness of the forest stand layering:

The antiquity of the community, due to which the "adaptation" of trees of different species to each other has reached a high degree of perfection;

Optimality of living conditions, due to which the number of tree species that can coexist is very large.

2. There is no shrub layer in the humid tropical forest. The life-form of the bush did not find any important place for itself here. Woody plants even of low height are represented by plants with a single trunk; they have a well-defined main trunk and are either dwarf trees or young trees that subsequently emerge into higher canopy horizons. This is apparently due to insufficient illumination, which leads to the formation of the main trunks by plants. Along with trees, plants with perennial herbaceous trunks several meters high, which are absent in the temperate zone, also grow here.

3. The herbaceous cover of a humid tropical forest is characterized by the predominance of one species with an insignificant admixture of other species.

Of the interlayer plants, it should be noted vines, extremely diverse in the way of climbing trees. Among them there are species that climb with antennae, cling, twine around a support or lean on it. An abundance of lianas with woody trunks is characteristic. Vines under the forest canopy, as a rule, do not branch and, only reaching the tree crown, give numerous leafy branches. If the tree cannot withstand the weight of the liana and falls, then this liana can crawl along the soil surface to the neighboring trunk and climb it. Vines hold the crowns of trees together and often keep them high above the ground, even when the trunks or large branches of the trees have rotted.

Several groups are distinguished among epiphytes.

Epiphytes with cisterns are found in tropical America and belong to the bromeliad family. They have rosettes of narrow leaves that are in close contact with each other. In such outlets, rainwater accumulates, in which protozoa, algae, and various multicellular invertebrates - crustaceans, ticks, insect larvae, including mosquitoes - carriers of malaria and yellow fever, settle. There are cases when even insectivorous plants - pemphigus that feed on the listed organisms live in these miniature pools. The number of such outlets can be several dozen in one tree.

Nested epiphytes and epiphytes-sconces characterized by the fact that, in addition to leaves rising into the air, they have or plexus roots ( nested epiphytes), or leaves pressed against the trunk of a tree ( epiphytes-sconces), among which and under which soil rich in nutrient organic substances accumulates.

The third group of epiphytes is semi-epiphytes from the family aroid... These plants, having started their life on the ground, climb trees, but maintain a connection with the ground, developing aerial roots. However, unlike those lianas, which are characterized by aerial roots, semi-epiphytes remain alive even after cutting their roots. In this case, they get sick for a while, but then they get stronger, bloom and bear fruit.

The rest of the epiphytes, which do not have any special adaptations to life on trees, are called protoepiphytes.

In relation to the light epiphytes are subdivided into the following ecological groups:

Shadow;

Solar;

Extremely xerophilic.

Small epiphytes that settle on the leaves of trees are called epiphylls... They refer to algae, mosses and lichens. Flowering epiphytes settling on the leaves of trees, they usually do not have time to complete their development cycle. The very existence of this group of epiphytes is possible only in a humid tropical forest, where the lifespan of each leaf sometimes exceeds a whole year, and the air humidity is so high that the surface of the leaves is constantly moistened.

Strangler Trees most often related to species genus ficus, is a very specific group of tropical rainforest plants. When their seeds land on a tree branch, they begin their lives as epiphytes. Usually, the seeds of strangler trees are brought onto the branches of birds, which feed on their sticky fruits.

Ficus (fig tree ) - a genus of evergreen plants (lianas, epiphytes, trees) of the mulberry family. More than 800 species are known, which grow mainly in the tropical rainforests of India, Africa and the Sunda Islands. Ficuses also include figs... Some ficuses contain rubber. In many countries, ficuses are cultivated as ornamental plants.

Trees of tropical rainforest are characterized by the phenomenon caulifloria or ramifloria - flower development on the trunks below the crown or on the thickest branches. This is due to the fact that with such an arrangement of flowers, it is easier for pollinators to find them, which can be both various butterflies and ants crawling along the trunks.

Tropical rainforest trees are characterized by a number of morphological features. Leaf blades of many types have "drip" drawn ends. This allows rainwater to drain off the leaves more quickly. The leaves and young stems of many plants have a special tissue made up of dead cells. This fabric - velamen- accumulates water and makes it difficult for it to evaporate during periods when there is no rain. Most of the feeding (sucking) roots of trees are located in the upper soil layer, which is much less thick than the corresponding soil layer in temperate forests. In this regard, the resistance of tropical rainforest trees to the action of winds and hurricanes is low. This is why many trees develop plank roots supporting trunks, and in more humid, swampy areas - stilted roots... Board-like roots rise to a height of 1 - 2 m.

Seasonal changes in tropical rainforest are negligible. Leaf fall can be of a different nature. The change of foliage in the bulk of trees can go on continuously throughout the year.

Tropical trees can bloom and bear fruit continuously throughout the year; many species bloom annually or every few years. However, abundant fruiting is not always followed by abundant flowering.

In tropical rainforests, there are monocarpics - plants that die off immediately after fruiting (some bamboos, palms, herbs). However, monocarpics are less common here than in seasonal climates.

The life of many inhabitants of the tropical rainforest is associated with the crowns of trees. it monkeys, semi-monkeys, sloths, squirrels, flying squirrels, wool-wings, from insectivores - tupai, mice and rats... Some of them, for example sloths, are inactive and long time carried out hanging from the branches. This makes it possible for algae to settle in the grooved hair of sloths, giving the animal a green color. The green coloration of sloths makes them invisible against the background of foliage.

Many mammals - woolly wings, flying squirrels, as well as reptiles - flying dragons of lizards flying frogs from amphibians - they have adaptations for gliding flight.

In humid tropical forests, there are many animals and hollow-nesting birds. These include squirrels, chipmunks, rats, tupai, woodpeckers, hornbills, owls, barts etc. Abundance of those climbing the branches the serpent, among which there are species that feed on birds' eggs, leads to the development of special adaptations in birds. So males hornbills brick holes in the hollows with clay, where their females sit on the eggs in such a way that only their beak protrudes out of the hollow. Males feed them throughout the entire incubation period. If the male dies, the female is also doomed to death, since she is not able to beat off a layer of clay from the inside and come out of the hollow. At the end of incubation, the male frees the female walled up by him.

Plant materials are used to build nests by representatives of a wide variety of animal groups. Weaver birds they build bag-shaped nests closed on all sides with narrow entrances. They build their nests from papery substance wasps... Some species of ants make nests from pieces of leaves, others from whole leaves that continue to grow, which they pull together and fasten them with a cobweb secreted by their larvae. The ant holds the larva in its paws and "sews" with its help the edges of the leaves.

From piles of rotting leaves they build nests on the soil surface weed chickens... In such nests, a temperature is maintained sufficient for the incubation of eggs and hatching of chicks from them. Chicks, hatching, do not see their parents, who have long left the nest, and lead an independent lifestyle.

Weed chickens (big-legged chickens) - a family of birds of the order of chickens. They have well-developed legs. In total, about 12 species are known to live in Australia and on the islands. The Pacific... Weed chickens bury their eggs in heaps of sand or rotting plants.

Termites, ordinary inhabitants of the tropical rainforest, do not arrange or hardly arrange adobe buildings here, as in the savannahs. They, as a rule, live in underground nests, since they cannot live in the light, even in the scattered one. To climb tree trunks, they build corridors of soil particles and, moving along them, eat the wood of trees, which is digested in their intestines with the help of symbionts from among the simplest. The weight of soil particles lifted by termites on tree trunks averages 3 c / ha.

The abundance of natural shelters leads to a decrease in the number of burrowing forms of mammals. A specific feature of the soil fauna of the tropical rainforest is a large number of large earthworms reaching a meter or more in length.

The high humidity of the environment is the reason for the appearance of leeches on land, in other biomes living in water. Ground leeches are abundant in tropical rainforests, where they attack animals and humans. Presence in their saliva hirudinin, preventing blood clotting, increases the blood loss of those animals that they attack.

The abundance of diverse species and life forms leads to the development of complex symbiotic relationships. Thus, a number of tropical rainforest plants have special voids in the trunks, where predatory ants settle, protecting these plants from leaf-cutting ants... To feed these predatory ants, host plants develop special protein-rich bodies called Belt and Müller bodies. Predatory ants, settling in the trunks of plants and eating high-calorie food, prevent any insects from entering the trunks and destroying the leaves of plants. Leaf-cutting ants (umbrella ants), cutting off pieces of leaves, transfer them to their underground nests, chew them and grow on them certain types mushrooms. Ants make sure that fungi do not form fruiting bodies. In this case, special thickenings appear at the ends of the hyphae of these mushrooms - bromation, rich in nutrients that ants use primarily for feeding young animals. When a female leaf cutter ant goes to mating flight, it usually takes pieces of fungal hyphae into its mouth, which allows the ants to grow bromination in the new colony.

Probably, in no community are the phenomena of patronizing color and shape so developed as in a humid tropical forest. There are many invertebrates here, the very name of which speaks of the similarity with parts of plants or some objects. These are stick insects, wandering leaves and other insects. Bright, frightening coloration, warning that the animal is inedible, is also widespread in tropical rainforests.

The biomass of tropical rainforest is usually equal in primary forests to 3,500-7,000, and sometimes up to 17,000 c / ha (in mountain tropical rainforests of Brazil); in secondary forests, it is 1,400-3,000 c / ha.

CLIMATE OF WET TROPICAL FOREST. A very warm and humid tropical (equatorial) climate with precipitation fairly evenly distributed throughout the year. The annual amplitude of air temperature is small: from 1 to 0 °, the temperature of the coldest month is not lower than 18 °, precipitation is not less than 1500 mm per year. Distribution: Amazon, eastern Central America, Greater Antilles, southern Florida, equatorial Africa, eastern Madagascar, Malabar coast, southern Sri Lanka, Malacca, Indo-Malay archipelago, Indonesia, most of New Guinea and the Philippine Islands. [... ]

Tropical rain forests (gilea, tropical rain forests), widespread in the equatorial latitudes, have many specific features. They develop in a humid greenhouse climate: average temperature The air of the coldest month is above 18 ° С, and the annual amount of precipitation with a more or less uniform distribution of them over the seasons of the year is 2000-4000 mm and more. Formed by evergreen large-leaved trees, these forests are distinguished by an amazing density and variety of floristic composition of tree species: in Indonesia alone, excluding Java, there are about 3 thousand species of trees with a diameter of more than 40 cm.The number of trees with a diameter of 10 cm or more per hectare ranges from 390 up to 1710, and the number of tree species in the same area - from 52 to 98 (P.W. Richards, 1961). [...]

Tropical rainforests of South America, equatorial Africa, South-East Asia... The amount of precipitation is more than 2400 mm / year, almost every day it's raining... Climate - without changing seasons, average annual temperature approximately equal to 28 ° C. The largest ecosystem in terms of species diversity and plant biomass. Forests with trees up to 60 m and more (mahogany, wool, chocolate, wood, sandalwood). On the trunks, branches - vines. The fauna is diverse: monkeys, snakes, lizards, flying squirrels, frogs, spiders, ants, parrots, hummingbirds, insects. Features - the soils are poor, most of the nutrients are contained in the biomass of superficially rooted vegetation. [...]

TROPICAL CLIMATE. The climate of the intertropical zone. According to Köppen, there are two main types: a tropical rainforest climate (Ah!) And a savannah climate (Ah). [...]

The humid tropical climate includes the climate of tropical forests, savannas and coastal regions. The first is characterized by: the number cloudy days in the year - 60-70%; the amount of monthly precipitation is on average 200-250 mm; the rate of decrease or increase in temperature is not more than 2 ° per hour; daily temperature fluctuations do not exceed 8-10 ° С; Maximum temperature air rarely exceeds 30-35 ° С; air humidity 90% only at certain hours of the day, and over 90% - in the wettest month; dew and fog in the evening and morning. The savannah climate is characterized by a strict periodic alternation of rains and droughts. During periods of drought, the climate of the savannah resembles that of the steppes, and in rainy periods, the climate of tropical forests. In coastal areas, the average air humidity is 80%, i.e., as a rule, lower than the air humidity of tropical forests; air temperature varies from 20 to 40 ° С; v sea ​​air contains salts. [...]

Full circulation is often observed in polymictic lakes, resulting from strong heating of the surface water layers during the day and cooling at night. This type is typical for the climate of savannas and mountain tropical forests (lakes Albert, Rudolph, Victoria - according to Beadle). In oligomictic lakes, circulation occurs irregularly - in short periods cold weather... These lakes are characteristic of the tropical rainforest zone (lakes in Indonesia). [...]

In tropical countries with humid climates, the conversion of some lands to agricultural areas is often difficult. These areas, due to the change in the regime of their use, suffer to a greater or lesser extent from changes in the level groundwater, soil erosion, disturbance of the structure of the fertile soil layer, up to its complete depletion, destruction of forests and untouched corners of nature, suitable for tourism or for the creation of national parks of protected nature. Damage done environment, coupled with rapid population growth, is responsible for the growing impoverishment of the rural population. Despite many noteworthy efforts, the ongoing destruction of the natural environment has not been halted. [...]

A - tropical humid climate; 1 - tropical rainforests; 2 - tropical savanna; B - dry climate; 3 - steppe; 4 - desert; B - humid mesothermal climate; 5 - warm, with dry winters (mussops and high savannahs); b - warm with dry summer (Mediterranean); 7 - moist, moderate; D - humid microthermal climate; 8 - cold with wet winters; 9 - cold with dry winters (monsoons); D - polar climate; 16 - myttdpa; 11 - eternal frosts. [...]

But not everywhere in tropical zones the climate is arid. On the eastern coasts of the continents, where the trade winds blow from the oceans, a lot of precipitation falls (Greater Antilles, the east coast of Brazil, the east coast of Africa). The climate of these regions is not much different from the equatorial one, although the annual temperature fluctuations are significant, since there is a significant difference in the height of the sun over the seasons. Thanks to a large number precipitation and high temperatures humid tropical forests grow here. [...]

Forest distribution the globe the composition of rocks is closely related to the types of climate. Thus, in humid tropical regions, predominantly deciduous forests grow, characterized by an extraordinary variety of their constituent tree species; in cold and moderately cold areas prevail coniferous forests consisting of a relatively small number of tree species. Historically developing in conditions of a more or less definite climate, tree species are adapted to the corresponding climatic conditions. It is known that one and the same botanical tree species growing in different climatic conditions can give different climatic ecotypes (races) adapted to exist in conditions of the corresponding climatic type difference. [...]

Macroclimate is the climate of large areas, such as geographic areas. According to the geographical and orographic location, characteristic macroclimates of the tundra, taiga, steppes, deserts, tropical rainforests have formed. [...]

In terms of the completeness of information on climate changes, the tropics are much inferior to the temperate zone. For this reason, it is tempting to suppose that at a time when the temperate latitudes were at the mercy of dramatic climate change and glacial invasions, the tropics were in the same state as they are today. This assumption is almost certainly wrong. On the contrary, there is a picture of changes in vegetation cover, parallel to those that occurred in the temperate zone: in warmer and wetter periods, the area of ​​tropical forests increased, and in periods of cooler and drier, when savanna prevailed, it decreased. In the modern distribution of both plants and animals, there are indications of what position these "islands of the rainforest surrounded by the sea of ​​the savannah" once occupied (Fig. 1.6). [...]

This hardy, showy tropical rainforest plant brings a glow of warmth to homes in cooler climates. The exquisite scent of delicate flowers and exotic narrow leaves will enliven any room. Spathiphyllum can be used in the interior of offices, shop windows, as well as in group flower arrangements in winter gardens. [...]

The distribution of the main groups of soils is associated with widespread types of climate through weathering and vegetation (Fig. 145). Unfortunately, climatic conditions, the most favorable for plant growth, do not always coincide with the natural fertility of the soil. [...]

The maximum thickness - 40-60 m and more - reaches the laterite weathering crust under humid tropical and subtropical forests... Equally small thickness is the weathering crust in deserts of different latitudes> and in the polar zones with a nival climate (from Latin nivalis - snowy, cold). Both here and there physical weathering prevails, and the development of the crust does not go beyond the formation of large blocks, rubble and sand. [...]

EQUATORIAL ZONE. Geographic area located near the equator; on land it is a tropical rainforest climate zone. [...]

The destruction of equatorial and subequatorial forests is of particular concern to scientists and the public. Over the past 25 years, their area has decreased by 50%. Annual losses amount to 27 million hectares, or 5% of the available amount. Once upon a time, rainforests covered 10% the earth's surface(15 million km2), but their area has already decreased by a third. The destruction of tropical rainforests directly leads to an increase in the rigidity and dryness of the climate. Together with the forests, their inhabitants also perish, many species of animals die out completely, the gene pool is being destroyed. [...]

JUNGLE jungle - tracing paper from Hindi jangal - thickets] - dense, difficult-to-pass tree-shrub-forest forests of areas with wet tropical climate.[ ...]

Jungle (from Sanskrit - jangala - thickets, thicket) - dense trees and shrubs with a large admixture of cereals (mainly bamboo) and rugged forests. Typical for areas with humid tropical and subtropical climates. The jungle is especially common in India, Indochina and the Sunda Islands. [...]

Annual growth is extremely important - the annual production of living plant material. It would be expected that the greatest increase is provided by plant communities with the highest biomass - forests. However, this is only partially true. Indeed, the maximum growth falls on the vegetation of constantly humid tropical forests (325 kg / ha), however, the growth of forests in temperate and especially boreal climates is much less. The increase in the vegetation of meadow steppes is very large (137 centners / ha, or more than 50% of their biomass). Deserts (10 c / ha) and tundra (10-25 c / ha) have the smallest increments. [...]

Representatives of the gibbertia genus grow in very different ecological conditions, and this is associated with a significant diversity of their life forms. Most species inhabit areas of Australia with arid continental climate.[ ...]

Content of the dead organic matter on the surface of the soil under vegetation different types is also not the same. A large amount of it is formed under forest communities, but not everywhere, but only in a boreal climate (300-350 centners / ha). The mass of dead organic matter in a constantly humid rainforest is 10 times less. The largest number dead terrestrial organic matter was found in dwarf shrub tundra (835 c / ha); the smallest, so far not amenable to accurate counting, is in the deserts. [...]

The succession ends with a stage when all species of the ecosystem, while multiplying, retain a relatively constant number and no further change in its composition occurs. This equilibrium state is called menopause, and the ecosystem is called menopause. In different abiotic conditions, different climax ecosystems are formed. In a hot and humid climate, it will be a rainforest rainforest, in a dry and hot climate it will be a desert. The main biomes of the earth are climax ecosystems of their respective geographic areas. [...]

The largest amount of nitrogen and ash elements is contained in the biosphere of forest vegetation; in almost all types of vegetation, the mass of ash elements is 2-3 times higher than the mass of nitrogen. The exception is tundra vegetation, in which the content of nitrogen and ash elements is approximately the same. The largest number of elements circulating during the year (i.e., the capacity of the biological cycle) is in humid tropical forests, then in the chernozem steppes and broadleaf forests temperate climate (in oak forests). [...]

In herbaceous and forest communities, it is likely that a significant proportion of solar energy (50-90%) is spent on the evaporation of water in the form of transpiration. Water loss with transpiration can be a limiting factor leading to wilting, especially in dry climates, in areas with intensive farming, or where soils have poor moisture holding capacity. At the same time, evaporation cools the leaves and is one of several processes that promote the circulation of nutrients. Other processes are the transport of ions through the soil to the roots, the transport of ions into the root, movement within the plant, and leaching from the leaves (Kozlovsky, 1964, 1968). Some of these processes require the expenditure of metabolic energy, which can limit the rate of transport of water and salts (Fried and Brochart, 1967). Hence transpiration is not just a function of exposed physical surfaces. The forest does not necessarily lose more water than grassy vegetation. The role of transpiration as an energy “subsidy” in moist forest conditions was discussed in Ch. 3. If the air is too humid (the relative humidity is close to 100%), as, for example, in mountainous "cloudy" tropical forests, trees are stunted and most of the vegetation consists of epiphytes, apparently due to the lack of "transpiration traction "(See G. Odum and Pidgin, 1970).