Tropical rain forest

from Wikipedia, the free encyclopedia
Regions with a tropical climate according to Köppen and Geiger :
  • Tropical rainforest climate (Af)
  • Tropical monsoon climate (Am)
  • Tropical savanna climate (Aw)
  • As a tropical rainforest one is vegetation type referred to only in the climate of the humid tropics can be found. Tropical rainforests exist in South and Central America , Africa , South Asia and Southeast Asia as well as Australia on both sides of the equator up to about the 10th parallel , in some places well beyond. In the Passat - monsoon zone in East Africa , the rainforest on the other hand is missing.

    Up to a height of about 1000 meters, one speaks of tropical lowland rainforest , above which the height of the trees continues to decrease, the undergrowth becomes denser and the species composition changes. Up to heights of around 2000 meters one speaks of tropical mountain rainforest , but the transition is fluid. The biodiversity in the mountain rainforest is often greater than in the lowland area: all five megadiversity centers on earth are located in humid tropical mountains.

    At even higher mountain heights , the tropical rainforest changes into the tropical cloud and cloud forests .


    Climatic conditions

    Daily rainfall in the Ecuadorian rainforest near Tena

    Due to the proximity to the equator, the length of the day remains largely constant over the course of the year. The sun is in the sky for about twelve hours a day, with twilight not even lasting half an hour. In the early morning, when the air and soil warm up quickly with increasing solar radiation, the evaporating rainwater and the water that the plants give off through their transpiration rises as warm, moist air and clusters in the sky in increasingly dense clouds . These clouds usually rain out in the afternoon or evening, often in connection with a thunderstorm .

    This year-round precipitation , which is particularly intense in spring and autumn - during the so-called rainy seasons - means that there is a humid climate for at least ten months of the year . Nevertheless, a considerable amount of the rain evaporates again quickly. This effect is reinforced by the foliage of the vegetation, so that the vegetation itself causes renewed precipitation. The annual rainfall is 2000 to 4000 mm, five times higher than in Central Europe , where the values ​​are 400 to 800 mm.

    On the windward side of tropical mountain slopes, precipitation can even rise to annual values ​​between 6,000 mm and 12,000 mm (on the Hawaiian Waiʻaleʻale ). In particular, where wet trade winds blow from the same direction all year round, the uphill rain always falls on the same side of the mountain, and there are very pronounced weather divisions on the mountain ridges .

    In general, the temperatures in tropical rainforests change only very slightly. The seasonal fluctuations are only around 6 ° C, the maximum daily temperature in the warmest month is around 30 ° C, in the coolest month it is around 24 ° C. The mean annual temperatures hardly fluctuate from year to year at only 0.5 ° C. Most pronounced are the differences between the maximum daytime and minimum nighttime temperatures, which can be up to 10 ° C. Because there are no distinguishable seasons with vegetation breaks, the climate of the tropical rainforests is also known as the time of day climate .


    The lowland rainforests are criss-crossed by a dense “network” of countless rivers
    View from above over the
    Amazon rainforest

    Characteristic of the external appearance of the evergreen tropical rainforest is the so-called multi - storey building , which extends from the roots over the herbaceous layer close to the ground and the up to five meter high floor of the bushes up to the dense main canopy at a height of 40 meters and individually up to 20 m above protruding retainers extends.

    Since there are different but relatively constant ecological conditions on each “floor”, an extremely large number of extremely specialized animal and plant species have developed in the course of evolution at different altitudes , which moreover often only live in a small area of distribution and therefore only a small one Exhibit population size. It so happens that the tropical rainforests of the world's highest species diversity tight both in terms of fauna and the flora possess.

    Due to the high amounts of precipitation, significant rivers flow through many tropical rainforests , first of all the Amazon , for example in Brazil, and then the Congo , which each form the two largest forest-river landscapes in the tropics.

    Material cycles

    Only small amounts of plant material cover the rainforest floor

    Evergreen tropical rainforests have material cycles that are independent of the seasons due to the year-round growing season. Most of the forests are on old, heavily weathered soils (see section Soils ). The mineral components of these soils, especially the kaolinite , can hardly store nutrients or water. In addition to nitrogen and phosphorus , nutrients such as potassium , calcium and magnesium are either transferred to the living biomass or bound to the humus . In those soils in which weathering has not yet progressed to a great depth, three-layer clay minerals can still be found in the subsoil , which can store larger quantities of nutrients. Most of the time, certain amounts of humus are still available down to greater depths. From there, deep-rooted trees can absorb nutrients.

    The litter is worked into the mineral soil by soil animals and, due to the climatic conditions, is decomposed extremely quickly and continuously by bacteria and fungi . Only small amounts are converted into stable humus compounds. Most of the dead organic substances are completely mineralized and the nutrients are quickly made available to the plants again in an inorganic form. Plants with shallow roots can absorb these nutrients directly. In mycorrhizal plants, the mycorrhizal fungi return the nutrients to the plants immediately after they have been released.

    Some parts of the plant do not even fall to the ground, but are decomposed at a great height and the nutrients are absorbed by epiphytic plants.

    If, on the other hand, is cleared , this leads to an increase in temperature in the topsoil, and the natural mineralization of the humus present there is accelerated, which releases additional nutrients. In the case of slash and burn, the aboveground biomass and litter burn. The carbon goes into the atmosphere as carbon dioxide and no organic matter can get into the ground as litter. These two effects (less input due to reduced litter input and more output due to increased mineralization) reduce the humus stocks in the soil. The nutrients present in biomass and litter are also present as oxides after the fire . Most of the nitrogen and sulfur compounds escape directly into the atmosphere, while most of the other nutrients are found in the ash. Since the humus on which most of them could have been stored is severely depleted, most of them are washed out quickly. The fire also causes an increase in the pH values in the topsoil, for a short time even in the alkaline range, after which they level off for a few years to values ​​between 5 and 6.5. This makes existing nutrients, especially phosphorus , more available.


    On the embankment of the Río Madre de Dios ( Peru ) the red, kaolinite-containing soil becomes visible

    Tropical rainforests are particularly lush areas because of the constant supply of water. This appearance of unlimited growth potential is deceptive, however, as it is only derived from the vegetation visible above the ground. In fact, in contrast to European mixed forests , the soil only has a limited nutrient storage capacity and is therefore relatively sterile. For millions of years, the soils of most rainforests have been exposed to warm and humid weather, so that the rock is extremely strong and in some places weathered up to 50 meters deep . Mainly kaolinite , iron oxides and aluminum oxides were formed from the silicates of the parent rock . Certain iron oxides, especially hematite , give tropical soils their red color. Quartz , if it was present in the parent rock, accumulates. The most common soil type is called Ferralsol (according to the international soil classification system World Reference Base for Soil Resources (WRB)). Ferralsoles have clay minerals with a very low cation exchange capacity and are usually moderately acidic (pH value around 5). You can only supply the plants with nutrients as long as the humus content is high (see section material cycles ). Acrisols are also common . They are more acidic in the topsoil and poorer in clay and humus, but have clay minerals with a slightly higher cation exchange capacity. In addition, small areas also occur Plinthosole on. These are soils with high concentrations of iron oxide, which form characteristic patterns through redox processes . Oxide-rich horizons can harden and are then called laterite . Laterite horizons are a physical barrier to root growth. In tropical mountains, such as in Southeast Asia, erosion causes rock that is either unweathered or not very weathered to come to the surface, so that the period of weathering was insufficient for ferralsoles to form. More fertile soils such as Cambisole , Alisole or Nitisole dominate here . Andosols are also common in volcanic areas .

    Flora and fauna

    Among other things, the widespread distribution of the individual tree species resulted in the greatest biodiversity on earth in the evergreen rainforest . Although the tropical rainforests only cover 7% of the earth's surface, according to various estimates, between 40% and more than 70% of all species living on earth are there, that is possibly more than 30 million animal and plant species.


    Stratification in the tropical rainforest

    In the tropical rainforest, the plants grow extremely close to each other as well as in a certain vertical staggering, which is known as stratification or storey structure. Often four to six different floors are described, which, however, cannot always be strictly separated from one another, but merge into one another; the characteristics of the various floors also depend on the location of the forest.

    • the bottom layer, consisting of the root system of the plants and of a usually very thin humus blanket
    • the herb layer, for example, the mosses , ferns and other ground cover are with very low light requirement can
    • the shrub layer to a height of 5 meters, are among the also young trees
    • the layer of low trees
    • the crown layer with its main canopy at a height of approx. 40 m
    • the so-called overhangs, known as the “giant trees” , which occasionally protrude up to approx. 60 m above the main canopy
    Flat, far-reaching root system of mighty buttress roots in the Brazilian rainforest

    The trees usually have flat, widely tapering roots, which are formed either as board or stilt roots .

    The climbing plants of the rainforest are divided into lianas , epiphytes and hemi-epiphytes . The epiphytes (epiphytes) are, for example, ferns and bromeliads . They grow on forks and branches of the trees, but do not enter into any physiological connection with the carrier tree . They use the stronger light there in the upper regions of the trees . Since there is a lack of water and nutrients at high altitude, they use so-called niche leaves to form cavities in which humus is created and water is collected. Many bromeliads in turn form cisterns with their leaves , in which water collects. This water is absorbed through the leaf surface with the help of special absorption organs ( suction scales ).

    Epiphytic orchids, in turn, have aerial roots that are covered with an absorbent fabric. Lianas, on the other hand, take root in the ground and only unfold their leaves in the canopy. They are also able to develop aerial roots to ensure an additional water supply. Hemi-epiphytes have found a middle ground for the supply of nutrients: They begin their life as an epiphyte (supply via the leaves) and, in the event of supply shortages, form connections to the soil in order to obtain water and nutrients.

    Lianas and epiphytes complement the appearance of the jungle vegetation. Up to 80 different types of sitters have been counted on a carrier tree.


    Arthropods (here leaf cutter ants ) represent the largest group of animals in the rainforest

    The fauna of the tropical rainforest is characterized by an extremely large biodiversity . The arthropods , i.e. insects , arachnids , millipedes and crustaceans, make up by far the largest share . In the course of time, natural selection led to an ever better adaptation of the fauna to the ecological conditions of the rainforest. For example, the strikingly colored poison dart frogs spend their entire lives in the treetops - their spawn develops in the puddles of bromeliad leaves . Like many other amphibians in the rainforests, they are very poisonous.

    Some reptiles in the rainforest reach a considerable size. There are several species of crocodiles or the South American anacondas . Slightly smaller reptiles come from the group of turtles and chameleons .

    The birds of the rainforest often have strikingly colorful plumage , including macaws , birds of paradise and hummingbirds .

    The mammals represent only a small group of species, the largest of them being the African forest elephant . The largest predator is the tiger in Asia and the jaguar in South and Central America . Even primates are found in most major rainforests. The orangutan that lives in the rainforests of Southeast Asia has become rare ; Gorilla , chimpanzee, and bonobo are found in Africa, and many smaller species of monkeys are found in the American rainforests. The rivers of the rainforests are very rich in fish. They feed on river dolphins and giant otters in South America .

    People in the rainforest

    Pygmy dwellings in the Congolese rainforest

    Tropical rainforests are not only home to animals, but also to people. Often these are indigenous peoples who lead a rather isolated existence in the forests and can live largely independently from the forest and its products. As a rule, they live as hunters and gatherers , but they also grow fruit and vegetables , some in the form of floor cultivation adapted to the ecological conditions . Some, like the pygmy peoples of Central Africa's tropical rainforests, identify themselves as "forest peoples".

    Further examples of people in the rainforest are the Palawan , an indigenous people with around 40,000 members who have lived in the last remaining pieces of tropical rainforest on the Philippine island of Palawan for thousands of years . A large number of indigenous peoples also live in the Amazon rainforest in Brazil and Peru . These include large groups such as the Yanomami with over 30,000 members, but also many smaller, uncontacted groups with only a few hundred members, who mostly live as nomads in the rainforest.

    The endangerment of the tropical rainforest also puts indigenous peoples and their way of life under pressure. Common problems are clearing of the rainforest and opening up for the exploitation of raw materials . Enforcing the internationally recognized rights of indigenous peoples (e.g. the Convention on Indigenous and Tribal Peoples in Independent Countries ) can also help protect the rainforest. For example, the Yanomami Park in Brazil, the largest recognized indigenous area in the tropical rainforest in the world, provides 9.6 million hectares of rainforest for the Yanomami and has minimized the entry of loggers and gold diggers .

    Endangerment of the tropical rainforest

    State of the rainforests in the main countries
    country Forest area, 2005
    (1000 km 2 )
    Annual loss
    2000-2005 (1000 km 2 )
    Annual loss
    2000-2005 (%)
    Cameroon 212 2.2 1.0
    Republic of the Congo 225 0.2 0.1
    Democratic Republic of Congo 1336 3.2 0.2
    Gabon 218 0.1 0.0
    Indonesia 885 18.7 2.0
    Malaysia 209 1.4 0.7
    Myanmar 322 4.7 1.4
    Thailand 145 0.8 0.4
    Brazil 4777 31.0 0.6
    Colombia 607 0.4 0.1
    Peru 687 0.9 0.1
    Venezuela 477 2.9 0.6
    Madagascar 128 0.4 0.3
    Papua New Guinea 294 1.4 0.5

    The five large rainforest areas in Asia, Africa, Madagascar, South America ( Neotropic Islands ) and New Guinea are endangered to different degrees by different human activities. Commercial logging is increasingly the leading cause, particularly in Southeast Asia. Hunting large vertebrates in accessible forest areas can have a major impact on ecosystems. Forest fires that are started by farmers after clearing are an increasing problem. Overall, deforestation is dominated by smallholders , although large-scale, commercial monocultures are becoming increasingly relevant, especially ranching in the Neotropics. Political instability and armed conflict are causing additional problems in some regions such as Africa.

    In 1950 the extent of the tropical rainforests was estimated to be 16 to 17 million km², that is about 11% of the earth's land area. In 1982 the evaluation of field surveys, aerial photographs and satellite images showed that only 9.5 million km² were left. A new inventory in 1985 showed the destruction of another million km².

    The deforestation rates vary significantly between regions, the highest they are currently in Southeast Asia (Indonesia). In the coming decades, the risk is expected to increase due to population growth.

    Protected areas can help protect rainforests, but are often underfunded and therefore not effective. Integrated Conservation and Development Projects have hardly been successful so far. Expanding the list of endangered species and certification measures can help, although the trade in wood, bushmeat and other forest products is very difficult to control.

    Overall, the situation is critical, but not hopeless. Even in the most severely threatened areas, biota survive in small protected areas or remaining forest fragments. More species will survive if parks are protected more effectively and unprotected areas are managed sustainably. Massive financial resources are required for this.


    Illegal logging in Brazil

    Legal and illegal logging is often the main factor in forest loss. In most cases, only a few tree species are exported, so the intensity is low. In Southeast Asia, on the other hand, many species are cleared, partly because the domestic market there is more important and less selective than the export market. New roads and infrastructure encourage increased logging, hunting and clearing by landless farmers. Forest fires are more likely after logging.

    The commercial hunt for bushmeat, the more locally oriented hunt for traditional medical devices, and the trade in wild animals kept as pets threaten many vertebrates in the tropics. This also disrupts interactions such as the propagation mechanisms of plants , seed-eaters and predation .

    Forest fires usually do not occur in ecologically undisturbed rainforests, except under extreme conditions such as El Niño . The fragmented crown closure and the availability of easily combustible material in logging areas make these areas particularly vulnerable to fires. Individual fires lead to positive feedback as they lower the canopy closure and provide fuel, which leads to susceptibility to fires after just a few weeks (instead of months) of drought. Forest fires have increased in frequency over the past 25 years due to fragmentation, logging, and sources of fire. Farmers often use slash and burn, but it is difficult to control these fires.

    Many factors contribute to deforestation, i.e. the complete removal of the forest. The most important factor is clearing by poor smallholders, typically migrants from other parts of the country. Large farms and ranches mostly arise from the consolidation of already cleared areas, although clearing by large farms is a major factor in some regions. Shifting farming is the most serious cause in Africa, ranching in tropical America, plantations in Southeast Asia and the mechanized cultivation of soybeans in Brazil. Deforestation rates differ significantly from region to region. In Asia, the rate is about twice that of Africa, while it is lowest in America. There is also variability within the regions, for example the deforestation rate in the Amazon region of Brazil, in parts of Madagascar and in central Sumatra is very high at more than 4% per year.

    Invasive species pose a threat to oceanic islands like Hawaii . Continental rainforests are much more resilient, although there, too, are increasing cases of disturbance and fragmentation.

    The global warming could affect tropical rain forests, the effects are not yet clear. Climate models predict changes in temperature and precipitation that are outside the currently observed tolerance range of many species. In most regions, the interactions of these climatic changes will presumably outweigh these direct effects; for example, more frequent periods of drought favor wood removal.

    Exposure by region


    Palm oil plantation on Java

    In Southeast Asia, more than half of the rainforest has disappeared and rates of degradation and loss are the highest in the tropics. The rate of deforestation increased in the 1980s and 1990s and may still do so. Poverty and population growth play an important role, but the high rates are the result of logging and conversion to cash crops and tree plantations . Wildlife is threatened by hunting for rare foods, traditional medicine, trophies, raw materials and pets.

    Most of the rainforests in the region remain in Indonesia, but the deforestation rate there is particularly high at 2%. Indonesia is the largest supplier of wood-based panels and other processed wood products. Illegal timber extraction provides the majority of the raw materials required for this. Deforestation by farmers is also favored by the removal of wood. Often, however, the same companies are responsible for logging and subsequent deforestation and the creation of plantations. Two thirds of the plantations on former forest areas are oil palms . Global demand for palm oil is expected to double over the next 20 years. Half of the increase will be covered by Indonesia, mainly Sumatra, Kalimantan and Papua.


    The rainforests in Africa suffer from rapid population growth and extreme poverty. There is also political instability and armed conflict. In West Africa , the rainforests have largely disappeared. Large areas remain in Central Africa . In the Democratic Republic of the Congo , the lack of rivers and roads prevents access to rainforests. In the accessible areas, however, hunting pressure is strong, both for self-sufficiency with protein and for commercial purposes. The greatest danger lies in the infrastructural development, since isolated areas are made accessible to farmers and hunters.


    Slash and burn in Madagascar

    The rainforests of Madagascar are threatened by high population growth and extreme poverty. On the eastern edge of the island, most of the original rainforest no longer exists; the remaining forest is heavily fragmented and degraded. Although deforestation rates have peaked, smallholders are still threatening the forests. The logging of wood plays a comparatively minor role in Madagascar, while invasive species play a comparatively large role.


    Deforestation in the Amazon basin

    Half of the world's remaining tropical rainforests are in the Amazon Basin. Deforestation rates are lower than in Asia and many African regions, but absolute deforestation is greater. The main problem is the conversion of forest to agricultural land, both from the southeast and west as well as from within. The forest is cleared by small farmers in particular via the access to roads in order to cultivate crops and raise livestock. Much of the infrastructure development is justified by the cultivation (and export) of soybeans. Deforestation, logging and forest fires are concentrated on the new roads. Road construction by the government is much more extensive than in any other rainforest region, one example being the BR-163 ; between 2004 and 2007 alone, around 17,000 km of additional roads were built each year. The Brazilian government did not have the capacity to control illegal deforestation, logging and mining over this large area. In Brazil, around 13% of the original rainforest had been cleared by the end of 2006; 85% of this cleared area was converted into pastureland, 15% into fields for growing soybeans. Deforestation in the Brazilian Amazon increased in 2019 under the new President Bolsonaro . The combination of global warming and deforestation makes the regional climate drier and could turn large parts of the rainforest into a savannah .

    The two other rainforest areas besides the Amazon basin, the Mata Atlântica and rainforest along the Pacific coast, are largely no longer available. Again, ranching and cash crops are the main drivers, although there are some promising conservation projects.

    New Guinea

    New Guinea is home to the third largest contiguous rainforest area (after the Amazon and Congo basins ). The vertebrate fauna differs significantly from that of the rest of Southeast Asia. Western New Guinea has a low population density, but the rainforest is increasingly threatened by palm oil plantations , the removal of wildlife and fires. The greatest danger, however, is the extraction of timber, especially from Merbau . The main parties involved are timber companies from Malaysia, traders in Singapore, buyers in Hong Kong and factories in China, where a merbau trunk is processed every minute. The ongoing road construction will further facilitate the extraction of wood.

    Papua New Guinea's rainforests were not threatened until recently, as the population density is very low and the land is controlled by clans. In the past two decades, however, there has been a boom in the timber industry in New Guinea. Corruption is a problem when granting timber extraction rights, as is future population growth.

    Protective measures

    Protected areas

    The most important measure to protect the rainforests are protected areas. However, the successes of various protected areas differed significantly from one another. Costa Rica's parks are relatively effective, while those in the Democratic Republic of the Congo are virtually ineffective. Poaching and crossing borders cause problems for many parks, although the vegetation inside the parks is usually in a much better condition than outside. As the population increases, so does the pressure on the parks. Satellite images show that 69% of the protected areas examined have experienced a decline in habitat within 50 km of the park boundary over the past 20 years.

    Protected areas vary greatly in size. Large parks like those in the Amazon are probably the only way to preserve complete ecosystems. But also smaller parks with up to a few hectares can preserve individual species.

    Parks can only be effective as a protective measure if they are actually protected. Many parks are chronically underfunded. Although tourism in politically stable countries can generate income in accessible parts of protected areas, the bottom line is that most parks cost more than they generate in income. In practice, the costs are often borne by residents who can no longer access resources and may be driven from their land. Without sufficient compensation, the chances of an effective park are therefore slim.

    During the last decade, a lot of money has been invested in Integrated Conservation and Development Projects (ICDP), which are intended to protect biodiversity and create economic development at the same time . However, ICDPs have so far not been successful in achieving these goals. A more recent approach is direct compensation from landowners and local communities.


    Protected areas are insufficient as protective measures because they are too small in number and area.

    Less destructive logging, such as reduced-impact logging (RIL), reduces damage to the soil and the next generation of trees. In addition, studies have shown that the financial costs of logging can be reduced with RIL. The problem here is that the majority of timber harvesting is either illegal or short-term, so that there is no incentive for sustainable management. The implementation of RIL also requires well-trained and motivated park employees, which few rainforest countries have.

    In many places, wood removal is concentrated on individual species, which theoretically simplifies control. The Washington Convention on Endangered Species has included some species on the list, such as Swietenia macrophylla or Gonystylus species. The exporting countries must ensure that the logging was legal and does not endanger the survival of the species. The Convention already has a major impact on international trade in primates and parrots, but does not affect domestic trade or bushmeat extraction. Strategies to curb bushmeat hunting include working with logging companies to keep hunters and meat from being transported, providing alternative sources of protein, education, and banning commercial trade.


    The certification of forest products has a long history. Eco-labels (e.g. from the Forest Stewardship Council ) work on the premise that some consumers are willing to pay more for such excellent, environmentally friendly products. However, only a very small proportion of tropical rainforest production is certified, as the costs of certification are seldom lower than the surcharges paid by consumers. Mobilizing consumers is very difficult, also because the origin of the raw materials in the end products is not obvious. Developed countries import large quantities of palm oil and soybeans. Palm oil is in soaps, cosmetics, and candles. Soybeans are refined into animal products. Overall, the effects of certification are minor, but pressure on producers who import raw materials (e.g. through increasing demand) could help.

    Organic cultivation

    A permaculture adapted to the ecological conditions is the cultivation of floors or floors .


    Rainforests have already disappeared in many areas of Asia and afforestation programs could help there. However, the technical problems are enormous and the processes are slow.

    Influence on the climate


    Trees absorb the greenhouse gas carbon dioxide (CO₂) from the earth's atmosphere through photosynthesis . An existing forest thus represents a CO₂ storage facility. However, existing forests are not CO₂ sinks , since in a primary forest there is no net growth at the end of the succession and therefore no CO₂ fixation . If a forest is cleared, the carbon stored in it is released immediately ( slash and burn ) or at a later point in time.

    The soils under the rainforest can be humus to great depths and thus have considerable reserves of organically bound carbon. Due to the increase in the soil temperature, clearing leads to accelerated decomposition of the organic components and to the release of large amounts of carbon dioxide.

    Decreasing carbon storage

    According to a study published in 2020, rainforests store significantly less CO₂ than they did in the 1990s due to global warming . If the negative trend persists, the rainforests could develop into a CO₂ emitter by 2035, according to the study. For their analysis, the scientists examined 300,000 trees in the rainforests of the Amazon and Africa over decades. According to the analysis, the rainforests already stored a third less carbon dioxide in the 2010s than in the 1990s.


    Furthermore, trees evaporate water and thus promote cloud formation . The huge clouds of evaporation that rise from the damp forest every day often prevent the direct rays of the sun from reaching the treetops and cool the earth in the atmosphere. The water potential of the clouds over the rainforests is enormous. Researchers have calculated that a drop of water evaporates five to six times over the Amazon region and rains down again before it reaches one of the many rivers.

    When clearing the rainforest, this water and cooling cycle may collapse. Without a forest, solar radiation hits the unprotected ground and warms the earth's surface there. The soil can dry out. Then much less or no protective clouds form over the former forest area. However, the exact consequences of deforestation on the water balance depend on the local conditions.

    Web links

    Commons : Tropical Rainforests  - Collection of pictures, videos and audio files

    Individual evidence

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