Tropical forests are a special natural zone that is distinguished by a huge variety of species of flora and fauna. Forests of this type are found in Central and South America, Africa and Asia, Australia and some Pacific islands.
Climatic conditions
As the name suggests, tropical forests are found in the dry tropical climate zone. They are partially found in humid equatorial climates. In addition, tropical forests are also found in the subequatorial zone, where humidity depends on circulation air masses. The average air temperature varies from +20 to +35 degrees Celsius. There are no seasons here, since the forests are quite warm all year round. The average humidity level reaches 80%. Precipitation is distributed unevenly throughout the territory, but about 2000 millimeters falls per year, and in some places more. Tropical forests of different continents and climate zones have some differences. It is for this reason that scientists divide tropical forests into wet (rain) and seasonal.
Tropical rainforests
Subspecies of tropical rainforests:
Rain forests are characterized by enormous amounts of rainfall. In some places it can fall 2000-5000 millimeters per year, and in others - up to 12,000 millimeters. They fall out evenly throughout the year. The average air temperature reaches +28 degrees.
Among the plants in humid forests grow palms and tree ferns, the myrtle and legume families.
Epiphytes and vines, ferns and bamboos are found here.
Some plants bloom all year round, while others have short-term blooms. There are sea grasses and succulents.
Seasonal rainforests
These forests have the following subspecies:
Monsoon
Savannah
Seasonal forests have a dry and a wet season. 3000 millimeters of precipitation falls per year. There is also a leaf fall season. There are evergreen and semi-evergreen forests.
The seasonal forests contain palm trees, bamboos, teak, terminalia, albizia, ebony trees, epiphytes, lianas, sugar cane.
Among the grasses there are annual species and cereals.
Bottom line
Tropical forests occupy a large area on the planet. They are the “lungs” of the earth, but people are cutting down trees too actively, which leads not only to environmental problems, but also to the extinction of many species of plants and animals.
Tropical rainforest, or hylea, which we do not quite correctly call jungle. They stretch in a wide ribbon along the equator and once encircled the world, and are now preserved mainly in the Amazon River basin, in Central America, on some islands of the Caribbean Sea, in the Congo River basin, on the coast of the Gulf of Guinea, on the Malacca Peninsula, in New Guinea, the Sunda Islands. , Philippine and some other islands of the Indian and Pacific oceans. Remnants of Hylaea still exist in Eastern India, Indochina and Sri Lanka.
Tropical rainforests have a strictly constant climate. The most notable feature of these forests is their high humidity. It is created by daily rains, in other places bringing up to 12 meters annual precipitation. That's a lot. After all, the plants growing here are able to absorb only 1/12 to 1/6 of the water falling on the forest. Part of the precipitation is temporarily accumulated in the axils of the leaves, various epiphytes and mosses. The rest of the moisture is evaporated by tree leaves into the air, or it goes deep into the soil.
Usually by morning the jungle is enveloped in thick fog. Only around nine o'clock do the sun's rays drive it off the “forest roof” and disperse the clouds. It is then that many animals rise into the crowns to take a sunbath, so necessary for most inhabitants of the forest wilds.
In the Asian jungle, the first to appear here are the apes-gibbons, living in small families. Sitting on the branches facing the sun, resting their heads on their knees and, just in case, clinging to the nearest branches with their hands, they begin their amazing morning choral singing. Both respectable heads of families and foolish children take part in the concert. Monkeys sing selflessly and often bring themselves to ecstasy. Hymns to the sun sound for 1.5-2 hours. When it gets hot, gibbon families hide in the dense foliage.
Under the burning rays of the sun, evaporation quickly increases, the air humidity above the forest canopy rapidly increases, and by two o’clock in the afternoon, when a lot of water vapor has accumulated, they condense into thunderclouds, and at five another downpour falls on the green roof, which will rage for the rest of the day , and maybe all night. Hurricanes are not uncommon here, with 150 millimeters of water falling in an hour. That is why, under the canopy of the equatorial forest, air humidity is kept at 90 and even 100 percent, and the wilds themselves are called wet forest. True, in many areas of the jungle at least once a year there is a short dry period when there is little precipitation, but even during this time the air humidity never drops below 40 percent.
The constantly wet ground and humid air allowed some invertebrates to move from the bodies of water where they usually live to land. Of these, the most unpleasant are leeches, which, having settled on the branches, patiently wait for the victim.
Other characteristic equatorial forest - constantly high air temperature. One should not think that it reaches extreme values here. Heat over 50 degrees, which happens, for example, in deserts, is impossible here, but the temperature never drops low and it is never cold in the jungle. In the ground level of the Congolese wilds it never rises above 36 and never falls below 18 degrees. Average annual temperatures on the first floor usually fluctuate between 25-28, and average monthly temperatures vary by only 1-2 degrees. A little more, but also small daily fluctuations, usually not exceeding 10 degrees. In the jungle, the coolest hours are the pre-dawn hours, and the hottest time of day is the end of the first half of the day. Sharper fluctuations in temperature and humidity are observed in the “attic” and on the “roof” itself.
The length of the day in the equatorial zone is very constant. It ranges from 10.5 to 13.5 hours, but under the canopy tropical forest Even at noon there is twilight. The lush foliage of tree crowns uses most of the energy of daylight for photosynthesis and almost does not let the sun's rays reach the ground. After all, the total area of leaves is 7-12 times larger than the area of the forest itself. On its first floor there is clearly not enough ultraviolet radiation, which is why the inhabitants of the jungle have such a need for sunbathing.
Down here, in the darkest places, the light intensity is only 0.2-0.3 percent of the intensity of full daylight. This is very little. It must be significantly lighter for green plants to survive. Only a very few of them are able to make do with 0.8 percent of the luminous flux. The life of plants under the canopy of the tropical forest would be completely impossible if it were not for the rare lace of sunlight, tiny oases of light. There are very few of them. 0.5-2.5 percent of the forest floor area is illuminated, and even then usually not for long. It's good if 2-3 hours a day. In addition, the light intensity in them is low, only 10-72 percent.
Rainforest trees in their infancy and teenage years are able to tolerate a lack of light, however, as they mature, they become the most sensitive jungle plants to lack of light. Forest giants are short-lived. Their natural lifespan is not long at all - from 15-20 to 80-100 years. With such short life and relative to the high need for light, self-renewal of the jungle would be impossible if the roof of the forest were just a little stronger. But it is precisely reliability that it lacks.
Fierce hurricanes with monstrous destructive power love to walk over the jungle. They not only break the tops of trees rising above the forest canopy, not only break through the “roof,” but often tear giants out of the ground by the roots, creating huge clearings up to 50-80 hectares in size. This is explained not only by the crushing force of the wind, but also by the nature of the root system of the trees themselves. After all, the soil layer underneath them is thin, and therefore their roots do not penetrate deeply. Only 10-30, rarely 50 centimeters and not held firmly. A flood of light rushes through holes in the forest canopy left by a hurricane, and growth begins to explode.
In such clearings many new plants grow at the same time. Peer trees stretch upward and grow in a race, trying to snatch as much light as possible. Therefore, they do not have a crown, or rather, it is narrow and strongly elongated upward. When the tree reaches mature age and its further growth stops, several large branches begin to gain strength, grow, and the crown expands, if neighbors - nearby trees - allow this to happen.
As much as the jungle is rich in trees, it is also poor in grass. Here there are from several dozen to one and a half hundred species of trees, and from 2 to 20 species of grass. This is the direct opposite of what we see in the north, where forests are usually made up of two to three or five species of trees, and herbs and shrubs are quite diverse. In tropical rainforests, grass does not form a continuous cover, and the herbaceous plants themselves, in our everyday understanding, do not at all resemble grasses. Some of them are curly and stretch upward. Others have woody stems, like bamboo, and almost no branching. These perennial plants can reach a height of 2-6 meters. It is difficult to call such giants grass. Finally, huge bananas with fleshy leaves, and they are not uncommon here, this is also a type of grass.
Herbaceous plants include ferns and selyaginella, which are somewhat similar to them. Usually these are creeping forms with aerial roots, trying to climb as high as possible. There are no bushes here like we are used to seeing in the north. On the ground floor, in the twilight of the rainforest, the plants stretch upward, not outward. But this does not mean that the space at the base of tree trunks is free. On the contrary, without an ax or a sharp machete - a long knife that is used to chop not too thick branches and trunks of young trees, you cannot take a single step here. The main culprits are vines, as well as aerial and additional support roots.
The roots extend from the trunks and large branches at a height of 1-2 meters or higher, go down and branch here, going into the ground far from the trunk itself. Columnar-shaped support roots and board-shaped root outgrowths at the base of tree trunks often grow together.
Aerial roots descending from somewhere above contribute to this chaos. To meet them, vines rush upward towards the sun, entwining everything and everyone. They cling to tree trunks so much that sometimes they are not visible, they rise into the crowns, thickly cover the branches, spread from tree to tree, sometimes descend back to the ground, reach a neighboring tree and again rush to the sky. The length of the vines is impressive: 60-100, and rattan palms stretch for more than 200 meters. There are killers among the vines. Having reached the top of the giant tree, they short term they grow so much foliage, which is placed here asymmetrically, that the support cannot withstand the excessive weight, and the tree falls. Falling to the ground, it cripples the vine. However, more often the killer survives and, reaching a nearby tree, again rushes towards the sun.
Strangler vines, wrapped like a noose around a tree trunk, squeeze it and stop the movement of juices. Often, in the safe embrace of a vine that has spread to neighboring trunks and strengthened itself there, a dead tree remains standing until it decays and falls apart.
As already mentioned, the trees of the tropical jungle reach monstrous sizes. The length and thickness of the trunks match. Here giants look quite ordinary, reaching three meters in diameter at human height, and there are also thicker ones. In the closed wilds everything stretches upward towards the sun. Therefore the trunks are straight. The lower lateral branches die off early, and in mature trees they begin at a dizzying height, never less than 20 meters from the ground.
Trees in tropical rainforests tend to have smooth, light-colored bark. With smooth rainwater drains completely, and too much of it would be retained in the rough, putrefactive processes could occur or fungi could settle, destroying the wood. And it is light so that the sun’s rays, if they get here, are more fully reflected and do not heat the trunks too much.
The flowers of tropical forest plants are usually brightly colored and have a strong aroma. Interestingly, they are most often located directly on trunks and large branches. The color, the smell, and the location are all designed to make them easier for insects and other pollinating animals to detect. It would be difficult to find flowers in a sea of foliage.
The leaves, especially those of the tallest trees of the tropical rainforest, are large, dense, leathery, with “drip” ends drawn down. They must withstand the force of hurricanes, withstand the onslaught of downpours and not prevent water from flowing down as quickly as possible. The leaves are short-lived, not many live more than 12 months. Their change occurs gradually and continues all year round. The amount of litter can reach 10 percent of the total forest biomass, but the litter layer is never thicker than 1-2 centimeters, and it is not found everywhere, since decay is intense. However, soil enrichment does not occur, since water flows wash nutrients into the lower horizons, inaccessible to the roots. The lush vegetation that tropical rainforest appears to be created on extremely poor soils.
No matter what hurricanes hit the jungle, at the bottom of the green ocean there is almost no air movement. Warm and humid air is not renewed at all. Here, as in a thermostat, ideal conditions for the life of all kinds of microbes, especially putrefactive ones. Everything here is rotting and rapidly decomposing. Therefore, despite the mass of flowering plants, in the depths of the forest there is a noticeable smell of rot.
Eternal summer creates favorable conditions for continuous growth, which is why tree trunk cuts often lack the familiar annual rings. In the jungle, it is common for plants in different stages of fruiting to coexist at the same time. The fruits on one of the trees may already be ripening, while the flower buds on the neighboring one are just beginning to form. Continuous activity is not typical for everyone. Some trees need a short rest, and during this period they can even shed their leaves, which is immediately taken advantage of by neighbors who manage to snatch a little more light.
The ability to grow all year round, the ability to “snatch” from the soil everything valuable that has not yet been carried away by water, allows even on poor soils to create huge biomass, a record for the earth’s biosphere. Usually it ranges from 3.5 to 7 thousand tons per hectare, but in some places it reaches 17 thousand tons! Of this mass, 70-80 percent falls on bark and wood, 15-20 percent are underground parts of the root system, and only 4-9 percent fall on leaves and other green parts of plants. And there are very few animals, only 0.02 percent, in other words, only 200 kilograms. This is the weight of all animals living on 1 hectare of forest! The annual increase is
6-50 tons per hectare, 1-10 percent of total jungle biomass. This is what a superforest is - wet tropical wilds!
Tropical rainforests stretch over large areas on both sides of the equator, but do not go beyond the tropics. Here the atmosphere is always rich in water vapor. The lowest average temperature is about 18°, and the highest is usually no higher than 35-36°.
With abundant warmth and moisture, everything here grows with remarkable speed. In these forests spring and autumn are invisible. All year round, some trees and shrubs bloom in the forest, while others fade. All year round It's summer and the vegetation is turning green. There is no leaf fall in our understanding of the word, when the forest is exposed for winter.
The change of leaves occurs gradually, and therefore it is not noticed. Young leaves bloom on some branches, often bright red, brown, and white. On other branches of the same tree, the leaves were fully formed and turned green. A very beautiful range of colors is created.
But there are bamboos, palm trees, and some types of coffee trees, which all bloom on the same day over an area of many square kilometers. This amazing phenomenon makes a stunning impression with the beauty of its blooms and aromas.
Travelers say that in such a forest it is difficult to find two neighboring trees belonging to the same species. Only in very rare cases do tropical forests have a uniform species composition.
If you look at the tropical forest from above, from an airplane, it will appear surprisingly uneven, sharply broken, not at all like flat surface temperate forests.
They are not similar in color either. When viewed from above, oak and other forests of ours appear uniformly green, only with the arrival of autumn they dress up in bright and variegated colors.
The equatorial forest, when viewed from above, appears to be a mixture of all tones of green, olive, yellow interspersed with red and white spots of flowering crowns.
Entering a tropical forest is not so easy: it is usually a dense thicket of plants, where, at first glance, they all seem tangled and intertwined. And it is difficult to immediately figure out which plant this or that trunk belongs to - but where are its branches, fruits, flowers?
Damp twilight reigns in the forest. The rays of the sun weakly penetrate the thicket, so the trees, bushes, and all the plants here stretch upward with amazing force. They branch little, only three to four orders of magnitude. One involuntarily recalls our oaks, pines, and birches, which produce five to eight orders of branches and spread their crowns widely in the air.
In equatorial forests, trees stand in thin, slender columns and somewhere at a height, often 50-60 meters, small crowns reach towards the Sun.
The lowest branches begin twenty to thirty meters from the ground. To see leaves, flowers, fruits, you need good binoculars.
Palm trees and tree ferns do not produce branches at all, throwing out only huge leaves.
Giant columns need good foundations, like the buttresses (slopes) of ancient buildings. And nature took care of them. In African equatorial forests, ficus trees grow, from the lower parts of whose trunks additional plank roots up to a meter or more in height develop. They hold the tree firmly against the wind. Many trees have such roots. On the island of Java, residents make table covers or cart wheels from plank roots.
Between the giant trees, smaller trees grow densely, in four or five tiers, and even lower - shrubs. Fallen trunks and leaves rot on the ground. The trunks are entwined with vines.
Hooks, thorns, mustaches, roots - in all ways, vines cling to tall neighbors, wrap around them, crawl over them, use devices popularly known as “devil’s hooks”, “cat’s claws”. They intertwine with each other, then as if merging into one plant, then again dividing in an uncontrollable desire for light.
These thorny barriers terrify the traveler, who is forced to take every step among them only with the help of an axe.
In America, along the valleys of the Amazon, in the virgin tropical forests, vines, like ropes, are thrown from one tree to another, climb up the trunk to the very top and settle comfortably in the crown.
Fight for the light! In a tropical rainforest there are usually few grasses on the soil, and shrubs are also few in number. Everything that lives must receive some amount of light. And many plants succeed in this because the leaves on the trees are almost always vertical or at a significant angle, and the surface of the leaves is smooth, shiny and perfectly reflects light. This arrangement of leaves is also good because it softens the impact of rain and downpours. And it prevents water from stagnating on the leaves. It is easy to imagine how quickly the leaves would fail if water were retained on them: lichens, mosses, and fungi would colonize them immediately.
But there is not enough light for plants to fully develop in the soil. How then can we explain their diversity and splendor?
A bunch of tropical plants not related to the soil at all. These are epiphytic plants - lodgers. They don't need soil. Trunks, branches, even leaves of trees provide them with excellent shelter, and there is enough warmth and moisture for everyone. A little humus forms in the axils of the leaves, in the crevices of the bark, and between the branches. The wind and animals will bring the seeds, and they germinate and develop well.
The very common bird's nest fern produces leaves up to three meters long, forming a fairly deep rosette. Leaves, bark flakes, fruits, and animal remains fall from the trees into it, and in a humid, warm climate they quickly form humus: the “soil” is ready for the roots of the epiphyte.
In the Botanical Garden in Calcutta they show such a huge fig tree that it is mistaken for a whole grove. Its branches have grown above the ground in the form of a green roof, which is supported by pillars - these are adventitious roots growing from the branches. The crown of the fig tree spreads over more than half a hectare, the number of its aerial roots is about five hundred. And this fig tree began its life as a parasite on date palm. Then she entwined her with her roots and strangled her.
The position of epiphytes is very advantageous compared to the “host” tree, which they use, making their way higher and higher towards the light.
They often carry their leaves above the top of the “host” trunk and deprive it of the sun’s rays. The “owner” dies, and the “tenant” becomes independent.
The words of Charles Darwin best describe tropical forests: “The greatest amount of life is accomplished when the greatest variety buildings."
Some epiphytes have thick, fleshy leaves and some swellings on the leaves. They have a supply of water in case there is not enough water.
Others have leathery, hard leaves, as if varnished, as if they didn’t have enough moisture. The way it is. In the hot season of the day, and even with a strong wind, in a highly raised crown, the evaporation of water increases sharply.
Another thing is the leaves of bushes: they are tender, large, without any adaptations to reduce evaporation - in the depths of the forest it is small. The grasses are soft, thin, with weak roots. There are many spore-bearing plants here, especially ferns. They scatter their leaves on the edges of the forest and in rare illuminated clearings. There are brightly flowering shrubs, large yellow and red cannas, and orchids with their intricately arranged flowers. But grasses are much less diverse than trees.
The overall green tone of the herbaceous plants is pleasantly interspersed with white, red, gold, and silver leaf spots. Whimsically decorated, they are not inferior in beauty to the flowers themselves.
It may seem at first glance that the tropical forest is poor in flowers. In fact, there are not so few of them,
they are simply lost in the green mass of foliage.
Many trees have self- or wind-pollinated flowers. Large, bright and fragrant flowers are pollinated by animals.
In the tropical forests of America, tiny hummingbirds with brilliant plumage hover over flowers for a long time, licking honey from them with a long tongue folded in the form of a tube. In Java, birds often act as pollinators. There are honeybirds there, small, similar in color to hummingbirds. They pollinate flowers, but at the same time they often “steal” honey without even touching the stamens and pistils. In Java, there are bats that pollinate vines with brightly colored flowers.
In cocoa trees, breadfruit trees, persimmons, and ficus trees, flowers appear directly on the trunks, which then turn out to be completely covered with fruits.
In equatorial rain forests there are often swamps and flowing lakes. The fauna here is very diverse. Most animals live in trees, eating fruits.
Rainforests different continents have a lot between them common features, and at the same time, each of them is different from the others.
In Asian forests there are many trees with valuable wood, plants that produce spices (pepper, cloves, cinnamon). Monkeys climb in the treetops. An elephant wanders on the outskirts of the tropical thicket. The forests are home to rhinoceroses, tigers, buffalos, Poisonous snakes.
The equatorial rain forests of Africa are famous for their impenetrable thickets. It is impossible to get through here without an ax or knife. And there are many tree species with valuable wood. The oil palm is often found, from the fruits of which oil, coffee tree and cocoa are extracted. In some places, in narrow valleys where fog accumulates and the mountains do not let them pass, tree ferns form entire groves. Heavy, dense fogs slowly creep upward and, cooling, pour heavy rains. In such natural greenhouses, spore plants feel at their best: ferns, horsetails, mosses, and curtains of delicate green mosses descend from the trees.
Gorillas and chimpanzees live in African forests. Monkeys tumble in the branches; baboons fill the air with their barks. There are elephants and buffalos. Crocodiles hunt all kinds of living creatures in rivers. Encounters with hippopotamus are common.
And mosquitoes and mosquitoes fly in clouds everywhere, hordes of ants crawl. Perhaps even this “little thing” is more noticeable than large animals. It bothers the traveler at every step, filling the mouth, nose and ears.
The relationship between tropical plants and ants is very interesting. On the island of Java, one epiphyte has a tuber at the bottom of its stem. Ants live in it and leave their excrement on the plant, which serves as fertilizer.
In the rain forests of Brazil there are real ant gardens. At a height of 20-30 meters above the ground, ants make their nests, dragging them onto branches and trunks along with soil, leaves, berries and seeds. Young plants sprout from them, fastening the soil in the nest with their roots and immediately receiving soil and fertilizers.
But ants are not always harmless to plants. Leaf-cutter ants are a real scourge. They attack coffee and orange trees and other plants in hordes. Having cut pieces from the leaves, they put them on their backs and move towards the nests in solid green streams, exposing the branches,
Fortunately, other types of ants can settle on plants and destroy these robbers.
The tropical forests of America along the banks of the Amazon River and its tributaries are considered the most luxurious in the world.
Vast flat areas, regularly flooded with water when rivers flood, are covered with riparian forests. Huge virgin forests stretch above the flood line. And the drier areas are occupied by forests, although less dense and lower.
There are especially many palm trees in coastal forests, forming entire groves that run in long alleys along the banks of rivers. Some of the palm trees spread their leaves like a fan, others stretch out feathery leaves 9-12 meters in length. Their trunks are straight and thin. In the undergrowth there are small palm trees with clusters of black and red fruits.
Palm trees give people a lot: the fruits are used as food, local residents obtain fiber from the stems and leaves, and the trunks are used as building material.
As soon as the rivers enter their channel, grasses develop in the forests with extraordinary speed, and not only on the soil. Green garlands of climbing and climbing herbaceous plants, colored with bright flowers, hang from trees and bushes. Passion flowers, begonias, “day beauties” and many other flowering plants form drapes on the trees, as if laid out by the hand of an artist.
Myrtles, Brazil nuts, flowering ginger and cannas are beautiful. Ferns and graceful feathery mimosas support the overall green tone.
In the forests above the river flood line, trees, perhaps the tallest of all tropical representatives, stand in a dense close formation on supports. Famous among them are Brazil nut and mulberry cotton with its huge plank supports. The most beautiful trees The Amazons consider laurel trees. There are a lot of leguminous acacias here, a lot of araceae. Philodendron and monstera are especially good with fantastic cuts and cuts on the leaves. There is often no undergrowth in this forest at all.
In lower, non-flooded forests, lower tree layers of palms, shrubs and low trees appear, sometimes very dense and almost impenetrable.
The herbaceous cover cannot be called luxurious: a few ferns and sedges. In some places there is not a single blade of grass over a significant area.
Almost the entire Amazonian lowland and part of the northern and eastern coasts of the mainland are occupied by rain forests.
Evenly high temperatures and plenty of precipitation make all days similar to one another.
Early in the morning the temperature is 22-23°, the sky is cloudless. The leaves are glistening with dew and fresh, but the heat is quickly increasing. By noon or a little later it is already unbearable. Plants drop leaves and flowers and appear completely withered. There was no air movement, the animals hid. But now the sky is filled with clouds, lightning flashes, and the thunderclaps are deafening.
Sharp gusts of blowing wind shake the crowns. And a blessed downpour revives all nature. There's a lot of float in the air. A stuffy, hot and humid night sets in. Leaves and flowers blown by the wind are flying.
A special type of forest covers sea coasts in tropical countries, protected from waves and winds. These are mangrove forests - dense thickets evergreen shrubs and low trees on flat banks near river mouths, in lagoons, and bays. The soil here is a swamp with black, foul-smelling silt; in it, with the participation of bacteria, there is a rapid decomposition of organic substances. At high tide, such thickets appear to emerge from the water.
With the ebb of the tide, their so-called roots are exposed - stilts, which extend far across the silt. Supporting roots go from the branches into the silt.
This root system anchors trees well in muddy soil and is not carried away by the tide.
Mangroves push the coastline onto the sea because plant debris accumulates between the roots and trunks and, mixing with silt, gradually forms land. Trees have special respiratory roots, which are very important in the life of these plants, since silt contains almost no oxygen. Sometimes they are serpentine in shape, in other cases they resemble an elbowed pipe or stick out from the mud like young stems.
The method of reproduction found in mangroves is curious. The fruit is still hanging on the tree, and the embryo is already sprouting in the form of a long pin, up to 50-70 centimeters. Only then does it break away from the fruit, fall into the silt, burying its end in it, and is not carried away by the water into the sea.
These plants have leathery, shiny, often fleshy leaves covered with silvery hairs. The leaves are arranged vertically, the stomata are reduced. All these are signs of plants in dry places.
It turns out to be a paradox: the roots are immersed in silt, they are constantly under water, and the plant lacks moisture. It is assumed that sea water, being saturated with salt, cannot be easily absorbed by the roots of trees and shrubs - and therefore they must evaporate sparingly.
Together with sea water plants get a lot table salt. The leaves are sometimes almost completely covered with its crystals, secreted by special glands.
The richness of species in tropical forests is exceptionally great, and it is achieved primarily by the fact that the use of space by plants is brought here by natural selection to extreme limits.
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TROPICAL MOIST FOREST CLIMATE. A very warm and humid tropical (equatorial) climate with precipitation fairly evenly distributed throughout the year. Annual amplitude air temperatures are low: 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-Malayan archipelago, Indonesia, most of New Guinea and the Philippine Islands.[...]
Tropical rainforests(hylaea, tropical rain forests), widespread in equatorial latitudes, have many specific features. They develop in a humid greenhouse climate: the average air temperature of the coldest month is above 18 °C, and the annual amount of precipitation with a more or less uniform distribution across the seasons is 2000-4000 mm or more. Formed by evergreen large-leaved trees, these forests are distinguished by an amazing density and diversity 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 to 1710, and the number of tree species in the same area ranges from 52 to 98 (P.W. Richards, 1961).[...]
Tropical rain forests South America, equatorial Africa, South-East Asia. Precipitation amount 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 higher (mahogany, wool, chocolate, wood, sandalwood). There are vines on the trunks and branches. 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 surface-rooted vegetation.[...]
TROPICAL CLIMATE. Climate of the intertropical zone. According to Koeppen, there are two main types: tropical rainforest climate (A!) and savannah climate (Au). [...]
The humid tropical climate includes the climate of tropical forests, savannas and coastal areas. The first is characterized by: the number of cloudy days per year - 60-70%; monthly precipitation averages 200-250 mm; the rate of decrease or increase in temperature is no more than 2° per hour; daily temperature fluctuations do not exceed 8-10° C; Maximum temperature the air is rarely above 30-35° C; air humidity is 90% only in certain hours of the day, and over 90.% - in the most wet month; dew and fog in the evening and morning. The savanna climate is characterized by a strict periodic alternation of rains and droughts. During periods of drought, the climate of savannas resembles that of steppes, and during periods of rain, 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° C; sea air contains salts.[...]
In polymictic lakes, complete circulation is often observed, resulting from the strong heating of the surface layers of water during the day and cooling at night. This type is typical for the climate of savannas and mountain tropical forests (Lake Albert, Rudolf, Victoria - according to Beadle). In oligomictic lakes, circulation occurs irregularly - in short periods cold weather. These lakes are typical for the zone of tropical rainforests (lakes of Indonesia).[...]
In tropical countries with humid climates, converting some land into agricultural areas is often very difficult. These areas, due to changes in the mode of their use, suffer to a greater or lesser extent from changes in the level of groundwater, soil erosion, disruption 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 creating national parks protected nature. Damage caused environment, coupled with rapid population growth, is causing increasing poverty rural population. Despite many noteworthy efforts, the ongoing destruction of the natural environment cannot be stopped.[...]
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 elevated savannas); b - warm with dry summers (Mediterranean); 7 - humid moderate; G - humid microthermal climate; 8 - cold with wet winter; 9 - cold with dry winter (monsoons); D - polar climate; 16 - myttdpa; 11 - eternal frost.[...]
But not everywhere in tropical zones the climate is arid. On the eastern coasts of the continents, where trade winds blow from the oceans, there is a lot of precipitation (Greater Antilles, eastern coast of Brazil, eastern coast of Africa). The climate of these areas is not much different from the equatorial one, although annual fluctuations temperatures are significant, as there is a significant difference in the height of the sun between seasons. Thanks to a large number precipitation and high temperatures Tropical rainforests grow here.[...]
The distribution of the world's forests by species composition is closely related to climate types. Thus, in humid tropical regions, predominantly deciduous forests grow, distinguished by the extreme diversity of their constituent tree species; in cold and moderately cold areas they predominate coniferous forests consisting of a relatively small number of tree species. Historically developing under conditions of a more or less specific climate, tree species turn out to be adapted to the corresponding climatic conditions. It is known that the same botanical species of tree species, growing in different climatic conditions, can give rise to different climatic ecotypes (races), adapted to exist in conditions of a corresponding difference in climatic type.[...]
Macroclimate is the climate of large areas, such as geographical zones. According to the geographical and orographic location, characteristic macroclimates of tundra, taiga, steppes, deserts, and tropical rainforests were formed.[...]
In terms of completeness of information about climate change, the tropics are much inferior temperate zone. For this reason, it is tempting to assume that at a time when the temperate latitudes were in the grip of dramatic climate changes and glacial invasions, the tropics were in the same state as they are now. This assumption is almost certainly wrong. On the contrary, a picture of changes is emerging vegetation cover, parallel to what happened in temperate zone: During warmer and wetter periods, the area of tropical forests increased, and during cooler and drier periods, when savanna predominated, it decreased. The modern distribution of both plants and animals contains indications of the position these “tropical forest islands surrounded by a savannah sea” once occupied (Fig. 1.6).[...]
This hardy, showy tropical rainforest plant brings a touch of warmth to homes in cooler climates. The exquisite aroma 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 soil groups is associated with widespread climate types 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 lateritic weathering crust under tropical and subtropical forests reaches its maximum thickness - 40-60 m or more. The weathering crust has an equally small thickness in deserts of various latitudes and in polar zones with a nival climate (from the Latin nivalis - snowy, cold). In both places, physical weathering predominates, and the development of the crust does not go beyond the formation of large blocks, rubble and sand.[...]
EQUATORIAL ZONE. Geographical area, located near the equator; on land it is a tropical rainforest climate zone.[...]
Of particular concern to scientists and the public is the destruction of equatorial and sub equatorial forests. Over the past 25 years, their area has decreased by 50%. Annual losses amount to up to 27 million hectares, or 5% of the available amount. Once upon a time, tropical rainforests covered 10% 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 harshness and dryness of the climate. Along with the forests, their inhabitants are also dying, many animal species are dying out completely, and the gene pool is being destroyed.[...]
JUNGLE jungle - tracing paper from Hindi jangal - thickets] - dense, impenetrable tree and shrub forests of areas with humid tropical climate.[ ...]
Jungle (from Sanskrit - jangala - thicket, thicket) - dense thickets of trees and shrubs with a large admixture of cereals (mainly bamboo) and impenetrable forests. Characteristic of areas with humid tropical and subtropical climate. Jungles are especially common in India, Indochina and the Sunda Islands.[...]
Extremely great importance has an annual increase - the annual production of living plant material. One would expect that the greatest increase would come from plant communities with the greatest biomass are forests. However, this is only partly true. Indeed, the maximum increase occurs in the vegetation of permanently humid tropical forests (325 c/ha), but the increase in forests of temperate and especially boreal climates is much less. The increase in vegetation of meadow steppes is very large (137 c/ha, or more than 50% of their biomass). The smallest increase the difference is between deserts (10 c/ha) and tundra (10-25 c/ha). [...]
In very different environmental conditions Representatives of the genus Gibbertia grow, and this is associated with a significant diversity of their life forms. Most species inhabit areas of Australia with arid continental climate.[ ...]
Keeping Dead organic matter on the soil surface under different types of vegetation also varies. A large amount of it is formed under forest communities, but not everywhere, but only in boreal climate conditions (300-350 c/ha). The mass of dead organic matter in a permanently humid tropical forest is 10 times less. The largest amount of dead terrestrial organic matter was found in shrub tundras (835 c/ha); the smallest, which cannot yet be accurately counted, is in deserts.[...]
Succession ends with a stage when all species of the ecosystem, while reproducing, maintain a relatively constant number and no further change in its composition occurs. This equilibrium state is called climax, and the ecosystem is called climax. Under different abiotic conditions, different climax ecosystems are formed. In hot and humid climate it will be a rainforest; in dry and hot conditions it will be a desert. The main biomes of the earth are the climax ecosystems of the corresponding geographical 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 greater 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 throughout the year (i.e., the capacity of the biological cycle) is in tropical rainforests, then in black earth steppes and deciduous forests temperate climate(in oak groves).[...]
In herbaceous and forest communities there is probably a significant proportion solar energy(50-90%) is spent on evaporation of water in the form of transpiration. Loss of water through transpiration may be the limiting factor leading to wilting, especially in dry climates, areas of intensive agriculture, or where soils have poor water holding capacity. However, evaporation cools the leaves and is one of several processes that promote the circulation of nutrients. Other processes are transport of ions through the soil to the roots, transport of ions into the root, movement within the plant and leaching from the leaves (Kozlovsky, 1964, 1968). Some of these processes require metabolic energy, which may limit the rate of transport of water and salts (Fried and Brochart, 1967). Therefore, transpiration is not simply a function of exposed physical surfaces. The forest does not necessarily lose more water than herbaceous vegetation. The role of transpiration as an energy “subsidy” in humid forest conditions was discussed in Chap. 3. If the air is too humid ( relative humidity close to 100%), as, for example, in montane "cloud" tropical forests, trees are stunted and most of the vegetation consists of epiphytes, apparently due to the lack of "transpiration draft" (see G. Odum and Pidgin , 1970).
Plants of equatorial forests cannot but arouse increased interest not only among specialists, but also among ordinary inquisitive travelers from all over the world. And this is not surprising.
Agree, many of us strive to visit overseas countries precisely for these exotic representatives of the flora. For example, the plants of equatorial America or Africa are very different from the herbs, flowers, trees and shrubs that we are used to seeing outside the window of our hometown. They look, smell and bloom completely differently, which means they evoke mixed emotions. You want to take a closer look at them, touch them and photograph them.
Plants of equatorial forests are a topic that can be discussed endlessly. This article is aimed at introducing readers to the most characteristic properties and living conditions of these representatives of the world of flora.
general information
First of all, let's try to define the concept of humid equatorial forests. Plants whose habitats are regions with pronounced equatorial, subequatorial and tropical climates inhabit this type natural area. It is worth paying attention to the fact that in this case, not only herbs, but also numerous trees and shrubs can be classified as various types of flora representatives.
At first glance, it’s hard to even imagine, but here there is up to 2000, or even 10,000 mm of precipitation per year.
These areas of land are characterized by enormous biodiversity; it is here that 2/3 of all plants and animals on our planet live. By the way, not everyone knows that millions of species are still undescribed.
On the lower tier in humid areas there is not enough light, but the undergrowth, as a rule, is weak, so a person can easily move along it. However, if for some reason the leaf canopy is missing or weakened, lower tier can quickly become covered with impenetrable thickets of vines and intricately woven trees. This is called the jungle.
Equatorial forest climate
Animals and plants, as we have already said, are diverse. This is due to the current climate, which means we need to talk about it in more detail.
This zone stretches along the equator with a shift to the south. The average temperature all year round is 24-28 degrees. The climate is quite hot and humid, although the seasons are not clearly defined.
This territory belongs to the region and precipitation falls evenly throughout the year. Such climatic conditions contribute to the development of evergreen vegetation, which is characterized by the so-called complex forest structure.
Flora of the equatorial territories of the planet
As a rule, moist evergreen forests, located in narrow stripes or peculiar spots along the equator, are diverse and contain a huge number of species. It’s hard to imagine that there are currently more than a thousand of them in the Congo Basin and on the coast alone.
Plants of the equatorial forests of the upper tier are represented by giant ficuses and palm trees, of which there are over 200 species. In the lower ones, mainly bananas and tree ferns grow.
The largest plants are often entwined with vines and flowering orchids. By the way, it is worth noting that sometimes in equatorial forests there are up to six tiers. Among the plants there are also epiphytes - mosses, lichens, ferns.
But in the depths of the forest you can find the largest flower on our planet - Rafflesia Arnoldi, the transverse diameter of which reaches 1 meter.
Fauna of the equatorial forest
It is unlikely that anyone will be surprised if we note that the fauna of equatorial forests is, first of all, rich in monkeys. Monkeys, chimpanzees, gorillas, howler monkeys and bonobos are especially common here and in huge quantities.
Of the land inhabitants, you can often find small ungulates; for example, in Africa, tourists often admire okapi, African deer and other unusual animals. The most common predators of the South American jungle, of course, are the jaguar and the puma. But in the African tropics, the owners are fast leopards and huge tigers.
Thanks to wet conditions The environment in the equatorial forests is home to many frogs, lizards and insects. The most common birds are hummingbirds, parrots and toucans.
As for reptiles, who doesn’t know about the pythons of Africa and Asia or the anaconda from the Amazon jungle? In addition, poisonous snakes, alligators, caimans and others are common in equatorial forests. dangerous representatives world of fauna.
What happens if you destroy the plants of equatorial forests?
During the deforestation of the equatorial forest, people, sometimes without realizing it, destroy the habitat of many animals and take food from termites. In addition, this forest also holds back the onset of deserts that are destructive to all living things.
But that's not all. The fact is that moist equatorial forests, although they occupy a relatively small part of the Earth, are the so-called green lungs of our planet. It is here that about 1/3 of the Earth's oxygen is produced, so the destruction of the equatorial forest will cause irreversible environmental consequences, including an increase in the content of the latter, in turn, will lead to an increase average temperature, will increase the likelihood and therefore entail the subsequent flooding of many fertile lands.
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