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Rain Forests…

Rainforest Forests that occur in continually wet climates with no dry season. There are relatively small areas of temperate rainforests in the Americas and Austral­asia, but most occur in the tropics and subtropics.The most extensive tropical rainforests are in the Americas. These were originally 1.54 × 106 mi2 (4 × 106 km2) in extent, about half the global total, and mainly in the Amazon basin. A narrow belt also occurs along the Atlantic coast of Brazil, and a third block lies on the Pacific coast of South America, extending from northern Peru to southern Mexico.Tropical rainforests have a continuous canopy (commonly 100–120 ft or 30–36 m tall) above which stand huge emergent trees, reaching 200 ft (60 m) or taller. Within the rainforest canopy are trees of many different sizes, including pygmies, that reach only a few feet. Trees are the main life form and are often, for purposes of description and analysis, divided into strata or layers. Trees form the framework of the forest and support an abundance of climbers, orchids, and other epiphytes, adapted to the microclimatic conditions of the different zones of the canopy, from shade lovers in the gloomy, humid lower levels, to sun lovers in the brightly lit, hotter, and drier upper levels. Most trees have evergreen leaves, many of which are pinnate or palmate. These features of forest structure and appearance are found throughout the world’s lowland tropical rainforests. There are other equally distinctive kinds of rainforest in the lower and upper parts of perhumid tropical mountains, and additional types on wetlands.Rainforests occur where the monthly rainfall exceeds 4 in. (100 mm) for 9–12 months. They merge into other seasonal or monsoon forests where there is a stronger dry season (3 months or more with 2.5 in. or 60 mm of rainfall). The annual mean temperature in the lowlands is approximately 64°F (18°C). There is no season unfavorable for growth.Primary rainforests are exceedingly rich in species of both plants and animals. There are usually over 100 species of trees 2.5 in. (10 cm) in diameter or bigger per 2.4 acres (1 ha). There are also numerous species of climbers and epiphytes. Flowering and fruiting occur year-round, but commonly there is a peak season; animal breeding may be linked to this. Secondary rainforests are much simpler. There are fewer tree species, less variety from location to location, and fewer epiphytes and climbers; the animals are also somewhat different. See also Ecological succession.Tropical rainforests are a source of resins, dyes, drugs, latex, wild meat, honey, rattan canes, and innumerable other products essential to rural life and trade. Modern technology for extraction and for processing has given timber of numerous species monetary value, and timber has come to eclipse other forest products in importance. The industrial nations use much tropical hardwood for furniture, construction, and plywood. Rainforest timbers, however, represent only 11% of world annual industrial wood usage, a proportion that has doubled since 1950. West Africa was the first main modern source, but by the 1960s was eclipsed by Asia, where Indonesia and Malaysia are the main producers of internationally traded tropical hardwoods. Substantial logging has also developed in the neotropics. See also Forest ecosystem.rainforest Lush forest, generally composed of tall, broad-leaved trees and usually found in wet tropical regions around the Equator. Despite increased awareness of the rainforests’ importance during the late 20th century, they continue to be cleared. Rainforests grow mainly in South and Central America, West and Central Africa, Indonesia, parts of Southeast Asia, and tropical Australia, where the climate is relatively humid with no marked seasonal variation. Depending on the amount of annual rainfall, the trees may be evergreen or mainly deciduous. The former require more water. Temperatures are high, usually about 86 °F (30 °C) during the day and 68 °F (20 °C) at night. Soil conditions vary with location and climate, though most rainforest soils tend to be permanently moist and not very fertile, because the hot, humid weather causes organic matter to decompose rapidly and to be absorbed quickly by tree roots and fungi. Rainforests have several layers. The highest continuous layer, called the canopy, extends across the treetops at a height of 100 – 165 ft (30 – 50 m). Most animals live among the leaves and branches. Below the canopy is a thick understory filled with small trees, lianas, and epiphytes. The space directly above the ground can be occupied by tree branches, twigs, and foliage, but, contrary to popular belief, the rainforest floor is not impassable. Rather, it is bare except for a thin layer of humus and fallen leaves. Animals inhabiting this layer (e.g., gorillas, elephants, jaguars, and bears) are adapted to walking or climbing for only short distances. Burrowing animals, such as armadillos and caecilians, are found in the soil, as are microorganisms that help decompose and recycle the organic litter accumulated by other plants and animals from all layers. The climate of the ground layer is unusually stable because the upper stories of tree canopies and the lower branches filter out sunlight, retain heat, and reduce wind speeds, keeping the temperature fairly even.

Rainforest layers

The rainforest is divided into five different parts, each with different plants and animals, adapted for life in that particular area.

Emergent layer

This layer contains a small number of very large trees which grow above the general canopy, reaching heights of 45-55 m, although on occasion a few species will grow to 60 m or 70 m tall. They need to be able to withstand the hot temperatures and dry winds. Eagles, butterflies, bats and certain monkeys inhabit this layer. Some of these animals never go to the ground in thier lives. They have thick leaves and very stong roots called butruss roots, these help support the tree.

Canopy layer

Further information: Canopy (forest) 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 adjacent treetops.The canopy, by some estimates, is home to 40% of all plant species, suggesting that perhaps half of all life on Earth could be found there. The fauna is similar to that found in the emergent layer, but more diverse. A quarter of all insect species are believed to exist in the rainforest canopy.Scientists have long suspected the richness of the canopy as a habitat, but have only recently developed practical methods of exploring it. As long ago as 1917, U.S. 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 exploration 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 methods 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 is called Dendronautics.

Understorey layer

There is a space between the canopy and the forest floor, which is known as the understorey . This is home to a number of birds, snakes, and lizards, as well as predators such as jaguars, boa constrictors, ocelots, and leopards. Armadillos also live here. 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 reaches the understorey. This layer can also be called a shrub layer.

Shrub Layer

The layer just above the floor, consists of mainly large-leaved plants and small trees able to survive on the meager amount of light let through by the canopy, this is due to the plants having maximim photosynthesis potential.

Forest floor

This region receives only 2% of the rainforest’s sunlight. Thus, only specially adapted plants 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, as little sunlight penetrates to ground level. It also contains decaying plant and animal matter, which disappears quickly due to the warm, humid conditions promoting rapid decay. Many forms of fungi grow here which help decay the animal and plant waste.

Fauna

Rainforests support a very broad array of fauna including mammals, reptiles, birds and invertebrates. Mammals may include primates, felids and other families. Reptiles include snakes, turtles, chameleons and other families. Birds include such families as vangidae and Cuculidae. Dozens of families of invertebrates are found in rainforests. More than half of the world’s species of plants and animals are found in the rainforest. This amounts to over 5 million species of plants and animals.

Human uses

Main article: Tropical rainforest#Human usesMany foods originally came from tropical forests, and are still mostly grown on plantations in regions that were formerly primary forest.[6] Tropical rainforests are also the source of many medicinal drugs, with over half the medications originating from the rainforest. Tropical rainforests also provide timber as well as animal products such as meat and hides. Rainforests also have value as tourism destinations and for the ecosystem services provided. on top of this many tribes live here.

Deforestation

Main article: DeforestationTropical and temperate rain forests have been subjected to heavy logging and agricultural clearance throughout the 20th century, and the area covered by rainforests around the world is rapidly shrinking. Biologists have estimated that large numbers of species are being driven to extinction (possibly more than 50,000 a year) due to the removal of habitat with destruction of the rainforests [1]. Protection and regeneration of the rainforests is a key goal of many environmental charities and organizations. (It is doubtful that this rate will be sustained as the relative cost of logging rises with dwindling resources.) About half the world’s species of animals and plants depend upon these forests for their survival.[citation needed]Another factor causing the loss of rainforest is expanding urban areas. Littoral Rainforest growing along coastal areas of eastern Australia is now rare due to ribbon development to accommodate the demand for seachange lifestyles.

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