RainforestTodayTomorror

Rainforests are forests characterized by high rainfall, with definitions based on a mini-mum normal annual rainfall of 1750-2000 mm (68-78 inches). The monsoon trough, alternatively known as the intertropical

convergence zone, plays a significant role in creating the climatic conditions necessary for the Earth’s tropical rainforests.Around 40% to 75% of all biotic species are indigenous to the rainforests.[1] It has been estimated that there may be many millions of species of plants, insects and microorgan-isms still undiscovered in tropical rainfor-

ests. Tropical rainforests have been called the “jewels of the Earth” and the “world’s largest pharmacy”, because over one quar-ter of natural medicines have been discov-ered there.[2] Rainforests are also responsi-ble for 28% of the world’s oxygen turnover, sometimes misnamed oxygen production,[3] processing it through photosynthesis from carbon dioxide and consuming it through respiration.The undergrowth in a rainforest is restrict-ed in many areas by the poor penetration of sunlight to ground level. This makes it easy to walk through undisturbed, mature rainforest. If the leaf canopy is destroyed or thinned, the ground beneath is soon colo-nized by a dense, tangled growth of vines, shrubs and small trees, called a jungle. There are two types of rainforest, tropical rain-forest and temperate rainforest. Tropical rainforests are characterized in two words: warm and wet. Mean monthly temperatures exceed 18 °C (64 °F) during all months of the year.[4] Average annual rainfall is no less than 168 cm (66 in) and can exceed 1,000 cm (390 in) although it typically lies be-tween 175 cm (69 in) and 200 cm (79 in).[5]

Many of the world’s rainforests are associat-ed with the location of the monsoon trough, also known as the intertropical convergence zone.[6] Tropical rainforests are rainforests in the tropics, found in the equatorial zone

(between the Tropic of Cancer and Tropic of Capricorn). Tropical rainforest is present in Southeast Asia (from Myanmar (Burma) to Philippines, Malaysia, Indonesia, Papua New Guinea and northeastern Australia), Sri Lanka, sub-Saharan Africa from Cam-eroon to the Congo (Congo Rainforest), South America (e.g. the Amazon Rainforest), Central America (e.g. Bosawás, southern Yu-catán Peninsula-El Peten-Belize-Calakmul), and on many of the Pacific Islands (such as Hawaiʻi). Tropical rainforests have been

Tropical

called the “Earth’s lungs”, although it is now known that rainforests contribute little net oxygen addition to the atmosphere through photosynthesis.[7][8].

Temperate forests cover a large part of the globe, but temperate rainforests only occur in few regions around the world. Temper-ate rainforests are rainforests in temperate regions. They occur in North America (in the Pacific Northwest, the British Colum-bia Coast and in the inland rainforest of the Rocky Mountain Trench east of Prince George), in Europe (parts of the British Isles such as the coastal areas of Ireland and Scot-land, southern Norway, parts of the western Balkans along the Adriatic coast, as well as

Temperatein the North West of Spain and coastal areas of the eastern Black Sea, including Georgia and coastal Turkey), in East Asia (in south-ern China, Taiwan, much of Japan and Ko-rea, and on Sakhalin Island and the adjacent Russian Far East coast), in South America (southern Chile) and also in Australia and New Zealand.

A tropical rainforest is typically divided into four main layers, each with different plants and animals adapted for life in that particular area: the emergent, canopy, un-derstorey and forest floor layers.

The emergent layer contains a small number of very large trees called emergents, which grow above the general canopy, reaching heights of 45–55 m, although on occasion a few species will grow to 70–80 m tall.[9][10] They need to be able to withstand the hot temperatures and strong winds that occur above the canopy in some areas. Eagles, but-terflies, bats and certain monkeys inhabit this layer. The canopy layer contains the majority of the largest trees, typically 30–45 m tall. The densest areas of biodiversity are

found in the forest canopy, a more or less continuous cover of foliage formed by adja-cent treetops. The canopy, by some estimates, is home to 50 percent of all plant species, suggesting that perhaps half of all life on

Earth could be found there. Epiphytic plants attach to trunks and branches, and obtain water and minerals from rain and debris that collects on the supporting plants. The fauna is similar to that found in the emer-gent layer, but more diverse. A quarter of all insect species are believed to exist in the rainforest canopy. Scientists have long sus-pected the richness of the canopy as a habi-

tat, but have only recently developed prac-tical methods of exploring it. As long ago as 1917, naturalist William Beebe declared that “another continent of life remains to be discovered, not upon the Earth, but one to two hundred feet above it, extending over thousands of square miles.” True explora-tion of this habitat only began in the 1980s, when scientists developed methods to reach the canopy, such as firing ropes into the trees using crossbows. Exploration of the canopy is still in its infancy, but other meth-ods include the use of balloons and airships to float above the highest branches and the building of cranes and walkways planted on the forest floor. The science of accessing tropical forest canopy using airships or sim-ilar aerial platforms is called dendronautics.[11] The understorey layer lies between the canopy and the forest floor. The understo-rey (or understory) is home to a number of birds, snakes and lizards, as well as preda-tors such as jaguars, boa constrictors and leopards. The leaves are much larger at this level. Insect life is also abundant. Many seedlings that will grow to the canopy level are present in the understorey. Only about

5% of the sunlight shining on the rainforest canopy reaches the understorey.

This layer can be called a shrub layer, al-though the shrub layer may also be consid-ered a separate layer. The forest floor, the bottom-most layer, receives only 2% of the sunlight. Only plants adapted to low light can grow in this region. Away from river-banks, swamps and clearings, where dense undergrowth is found, the forest floor is relatively clear of vegetation because of the low sunlight penetration. It also contains decaying plant and animal matter, which

understorey

disappears quickly, because the warm, hu-mid conditions promote rapid decay. Many forms of fungi growing here help decay the animal and plant waste.

The forest floor, the bottom-most layer, re-ceives only 2% of the sunlight. Only plants adapted to low light can grow in this region. Away from riverbanks, swamps and clear-ings, where dense undergrowth is found, the forest floor is relatively clear of vegetation because of the low sunlight penetration. It also contains decaying plant and animal matter, which disappears quickly, because

flora & Faunathe warm, humid conditions promote rapid decay.

Many forms of fungi growing here help de-cay the animal and plant waste. More than half of the world’s species of plants and ani-mals are found in the rainforest.[12] Rain-forests support a very broad array of fauna, including mammals, reptiles, birds and in-vertebrates.

Mammals may include primates, felids and other families. Reptiles include snakes, tur-tles, chameleons and other families; while birds include such families as vangidae and Cuculidae. Dozens of families of inverte-brates are found in rainforests.

Fungi are also very common in rainforest areas as they can feed on the decomposing remains of plants and animals. Many rain-forest species are rapidly disappearing due to deforestation, habitat loss and pollution of the atmosphere.[13]

Despite the growth of vegetation in a tropi-cal rainforest, soil quality is often quite poor.

Rapid bacterial decay prevents the accumu-lation of humus.

The concentration of iron and aluminium oxides by the laterization process gives the oxisols a bright red colour and sometimes produces mineral deposits such as bauxite.

Most trees have roots near the surface, be-cause there are insufficient nutrients below the surface; most of the trees’ minerals come from the top layer of decomposing leaves and animals.

On younger substrates, especially of volcan-ic origin, tropical soils may be quite fertile. If rainforest trees are cleared, rain can accu-mulate on the exposed soil surfaces, creat-ing run-off and beginning a process of soil erosion. Eventually streams and rivers form and flooding becomes possible.

A natural rainforest emits and absorbs vast quantities of carbon dioxide. On a global scale, long-term fluxes are approximately in balance, so that an undisturbed rainfor-est would have a small net impact on at-mospheric carbon dioxide levels,[14] though they may have other climatic effects (on cloud formation, for example, by recycling water vapour).

No rainforest today can be considered to be undisturbed.[15] Human induced defor-estation plays a significant role in causing rainforests to release carbon dioxide,[16] as do other factors, whether human-induced or natural, which result in tree death, such as burning and drought.[17] Some climate models operating with interactive vegetation predict a large loss of Amazonian rainforest

around 2050 due to drought, forest dieback and the subsequent release more carbon di-oxide.[18] Five million years from now, the Amazon rainforest may long since have dried and transformed itself into savannah, killing itself in the progress (changes such as this may happen even if all human defor-estation activity ceases overnight).[19]

The descendants of our known animals may adapt to the dry savannah of the former Amazonian rainforest and thrive in the new, warmer temperatures.[19]. A natural rain-forest emits and absorbs vast quantities of carbon dioxide.

On a global scale, long-term fluxes are ap-proximately in balance, so that an undis-turbed rainforest would have a small net impact on atmospheric carbon dioxide lev-els,[14] though they may have other climatic effects (on cloud formation, for example, by recycling water vapour). No rainforest to-day can be considered to be undisturbed.[15] Human induced deforestation plays a significant role in causing rainforests to re-lease carbon dioxide,[16] as do other factors,

whether human-induced or natural, which result in tree death, such as burning and drought.[17] Some climate models operating with interactive vegetation predict a large loss of Amazonian rainforest around 2050 due to drought, forest dieback and the sub-sequent release mor carbon dioxide.[18]

Five million years from now, the Amazon rainforest may long since have dried and transformed itself into savannah, killing it-self in the progress (changes such as this may happen even if all human deforestation activity ceases overnight).[19] The descend-ants of our known animals may adapt to the dry savannah of the former Amazonian rainforest and thrive in the new, warmer temperatures.[19]

Tropical rainforests provide timber as well as animal products such as meat and hides. Rainforests also have value as tourism des-tinations and for the ecosystem services provided. Many foods originally came from tropical forests, and are still mostly grown on plantations in regions that were formerly primary forest.[20] Also, plant derived medi-

effect on climate

deforestationcines are commonly used for fever, fungal infections, burns, gastrointestinal problems, pain, respiratory problems, and wound treat-ment.[21]

On January 18, 2007, FUNAI reported also that it had confirmed the presence of 67 different uncontacted tribes in Brazil, up from 40 in 2005. With this addition, Brazil has now overtaken the island of New Guin-ea as the country having the largest number of uncontacted tribes.[22] The province of Irian Jaya or West Papua in the island of New Guinea is home to an estimated 44 un-contacted tribal groups.[23] The tribes are in danger because of the deforestation, es-pecially in Brazil.

Central African rainforest is home of the Mbuti pygmies, one of the hunter-gather-er peoples living in equatorial rainforests characterised by their short height (below one and a half metres, or 59 inches, on av-erage). They were the subject of a study by Colin Turnbull, The Forest People, in 1962.[24] Pygmies who live in Southeast Asia are, amongst others, referred to as “Neg-

rito”. Tropical and temperate rainforests have been subjected to heavy logging and agricultural clearance throughout the 20th century and the area covered by rainforests around the world is shrinking.[25]

Biologists have estimated that large numbers of species are being driven to extinction (possibly more than 50,000 a year; at that rate, says E. O. Wilson of Harvard University, a quarter or more of all species on Earth could be exterminated within 50 years)[26] due to the removal of habitat with destruc-tion of the rainforests.

Another factor causing the loss of rainforest is expanding urban areas. Littoral rainfor-est growing along coastal areas of eastern Australia is now rare due to ribbon devel-opment to accommodate the demand for seachange lifestyles.[27]The forests are being destroyed at a rapid pace.[28][29][30] Almost 90% of West Africa’s rainforest has been destroyed.[31] Since the arrival of humans 2000 years ago, Madagas-car has lost two thirds of its original rain-forest.[32] At present rates, tropical rainfor-

Rainforestmakea

difference