Rain Forest
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| Guyanese rainforest | |||
| Features | Geographical Distribution | ||
| Area: 12.3 million (km ) Climate : Equatorial Vegetation types : deciduous evergreen forest Latitudes : intertropical |  | ||
The rainforest is a biome of the tropics characterized by a vegetation type with trees and a tall, dense and very hot humid climate.
The forest is the richest in species diversity for both trees to flora or fauna in general (up to several hundred species of trees per hectare, against a dozen at most in temperate). It is characterized by large trees to grow slowly so they do not emerge on the canopy , at which they procure often strong buttresses. Species, endemic genera or families are the highest among the ecosystems of the land.
The term also refers to the equatorial forest primeval forest that occupies this biome (in other cases, we use the term secondary forest) Geographic spread Rainforest occupies a little less than a tenth of the area of all forests , representing 12.3 million square kilometers, but is home to the most specific biodiversity. These forests are located between the tropics and tropics are saying, they broadly follow the equator thermal (or meteorological equator ). The rainforest is located in the regions of the tropics subjected to equatorial climate. This climate has a strong main features humidity and ambient heat as well as equal standing more or less pronounced for the duration of day and night throughout the year. Type hot, it systematically presents monthly averages above 18 C. The temperature recorded every year in these regions is around 25-30 C with a temperature range relatively low: about 5 C. This monotony is also expressed in thermal temperature differences day / night. The rains are strong in the equatorial regions: above 1500 mm / year with still more than 100 mm per month (average 200 mm), but the marked character of the climate is rather the result of constant rain (it rains for 3 / 4 of the year) and therefore a moisture constant high (80% in soil on average). The cloud forests or cloud forests and mountain forests , located between 1000 and 3000 meters of altitude , benefiting from precipitation well above the forests of the plains : 2 000-8 000 mm depending on altitude and temperature drop 0.6 C per 100 m elevation gain. This whole climate is characterized by the presence of the trade winds. This wind direction is North in the northern hemisphere and southeasterly in the southern hemisphere is an important component of the climate by its contribution to rainfall , and exerts its influence from sea level to 2000 m altitude. In areas near the equator , the winds are powerful ocean winds, these winds are gentle and slow (20 mph) that bring rain - evaporation ocean - in the equatorial regions, conversely arid regions where continental trade winds that are active n'amnent qu'aridit. The farther from the equator ( weather ), the closer a tropical climate with alternating seasons which admits a dry season in contrast to the equator , but also an increase in the temperature range of annual and the atmospheric pressure is lower in areas near the equator. Because of the density of the forest, terracing and tree strata of the permanent presence of the light penetrates leaves difficult. Although this biome is the richest and most complex of the planet, the soil of the rainforest is nevertheless fragile, thin and poor because the nutrients are captives of the vegetation. Anything is indeed decomposed quickly recycled and recirculated or driven into groundwater. The epiphytes thrive in tropical forests due to heat, but mainly because of the humidity. Indeed it is in the cloud forests, known as cloud forests , they are most abundant, thanks to the constant fog of these areas. These are plants and flowers that grow only in the fog and humidity. It is very wet By itself, this ecosystem contains 70% of plant species known. Its vegetation is characterized by vertical stratification is largely dominated by plants, especially species and flowering trees. Can be found between 80 and 200 species of trees per hectare in mature tropical forests. However, we shall find that rare for two individuals of the same species in one hectare. One or two species can not dominate themselves in specific areas such as wetlands. The leaves tend to have very elongated ends that accelerate the evacuation of water because water stagnant gene assimilative and respiratory functions of the tree and helps plant epiphytes. There is little buds because there is no bad season to overcome. When they exist, they are protected by hair, the mucilage or leaves school. The canopy of the rainforest is an ecosystem in itself. It consists of trees that can reach heights of 30 to 50 meters. Emergent trees do not form a dense stratum: they are exposed to high temperatures, sometimes violent winds and low-humidity air. The upper canopy is constantly occupied by different species of animals, many of them spend most of their lives. The mangrove is not for the rainforest itself, but it allows a transition between it and the ocean, it suffers the same climate but different because its biome is semi-aquatic and salty. It would appear that generally, tropical forests store (slightly) more carbon than they release and thereby contributing to reducing greenhouse gas emissions. In practice, the lower surfaces (often by burning) just obliterates this review. However, there are interesting attempts of large-scale planting of forests to be carbon sinks (keeping in mind the ecological poverty of this type of medium). The forest ensures the preservation of biodiversity, plays an important role in the water cycle. It also allows logging for human needs. Pharmacopoeia uses molecules from the forest. The main threat to these ecosystems is the deforestation , logging more than itself, is change of land use is problematic: conversion to plantations ( oil palm , eucalyptus , pine), agriculture ( soybean , cane sugar ) or urbanization. According to FAO , deforestation for each year over 13 million hectares. All the rainforests in the world are concerned. 
Climate
The struggle for light
Soils
Symbiosis
epiphytes
Vegetation
The canopy
Mangrove
Roles
Deforestation
References
See also
Related articles
External Links
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