Natural areas of the earth. Natural zones of the southern continents Natural zones of the world: what is it
geographical eurasia natural area
Geographic zoning is a pattern of differentiation of the geographical (landscape) shell of the Earth, manifested in a consistent and definite change in geographical zones and zones, due, first of all, to changes in the amount of radiant energy from the Sun falling on the Earth’s surface, depending on geographical latitude. Such zoning is inherent in most components and processes of natural territorial complexes - climatic, hydrological, geochemical and geomorphological processes, soil and plant cover and fauna, and partly the formation of sedimentary rocks. A decrease in the angle of incidence of solar rays from the equator to the poles causes the formation of latitudinal radiation belts - hot, two moderate and two cold. The formation of similar thermal and, even more so, climatic and geographical zones is associated with the properties and circulation of the atmosphere, which big influence affects the distribution of land and oceans (the reasons for the latter are azonal). The differentiation of natural zones on land itself depends on the ratio of heat and moisture, which varies not only by latitude, but also from the coasts inland (sector pattern), therefore we can talk about horizontal zoning, a particular manifestation of which is latitudinal zonation, well expressed on the territory of the Eurasian continent.
Each geographical zone and sector has its own set (spectrum) of zones and their sequence. The distribution of natural zones is also manifested in the natural change of altitudinal zones, or belts, in the mountains, which is also initially determined by the azonal factor - relief, however, certain spectra of altitudinal zones are characteristic of certain belts and sectors. Zoning in Eurasia is characterized for the most part as horizontal, with the following zones identified (their name comes from the predominant type of vegetation cover):
Arctic desert zone;
Tundra and forest-tundra zone;
Taiga zone;
Zone of mixed and deciduous forests;
Zone of forest-steppes and steppes;
Semi-desert and desert zone;
Zone of hard-leaved evergreen forests and shrubs (the so-called
"Mediterranean" zone);
Zone of variable-humid (including monsoon) forests;
Zone of humid equatorial forests.
Now all the presented zones will be examined in detail, their main characteristics, be it climatic conditions, vegetation, fauna.
The Arctic desert (“Arktos” translated from Greek means bear) is a natural area part of the Arctic geographical belt, the basin of the Arctic Ocean. This is the northernmost of the natural zones and is characterized by an arctic climate. The spaces are covered with glaciers, rubble and fragments of stones.
The climate of the Arctic deserts is not very diverse. The weather conditions are extremely harsh, with strong winds, little rainfall, very low temperatures: in winter (down to? 60 °C), on average? 30? C in February, the average temperature of even the most warm month close to 0 °C. Snow cover on land lasts almost all year round, disappearing only for a month and a half. Long polar days and nights, lasting five months, and short off-seasons give a special flavor to these harsh places. Only Atlantic currents bring additional heat and moisture to some areas, such as the western shores of Spitsbergen. This state is formed not only due to the low temperatures of high latitudes, but also due to the high ability of snow and ice to reflect heat - albedo. The annual amount of precipitation is up to 400 mm.
Where everything is covered in ice, life seems impossible. But this is not true at all. In places where nunataks emerge from under the ice to the surface, there is a plant world of its own. Mosses, lichens, some types of algae and even cereals and flowering plants live in cracks in rocks where small amounts of soil accumulate, in thawed areas of glacial deposits - moraines, near snowfields. Among them are bluegrass, cotton grass, polar poppy, dryad partridge grass, sedge, dwarf willows, birches, and various types of saxifrage. But the recovery of vegetation is extremely slow. Although during the cold polar summer it manages to bloom and even bear fruit. Numerous birds find shelter and nest on the coastal rocks in the summer, roosting on the rocks " bird markets", - geese, gulls, eiders, terns, waders.
Numerous pinnipeds also live in the Arctic - seals, seals, walruses, elephant seals. Seals feed on fish, swimming to the ice of the Arctic Ocean in search of fish. Their elongated, streamlined body shape helps them move through the water at tremendous speed. The seals themselves are yellowish-gray, with dark spots, and their cubs have beautiful snow-white fur, which they retain until adulthood. Because of her, they received the name squirrels.
The terrestrial fauna is poor: arctic fox, polar bear, lemming. The most famous inhabitant of the Arctic is the polar bear. This is the largest predator on Earth. The length of its body can reach 3 m, and the weight of an adult bear is about 600 kg and even more! The Arctic is the kingdom of the polar bear, where he feels in his element. The absence of land does not bother the bear; its main habitat is the ice floes of the Arctic Ocean. Bears are excellent swimmers and often swim far into the open sea in search of food. The polar bear eats fish and hunts seals, seals, and walrus cubs. Despite its power, the polar bear needs protection; it is listed in both the International and Russian Red Books.
In the high northern latitudes (these are territories and waters lying north of the 65th parallel) there is a natural zone of arctic deserts, a zone of eternal frost. The boundaries of this zone, like the boundaries of the Arctic as a whole, are quite arbitrary. Although the space around the North Pole does not have land, its role here is played by continuous and floating ice. In high latitudes there are islands and archipelagos washed by the waters of the Arctic Ocean, and within their boundaries lie the coastal zones of the Eurasian continent. These pieces of land are almost entirely or for the most part bound by “eternal ice,” or rather, the remnants of huge glaciers that covered this part of the planet during the last ice age. Arctic glaciers in archipelagos sometimes extend beyond the land and into the sea, such as some glaciers in Spitsbergen and Franz Josef Land.
In the Northern Hemisphere, along the outskirts of the Eurasian continent south of the polar deserts, as well as on the island of Iceland, there is a natural tundra zone. Tundra is a type of natural zone that lies beyond the northern limits of forest vegetation, a space with permafrost soil that is not flooded by sea or river waters. The tundra is located north of the taiga zone. The nature of the surface of the tundra is swampy, peaty, rocky. The southern border of the tundra is taken to be the beginning of the Arctic. The name comes from the Sami language and means “dead land”.
These latitudes can be called subpolar; winters here are harsh and long, and summers are cool and short, with frosts. The temperature of the warmest month - July does not exceed +10... + 12 °C; it can snow already in the second half of August, and the established snow cover does not melt for 7-9 months. Up to 300 mm of precipitation falls in the tundra per year, and in areas of Eastern Siberia, where the continental climate increases, their amount does not exceed 100 mm per year. Although there is no more precipitation in this natural zone than in the desert, it falls mainly in the summer and, at such low summer temperatures, evaporates very poorly, so excess moisture is created in the tundra. Frozen over time harsh winter In summer, the ground thaws only a few tens of centimeters, which does not allow moisture to seep deeper, it stagnates, and waterlogging occurs. Even in minor depressions in the relief, numerous swamps and lakes are formed.
Cold summers, strong winds, excess moisture and permafrost determine the nature of vegetation in the tundra. +10… +12°C are the maximum temperatures at which trees can grow. In the tundra zone they acquire special, dwarf forms. On humus-poor infertile tundra-gley soils, dwarf willows and birches with curved trunks and branches, low-growing shrubs and shrubs grow. They press themselves to the ground, densely intertwined with each other. The endless flat plains of the tundra are covered with a thick carpet of mosses and lichens, hiding small trunks of trees, shrubs and grass roots.
As soon as the snow melts, the harsh landscape comes to life, all the plants seem to be in a hurry to use the short warm summer for their growing season. In July the tundra becomes carpeted flowering plants- polar poppies, dandelions, forget-me-nots, mynaria, etc. The tundra is rich in berry bushes - lingonberries, cranberries, cloudberries, blueberries.
Based on the nature of the vegetation, three zones are distinguished in the tundra. Northern arctic tundra It has a harsh climate and very sparse vegetation. The moss-lichen tundra located to the south is softer and richer in plant species, and in the very south of the tundra zone, in the shrub tundra, you can find trees and shrubs reaching a height of 1.5 m. To the south, the shrub tundra is gradually replaced by forest-tundra - a transition zone between tundra and taiga. This is one of the most swampy natural areas, because more precipitation falls here (300-400 mm per year) than can evaporate. Low-growing trees such as birch, spruce, and larch appear in the forest-tundra, but they grow mainly along river valleys. The open spaces are still occupied by vegetation characteristic of the tundra zone. To the south, the area of forests increases, but even there the forest-tundra consists of an alternation of open forests and treeless spaces, overgrown with mosses, lichens, shrubs and shrubs.
Mountain tundras form a high-altitude zone in the mountains of the subarctic and temperate zones. On rocky and gravelly soils from high-altitude open forests they begin as a shrub belt, as in the lowland tundra. Above are moss-lichens with cushion-shaped subshrubs and some herbs. The upper belt of mountain tundras is represented by crustose lichens, sparse squat cushion-shaped shrubs and mosses among stone placers.
The harsh climate of the tundra and the lack of good food force the animals living in these regions to adapt to difficult conditions life. The largest mammals of the tundra and forest-tundra - reindeer. They are easily recognized by the huge horns that not only males, but also females have. The horns first move back, and then bend up and forward, their large processes hang over the muzzle, and the deer can rake snow with them, getting food. Deer see poorly, but have sensitive hearing and a keen sense of smell. Their dense winter fur consists of long, hollow, cylindrical hairs. They grow perpendicular to the body, creating a dense thermal insulation layer around the animal. In the summer, deer grow softer, shorter fur.
Large diverging hooves allow the deer to walk on loose snow and soft ground without falling through. In winter, deer feed mainly on lichens, digging them out from under the snow, the depth of which sometimes reaches 80 cm. They do not refuse lemmings, voles, they can destroy bird nests, and in hungry years they even gnaw each other’s antlers.
Deer lead a nomadic lifestyle. In the summer they feed in the northern tundra, where there are fewer midges and gadflies, and in the fall they return to the forest-tundra, where there is more food and warmer winters. During seasonal transitions, animals cover distances of 1000 km. Reindeer run fast and swim well, which allows them to escape from their main enemies - wolves.
Reindeer of Eurasia are distributed from the Scandinavian Peninsula to Kamchatka. They live in Greenland, on the Arctic islands and on the northern coast of North America.
For a long time, the peoples of the North domesticated reindeer, receiving from them milk, meat, cheese, clothing, shoes, material for tents, vessels for food - almost everything necessary for life. The fat content of the milk of these animals is four times higher than that of cows. Reindeer are very hardy; one reindeer can carry a load weighing 200 kg, walking up to 70 km per day.
Along with reindeer, polar wolves, arctic foxes, arctic hares, white partridges, and polar owls live in the tundra. In summer a lot of people arrive migratory birds Geese, ducks, swans, and waders nest along the banks of rivers and lakes.
Of the rodents, lemmings are especially interesting - touching furry animals the size of a palm. There are three known species of lemmings, which are common in Norway, Greenland and Russia. All lemmings are brown in color, and only the hoofed lemming changes its skin to white in winter. These rodents spend the cold period of the year underground; they dig long underground tunnels and actively reproduce. One female can give birth to up to 36 cubs per year.
In the spring, lemmings come to the surface in search of food. Under favorable conditions, their population can increase so much that there is not enough food for everyone in the tundra. Trying to find food, lemmings make mass migrations - a huge wave of rodents rushes across the endless tundra, and when a river or sea is encountered on the way, the hungry animals, under the pressure of those running after them, fall into the water and die in the thousands. The life cycles of many polar animals depend on the number of lemmings. If there are few of them, the polar owl, for example, does not lay eggs, and arctic foxes - polar foxes - migrate south, to the forest-tundra, in search of other food.
The white, or polar, owl is undoubtedly the queen of the tundra. Its wingspan reaches 1.5 m. Old birds are dazzlingly white, while young ones are variegated in color, both have yellow eyes and a black beak. This magnificent bird flies almost silently, hunting voles, lemmings, and muskrats at any time of the day. She attacks partridges, hares and even catches fish. In summer White Owl lays 6-8 eggs, making a nest in a small depression on the ground.
But due to human activity (and primarily due to oil production, construction and operation of oil pipelines), the danger of environmental disaster looms over many parts of the Russian tundra. Due to fuel leaks from oil pipelines, the surrounding area is polluted; burning oil lakes and completely burnt areas that were once covered with vegetation are often encountered.
Despite the fact that during the construction of new oil pipelines, special passages are made so that deer can move freely, the animals are not always able to find and use them.
Road trains move across the tundra, leaving behind garbage and destroying vegetation. The tundra soil layer damaged by tracked vehicles takes decades to recover.
All this leads to increased pollution of soil, water and vegetation, and a decrease in the number of deer and other inhabitants of the tundra.
Forest-tumndra is a subarctic type of landscape in which, in the interfluves, oppressed woodlands alternate with shrubby or typical tundra. Various researchers consider forest-tundra to be a subzone of either tundra, taiga, and, more recently, tundra forests. Forest-tundra landscapes stretch in a strip from 30 to 300 km wide from the Kola Peninsula to the Indigirka basin, and to the east they are distributed fragmentarily. Despite the low amount of precipitation (200-350 mm), the forest-tundra is characterized by a sharp excess of moisture over evaporation, which determines the widespread occurrence of lakes from 10 to 60% of the subzone area.
Average air temperatures in July are 10-12°C, and in January, depending on the increase in continental climate, from -10° to -40°C. With the exception of rare taliks, the soils are everywhere permafrost. The soils are peaty-gley, peat-swamp, and under open forests - gley-podzolic (podbur).
The flora has the following character: shrub tundras and open forests change due to longitudinal zonation. On the Kola Peninsula - warty birch; east to the Urals - spruce; V Western Siberia-- spruce with Siberian larch; east of Putorana - Daurian larch with lean birch; to the east of the Lena there is Kayander larch with skinny birch and alder, and to the east of Kolyma dwarf cedar is mixed in with them.
The fauna of the forest-tundra is also dominated by lemmings of various species in different longitudinal zones, reindeer, arctic foxes, white and tundra partridges, polar owls and a wide variety of migratory, waterfowl and small birds that settle in bushes. Forest-tundra is a valuable reindeer pasture and hunting grounds.
To protect and study the natural landscapes of the forest-tundra, nature reserves and national parks have been created, including the Taimyr Nature Reserve. Reindeer husbandry and hunting are traditional occupations of the indigenous population, who use up to 90% of the territory for reindeer pastures.
The natural taiga zone is located in the north of Eurasia. Taiga is a biome characterized by the predominance of coniferous forests. It is located in the northern subarctic humid geographical zone. Coniferous trees form the basis of plant life there. In Eurasia, originating on the Scandinavian Peninsula, it spread to the shores of the Pacific Ocean. The Eurasian taiga is the largest continuous forest zone on Earth. It occupies more than 60% of the territory Russian Federation. The taiga contains huge reserves of wood and supplies large amounts of oxygen to the atmosphere. In the north, the taiga smoothly turns into forest-tundra, gradually taiga forests are replaced by open forests, and then by separate groups of trees. The furthest taiga forests enter the forest-tundra are along river valleys, which are most protected from strong northern winds. In the south, the taiga also smoothly transitions into coniferous-deciduous and broad-leaved forests. In these areas, humans have interfered with the natural landscapes for many centuries, so now they represent a complex natural-anthropogenic complex.
On the territory of Russia, the southern border of the taiga begins approximately at the latitude of St. Petersburg, stretches to the upper reaches of the Volga, north of Moscow to the Urals, further to Novosibirsk, and then to Khabarovsk and Nakhodka. Far East, where they are replaced by mixed forests. All of Western and Eastern Siberia, most of the Far East, the mountain ranges of the Urals, Altai, Sayan, Baikal region, Sikhote-Alin, Greater Khingan are covered with taiga forests.
The climate of the taiga zone within the temperate climate zone varies from marine in the west of Eurasia to sharply continental in the east. In the west, there are relatively warm summers (+10 °C) and mild winters (-10 °C), and more precipitation falls than can evaporate. Under conditions of excess moisture, the decay products of organic and mineral substances are carried into the lower soil layers, forming a clarified podzolic horizon, from which the predominant soils of the taiga zone are called podzolic. Permafrost contributes to the stagnation of moisture, so significant areas within this natural zone, especially in the north of European Russia and Western Siberia, are occupied by lakes, swamps and swampy woodlands. Dark coniferous forests growing on podzolic and frozen-taiga soils are dominated by spruce and pine and, as a rule, there is no undergrowth. Twilight reigns under the closing crowns; in the lower tier grow mosses, lichens, herbs, dense ferns and berry bushes - lingonberries, blueberries, blueberries. In the north-west of the European part of Russia, pine forests predominate, and on the western slope of the Urals, which is characterized by large clouds, sufficient precipitation and heavy snow cover, spruce-fir and spruce-fir-cedar forests.
On the eastern slope of the Urals, the humidity is less than on the western, and therefore the composition of forest vegetation here is different: light coniferous forests predominate - mainly pine, in places with an admixture of larch and cedar (Siberian pine).
The Asian part of the taiga is characterized by light coniferous forests. In the Siberian taiga, summer temperatures in a continental climate rise to +20 °C, and in winter in northeastern Siberia they can drop to -50 °C. On the territory of the West Siberian Lowland, predominantly larch and spruce forests grow in the northern part, pine forests in the central part, and spruce, cedar and fir in the southern part. Light coniferous forests are less demanding on soil and climatic conditions and can grow even on infertile soils. The crowns of these forests are not closed, and through them the sun's rays freely penetrate into the lower tier. The shrub layer of the light-coniferous taiga consists of alder, dwarf birches and willows, and berry bushes.
In Central and North-Eastern Siberia, in conditions of harsh climate and permafrost, larch taiga dominates. For centuries, almost the entire taiga zone suffered from the negative impact of human economic activity: slash-and-burn agriculture, hunting, haymaking in river floodplains, selective logging, air pollution, etc. Only in remote areas of Siberia today can one find corners of virgin nature. The balance between natural processes and traditional economic activities, which has developed over thousands of years, is now being destroyed, and the taiga as a natural complex is gradually disappearing.
To generalize, the taiga is characterized by the absence or weak development of undergrowth (since there is little light in the forest), as well as the monotony of the grass-shrub layer and moss cover (green mosses). Species of shrubs (juniper, honeysuckle, currant, willow, etc.), shrubs (blueberries, lingonberries, etc.) and herbs (oxalis, wintergreen) are few in number.
In northern Europe (Finland, Sweden, Norway, Russia) spruce forests predominate. The taiga of the Urals is characterized by light coniferous forests of Scots pine. Siberia and the Far East are dominated by sparse larch taiga with an undergrowth of dwarf cedar, Daurian rhododendron, etc.
The fauna of the taiga is richer and more diverse than the fauna of the tundra. Numerous and widespread: lynx, wolverine, chipmunk, sable, squirrel, etc. Among the ungulates, there are reindeer and red deer, elk, and roe deer; Rodents are numerous: shrews, mice. Common birds include: capercaillie, hazel grouse, nutcracker, crossbills, etc.
In the taiga forest, compared to the forest-tundra, conditions for animal life are more favorable. There are more sedentary animals here. Nowhere in the world, except for the taiga, are there so many fur-bearing animals.
The fauna of the taiga zone of Eurasia is very rich. Both large predators live here - brown bear, wolf, lynx, fox, and smaller predators - otter, mink, marten, wolverine, sable, weasel, ermine. Many taiga animals survive the long, cold and snowy winter in a state of suspended animation (invertebrates) or hibernation (brown bear, chipmunk), and many bird species migrate to other regions. Passerines, woodpeckers, and grouse - capercaillie, hazel grouse, and grouse - constantly live in taiga forests.
Brown bears are typical inhabitants of vast forest areas, not only the taiga, but also mixed forests. There are 125-150 thousand brown bears in the world, two thirds of which live in the Russian Federation. The sizes and colors of the subspecies of brown bears (Kamchatka, Kodiak, grizzly, European brown) are different. Some brown bears reach three meters in height and weigh more than 700 kg. They have a powerful body, strong five-fingered paws with huge claws, a short tail, a large head with small eyes and ears. Bears can be reddish and dark brown, almost black, and in old age (by 20-25 years) the tips of the fur turn gray and the animal becomes gray. Bears eat grass, nuts, berries, honey, animals, carrion, dig up anthills and eat ants. In the fall, bears feed on nutritious berries (they can eat over 40 kg per day) and therefore quickly gain weight, gaining almost 3 kg in weight every day. During the year, bears travel from 230 to 260 kilometers in search of food, and with the approach of winter they return to their dens. Animals make winter “apartments” in natural dry shelters and line them with moss, dry grass, branches, pine needles and leaves. Sometimes male bears sleep outdoors all winter. The brown bear's winter sleep is very light; in fact, it is winter torpor. During the thaw, individuals who have not managed to gain enough fat during the fall go in search of food. Some animals - the so-called connecting rods - do not hibernate at all during the winter, but wander in search of food, posing a great danger to people. In January-February, the female gives birth to from one to four cubs in the den. Babies are born blind, without fur and teeth. They weigh just over 500 grams, but grow quickly on mother's milk. In the spring, furry and nimble cubs emerge from the den. They usually stay with their mother for two and a half to three years, and finally mature by the age of 10.
Wolves are common in many areas of Europe and Asia. They are found in the steppe, desert, mixed forests and taiga. The body length of the largest individuals reaches 160 cm and weight 80 kg. Mostly wolves are gray, but tundra wolves are usually somewhat lighter, and desert wolves are grayish-red. These ruthless predators are distinguished by their developed intelligence. Nature has equipped them with sharp fangs, powerful jaws and strong paws, therefore, when chasing a victim, they are able to run many tens of kilometers and can kill an animal much larger and stronger than themselves. The main prey of the wolf are large and medium-sized mammals, usually ungulates, although they also hunt birds. Wolves usually live in pairs, and in late autumn they gather in packs of 15 - 20 animals.
Lynx is found in the taiga zone from Scandinavia to the shores of the Pacific Ocean. She climbs trees well, swims well and feels confident on the ground. High legs, a strong body, sharp teeth and excellently developed sensory organs make her dangerous predator. The lynx hunts birds, small rodents, less often small ungulates, and sometimes foxes, domestic animals, and gets into herds of sheep and goats. At the beginning of summer, in a deep, well-covered hole, a female lynx gives birth to 2-3 cubs.
The Siberian chipmunk lives in the taiga forests of Siberia - typical representative genus of chipmunks, which is also found in Northern Mongolia, China and Japan. The body length of this funny animal is about 15 cm, and the length of its fluffy tail is 10 cm. On the back and sides, there are 5 longitudinal dark stripes on a light gray or reddish background, characteristic of all chipmunks. Chipmunks make nests under fallen trees or, less commonly, in tree hollows. They feed on seeds, berries, mushrooms, lichens, insects and other invertebrates. For the winter, chipmunks store about 5 kg of seeds and, hibernating in the cold season, do not leave their shelters until spring.
The color of squirrels depends on their habitat. In the Siberian taiga they are reddish or copper-gray with a blue tint, and in European forests they are brown or reddish. The squirrel weighs up to a kilogram, and its body length reaches 30 cm, its tail is about the same length. In winter, the animal’s fur is soft and fluffy, and in summer it is coarser, shorter and shiny. The squirrel is well adapted for life in trees. A long, wide and light tail helps her to deftly jump from tree to tree. The squirrel swims beautifully, raising its tail high above the water. She makes a nest in a hollow or builds a so-called gayno from tree branches, which has the shape of a ball with a side entrance. The squirrel's nest is carefully lined with moss, grass, and rags, so even in severe frosts it is warm there. Squirrels give birth to cubs twice a year; in one litter there are from 3 to 10 squirrels. The squirrel feeds on berries, seeds of coniferous trees, nuts, acorns, mushrooms, and when there is a lack of food, it gnaws the bark from shoots, eats leaves and even lichens, sometimes hunts birds, lizards, snakes, and destroys nests. The squirrel stores up for the winter.
The taiga of Eurasia, mainly the massifs of the Siberian taiga, is called the green “lungs” of the planet, since the oxygen and carbon balance of the surface layer of the atmosphere depends on the state of these forests. To protect and study the typical and unique natural landscapes of the taiga in North America and Eurasia, a number of reserves and national parks, including Wood Buffalo, Barguzinsky Reserve, etc. Industrial timber reserves are concentrated in the taiga, discovered and developed large deposits minerals (coal, oil, gas, etc.). There is also a lot of valuable wood
Traditional occupations of the population are hunting fur-bearing animal, collection of medicinal raw materials, wild fruits, nuts, berries and mushrooms, fishing, forestry, (building houses), cattle breeding.
The zone of mixed (coniferous-deciduous) forests is a natural zone characterized by a symbiosis of coniferous and deciduous forests. The condition for this is the possibility of them occupying specific niches in the ecological system of the forest. As a rule, it is customary to speak of mixed forests when there is an admixture of deciduous or coniferous trees constitutes more than 5% of the total.
Mixed forests, together with taiga and broad-leaved forests, make up the forest zone. The forest stand of a mixed forest is formed by trees of various species. Within the temperate zone, several types of mixed forests are distinguished: coniferous-deciduous forest; secondary small-leaved forest with an admixture of coniferous or broad-leaved trees and mixed forest consisting of evergreen and deciduous tree species. In the subtropics, mainly laurel-leaved and coniferous trees grow in mixed forests.
In Eurasia, the zone of coniferous-deciduous forests is widespread to the south of the taiga zone. Quite wide in the west, it gradually narrows towards the east. Small areas of mixed forests are found in Kamchatka and the south of the Far East. The mixed forest zone is characterized by a climate with cold, snowy winters and warm summer. Winter temperatures in areas of the marine temperate climate are positive, and as they move away from the oceans they drop to -10 °C. The amount of precipitation (400-1000 mm per year) is not much greater than evaporation.
Coniferous-broad-leaved (and in continental regions - coniferous-small-leaved) forests grow mainly on gray forest and soddy-podzolic soils. The humus horizon of soddy-podzolic soils, located between the forest litter (3-5 cm) and the podzolic horizon, is about 20 cm. The forest floor of mixed forests consists of many grasses. Dying and rotting, they constantly increase the humus horizon.
Mixed forests are distinguished by a clearly visible layering, that is, a change in the composition of vegetation along the height. The upper tree layer is occupied by tall pines and spruces, and below grow oaks, lindens, maples, birches, and elms. Under the shrub layer formed by raspberries, viburnum, rose hips, and hawthorn, shrubs, herbs, mosses and lichens grow.
Coniferous-small-leaved forests, consisting of birch, aspen, and alder, are intermediate forests in the process of coniferous forest formation.
Within the mixed forest zone, there are also treeless spaces. Elevated treeless plains with fertile gray forest soils are called opoles. They are found in the south of the taiga and in the zones of mixed and deciduous forests of the East European Plain.
Polesie - low treeless plains, composed of sandy deposits of melted glacial waters, are common in eastern Poland, in Polesie, in the Meshchera Lowland and are often swampy.
In the south of the Russian Far East, where seasonal winds—monsoons—predominate within the temperate climate zone, mixed and broad-leaved forests called the Ussuri taiga grow on brown forest soils. They are characterized by a more complex tiered structure, huge variety species of plants and animals.
The territory of this natural zone has long been developed by humans and is quite densely populated. Agricultural lands, towns, and cities are spread over large areas. A significant part of the forests has been cut down, so the composition of the forest in many places has changed, and the proportion of small-leaved trees in it has increased.
Fauna of mixed and deciduous forests. Animals and birds living in mixed forests are characteristic of the forest zone as a whole. Foxes, hares, hedgehogs and wild boars are found even in well-developed forests near Moscow, and moose sometimes go out onto the roads and on the outskirts of villages. There are a lot of squirrels not only in forests, but also in city parks. Along the banks of rivers in quiet places, away from populated areas, you can see beaver lodges. Mixed forests are also home to bears, wolves, martens, badgers, and a diverse world of birds.
It is not for nothing that the European moose is called a forest giant. Indeed, this is one of the largest ungulates in the forest zone. Average weight a male weighs about 300 kg, but there are giants weighing more than half a ton (the largest moose are East Siberian moose, their weight reaches 565 kg). The males have a head decorated with huge spade-shaped horns. Moose fur is coarse, gray-brown or black-brown in color, with a bright tint on the lips and legs.
Moose prefer young clearings and copses. They feed on branches and shoots of deciduous trees (aspen, willow, rowan), and in winter on pine needles, mosses and lichens. Moose are excellent swimmers; an adult animal can swim for two hours at a speed of about ten kilometers per hour. Moose can dive, searching underwater for tender leaves, roots and tubers of aquatic plants. There are known cases when moose dived for food to a depth of more than five meters. In May-June, the moose cow gives birth to one or two calves; they go with their mother until autumn, feeding on her milk and green food.
The fox is a very sensitive and careful predator. It is about a meter long and has a fluffy tail almost the same size, and triangular ears on its sharp, elongated muzzle. Foxes are most often colored red in various shades, the chest and abdomen are usually light gray, and the tip of the tail is always white.
Foxes prefer mixed forests, alternating with clearings, meadows and ponds. They can be seen near villages, on forest edges, on the edge of a swamp, in groves and bushes among fields. The fox navigates the area mainly with the help of smell and hearing; its vision is much less developed. She is a pretty good swimmer.
Usually the fox settles in abandoned badger holes; less often, it independently digs a hole 2-4 m deep with two or three exits. Sometimes in complex system foxes and badgers settle nearby badger holes. Foxes lead a sedentary lifestyle, often go out hunting at night and at dusk, feed mainly on rodents, birds and hares, and in rare cases attack roe deer cubs. On average, foxes live 6-8 years, but in captivity they can live up to 20 years or longer.
The common badger is found throughout Europe and Asia up to the Far East. The size of an average dog, it has a body length of 90 cm, a tail of 24 cm, and a weight of about 25 kg. At night the badger goes hunting. Its main food is worms, insects, frogs, and nutritious roots. Sometimes he eats up to 70 frogs in one hunt! In the morning the badger returns to the hole and sleeps until the next night. The badger hole is a permanent structure with several floors and about 50 entrances. A central burrow 5-10 m long, lined with dry grass, is located at a depth of 1-3 or even 5 m. The animals carefully bury all waste in the ground. Badgers often live in colonies, and then the area of their burrows reaches several thousand square meters. Scientists believe that some badger burrows are over a thousand years old. By winter, the badger accumulates a significant reserve of fat and sleeps in its hole all winter.
The common hedgehog is one of the most ancient mammals - its age is about 1 million years. The hedgehog has poor eyesight, but a well-developed sense of smell and hearing. To defend itself from enemies, the hedgehog curls up into a prickly ball, which no predator can handle (the hedgehog has about 5,000 spines 20 mm long). In Russia, hedgehogs with gray spines, on which dark transverse stripes are visible, are more common. Hedgehogs live in birch forests with thick grass cover, in thickets of bushes, in old clearings, and in parks. The hedgehog feeds on insects and invertebrates ( earthworms, slugs and snails), frogs, snakes, eggs and chicks of birds nesting on the ground, sometimes berries. Hedgehogs make winter and summer burrows. In winter ones they sleep from October to April, and in summer ones hedgehogs are born. Shortly after birth, the cubs develop soft white needles, and 36 hours after birth, dark-colored needles.
The mountain hare lives not only in forests, but also in the tundra, birch forests, overgrown clearings and burnt areas, and sometimes in steppe bushes. In winter, the brownish or gray color of the skin changes to pure white, only the tips of the ears remain black, and fur “skis” grow on the paws. The mountain hare feeds on herbaceous plants, shoots and bark of willow, aspen, birch, hazel, oak, and maple. The hare does not have a permanent den; in case of danger, it prefers to flee. IN middle lane Usually, twice a summer, a hare gives birth to 3 to 6 cubs. The young become adults after wintering. The number of white hare varies significantly from year to year. During years of high numbers, hares severely damage young trees in forests and make mass migrations.
Deciduous forest is a forest in which there are no coniferous trees.
Deciduous forests are common in fairly humid areas with mild winters. Unlike coniferous forests, a thick layer of litter does not form in the soils of deciduous forests, since a warmer and more humid climate contributes to the rapid decomposition of plant residues. Although leaves fall annually, the mass of deciduous litter is not much greater than that of conifers, since deciduous trees are more light-loving and grow less frequently than conifers. Deciduous litter, compared to coniferous litter, contains twice as much nutrients, especially calcium. Unlike coniferous humus, biological processes with the participation of earthworms and bacteria actively occur in less acidic deciduous humus. Therefore, almost all the litter decomposes by spring, and a humus horizon is formed, connecting nutrients in the soil and preventing their leaching.
Deciduous forest is divided into broad-leaved forests and small-leaved forests.
European broadleaf forests are endangered forest ecosystems. Just a few centuries ago they occupied most Europe and were among the richest and most diverse on the planet. In the XVI - XVII centuries. natural oak forests grew over an area of several million hectares, and today, according to forest fund records, there are no more than 100 thousand hectares left. So, over several centuries, the area of these forests has decreased tenfold. Formed by deciduous trees with wide leaf blades, broad-leaved forests are common in Europe, Northern China, Japan and the Far East. They occupy an area between mixed forests in the north and steppes, Mediterranean or subtropical vegetation in the south.
Broad-leaved forests grow in areas with humid and moderately humid climates, which are characterized by uniform distribution precipitation (400 to 600 mm) throughout the year and relatively high temperatures. The average temperature in January is -8...0 °C, and in July +20...+24 °C. Moderately warm and humid climatic conditions, as well as the active activity of soil organisms (bacteria, fungi, invertebrates) contribute to the rapid decomposition of leaves and the accumulation of humus. Under broad-leaved forests, fertile gray forest and brown forest soils, and less commonly chernozems, are formed.
The upper tier of these forests is occupied by oak, beech, hornbeam and linden. Ash, elm, maple, and elm are found in Europe. The undergrowth is formed by shrubs - hazel, warty euonymus, and forest honeysuckle. The dense and tall grass cover of European broad-leaved forests is dominated by pine grass, green grass, hoofweed, lungwort, woodruff, hairy sedge, spring ephemeroids: corydalis, anemone, snowdrop, scilla, goose onion and etc.
Modern broad-leaved and coniferous-deciduous forests formed five to seven thousand years ago, when the planet warmed and broad-leaved tree species were able to move far to the north. In subsequent millennia, the climate became colder and the area of broad-leaved forests gradually decreased. Since the most fertile soils of the entire forest zone formed under these forests, the forests were intensively cut down, and their place was taken by arable land. In addition, oak, which is a very durable wood, was widely used in construction.
The reign of Peter I became for Russia the time of the creation of a sailing fleet. The “royal idea” required a large amount of high-quality wood, so the so-called ship groves were strictly protected. Forests that were not included in protected areas were actively cut down by residents of the forest and forest-steppe zones for arable land and meadows. In the middle of the 19th century. The era of the sailing fleet ended, ship groves were no longer protected, and forests began to be cleared even more intensively.
By the beginning of the 20th century. Only fragments of the once unified and vast belt of broad-leaved forests have survived. Even then they tried to grow new oaks, but this turned out to be difficult: young oak groves died due to frequent and severe droughts. Research conducted under the guidance of the great Russian geographer V.V. Dokuchaev, showed that these disasters were associated with large-scale deforestation and, as a consequence, changes in the hydrological regime and climate of the territory.
Nevertheless, even in the 20th century, the remaining oak forests were intensively cut down. Insect pests and cold winters at the end of the century made the extinction of natural oak forests inevitable.
Today, in some areas where broad-leaved forests once grew, secondary forests and artificial plantations, dominated by coniferous trees, have spread. It is unlikely that it will be possible to restore the structure and dynamics of natural oak forests not only in Russia, but throughout Europe (where they have experienced even stronger anthropogenic influence).
The fauna of broad-leaved forests is represented by ungulates, predators, rodents, insectivores, and bats. They are distributed predominantly in those forests where living conditions are least modified by humans. Moose, red and sika deer, roe deer, fallow deer, and wild boar live here. Wolves, foxes, martens, hori, stoats and weasels represent a group of predators in deciduous forests. Among the rodents there are beavers, nutria, muskrats, and squirrels. The forests are inhabited by rats and mice, moles, hedgehogs, shrews, as well as various types of snakes, lizards and marsh turtles. The birds of broad-leaved forests are diverse. Most of them belong to the order of passerines - finches, starlings, tits, swallows, flycatchers, warblers, larks, etc. Other birds also live here: crows, jackdaws, magpies, rooks, woodpeckers, crossbills, as well as large birds- hazel grouse and black grouse. Among the predators there are hawks, harriers, owls, owls and eagle owls. The swamps are home to waders, cranes, herons, various species of ducks, geese and seagulls.
Red deer previously lived in forests, steppes, forest-steppes, semi-deserts and deserts, but deforestation and plowing of the steppes led to their numbers sharply declining. Red deer prefer light, mainly deciduous forests. The body length of these graceful animals reaches 2.5 m, weight - 340 kg. Deer live in a mixed herd of about 10 individuals. The herd is most often headed by an old female, with whom her children of different ages live.
In autumn, males gather a harem. Their roar, reminiscent of the sound of a trumpet, can be heard 3-4 km away. Having defeated rivals, the deer acquires a harem of 2-3, and sometimes up to 20 females - this is how the second type of reindeer herd appears. At the beginning of summer, a doe gives birth to a fawn. It weighs 8-11 kg and grows very quickly up to six months. A newborn fawn is covered with several rows of light spots. From one year on, males begin to develop antlers; after a year, deer shed their antlers, and new ones immediately begin to grow. Deer eat grass, leaves and shoots of trees, mushrooms, lichens, reeds and saltwort; they will not refuse wormwood, but pine needles are destructive for them. In captivity, deer live up to 30 years, and in natural conditions no more than 15.
Beavers -- large rodents-- common in Europe and Asia. The beaver's body length reaches 1 m, weight - 30 kg. The massive body, flattened tail and swimming membranes on the toes of the hind legs are maximally adapted to the aquatic lifestyle. Beaver fur is from light brown to almost black; animals lubricate it with a special secretion, protecting it from getting wet. When a beaver dives into water, its ears fold lengthwise and its nostrils close. A diving beaver uses air so economically that it can stay under water for up to 15 minutes. Beavers settle on the banks of slowly flowing rivers forest rivers, oxbow lakes and lakes, preferring reservoirs with abundant aquatic and coastal vegetation. Beavers make burrows or huts near water, the entrance to which is always located under the surface of the water. In reservoirs with unstable water levels below their “houses,” beavers build famous dams. They regulate the flow so that the hut or hole can always be accessed from the water. Animals easily gnaw branches and fell large trees, gnawing them at the base of the trunk. A beaver fells an aspen with a diameter of 5-7 cm in 2 minutes. Beavers feed on aquatic herbaceous plants - reeds, egg capsules, water lilies, iris, etc., and in the fall they cut down trees, preparing food for the winter. In the spring, the beaver gives birth to beaver cubs, which can swim within two days. Beavers live in families; only in the third year of life do young beavers leave to start their own family.
Wild pigs - wild boars - are typical inhabitants of deciduous forests. The boar has a huge head, an elongated muzzle and a long strong snout ending in a movable “patch”. The beast's jaws are equipped with serious weapons - strong and sharp triangular fangs, curved up and back. Boars' vision is poorly developed, and their sense of smell and hearing is very subtle. Boars may encounter a hunter standing motionless, but will hear even the slightest sound made by him. Boars reach a length of 2 m, and some individuals weigh up to 300 kg. The body is covered with elastic, durable bristles of a dark brown color.
They run quite fast, swim excellently and are able to swim across a body of water several kilometers wide. Boars are omnivorous animals, but their main food is plants. Wild boars are very fond of acorns and beech nuts, which fall to the ground in the fall. They do not refuse frogs, worms, insects, snakes, mice and chicks.
Piglets are usually born in mid-spring. They are covered on the sides with longitudinal dark brown and yellow-gray stripes. After 2-3 months, the stripes gradually disappear, the piglets first become ash-gray and then black-brown
Small-leaved forests are forests formed by deciduous (summer-green) trees with narrow leaf blades.
Tree species are represented mainly by birch, aspen and alder; these trees have small leaves (compared to oak and beech).
Distributed in the forest zone of the West Siberian and East European plains, widely represented in the mountains and plains of the Far East, they are part of the Central Siberian and West Siberian forest-steppe, forming a strip of birch forests (kolki). Small-leaved forests make up a strip of deciduous forests that stretches from the Urals to the Yenisei. In Western Siberia, small-leaved forests form a narrow subzone between the taiga and forest-steppe. Ancient stone-birch forests in Kamchatka form the upper forest belt in the mountains.
Small-leaved forests are light-colored forests, they are distinguished by a wide variety of grass cover. These ancient forests were later replaced by taiga forests, but under human influence on taiga forests (clearing of taiga forests and fires) they again occupied large areas. Small-leaved forests, due to the rapid growth of birch and aspen, have good renewability.
Unlike birch forests, aspen forests are very resistant to human influence, since aspen reproduces not only by seeds, but also vegetatively; they are characterized by the highest average growth rates.
Small-leaved forests often grow in floodplains, where they are most widely represented by willow trees. They stretch along the riverbeds for many kilometers in some places and are formed by several species of willows. Most often these are trees or large shrubs with narrow leaves that develop long shoots and have high growth energy.
Forest-steppe is a natural zone of the Northern Hemisphere, characterized by a combination of forest and steppe areas.
In Eurasia, forest-steppes stretch in a continuous strip from west to east from the eastern foothills of the Carpathians to Altai. In Russia, the border with the forest zone passes through cities such as Kursk and Kazan. To the west and east of this strip, the continuous extension of the forest-steppe is disrupted by the influence of the mountains. Certain areas of forest-steppes are located within the Middle Danube Plain and a number of intermountain basins Southern Siberia, Northern Kazakhstan, in Mongolia and the Far East, and also occupy part of the Songliao Plain in northeast China. The climate of the forest-steppe is temperate, usually with moderately hot summers and moderately cool winters. Evaporation slightly prevails over precipitation.
Forest-steppe is one of the zones that make up the Temperate Zone. The temperate zone implies the presence of four seasons - winter, spring, summer and autumn. In the temperate zone, the change of seasons is always clearly expressed.
The climate of the forest-steppe is usually temperate continental. Annual precipitation is 300--400 mm per year. Sometimes evaporation is almost equal to precipitation. Winter in the forest-steppe is mild, the average January temperature is? 7 degrees in the city of Kharkov, Ukraine (the southern border of the forest-steppe) to about? 10 degrees in Orel, where the mixed forest zone begins. Sometimes in the forest-steppe in winter both severe frosts and mild winters can rage. The absolute minimum in the forest-steppe zone is usually equal to?36?40 degrees. Summer in the forest-steppe is sometimes hot and dry. Sometimes it can be cold and rainy, but this is rare. Most often, summer is characterized by fickle, unstable weather, which can be very different, depending on the activity of certain atmospheric processes. The average July temperature, depending on the location, ranges from 19.50C to 250C. The absolute maximum in the forest-steppe is about 37-39 degrees in the shade. However, heat in the forest-steppe occurs less often than extreme cold, while in the steppe zone it is the other way around. One of the features of the forest-steppe is that the flora and fauna of the forest-steppe is an average between the flora and fauna of the mixed forest zone and the steppe zone. Both drought-resistant plants and plants characteristic of the forest, more northern, zone grow in the forest-steppe. The same applies to the animal world.
I will give a description, as well as a comparative description of steppes and deserts, in the second part of this chapter. Now let's move on to considering the natural zone - semi-desert.
Semi-desert, or desert steppe, is a type of landscape that forms in an arid climate.
Semi-deserts are characterized by the absence of forests and specific vegetation and soil cover. They combine elements of steppe and desert landscapes.
Semi-deserts are found in temperate, subtropical and tropical zones of the Earth and form a natural zone located between the steppe zone in the north and the desert zone in the south.
In the temperate zone, semi-deserts are located in a continuous strip from west to east of Asia from the Caspian lowland to the eastern border of China. In the subtropics, semi-deserts are widespread on the slopes of plateaus, plateaus and highlands (Anatolian Plateau, Armenian Plateau, Iranian Plateau, etc.).
Semi-desert soils, formed in dry and semi-arid climates, are rich in salts, since precipitation is small and salts are retained in the soil. Active soil formation is possible only where soils receive additional moisture from rivers or groundwater. Compared to atmospheric precipitation, groundwater and river waters there are much saltier. Due to the high temperature, evaporation is high, during which the soil dries out and salts dissolved in water crystallize.
The high salt content causes the soil to become alkaline, to which plants have to adapt. Most cultivated plants cannot tolerate such conditions. Sodium salts are especially harmful, since sodium prevents the formation of a granular soil structure. As a result, the soil turns into a dense, structureless mass. In addition, excess sodium in the soil prevents physiological processes and plant nutrition.
The highly sparse vegetation cover of a semi-desert often appears in the form of a mosaic consisting of perennial xerophytic grasses, turf grasses, saltworts and wormwoods, as well as ephemerals and ephemeroids. Succulents, mainly cacti, are common in America. In Africa and Australia, thickets of xerophytic shrubs (see Scrub) and sparse low-growing trees (acacia, doum palm, baobab, etc.) are typical.
Among the animals of the semi-desert, hares, rodents (gophers, jerboas, gerbils, voles, hamsters) and reptiles are especially numerous; from ungulates - antelopes, bezoar goat, mouflon, wild ass, etc. small predators ubiquitous: jackal, striped hyena, caracal, steppe cat, fennec fox, etc. Birds are quite diverse. Many insects and arachnids (karakurt, scorpions, phalanges).
To protect and study the natural landscapes of the world’s semi-deserts, a number of national parks and reserves have been created, including the Ustyurt Nature Reserve, Tiger beam, Aral-Paigambar. The traditional occupation of the population is pasture farming. Oasis agriculture is developed only on irrigated lands (near water bodies).
The subtropical climate of the Mediterranean is dry, precipitation in the form of rain falls in winter, even mild frosts are extremely rare, summers are dry and hot. The subtropical forests of the Mediterranean are dominated by thickets of evergreen shrubs and low trees. Trees stand sparsely, and various herbs and shrubs grow wildly between them. Junipers, noble laurel, strawberry trees that shed their bark annually, wild olives, delicate myrtle, and roses grow here. These types of forests are characteristic mainly in the Mediterranean, and in the mountains of the tropics and subtropics.
The subtropics on the eastern edges of the continents are characterized by a more humid climate. Atmospheric precipitation falls unevenly, but there is more rain in the summer, that is, at a time when vegetation especially needs moisture. Dense humid forests of evergreen oaks, magnolias, and camphor laurel predominate here. Numerous lianas, thickets of tall bamboos and various shrubs enhance the uniqueness of the humid subtropical forest.
Subtropical forest differs from humid tropical forests in lower species diversity, a decrease in the number of epiphytes and lianas, as well as the appearance of coniferous and tree ferns in the forest stand.
Moist evergreen forests are located in narrow stripes and spots along the equator. The largest tropical rain forests exist in the Amazon River basin (Amazon A tropical forest), in Nicaragua, in the southern part of the Yucatan Peninsula (Guatemala, Belize), for the most part Central America(where they are called "selva"), in equatorial Africa from Cameroon to the Democratic Republic of the Congo, in many areas of Southeast Asia from Myanmar to Indonesia and Papua New Guinea, in the Australian state of Queensland.
Tropical rainforests are characterized by:
· continuous vegetation growth throughout the year;
· diversity 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, poorly developed bark, buds not protected by bud scales, in monsoon forests- deciduous trees;
· formation of flowers and then fruits directly on trunks and thick branches (cauliflory).
“Green Hell” - this is what many travelers of past centuries who visited here called these places. Tall multi-tiered forests stand like a solid wall, under the thick crowns of which there is constantly darkness, monstrous humidity, constant high temperatures, there is no change of seasons, and rainfalls regularly fall with an almost continuous stream of water. The forests of the equator are also called permanent rain forests.
The upper floors are at a height of up to 45 m and do not have a closed cover. As a rule, the wood of these trees is the strongest. Below, at a height of 18-20 m, there are tiers of plants and trees, forming a continuous closed canopy and almost preventing sunlight from passing down to the ground. The rarer lower zone is located at an altitude of about 10 m. Shrubs and herbaceous plants, such as pineapples and bananas, and ferns, grow even lower. Tall trees have thickened, overgrown roots (they are called plank-shaped), which help the gigantic plant maintain a strong connection with the soil.
In warm and humid climate The decomposition of dead plants occurs very quickly. From the resulting nutritional composition, substances for the life of the gyl plant are taken. Among such landscapes flow the deepest rivers on our planet - the Amazon in the rural areas of South America, the Congo in Africa, the Brahmaputra in Southeast Asia.
Partially the rain forests have already been cleared. In their place, man cultivates various cultures, including coffee, oil palm and rubber palms.
Like vegetation, the fauna of humid equatorial forests is located at different altitude levels of the forest. The less populated lower tier is home to various insects and rodents. In India, Indian elephants live in such forests. They are not as large as African ones and can move under the cover of multi-story forests. Hippos, crocodiles and water snakes live in deep rivers and lakes and on their banks. Among rodents there are species that live not on the ground, but in the crowns of trees. They acquired devices that allow them to fly from branch to branch - leathery membranes similar to wings. Birds are very diverse. Among them there are very small bright sunbirds that extract nectar from flowers, and quite large birds, such as a huge turaco or banana-eater, a hornbill with a powerful beak and a growth on it. Despite its size, this beak is very light, like the beak of another forest dweller - the toucan. The toucan is very beautiful - bright yellow neck plumage, green beak with a red stripe, and turquoise skin around the eyes. And of course, one of the most common birds of moist evergreen forests is a variety of parrots.
Monkey. When jumping from branch to vine, monkeys use their paws and tails. Chimpanzees, monkeys, and gorillas live in the equatorial forests. The permanent habitat of gibbons is at an altitude of about 40-50 m above the ground, in the crowns of trees. These animals are quite light (5-6 kg) and literally fly from branch to branch, swinging and clinging with flexible front paws. Gorillas are the most major representatives monkeys Their height exceeds 180 cm, and they weigh much more than a person- up to 260 kg. Despite the fact that their impressive size does not allow gorillas to jump along branches as easily as orangutans and chimpanzees, they are quite fast. Gorilla packs live primarily on the ground, roosting in branches only to rest and sleep. Gorillas only eat plant foods, which contains a lot of moisture and allows them to quench their thirst. Adult gorillas are so strong that large predators are afraid to attack them.
Anaconda. The monstrous size (up to 10 meters) of the anaconda allows it to hunt large animals. Usually these are birds, other snakes, small mammals that come to a watering hole, but crocodiles and even people can be among the victims of the anaconda. When attacking a victim, pythons and anacondas first strangle it; and then gradually swallow, “putting on” the body of the prey like a glove. Digestion is slow, so these huge snakes go without food for a long time. Anacondas can live up to 50 years. Boa constrictors give birth to live young. In contrast, pythons that live in the humid forests of India, Sri Lanka, and Africa lay eggs. Pythons also achieve very large sizes and can weigh up to 100 kg.
Comparative analysis of steppe and desert zones
In the process of writing this course work, a comparison of two natural zones was carried out and the following picture was obtained. It will be presented in table form (Appendix 1).
The common features are:
1) a type of landscape characterized by a flat surface (only with small hills)
2) complete absence of trees
3) similar fauna (both in species composition and in some ecological features)
4) similar humidification conditions (both zones are characterized by excessive evaporation and, as a consequence, insufficient moisture)
5) it is possible to distinguish the types of these zones (for example, in the forest-steppe zone it is impossible to indicate additional types)
6) the location of the steppes and deserts of Eurasia in the temperate zone (with the exception of the desert territories of the Arabian Peninsula)
The differences are as follows:
1) latitudinal localization: deserts are located further south than the steppe zone
2) a significant difference is the types of soils: steppes have chernozems, and deserts have brown soils
3) steppe soils have a high humus content, and desert soils are highly saline
4) the climate regime is also not the same: in the steppe one can observe a sharp change in seasons, while in deserts a temperature imbalance is observed throughout the day
5) the amount of precipitation in the steppe is much higher
6) grasses growing in the steppe form an almost closed carpet; in deserts, the distance between individual plants can reach several tens of meters.
The earth's surface and moisture conditions in different parts of the continents, natural zones do not form continuous strips parallel to the equator. Only in and on some large plains do they extend in the latitudinal direction, replacing each other from north to south. More often they change in the direction from the coasts of the oceans to the interior of the continents, and sometimes they stretch almost along the meridians.
Natural zones are also formed in: from the equator to the poles, the properties of surface waters, the composition of vegetation and fauna change. There is also. However, oceanic natural complexes do not have pronounced external differences.
There is great diversity on Earth. However, against the background of this diversity, large parts stand out - natural areas and. This is due to the different ratio of heat and moisture that the earth's surface receives.
Formation of natural areas
The uneven distribution of solar heat over the Earth's surface is the main reason for the heterogeneity of the geographical envelope. In almost every landmass, the oceanic parts are better moistened than the interior, continental areas. Humidification depends not only on the amount of precipitation, but also on the ratio of heat and moisture. The warmer it is, the more moisture that falls with precipitation evaporates. The same amount of precipitation can lead to excessive moisture in one zone and insufficient moisture in another. Thus, the annual precipitation amount of 200 mm in the cold subarctic zone is excessive (swamps are formed), and in hot tropical zones it is sharply insufficient (deserts exist).
Due to differences in the amount of solar heat and moisture, natural zones are formed within geographic zones - large areas with uniform temperature and moisture conditions, similar surface and groundwater characteristics, and fauna.
Features of the natural zones of the continents
In the same natural areas on different continents, the vegetation and fauna have similar features.
At the same time, the characteristics of the distribution of plants and animals, in addition to climate, are influenced by other factors: geological history continents, relief and features of rocks, people. The unification and separation of continents, changes in their topography and climate in the geological past became the reason that different species of plants and animals live in similar natural conditions, but on different continents. For African savannas, for example, antelopes, buffalos, zebras, African ostriches are typical, and in South America several species of deer, armadillos and an ostrich-like flightless bird rhea. On each continent there are endemic species (endemics), characteristic only of that continent.
Under the influence of human activity, the geographical environment undergoes significant changes. To preserve representatives of the organic world and typical natural complexes, specially protected areas, reserves, etc. are created in all natural zones of the world. national parks, in contrast, nature conservation is combined with tourism and people's recreation.
Remember:
Question: What is a natural complex?
Answer: A natural complex is a relatively homogeneous area of the earth’s surface, the unity of which is determined by its geographical location, general history development and modern similar natural processes. All components of nature interact within the natural complex: Earth's crust with its inherent structure in a given place, the atmosphere with its own properties (the climate characteristic of this place), water, the organic world. As a result, each natural complex is a new integral formation that has certain characteristics that distinguish it from others. Natural complexes within the land are usually called natural territorial complexes (NTC). On the territory of Africa there are large natural complexes - the Sahara, the East African Highlands, the Congo Basin (Equatorial Africa), etc. Formed in the ocean and another body of water (lake, river) - natural aquatic (NAC); natural-anthropogenic landscapes (NAL) are created by human economic activity on a natural basis.
Question: What do the terms “latitudinal zonation” and “altitudinal zonation” mean?
Answer: Altitudinal zonation is a natural change in natural complexes in the mountains associated with changes climatic conditions in height. The number of altitudinal zones depends on the height of the mountains and their position in relation to the equator. The change in altitudinal zones and the order of their placement are similar to the change in natural zones on the plains, although they have some features associated with the nature of the mountains, as well as with the existence of altitudinal belts that have no analogues in the lowland territories.
Question: What kind of appearance? natural component give names to natural areas?
Answer: A natural zone (geographical zone) is a land area (part of a geographical zone) with certain conditions of temperature and moisture (the ratio of heat and moisture). It is distinguished by the relative homogeneity of flora and fauna and soils, precipitation and runoff regimes, and the characteristics of exogenous processes. The change of natural zones on land is subject to the laws of latitudinal (geographical) zoning, as a result of which natural zones on the plains naturally replace each other either in the latitudinal direction (from the poles to the equator) or from the oceans to the interior of the continents. Most zones are named after the predominant type of vegetation (for example, tundra zone, coniferous forest zone, savanna zone, etc.).
My geographical research:
Question: Which continent has the largest set of natural areas and which has the smallest?
Answer: The Eurasian continent has the largest set of natural zones.
The continent of Antarctica has the smallest set of natural areas.
Question: Which continents are close to each other in terms of their set of natural zones?
Answer: In terms of the set of natural zones, the continents of Eurasia and North America are close to each other.
Question: On which continents the location of natural zones is close to the latitudinal one?
Answer: There are not so many areas in which natural zones have a precise latitudinal extension and they occupy very limited areas on the Earth’s surface. In Eurasia, such areas include East End Russian Plain and West Siberian Plain. On the Ural ridge separating them, latitudinal zoning is disrupted by vertical zonality. Within North America, the areas in which natural zones have a strictly latitudinal position are even smaller than in Eurasia: latitudinal zoning is expressed with sufficient clarity only between 80 and 95° W. e. In equatorial Africa, areas with zones stretching strictly from west to east are significant, they occupy the western (large) part of the continent, and do not extend to the east further than 25° east. d. In the southern part of the continent, the areas of zones elongated in longitude extend almost to the tropics. In South America and Australia there are no areas with clearly defined latitudinal zonality; there are only boundaries of zones that are similar in longitude in extent (in the southern part of Brazil, Paraguay and Argentina, as well as in the central part of Australia). So, the location of natural zones in the form of strips stretching strictly from west to east is observed in the following conditions: 1) on plains, 2) in areas of temperate continentality, remote from advection centers, where conditions of heat and moisture are close to average latitudinal values, and 3) in areas where the amount of average annual precipitation varies from north to south.
Areas that meet such conditions have a limited distribution on the Earth's surface, and therefore latitudinal zoning in its pure form is relatively rare.
Question: On which continents do natural zones have a nearly meridional strike?
Answer: Distance from the oceans and the peculiarities of the general circulation of the atmosphere are the main reasons for the meridional change of natural zones; in Eurasia, where the land reaches its maximum size, the meridional change of natural zones can be traced especially well.
In the temperate zone, westerly transport brings moisture relatively uniformly to the western coasts. On the eastern coasts there is a monsoon circulation (rainy and dry seasons). When moving inland, the forests of the western coast give way to steppes, semi-deserts and deserts. As you approach the east coast, forests reappear, but of a different type.
Questions and tasks:
Question: What determines the moisture content of areas? How does hydration affect natural complexes?
Answer: Humidification of territories depends on the amount of precipitation, the ratio of heat and moisture. The warmer it is, the more moisture evaporates.
Equal amounts of precipitation in different belts leads to different consequences: for example, 200 ml. precipitation in the cold subarctic zone is excessive (can lead to the formation of swamps), and in the tropical zone it is too insufficient (can lead to the formation of deserts).
Question: Why do natural zones on continents not always change consistently from north to south?
Answer: The location of natural zones on continents is subject to the law of broad zonality, that is, they change from north to south with an increase in the amount of solar radiation. However, there is also significant differences, are explained by the conditions of atmospheric circulation over the continent, some natural zones replace each other from west to east (along the meridianity), because the eastern and western outskirts of the continent are the most humid, and the interior areas are much drier.
Question: Are there natural complexes in the ocean and why?
Answer: In the ocean there is a division into natural belts or zones, it is similar to the division according to the principle of latitudinal zonation of natural land zones, only without distinguishing climate types.
That is, arctic, subarctic, northern and southern temperate, northern and southern subtropical, northern and southern tropical, northern and southern subequatorial, equatorial, subantarctic, antarctic.
In addition, large and smaller natural complexes are distinguished: the largest are oceans, smaller ones are seas, even smaller ones are bays, straits, the smallest are parts of bays, and so on.
In addition, the law of altitudinal zonation is also valid in the ocean, as on land, which makes it possible to divide the natural complexes of the ocean into littoral complexes (coastal waters, shallow waters), pelagic zones (surface waters in the open sea), bathyal zones (medium deep areas of the oceans) and abyssal zones (the deepest waters). parts of the ocean).
Natural area - a territory with similar conditions of temperature and moisture, which determine generally homogeneous soils, vegetation and fauna. On the plains, the zones extend in the latitudinal direction, naturally replacing each other from the poles to the equator. Often, significant distortions in the pattern of the zone are introduced by the relief and the relationship between land and sea.
Arctic and Antarctic deserts . These are cold deserts with very low air temperatures in the Arctic and Antarctica. In this area, snow and ice persist almost all year round. In the warmest month - August - in the Arctic the air temperature is close to 0°C. Ice-free areas are bound by permafrost. Very intense frost weathering. There is little precipitation - from 100 to 400 mm per year in the form of snow. In this zone, the polar night lasts up to 150 days. Summer is short and cold. Only 20 days, rarely 50 days a year, the air temperature exceeds 0°C. The soils are thin, underdeveloped, rocky, and there are widespread scatterings of coarsely broken material. Less than half of the Arctic and Antarctic deserts are covered with sparse vegetation. It is devoid of trees and bushes. Crucible lichens, mosses, various algae, and only some flowering plants are common here. The animal world is richer than the plant world. These are polar bears, arctic foxes, polar owls, deer, seals, and walruses. Among the birds, there are penguins, eiders and many other birds that nest on rocky shores and form “bird colonies” in the summer. In the ice desert zone, marine animals are hunted; among birds, eiders are of particular interest, with their nests lined with down. Eider down is collected from abandoned nests to produce clothing worn by polar sailors and pilots. In the icy desert of Antarctica there are Antarctic oases. These are areas of the continental coastal strip free from ice cover, with an area of several tens to hundreds of square meters. kilometers. The organic world of oases is very poor; there are lakes.
Tundra. This is an area that lies within parts of the Arctic and subarctic zones in the Northern Hemisphere; in the Southern Hemisphere, the tundra is distributed only on some islands. This is an area with a predominance of moss-lichen vegetation, as well as low-growing perennial grasses, shrubs and low bushes. The trunks of shrubs and the roots of grasses are hidden in the moss and lichen turf.
The climate of the tundra is harsh, the average July temperature only in the south of the natural zone does not exceed +11°C, snow cover lasts 7-9 months. Precipitation amounts to 200-400 mm, and in some places up to 750 mm. main reason treeless tundra - low air temperatures combined with high relative humidity, strong winds, widespread permafrost. The tundra also creates unfavorable conditions for the germination of seeds of woody plants on the moss-lichen cover. Plants in the tundra are pressed to the surface of the soil, forming densely intertwined shoots in the form of a pillow. In July, the tundra is covered with a carpet of flowering plants. Due to excess moisture and permafrost, there are many swamps in the tundra. On the warmed banks of rivers and lakes you can find poppies, dandelions, polar forget-me-nots, and pink myrtle flowers. Based on the predominant vegetation in the tundra, 3 zones are distinguished: arctic tundra , characterized by sparse vegetation due to the severity of the climate (in July +6°C); moss-lichen tundra , characterized by richer vegetation (in addition to mosses and lichens, sedge, bluegrass, and creeping willow are found here), and shrub tundra , located in the south of the tundra zone and characterized by richer vegetation, which consists of thickets of willow and alder bushes, which in some places rise to the height of a person. In areas of this subzone, shrubs are an important source of fuel. The soil of the tundra zone is predominantly tundra-gley, characterized by gleying (see “Soils”). She is infertile. Frozen soils with a thin active layer are widespread. The fauna of the tundra is represented by reindeer, lemmings, arctic foxes, ptarmigan, and in summer - many migratory birds. Shrub tundra gradually turns into forest-tundra.
Forest-tundra . This is a transition zone between the tundra and the temperate forest zone. It is distributed in the Northern Hemisphere in North America and Eurasia. The climate is less severe than in the tundra: the average July temperature here is +10-14°C. The annual precipitation is 300-400 mm. There is more precipitation in the forest-tundra than evaporates, so the forest-tundra is characterized by excessive moisture; it is one of the most swampy natural zones. Snow cover lasts for more than six months. Floods on the rivers of the forest-tundra usually occur in the summer, since the rivers of this zone are fed by melt water, and the snow melts in the forest-tundra in the summer. Woody vegetation that appears in this zone grows along river valleys, since rivers have a warming effect on the climate of this zone. The forest islands consist of birch, spruce, and larch. The trees are stunted and in some places bent to the ground. The area of forests increases in the forest-tundra as you move along it to the south. In the interfluves there are low-growing and sparse forests. Thus, the forest-tundra consists of an alternation of treeless shrub areas and open forests. Tundra (peat-swamp) or forest soils. The fauna of the forest-tundra is similar to the fauna of the tundra. It is also home to Arctic foxes, ptarmigan, snowy owls and a wide variety of migratory waterfowl. The forest-tundra contains the main winter pastures for reindeer and hunting grounds.
Temperate forests . This natural zone is located in a temperate climate zone and includes subzones taiga, mixed and deciduous forests, monsoon forests temperate zone. Differences in climatic features contribute to the formation of vegetation characteristic of each subzone.
Taiga (Turk.). This zone of coniferous forests is located in northern North America and northern Eurasia. The climate of the subzone ranges from maritime to sharply continental with relatively warm summers (from 10°C to 20°C), and the lower the winter temperatures, the more continental the climate is (from -10°C in northern Europe to -50°C in northeastern Europe). Siberia). Permafrost is widespread in many areas of Siberia. The subzone is characterized by excessive moisture and, as a consequence, swampy interfluve spaces. There are two types of taiga: light coniferous And thoseconiferous. Light coniferous taiga - These are the least demanding pine and larch forests in terms of soil and climatic conditions, the sparse crown of which allows the sun's rays to reach the ground. Pines, having an extensive root system, have acquired the ability to use nutrients from infertile soils, which is used to stabilize soils. This feature allows these plants to grow in areas with permafrost. The shrub layer of the light-coniferous taiga consists of alder, dwarf birches, polar birches, polar willows, and berry bushes. This type of taiga is common in Eastern Siberia. Dark coniferous taiga - These are conifers, consisting of numerous species of spruce, fir, and cedar. This taiga, unlike the light-coniferous taiga, has no undergrowth, since its trees are tightly closed, and it is quite gloomy in these forests. The lower tier consists of shrubs (lingonberries, blueberries, blueberries) and dense ferns. This type of taiga is common in the European part of Russia and Western Siberia.
The soils of the taiga zone are podzolic. They contain little humus, but when fertilized they can provide a high yield. In the taiga of the Far East there are acidic soils.
The fauna of the taiga zone is rich. There are numerous predators here that are valuable game animals: otter, marten, sable, mink, weasel. Large ones include wolves, bears, lynxes, and wolverines. In North America, bison and wapiti deer used to be found in the taiga zone. Now they live only in nature reserves. The taiga is also rich in rodents, the most typical of which are beavers, muskrats, squirrels, hares, and chipmunks. The world of birds is very diverse.
Temperate mixed forests . These are forests with different tree species: coniferous-broad-leaved, small-leaved and pine. This zone is located in the north of North America (on the border of the USA and Canada), and in Eurasia it forms a narrow strip between the taiga and the zone of broad-leaved forests. The mixed forest zone is also found in Kamchatka and the Far East. In the Southern Hemisphere, this forest zone occupies small areas in southern South America and New Zealand.
The climate of the mixed forest zone is maritime or transitional to continental (towards the center of the continent), summers are warm, winters are moderately cold (in maritime climates with positive temperatures, and in more continental climate up to -10°С). There is sufficient moisture here. The annual amplitude of temperature fluctuations, as well as the annual amount of precipitation, vary from oceanic regions to the center of the continent.
The diversity of vegetation in the mixed forest zone of the European part of Russia and the Far East is explained by differences in climate. For example, on the Russian Plain, where precipitation falls all year round thanks to the westerly winds coming from the Atlantic, European spruce, oak, elm, fir, and beech are common - coniferous-deciduous forests.
The soils in the mixed forest zone are gray forest and soddy-podzolic, while in the Far East they are brown forest.
The fauna is similar to the fauna of the taiga and the deciduous forest zone. Elk, sable, and bear live here.
Mixed forests have long been subject to severe deforestation and loss. They are best preserved in North America and the Far East, and in Europe they are cut down for agricultural land - field and pasture lands.
Temperate broadleaf forests . They occupy the east of North America, Central Europe, and also form an altitudinal zone in the Carpathians, Crimea and the Caucasus. In addition, isolated pockets of broad-leaved forests are found in the Russian Far East, Chile, New Zealand and central Japan.
The climate is favorable for the growth of deciduous trees with a wide leaf blade. Here, moderate continental air masses bring precipitation from the oceans (from 400 to 600 mm) mainly in the warm season. The average temperature in January is -8°-0°C, and in July +20-24°C.
Beech, hornbeam, elm, maple, linden, and ash grow in the forests. In the deciduous forest zone of North America, species are found that are not found on other continents. These are American oak species. The predominant species here are trees with a powerful spreading crown, often entwined with climbing plants: grapes or ivy. To the south there are magnolias. For European broad-leaved forests, oak and beech are the most typical.
The fauna of this natural zone is close to the taiga, but there are animals such as black bears, wolves, minks, raccoons, which are not typical for the taiga. Many animals of the broad-leaved forests of Eurasia are under protection, as the number of individuals is sharply declining. These include animals such as bison and Ussuri tiger.
The soils under broad-leaved forests are gray forest or brown forest. This zone has been heavily developed by humans, forests have been cleared over large areas, and the lands have been plowed. In its true form, the zone of broad-leaved forests has been preserved only in areas inconvenient for arable farming and in nature reserves.
Forest-steppe . This natural zone is located within the temperate climate zone and represents a transition from forest to steppe, with alternating forest and steppe landscapes. It is widespread in the Northern Hemisphere: in Eurasia from the Danube Lowland to Altai, further in Mongolia and the Far East; in North America, this zone is located in the northern Great Plains and western Central Plains.
Forest-steppes are naturally distributed within continents between forest zones, which here choose the most humidified areas, and the steppe zone.
The climate of the forest-steppes is moderate continental: winters are snowy and cold (from -5°C to -20°C), summers are warm (+18°C to +25°C). In different longitudinal zones, forest-steppe varies in precipitation (from 400 mm to 1000 mm). Humidification is slightly below sufficient, evaporation is very high.
In the forests that alternate steppes, broad-leaved (oak) and small-leaved tree species (birch) are more common, and conifers are less common. The soils of the forest-steppe are mainly gray forest soils, which alternate with chernozems. The nature of the forest-steppe zone has been greatly changed by human economic activity. In Europe and North America, the plowed area reaches 80%. Since this zone has fertile soils, wheat, corn, sunflowers, sugar beets and other crops. The fauna of the forest-steppe zone includes species characteristic of the forest and steppe zones.
The West Siberian forest-steppe with numerous birch groves-kolok (singular number - kolok) is specific. Sometimes they have an admixture of aspen. The area of individual pegs reaches 20-30 hectares. Numerous forests, alternating with areas of steppes, create the characteristic landscape of Southwestern Siberia.
Steppes . This is a landscape with a herbaceous vegetation type, located in the temperate and partly subtropical zone. In Eurasia, the steppe zone extends in a latitudinal direction from the Black Sea to Transbaikalia; in North America, the Cordillera distributes air flows in such a way that the zone of insufficient moisture and with it the steppe zone are located from north to south along the eastern edge of this mountainous country. In the Southern Hemisphere, the steppe zone is located within the subtropical climate of Australia and Argentina. Atmospheric precipitation (from 250 mm to 450 mm per year) falls here irregularly and is insufficient for the growth of trees. Winter is cold, average temperature below 0°C, in some places down to -30°, with little snow. Summer is moderately hot - +20°С, +24°С, drought is common. Inland waters in the steppe are poorly developed, river flow is small, and rivers often dry up.
The undisturbed vegetation of the steppe is a thick grass cover, but undisturbed steppes throughout the world remain only in nature reserves: all steppes are plowed. Depending on the nature of vegetation in the steppe zone, three subzones are distinguished. They differ from each other in the predominant vegetation. This meadow steppes (bluegrass, bonfire, timothy), cereals and southern wormwood-cereals .
The soils of the steppe zone - chernozems - have a significant humus horizon, due to which they are very fertile. This is one of the reasons for the highly plowed area.
The fauna of the steppes is rich and diverse, but it has changed greatly under the influence of humans. Disappeared in the 19th century wild horses, tours, bison, roe deer. Deer are pushed into forests, saigas - into virgin steppes and semi-deserts. Now the main representatives of the animal world of the steppes are rodents. These are gophers, jerboas, hamsters, voles. Bustards, little bustards, larks and others are occasionally seen.
The steppes and partly forest-steppes of the temperate and subtropical zones of North America are called prairies . Currently they are almost completely plowed. Part of the American prairies is dry steppes and semi-deserts.
The subtropical steppe on the plains of South America, located mainly in Argentina and Uruguay, is called pump . In the eastern regions, where precipitation falls from the Atlantic Ocean, there is sufficient moisture, but to the west the aridity increases. Most of the pampa territory is plowed, but in the west there are still dry steppes with thorny bushes, used as pastures for livestock.
Semi-deserts and temperate deserts . In the south, the steppes turn into semi-deserts, and then into deserts. Semi-deserts and deserts are formed in dry climates, where there is a long and hot warm period (+20-25°C, sometimes up to 50°C), strong evaporation, which is 5-7 times the amount of annual precipitation (up to 300 mm in year). Poor surface runoff, poor development inland waters, there are many drying riverbeds, the vegetation is not closed, sandy soils heat up during the day, but quickly cool down during the cool night, which contributes to physical weathering. The winds dry out the land very strongly here. Temperate deserts differ from deserts of other geographical zones in colder winters (-7°C-15°C). Deserts and semi-deserts of the temperate zone are widespread in Eurasia from the Caspian lowland to the northern bend of the Yellow River, and in North America - in the foothills and basins of the Cordillera. In the Southern Hemisphere, temperate deserts and semi-deserts are found only in Argentina, where they occur in broken areas in the interior and foothills. Among the plants found here are steppe feather grass, fescue, wormwood and solyanka, camel thorn, agave, and aloe. Animals include saigas, turtles, and many reptiles. The soils here are light chestnut and brown desert, often saline. Under conditions of sharp temperature fluctuations during the day with little moisture, a dark crust forms on the surface of deserts - a desert tan. It is sometimes called protective, as it protects rocks from rapid weathering and destruction.
The main use of semi-deserts is grazing livestock (camels, fine-wool sheep). Farming of drought-resistant crops is possible only in oases. Oasis (from the Greek name for several populated places in the Libyan Desert) is a place where tree, shrub and herbaceous vegetation grows in deserts and semi-deserts, in conditions of more abundant surface and ground moisture compared to neighboring areas and areas. The sizes of oases vary: from ten to tens of thousands of kilometers. Oases are centers of population concentration, areas of intensive agriculture on irrigated lands (Nile Valley, Fergana Valley in Central Asia).
Deserts and semi-deserts of the subtropical and tropical zones . These are natural zones located in both hemispheres, on all continents along tropical zones of high atmospheric pressure. Most often, semi-deserts of the subtropical zone are located in the transitional part from deserts to mountain steppes in the form of an altitudinal zone in the inland parts of the Cordillera and Andes of America, in western Asia, Australia and especially widely in Africa. The climate of the deserts and semi-deserts of these climatic zones is hot: the average temperature in summer rises to +35°C, and in the coldest months of winter it does not fall below +10°C. Precipitation is 50-200 mm, in semi-deserts up to 300 mm. Sometimes precipitation occurs in short bursts of rain, and in some areas there may be no precipitation for several years in a row. With a lack of moisture, the weathering crust is very thin.
Groundwater lies very deep and can be partially saline. Only plants that can tolerate overheating and dehydration can live in such conditions. They have a deeply branched root system and small leaves or spines that reduce evaporation from the leaf surface. Some plants have leaves that are pubescent or covered with a waxy coating, which protects them from sunlight. In the semi-deserts of the subtropical zone, cereals are common and cacti appear. In the tropical zone, the number of cacti increases, agaves and sand acacias grow, and various lichens are common on the stones. A characteristic plant for the Namib Desert, located in the tropical zone of South Africa, is the amazing Welwigia plant, which has a short trunk, from the top of which two leathery leaves extend. Welwigia can be up to 150 years old. The soils are gray soils, gravelly, gray-brown, they are not very fertile, since the layer of humus is thin. The fauna of deserts and semi-deserts is rich in reptiles, spiders, and scorpions. There are camels, antelopes, and rodents are quite widespread. Agriculture in semi-deserts and deserts of the subtropical and tropical zones is also possible only in oases.
Hardleaf forests . This natural zone is located within the subtropical zone of the Mediterranean type. They mainly grow in southern Europe, northern Africa, southwest and southeast Australia. Some fragments of these forests are found in California, Chile (south of the Atacama Desert). Hard-leaved forests grow in a mild, moderately warm climate with hot (+25°C) and dry summers and cool and rainy winters. The average precipitation is 400-600 mm per year with rare and short-lived snow cover. The rivers are mainly fed by rain, and floods occur in the winter months. In rainy winter conditions, grasses grow rapidly.
The fauna has been severely exterminated, but herbivorous and leaf-eating forms, many birds of prey and reptiles are characteristic. In the forests of Australia you can find the koala bear, which lives in trees and leads a nocturnal, sedentary lifestyle.
The territory of hard-leaved forests is well developed and has been significantly changed by human economic activity. Large areas of forest here have been cut down, and their place has been taken by oilseed plantations, orchards and pastures. Many tree species have hard wood, which is used as a building material, and oils, paints, and medicines are made from the leaves (eucalyptus). Large harvests of olives, citrus fruits, and grapes are harvested from the plantations of this zone.
Subtropical monsoon forests . This natural zone is located in the eastern parts of the continents (China, southeastern USA, eastern Australia, southern Brazil). It is located in conditions that are the most humid compared to other zones of the subtropical zone. The climate is characterized by dry winters and wet summers. Annual precipitation is greater than evaporation. The maximum amount of precipitation falls in summer due to the influence of monsoons, bringing moisture from the ocean. In the territory of monsoon forests, inland waters are quite rich, and fresh groundwater lies shallow.
Here, on red soils and yellow soils, tall mixed forests grow, among which there are evergreen and deciduous forests that shed their leaves during the dry season. Species composition plants may vary depending on soil conditions. The forests contain subtropical species of pines, magnolias, camphor laurel, and camellias. Swamp cypress forests are common on the flooded coasts of Florida in the United States and in the Mississippian lowlands.
The monsoon forest zone of the subtropical zone has been developed by man for a very long time. In place of cleared forests, there are field and pasture lands; rice, tea, citrus fruits, wheat, corn and industrial crops are grown here.
Forests of tropical and subequatorial zones . They are located along eastern Central America, the Caribbean islands, Madagascar, southeast Asia, and northeast Australia. There are clearly two seasons here: dry and wet. The existence of forests in the dry and hot tropical zone is possible only thanks to the precipitation that the monsoons bring from the oceans in summer. In the subequatorial belt, precipitation occurs in the summer, when equatorial air masses dominate here. Depending on the degree of moisture, forests of the tropical and subequatorial zones are distinguished permanently wet and seasonally wet(or variable-humid) forests. Seasonally wet forests are characterized by a relatively poor species composition of tree species, especially in Australia, where these forests consist of eucalyptus, ficus, and laurels. Often in seasonally wet forests there are areas where teak and sal grow. There are very few palm trees in the forests of this group. In terms of their species diversity of flora and fauna, permanently humid forests are close to equatorial forests. There are many palm trees, evergreen oaks, and tree ferns. There are many lianas and epiphytes of orchids and ferns. The soils located under forests are mainly lateritic. During the dry season (winter), most deciduous trees do not shed all their leaves, but some species remain completely bare.
Savannah . This natural zone is located mainly within the subequatorial climate, although it is also found within the tropical and subtropical zones. In the climate of this zone, the change in wet and dry seasons of the year is clearly expressed at consistently high temperatures (from + 15 ° C to + 32 ° C). As you move away from the equator, the period of the wet season decreases from 8-9 months to 2-3, and precipitation decreases from 2000 to 250 mm per year.
Savannas are characterized by a predominance of herbaceous cover, among which tall (up to 5 m) grasses dominate. Shrubs and single trees rarely grow among them. The grass cover near the borders with the equatorial belt is very thick and high, and near the borders with semi-deserts it is sparse. A similar pattern can be seen in trees: their frequency increases towards the equator. Among the savannah trees you can find a variety of palm trees, umbrella acacias, tree-like cacti, eucalyptus trees, and baobab trees that store water.
Savannah soils depend on the length of the rainy season. Closer to the equatorial forests, where the rainy season lasts up to 9 months, are red ferralite soils. Closer to the border of savannas and semi-deserts there are red-brown soils, and even closer to the border, where rain falls for 2-3 months, unproductive soils with a thin layer of humus are formed.
The fauna of savannas is very rich and diverse, as the high grass cover provides food for the animals. Elephants, giraffes, hippos, and zebras live here, which in turn attract lions, hyenas and other predators. The bird world of this zone is also rich. Sunbirds live here, ostriches - the largest birds on Earth, a secretary bird that hunts small animals and reptiles. There are a lot of termites in the savannah.
Savannas are widespread in Africa, where they occupy 40% of the continent's territory, in South America, Australia and India.
Tall grass savannas in South America, on the left bank of the Orinoco River, with a dense, mainly cereal grass cover, with individual specimens or groups of trees, are called llanos (from the Spanish plural of “plains”). The savannas of the Brazilian plateau, where the area of intensive livestock farming is located, are called campos .
Today, savannas play a very important role in human economic life. Significant areas of this zone are plowed, grains, cotton, peanuts, jute, and sugar cane are grown here. In drier areas, livestock farming is developed. Many tree species are used on the farm, since their wood does not rot in water. Human activities often lead to desertification of savannas.
Equatorial rainforests . This natural zone is located in an equatorial and partly subequatorial climate. These forests are found in the Amazon, Congo, Malay Peninsula and Sunda Islands, as well as other smaller islands.
The climate here is hot and humid. Temperature all year round is +24-28°C. The seasons are not expressed here. Humid equatorial forests are located within an area of low pressure, where, as a result of intense heating, upward air currents are formed and a lot of precipitation falls (up to 1500 mm per year) throughout the year.
On the coasts, where the wind from the ocean influences, precipitation falls even more (up to 10,000 mm). Precipitation falls evenly throughout the year. Such climatic conditions contribute to the development of lush evergreen vegetation, although, strictly speaking, trees change leaves: some shed them every six months, others after a completely arbitrary period, and others replace their leaves in parts. Flowering periods also vary, and are even more erratic. The most common cycles are ten and fourteen months. Other plants may bloom once every ten years. But at the same time, plants of the same species bloom at the same time so that they have time to pollinate each other. Plants in this zone have little branching.
The trees of humid equatorial forests have disc-shaped roots, large leathery leaves, the shiny surface of which saves them from excessive evaporation and scorching rays of the sun, from the impact of rain jets during heavy downpours. Many leaves end in a graceful spine. It's a tiny drain. In plants of the lower tier, the leaves, on the contrary, are thin and delicate. The upper tier of equatorial forests is formed by ficus and palm trees. In South America, ceiba grows in the upper tier, reaching a height of 80 m. Bananas and tree ferns grow in the lower tiers. Large plants are entwined with vines. There are many orchids on the trees of equatorial forests, epiphytes are also found, and sometimes flowers form directly on the trunks. For example, cocoa tree flowers. In the forest of the equatorial belt it is so hot and humid that favorable conditions are created for the development of moss and algae that cling to the crown and hang from the branches. They are epiphytes. Tree flowers in the crown cannot be pollinated by the wind because the air there is practically still. Consequently, they are pollinated by insects and small birds, which are lured by their brightly colored corolla or sweet scent. The fruits of the plants are also brightly colored. This allows them to solve the problem of transporting seeds. The ripe fruits of many trees are eaten by birds and animals; the seeds are not digested and, together with the droppings, end up far from the parent plant.
There are many native plants in equatorial forests. These are primarily vines. They begin their life on the ground in the form of a small bush, and then, tightly wrapping themselves around the stem of a giant tree, they climb up. The roots are in the soil, so the plant’s nutrition does not come from the giant tree, but sometimes the use of these trees for support by vines can lead to oppression and death. Some ficus trees are also “robbers”. Their seeds germinate on the bark of a tree, the roots tightly grip the trunk and branches of this host tree, which begins to die. Its trunk is rotting, but the roots of the ficus have become thick and dense and are already able to support themselves.
Equatorial forests are home to many valuable plants, such as the oil palm, from the fruits of which palm oil is obtained. The wood from many trees is used to make furniture and is exported in large quantities. This group includes ebony, the wood of which is black or dark green. Many plants of equatorial forests produce valuable fruits, seeds, juice, and bark, which are used in technology and medicine.
The equatorial forests of South America are called selva . Selva is located in the periodically flooded area of the Amazon River basin. Sometimes, when describing moist equatorial forests, the name is used hylea , sometimes these forests are called jungle , although, strictly speaking, jungles are the forest thickets of South and Southeast Asia located within the subequatorial and tropical climate.
The southern continents include Africa, South America, Australia and Antarctica. They are connected by their location in the Southern Hemisphere of the Earth, as well as by a mostly hot climate, with the exception of Antarctica. Natural areas southern continents have many common features, but the characteristics of vegetation and fauna determine geographical zones on which they are located.
Antarctica
It is the southernmost continent, but its entire surface is covered with blocks of ice and snow. Even in summer, the temperature here rarely exceeds 0-5 degrees Celsius. The soils are frozen by permafrost, which prevents vegetation from developing. In the natural zone of the Antarctic deserts one can find only a sparse growth of mosses and lichens. The local fauna is also very poor. Polar bears live here, seals and walruses can be found on the coast, and in summer bird colonies form on the rocks.
Rice. 1. Antarctica is the southernmost continent on the planet.
Africa
Africa is rightfully considered the hottest continent on Earth. Its distinctive feature is its symmetrical location relative to the equator. This means that the equatorial line divides the continent into two equal parts. As a result, Africa is characterized by the presence of several natural zones, including moist equatorial and variable-humid forests, savannas, tropical deserts, and hard-leaved forests.
The African continent is home to the largest desert in the world - the Sahara. Despite the apparent lifelessness, here you can still find sparse vegetation and representatives of the animal world that have adapted to life in the difficult desert conditions.
Australia
Australia is considered the driest continent, so it is not surprising that you will not find lush and varied vegetation here. There are practically no forests in Australia, but there are many deserts.
Due to the flat topography of the continent, latitudinal zoning is most pronounced here. Since the main part of the continent is located in tropical latitudes, tropical deserts and semi-deserts predominate here. A much smaller area is occupied by savannas, tropical and subtropical forests.
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Rice. 2. Nature of Australia.
For a long time Australia was in great isolation. This is precisely what explains the antiquity and originality of the local flora and fauna, the majority of which are endemic - species that live exclusively on this continent.
South America
This is a unique continent on which more than half of all tropical and equatorial forests on the planet grow. The climate on the mainland is moderately humid and warm, the temperature difference between seasons is insignificant.
Rice. 3. Equatorial forests of South America.
Natural zones are distributed unevenly due to the strong differences between the western and eastern parts of the continent, and are represented by several species:
- selva- equatorial rain forests;
- Llanos- zone of savannas and woodlands;
- pump- subtropical steppes;
- Patagonia- deserts and semi-deserts;
- temperate forests.
The flora and fauna are mostly represented by endemic species.
What have we learned?
In view of his geographical location the southern continents have many similar features. However, each of them has natural areas with a unique flora and natural world that cannot be found anywhere else on the planet.
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