For tropical wet evergreen, or, as they are sometimes called, rain forests, are characterized by a three-tier structure of the tree canopy. The tiers are poorly demarcated. The upper tier consists of giant trees with a height of 45 m or more, with a diameter of 2-2.5 m. The middle tier is represented by trees about 30 m high with a trunk diameter of up to 90 cm. The third tier grows smaller, exclusively shade-tolerant trees. There are many palm trees in these forests. Their main growing area is the Amazon basin. Here they occupy vast areas, including, in addition to the northern part of Brazil, French Guiana, Suriname, Guyana, southern part Venezuela, west and south of Colombia, Ecuador and east of Peru. In addition, this type of forest is found in Brazil in a narrow strip along the Atlantic coast between 5 and 30° S. Similar evergreen forests also grow on the Pacific coast from the Panama border to Guayaquil in Ecuador. All species of the genus Switenia (or mahogany), rubber plants of the genus Hevea, Brazil nut (Bertolletia excelsa) and many other valuable species are concentrated here.

Tropical variable-moist deciduous forests distributed in southeastern Brazil and southern Paraguay. The tree species in them are relatively small in height, but often with thick trunks. Legumes are widely represented in forests. Subtropical deciduous broadleaf forests most common in southern Brazil and Parguay, western Uruguay and northern Argentina along the Paraná and Uruguay rivers. Mountain evergreen forests cover the slopes of the Andes from Venezuela to central Bolivia. These forests are characterized by thin-trunked, low trees that form closed stands. Due to the fact that these forests occupy steep slopes and are significantly removed from populated areas, they are developed very little.

Araucaria forests are located in two areas isolated from each other. Brazilian Araucaria (Araucaria brasiliana) is dominant in the states of Paraná, Santa Catarina and Rio Grande do Sul in Brazil, as well as in Uruguay, Eastern Paraguay and Argentina. A less significant massif is formed by forests of Chilean araucaria (A. araucana), found in the Andes at 40° S. in the altitude range from 500 to 3000 m above sea level. seas. These forests are characterized by hardwood species, of which the embuya (Phoebe porosa) is the most important. In the undergrowth of Araucaria forests, the mate bush, or Paraguayan tea (Ilex paraguariensis), is widespread, also grown on plantations.

Low-growing xerophilous forests distributed in eastern Brazil, northern Argentina and western Paraguay. The most important tree species of these forests is red querbacho (Schinopsis sp.), from which tannin is obtained. Mangrove forests occupy coastal strip Atlantic part South America. These forests are dominated by the red mangrove (Rhizophora mangle), forming pure stands or mixed with Avicennia marina and Conocarpus erecta.

In addition to timber harvesting, the forests of the continent produce rubber, food products (seeds, nuts, fruits, beans, leaves, etc.), oils, medicinal substances, tannin, resins, including chicle (Zschokkea lascescens), which goes to the USA as raw materials for the production of chewing gum.

Venezuela. Evergreen (on laterites) and deciduous forests grow on the slopes of the Andes spurs and the Guiana Highlands. On the territory of the low llanos, tall grass savanna with groves of Mauritius palms is common, and in the high llanos there are xerophilic open forests and shrub communities. Around Lake Maracaibo there are mangroves, giving way to low-growing xerophilic forests, and to the south - evergreen tropical forests. In the south of the country, in the upper reaches of the river. Orinoco and its right tributaries, moist evergreens grow tropical forests, almost inaccessible for use. Tree species of economic value include mahogany, roble-colorado, baku, balsa, espave (Anacardium spp.), angelino (Ocotea caracasana), oleo-vermelho (Myroxylon balsamum), pao-roxo, guaiacum, tabebuia (Tabebuia pentaphylla). ), ceiba (Ceiba pentandra), almasigo (Bursera simaruba), courbaril (Hymenaea courbaril), adobe (Samanea saman), etc.

Landscape in the center of Venezuela

Colombia. By natural conditions Two regions are distinguished: eastern (plain) and western (mountainous, where the Colombian Andes stretch). The first area is largely occupied by moist evergreen forests of the Magdalena basins and the left tributaries of the Amazon. In the north of the Guajira Peninsula and west of it, along the coast Caribbean Sea, there are low-growing xerophilous forests in which divi-divi beans (Libidibia coriaria) are harvested to obtain tannin. Guaiac wood (Guaiacum spp.) is also harvested here - this is one of the hardest and heaviest woods in the world, used for the manufacture of rollers, blocks and other mechanical engineering products.

Mangrove forests stretch along the Pacific and Caribbean coasts. In the evergreen tropical Hylaia, especially in the lower part of the Magdalena basin and along the mouth of the river. Atrato, the wood of cativo (Prioria copaifera), as well as baku, or “Colombian mahogany” (Cariniana spp.), caoba, or true mahogany (Swietenia macrophylla), roble-colorado, or Panamanian mahogany (Platymiscium spp.) is harvested for export. , purple tree, or pao-roxo (Peltogyne spp.), etc. In the eastern part of the elevated plain along the tributaries of the Orinoco, savanna-llanos with sparse trees and gallery forests with the Mauritius palm (Mauricia sp.) are common. The forests of the mountainous regions of the Andes are characterized by a peculiar altitudinal zonation. On the lower parts of the leeward slopes and on the northern ridges, deciduous forests or thorny bushes are common. In the adjacent part of the mountains (from 1000 to 2000 m) there are montane broad-leaved evergreen forests with tree ferns, wax palm (Copernicia cerifera), cinchona, coca (Erythroxylon coca) and various orchids. Cultivated plants include cocoa and coffee trees. At altitudes from 2000 to 3200 m, humid alpine hylea, which contains many species of evergreen oaks, shrubs and bamboos.

Ecuador. There are three natural areas on the territory of the country: 1) watershed plateau with humid equatorial forests - hylea, or selva(together with the upper reaches of the left tributaries of the Amazon); 2) Andes ridges; 3) Pacific forest-savanna plain and the western slopes of the Andes. Evergreen tropical forests of the first region are poorly studied and difficult to access. On the western slopes of the Andes, up to an altitude of 3000 m, evergreen mountain broad-leaved forests (hylaea) grow, largely disturbed by slash-and-burn agriculture. They produce a lot of cinchona bark, as well as balsa, kapok from ceiba fruits, and leaves of the toquilla palm, or hipihapa (Carludovica palmata), used for making Panama hats. Here you can also find the tagua palm (Phytelephas spp.), the hard endosperm of which is used to produce buttons, and various rubber plants. The lower western slopes are characterized by evergreen tropical forests. In the river valley Guayas is intensively harvested for export of balsa wood.

Guyana, Suriname, Guiana. The forests of these countries, located along the Atlantic coast and along the Guiana Highlands, are tropical evergreen with a number of valuable species. Especially stands out green tree, or betabaro (Ocotea rodiaei), which is exported in Guyana and Suriname. No less valuable are apomate (Tabebuia pentaphylla), canalete (Cordia spp.), pequia (Caryocar spp.), espave (Anacardium spp.), habillo (Hura crepitans), wallaba (Eperua spp.), carapa (Carapa guianensis), virola (Virola spp.), simaruba (Simaruba spp.), etc.

Brazil. The flora contains over 7 thousand species of trees and shrubs, of which in the Amazonian jungle there are over 4.5 thousand species. Tall bertholiaceae grow (producing Brazil nuts, etc.), various rubber plants, including Hevea brasiliensis, which has become a valuable plantation crop in many countries of South Asia and Africa, laurels, ficus trees, Brazilian mahogany, or “pau brazil”, which gave the country its name (Caesalpinia echinata), chocolate tree or cacao, mahogany, jacaranda or rosewood, oleo vermelho, roble colorado and sapucaya or paradise nut (Lecythis ustata), and many others. In the east, the selva turns into light palm forests, among which we note the valuable babasa palm (Orbignya speciosa), which has highly nutritious nuts. To the south of the Amazon jungle, landscapes of tropical dry woodlands are common - caatinga, in which trees grow that shed leaves during the dry season and accumulate moisture during the rainy season, for example, bottle tree (Cavanillesia arborea), thorny bushes, cacti (Cereus squamulosus). In the floodplains, the carnauba, or wax, palm (Copernicia cerifera) is found, from the leaves of which wax is collected, used in technology. To the south, palm-dominated forests and savannas are adjacent to subtropical deciduous forests. In the southeast of the country, along the Brazilian Highlands, araucaria forests of the Brazilian, or Paranan, araucaria (Pineiro, or “Brazilian pine”) extend. Along with it, embuia, tabebuia, and cordia grow, and in the undergrowth of yerbamate - Paraguayan tea is prepared from its leaves. Araucaria forests are subject to intensive exploitation.

Along the Atlantic coast and at the mouth of the Amazon, mangrove forests are dominated by red mangrove, with a mixture of black mangrove (Avicennia marina) and white mangrove (Conocarpus erecta). Tannin is extracted from the bark of these trees.

Road from Calama (Chile) to La Paz (Bolivia)

Chile. The main forest area is concentrated in the southern half of the country along the Pacific slopes of the Andes. In the area of ​​41-42° S. There is a significant tract of araucaria forests, dominated by pure stands of pino, or Chilean araucaria, often called “Chilean pine” (Araucaria araucana). To the south are mixed deciduous temperate forests with different types southern beech (Nothofagus spp.), representatives of laurel trees - lingue (Persea lingue), ulmo (Beilschmiedia berteroana). In the far south there are coniferous forests of alerce (Fitzroya cupressoides) and cypres (Pilgerodendron uviferum) with an admixture of canelo (Drimys winteri). The bark of the latter contains substances with antiscorbutic properties.

Argentina. Several natural areas stand out. In the east, evergreen forests dominate, in which more than 100 species of trees grow, having important economic importance. Among them are cabreuva (Myrocarpus frondosus), kangerana (Cabralea oblongifolia), Brazilian araucaria, tabebuia, etc. In the west, evergreen forests grow on the slopes of the Andes at an altitude of 2000-2500 m above sea level. seas. Palo blanco (Calycophyllum multiflorum), cedro salteno (Cedrela balansae), roble criolo (Amburana cearensis), nogal criolo (Juglans australis), tarco (Jacaranda mimosifolia), tipa blanco (Tipuana tipu), etc. are common in them. In the south, along the slopes of the Andes, subantarctic vegetation extends, among which several species of southern beech, alerce, "Cordilleran cypress" (Austrocedrus chilensis), etc. are distinguished. In the Gran Chaco Forest region, xerophilous forests are widespread, in which several species of quebracho, algarrobo, palosanto (Bulnesia sarmientoi), guaiacano (Caesalpinia paraguarensis), etc. To the south, on the eastern slopes of the Andes, there are xerophilic broad-leaved forests of the temperate zone with algarrobo, acacia (Acacia caven), hackberry (Celtis spinosa), quebracho-blanco.

Paraguay. Forest cover 51%. In the east of the country, mixed tropical evergreen and deciduous forests are common, turning into open forests and savannas in the west (in the Gran Chaco region). The main tree species is quebracho-blanco (Aspidosperma quebracho-blanco).

Uruguay. Forests occupy a small part common territory country and are located in the lower reaches of the Rio Negro and in the valley of the river. Uruguay. The country's forest cover is 3%. Large areas are beginning to be occupied by artificial plantings - pine trees on coastal dunes and eucalyptus plantations.

Published from the monograph: A.D. Bukshtynov, B.I. Groshev, G.V. Krylov. Forests (Nature of the world). M.: Mysl, 1981. 316 p.

The continent of South America is located in all geographical zones, with the exception of the sub-Antarctic and Antarctic. The wide northern part of the continent lies at low latitudes, so the equatorial and subequatorial belts are most widespread. A distinctive feature of the continent is the widespread development of forest natural areas (47% of the area). 1/4 of the planet’s forests are concentrated on the “green continent”(Fig. 91, 92).

South America gave humanity many cultivated plants: potatoes, tomatoes, beans, tobacco, pineapple, hevea, cocoa, peanuts, etc.

Natural areas

In the equatorial geographical zone there is a zone equatorial rain forests , occupying Western Amazonia. They are named by A. Humboldt hylea, and by the local population - the village. The equatorial rainforests of South America are the richest forests on Earth in terms of species composition. They are rightfully considered the “gene pool of the planet”: they contain more than 45 thousand plant species, including 4,000 woody ones.

Rice. 91. Endemic animals of South America: 1- giant anteater; 2- hoatzin; 3 - lama; 4 - sloth; 5 - capybaras; 6 - battleship

Rice. 92. Typical trees of South America: 1 - Chilean araucaria; 2 - wine palm; 3 - chocolate tree (cocoa)

There are flooded, non-flooded and mountain hylia. In river floodplains, flooded with water for a long period, impoverished forests of low trees (10-15 m) with breathing and stilt roots grow. Cecropia (“ant tree”) predominates; giant Victoria regia swim in the reservoirs.

In elevated areas, rich, dense, multi-tiered (up to 5 tiers) flood-free forests are formed. The single-standing ceiba (cotton tree) and the Brazil nut-bearing bertolecia grow to a height of 40-50 m. The upper tiers (20-30 m) are formed by trees with valuable wood (rosewood, pau brazil, mahogany), as well as ficus and hevea, from the milky juice of which rubber is obtained. In the lower tiers, under the canopy of palm trees, chocolate and melon trees grow, as well as ancient plants on Earth - tree ferns. The trees are densely intertwined with lianas; among the epiphytes there are many brightly colored orchids.

Mangrove vegetation, poor in composition (nipa palm, rhizophora), is developed near the coast. Mangroves- these are thickets of evergreen trees and shrubs of the wetland zone sea ​​tides and ebb tides of tropical and equatorial latitudes, adapted to salt water.

Moist equatorial forests form on red-yellow ferrallite soils, poor nutrients. Falling leaves in hot and humid climate quickly rots, and the humus is immediately absorbed by plants, without having time to accumulate in the soil.

Hylaea animals are adapted to life in trees. Many have a prehensile tail, such as the sloth, opossum, prehensile-tailed porcupine, broad-nosed monkeys(howler monkeys, arachnids, marmosets). The ponds are home to peccary pigs and tapirs. There are predators: jaguar, ocelot. There are numerous turtles and snakes, including the longest one - the anaconda (up to 11 m). South America is the “continent of birds”. Hylea is home to macaws, toucans, hoatzins, tree hens and the smallest birds - hummingbirds (up to 2 g).

The rivers are teeming with caimans and alligators. They are home to 2,000 species of fish, including dangerous predatory piranha and the largest in the world - arapaima (up to 5 m in length and weighing up to 250 kg). There are electric eel and freshwater dolphin inia.

Zones stretch across three geographical zones variable- rain forests . Subequatorial variable-humid forests occupy the eastern part of the Amazonian lowland and the adjacent slopes of the Brazilian and Guiana plateaus. The presence of a dry period causes the appearance of deciduous trees. Among the evergreens, cinchona, ficus, and balsa, which have the lightest wood, predominate. In tropical latitudes, on the moist eastern edge of the Brazilian Plateau, rich evergreen tropical forests, similar in composition to equatorial ones, grow on mountain red soils. The southeast of the plateau on red soils and yellow soils is occupied by sparse subtropical moist forests. They are formed by Brazilian araucaria with an undergrowth of yerba mate (“Paraguayan tea”) shrubs.

Zone savannas and woodlands distributed in two geographical zones. In subequatorial latitudes it covers the Orinoco Lowland and interior areas The Brazilian plateau, in the tropical - the Gran Chaco plain. Depending on the moisture content, wet, typical and desert savannas are distinguished. Under them, red, brown-red and red-brown soils develop, respectively.

Tallgrass wet savanna in the Orinoco River basin is traditionally called Llanos. It is flooded for up to six months, turning into an impassable swamp. Grains and sedges grow; Of the trees, the Mauritius palm dominates, which is why the llanos is called the “palm savanna.”

On the Brazilian plateau, savannas were called campos. Wet shrub-tree savanna occupies the center of the plateau, while typical grassy savanna occupies the south. Low-growing shrubs grow against the background of cereal vegetation (bearded grass, feather grass). Among the trees, palms (wax, oil, vine palms) dominate. The arid northeast of the Brazilian Plateau is occupied by desert savanna - caatinga. This is a woodland of thorny bushes and cacti. There is a bottle-shaped tree that stores rainwater - the Bombax cottonweed.

Savannas continue into tropical latitudes, occupying the Gran Chaco plain. Only in tropical woodlands is the quebracho ("break the axe") tree found, with hard and heavy wood that sinks in water. The savannas contain plantations of coffee, cotton, and bananas. Dry savannas are an important area for grazing.

Savannah animals are characterized by a protective brown coloration (spice-horned deer, red nose, maned wolf, rhea ostrich). Rodents are abundantly represented, including the largest in the world, the capybara. Many Hylaea animals (armadillos, anteaters) also live in savannas. Termite mounds are ubiquitous.

In the Laplata Lowland south of 30° S. w. are being formed subtropical steppes . In South America they were called pump. It is characterized by rich forb-grass vegetation (wild lupine, pampas grass, feather grass). The chernozem soils of the pampa are very fertile and therefore heavily plowed. The Argentine pampa is the main growing area for wheat and forage grasses in South America. The fauna of the pampa is rich in rodents (tuco-tuco, viscacha). There are Pampas deer, Pampas cat, puma, and rhea ostrich.

Semi-deserts and deserts South America extends across three geographical zones: tropical, subtropical and temperate. In the west of the tropics, tropical deserts and semi-deserts stretch in a narrow strip along the Pacific coast and on the high plateaus of the Central Andes. This is one of the driest areas on Earth: in the Atacama Desert it may not rain for years. On the infertile gray soils of coastal deserts, dry cereals and cacti grow, receiving moisture from dew and fog; on the gravelly soils of high-mountain deserts there are creeping and cushion-shaped grasses and thorny shrubs.

Animal world tropical deserts poor The inhabitants of the highlands are llamas, spectacled bears, and chinchillas with valuable fur. There is the Andean condor - the largest bird in the world with a wingspan of up to 4 m.

To the west of the pampa, subtropical semi-deserts and deserts are common in a continental climate. On gray soils there is a light forest of acacias and cacti, and on salt marshes - solyankas. In the harsh temperate latitudes of lowland Patagonia on brown semi-desert soils dry cereals and thorny shrubs grow.

The southwestern edge of the continent in two zones is occupied by forest natural zones. In the subtropics in Mediterranean conditions maritime climate a zone is being formed dry hard-leaved forests and shrubs . The coast and slopes of the Chilean-Argentine Andes (between 28° and 36° S) are covered with forests of evergreen southern beech, teak, and persea on brown and gray-brown soils.

Located further south wet evergreen And mixed forests . In the northern Patagonian Andes, moist evergreen forests grow on montane brown forest soils in a subtropical humid climate. With abundant moisture (more than 3000-4000 mm of precipitation), these rain forests are multi-layered and rich, for which they received the name “subtropical hylea”. They consist of evergreen beeches, magnolias, Chilean araucaria, Chilean cedar, South American larch with a rich understory of tree ferns and bamboos. In the south of the Patagonian Andes, in a temperate maritime climate, mixed forests of deciduous beech and coniferous podocarpus grow. Here you can find puda deer, Magellanic dog, otter, and skunk.

High Andean region occupies a vast territory with a well-defined altitudinal zone, most fully manifested in equatorial latitudes. Common up to an altitude of 1500 m hot belt- hylea with an abundance of palms and bananas. Above the 2000 m mark there is a temperate zone with cinchona, balsa, tree ferns and bamboos. A cold belt extends to the 3500 m mark - a high-mountain hylea of ​​low-growing crooked forests. It is replaced by a frost belt with high-mountain meadows of paramos cereals and low-growing shrubs. Above 4700 m there is a belt of eternal snow and ice.

References

1. Geography 8th grade. Tutorial for 8th grade institutions of general secondary education with Russian as the language of instruction / Edited by Professor P. S. Lopukh - Minsk “People's Asveta” 2014

Geographical location, natural conditions

In the subequatorial zone, due to seasonal precipitation and uneven distribution of precipitation over the territory, as well as contrasts in the annual course of temperatures, landscapes of subequatorial variable humid forests develop on the plains of Hindustan, Indochina and in the northern half of the Philippine Islands.

Variably humid forests occupy the most humid areas of the lower reaches of the Ganges-Brahmaputra, coastal areas of Indochina and the Philippine archipelago, and are especially well developed in Thailand, Burma, and the Malay Peninsula, where at least 1,500 millimeters of precipitation falls. On drier plains and plateaus, where precipitation does not exceed 1000-800 millimeters, seasonally wet monsoon forests grow, which once covered large areas of the Hindustan Peninsula and southern Indochina (Korat Plateau). With a decrease in precipitation to 800-600 millimeters and a reduction in the rainfall period from 200 to 150-100 days a year, forests are replaced by savannas, woodlands and shrubs.

The soils here are ferralitic, but predominantly red. As the amount of rain decreases, the concentration of humus in them increases. They are formed as a result of ferralite weathering (the process is accompanied by the decomposition of most of the primary minerals, with the exception of quartz, and the accumulation of secondary ones - kaolinite, goethite, gibbsite, etc.) and humus accumulation under forest vegetation humid tropics. They are characterized by low silica content, high aluminum and iron content, low cation exchange and high anion absorption capacity, predominantly red and variegated yellow-red color of the soil profile, and a very acidic reaction. Humus contains mainly fulvic acids. They contain 8-10% humus.

The hydrothermal regime of seasonally humid tropical communities is characterized by constantly high temperatures and a sharp change in wet and dry seasons, which determines the specific features of the structure and dynamics of their fauna and animal population, which significantly distinguish them from humid communities. tropical forests. First of all, the presence of a dry season, lasting from two to five months, determines the seasonal rhythm of life processes in almost all animal species. This rhythm is expressed in the timing of the breeding season mainly to the wet season, in the complete or partial cessation of activity during drought, in the migratory movements of animals both within the biome in question and beyond it during the unfavorable dry season. Falling into complete or partial anabiosis is characteristic of many terrestrial and soil invertebrates, amphibians, and migration is characteristic of some insects capable of flight (for example, locusts), birds, chiropterans and large ungulates.

Flora

Variably humid forests (Figure 1) are close in structure to hylaea, differing at the same time in a smaller number of species. In general, the same set remains life forms, diversity of lianas and epiphytes. Differences appear precisely in the seasonal rhythm, primarily at the level of the upper tier of the tree stand (up to 30% of the trees in the upper tier are deciduous species). At the same time, the lower tiers include a large number of evergreen species. The grass cover is represented mainly by ferns and dicotyledons. In general, these are transitional types of communities, in some places largely reduced by humans and replaced by savannas and plantations.

Figure 1 – Variably humid forest

The vertical structure of humid subequatorial forests is complex. Usually there are five tiers in this forest. The upper tree layer A is formed by the tallest trees, isolated or forming groups, the so-called emergents, raising their “heads and shoulders” above the main canopy - the continuous layer B. The lower tree layer C often penetrates into layer B. Stage D is usually called shrub. It is formed mainly by woody plants, of which only a few can hardly be called shrubs in the exact sense of the word, or rather “dwarf trees”. Finally, the lower tier E is formed by grasses and tree seedlings. The boundaries between adjacent tiers can be better or worse expressed. Sometimes one tree layer imperceptibly passes into another. In monodominant communities, tree layers are better expressed than in polydominant ones.

The most common type of wood is teak wood, which is characterized by teak wood. Trees of this species can be considered an essential component of the summer green forests of India, Burma, Thailand and the relatively dry areas of eastern Java. In India, where very small areas of these natural zonal forests still remain, the main trees that grow with teak wood are ebony trees and maradu, or Indian laurel; all these species produce valuable wood. But teak wood is in especially great demand because it has a number of valuable properties: it is hard, resistant to fungi and termites, and also weakly reacts to changes in humidity and temperature. Therefore, foresters specially grow teak wood (in Africa and South America). Monsoon forests are best studied in Burma and Thailand. In them, along with teak wood, there are Pentacme suavis, Dalbergia paniculata, Tectona hamiltoniana, whose wood is stronger and heavier than teak wood, then producing bast fibers Bauhinia racemosa, Callesium grande, Ziziphus jujuba, Holarrhenia dysenteriaca with white soft wood used for turning and wood carvings. One of the bamboo species, Dendrocalamus strictus, grows in the shrub layer. The grass layer consists mainly of grasses, among which the bearded vulture dominates. Along the shores of estuaries and in other areas of the sea coast protected from storms, the muddy tidal zone (littoral) is occupied by mangroves (Figure 2). Trees of this phytocenosis are characterized by thick, stilted roots extending from the trunks and lower branches like thin piles, as well as breathing roots protruding from the silt in vertical columns.

Figure 2 – Mangroves

Vast swamps stretch along the rivers in the tropical rain forest zone: heavy rains lead to regular high floods, and floodplains constantly remain flooded. Swamp forests are often dominated by palm trees and have less species diversity than drier areas.

Animal world

The fauna of seasonally humid subtropical communities is not as rich as the fauna of moist equatorial forests due to the dry period unfavorable for animals. Although the species composition of various groups of animals in them is specific, at the level of genera and families there is a noticeable great similarity with the Gilian fauna. Only in the driest variants of these communities—in open forests and thorny bushes—do species related to typical representatives of the fauna of arid communities begin to noticeably predominate.

Forced adaptations to drought contributed to the formation of a number of special animal species characteristic of a given biome. In addition, some species of phytophagous animals turn out to be more diverse in species composition here than in the Hylaea, due to the greater development of the herbaceous layer and, accordingly, the greater diversity and richness of herbaceous food.

The layering of the animal population in seasonally wet communities is noticeably simpler than in tropical rainforests. The simplification of layering is especially pronounced in open forests and shrub communities. However, this applies mainly to the tree layer, since the tree stand itself is less dense, diverse and does not reach the same height as in the hyla. But the herbaceous layer is much more clearly expressed, since it is not so strongly shaded by woody vegetation. The population of the litter layer is also much richer here, since the deciduousness of many trees and the drying out of grasses during the dry period ensure the formation of a fairly thick layer of litter.

The presence of a layer of litter formed by leaf and grass decay ensures the existence of a trophic group of saprophagous animals that is diverse in composition. The soil-litter layer is inhabited by roundworms-nematodes, annelids-megascolecids, small and large nooses, oribatid mites, springtails-collembolas, cockroaches, and termites. All of them are involved in the processing of dead plant matter, but the leading role is played by termites, already familiar to us from the fauna of the Gila.

Consumers of green plant mass in seasonal communities are very diverse. This is determined primarily by the presence of a well-developed herbaceous layer in combination with a more or less closed tree layer. Thus, chlorophytophages specialize either in eating tree leaves or using herbaceous plants, many feeding on plant sap, bark, wood and roots.

The roots of plants are eaten by the larvae of cicadas and various beetles - beetles, golden beetles, and darkling beetles. The juices of living plants are sucked by adult cicadas, bugs, aphids, scale insects and scale insects. Green plant matter is consumed by butterfly caterpillars, stick insects, herbivorous beetles - beetles, leaf beetles, and weevils. The seeds of herbaceous plants are used as food by harvester ants. The green mass of herbaceous plants is eaten mainly by various locusts.

Consumers of green vegetation are also numerous and diverse among vertebrates. These are terrestrial turtles from the genus Testudo, granivorous and frugivorous birds, rodents and ungulates

The monsoon forests of South Asia are home to the wild fowl (Callus gallus) and the common peacock (Pavo chstatus). Asian ring-necked parrots (Psittacula) forage for food in the treetops.

Figure 3 – Asian rathufa squirrel

Among herbivorous mammals, rodents are the most diverse. They can be found in all layers of seasonal tropical forests and woodlands. The tree layer is inhabited mainly by various representatives of the squirrel family - palm squirrels and the large ratufa squirrel (Figure 3). In the ground layer, rodents from the mouse family are common. In South Asia, the large porcupine (Hystrix leucura) can be found under the forest canopy; Rattus rats and Indian bandicots (Bandicota indica).

The forest floor is home to various predatory invertebrates - large centipedes, spiders, scorpions, and predatory beetles. Many spiders that build trapping nets, for example large nephilous spiders, also inhabit the tree layer of the forest. They hunt on the branches of trees and bushes small insects praying mantises, dragonflies, blackflies, predatory bugs.

Small predatory animals hunt rodents, lizards and birds. The most typical are various civets - civets, mongooses.

Of the large predators in seasonal forests, the leopard, which penetrates here from the gili, and tigers are relatively common.

Introduction

Eurasia is the largest continent on Earth, with an area of ​​53,893 thousand square kilometers, which is 36% of the land area. Population - more than 4.8 billion people.

The continent is located in the Northern Hemisphere between approximately 9° and 169° West longitude, with some of the islands of Eurasia located in the Southern Hemisphere. Most of continental Eurasia lies in the Eastern Hemisphere, although the extreme western and eastern ends of the continent are in the Western Hemisphere. Contains two parts of the world: Europe and Asia.

All climatic zones and natural zones are represented in Eurasia.

A natural zone is part of a geographical zone with homogeneous climatic conditions.

Natural areas take their name from the vegetation inherent in them and other geographical features. The zones naturally change from the equator to the poles and from the oceans deep into the continents; have similar temperature and moisture conditions, which determine homogeneous soils, vegetation, fauna and other components natural environment. Natural zones are one of the stages of physical-geographical zoning.

The main ones discussed in course work natural zones of subequatorial and equatorial belts Eurasia - a zone of variable humid forests, including monsoon forests, a zone of savannahs and woodlands, a zone of equatorial forests.

The zone of variable humid, monsoon forests develops on the plains of Hindustan, Indochina and in the northern half of the Philippine Islands, the zone of savannahs and woodlands - on the Deccan Plateau and the interior of the Indochina Peninsula, humid equatorial forests - throughout the Malay Archipelago, the southern half of the Philippine Islands, the southwest the islands of Ceylon and the Malacca Peninsula.

The course work provides a detailed description of these natural zones, reflecting the geographical location, climate, soils, flora his environmental features, animal population and its ecological features. A current topic is also developed - environmental problems of the equatorial and subequatorial belts of Eurasia. First of all, these include the deforestation of moist equatorial forests and the desertification of savannas under the influence of grazing.

Zone of variable humid, including monsoon forests

Geographical location, natural conditions

In the subequatorial zone, due to seasonal precipitation and uneven distribution of precipitation over the territory, as well as contrasts in the annual course of temperatures, landscapes of subequatorial variable humid forests develop on the plains of Hindustan, Indochina and in the northern half of the Philippine Islands.

Variably humid forests occupy the most humid areas of the lower reaches of the Ganges-Brahmaputra, coastal areas of Indochina and the Philippine archipelago, and are especially well developed in Thailand, Burma, and the Malay Peninsula, where at least 1,500 millimeters of precipitation falls. On drier plains and plateaus, where precipitation does not exceed 1000-800 millimeters, seasonally wet monsoon forests grow, which once covered large areas of the Hindustan Peninsula and southern Indochina (Korat Plateau). With a decrease in precipitation to 800-600 millimeters and a reduction in the rainfall period from 200 to 150-100 days a year, forests are replaced by savannas, woodlands and shrubs.

The soils here are ferralitic, but predominantly red. As the amount of rain decreases, the concentration of humus in them increases. They are formed as a result of ferralite weathering (the process is accompanied by the decomposition of most of the primary minerals, with the exception of quartz, and the accumulation of secondary ones - kaolinite, goethite, gibbsite, etc.) and humus accumulation under the forest vegetation of the humid tropics. They are characterized by low silica content, high aluminum and iron content, low cation exchange and high anion absorption capacity, predominantly red and variegated yellow-red color of the soil profile, and a very acidic reaction. Humus contains mainly fulvic acids. They contain 8-10% humus.

The hydrothermal regime of seasonally humid tropical communities is constantly characterized high temperatures and a sharp change in wet and dry seasons, which determines the specific features of the structure and dynamics of their fauna and animal population, which markedly distinguish them from communities of tropical rainforests. First of all, the presence of a dry season, lasting from two to five months, determines the seasonal rhythm of life processes in almost all animal species. This rhythm is expressed in the timing of the breeding season mainly to the wet season, in the complete or partial cessation of activity during drought, in the migratory movements of animals both within the biome in question and beyond it during the unfavorable dry season. Falling into complete or partial anabiosis is characteristic of many terrestrial and soil invertebrates, amphibians, and migration is characteristic of some insects capable of flight (for example, locusts), birds, chiropterans and large ungulates.

Variably wet forests. The zone of variable wet (including monsoon) forests extends in the east and south of Eurasia. The vegetation here is represented by both coniferous and deciduous trees (cedar, pine, oak, walnut, gingko) and evergreens (palm trees, ficus, bamboo and magnolias), which grow mainly on red-yellow soils. The fauna is also characterized by significant species diversity: monkeys, tigers, leopards, as well as endemics - bamboo bear(panda), gibbon, etc.

Slide 11 from the presentation "Natural areas of Eurasia". The size of the archive with the presentation is 643 KB.

Geography 7th grade

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