The wet tropical forest , also known as ombrophilous or rainy, is a Biome zones intertropical, characterized by a vegetable Formation raised high and dense, as well as a hot and very wet climate.

The ombrophilous Forêt is richest in specific diversity, as well for the trees as for the flora or fauna in general (until several hundreds of species of trees per hectare, against ten to the maximum in moderate medium). It is characterized by trees of big sizes to slow growth as long as they emergent step on the Canopée, stage to which they often obtain strong buttress. The endemic species, kinds or families are highest there among the ecosystems of the emerged grounds.

The wet term tropical forest also indicates the primary forest which occupies this Biome (one speaks about secondary forest if not). ( Note: the names of the biomes are generally associated with the vegetable formation which occupies it.)

Extension

The ombrophilous forest occupies a little less than one tenth of the surface of all the Forêt S, that is to say 12,3 million km ², but it largely shelters the most specific biodiversity.

These wet , or ombrophilous tropical forests known as , or rain forests range between the two Tropique S and are thus known as intertropical, they follow the thermal equator overall (or weather).

  • In South America, these forests are very present - in particular in the basin of the Amazon and the plate of Guyanes -, they occupy more than 5 million km ² is nearly a third of the Continent.
  • In Central America, this Biome is observable in all the southern part of the area.
  • In Asia, there is nearly 3,5 million ombrophilous km ² of forest, they are in the South-East Asia, except for a central part of the Indo-China occupied by tropophilous forests, they extend from the septentrional China to the New Guinea and leave sometimes the place to the Mangrove S on the coasts.
  • On the west coast of the Africa they cover the zone located on the equator, of the Guinea to the Gabon then they go up somewhat the course of the Congo always while following the parallel 0°.
  • On the Littoral is, the tropical forest is done rarer, it is represented more only close to the littoral Kenya N, near to the Mangrove S like on the east coast to Madagascar and the neighbouring islands like the island of the Meeting.

Climate

The ombrophilous forest is located in the areas of the intertropical Zone subjected to a equatorial Climat.

This Climat has as main features a ambient moisture and a permanent Chaleur as well as a more or less marked equality of the duration of the day and night during all the year.

Heat

This Climat is of standard heat, the totality of its monthly averages are higher than 18°C. 25-30°C, it is the Température which one can meet all the year in these areas, with a thermal Amplitude relatively low: about 5°C.

This thermal monotony is also expressed in the variations in temperatures day/night.

Wet

The Précipitation S are strong in the equatorial areas: higher than 1500 mm/an with always more than 100 mm monthly (on average 200), but the marked character of the climate is rather the fact of constant precipitations (it rains during the 3/4 of the year) and thus of a permanent moisture (80% with the ground on average).

The forest of clouds or forests of mountains, located between 1000 and 2000 meters of Altitude, profit from Précipitation S largely higher than the Forêt S of the Plaine S: 2000 to 8000 mm according to altitude and the temperature drop by 0,6 °C for 100 m of profit of rise.

The trade wind

This Wind of north-eastern direction in the northern Hemisphere and south-east in the southern hemisphere is an important component of this Climat share its contribution of Précipitation S, it exerts its influence since the sea level up to 2000 m of altitude.

In the zones close to the equator, the influential Alizé S are the oceanic trade winds, they are these winds soft and slow (20 km/h) which brings the rain - by oceanic evaporation - in the equatorial areas, a contrario of the arid areas where the continental trade winds which are active there bring only aridity.

Note: more one moves away from the equator (weather), more one approaches a tropical climate at alternate seasons which admits a Saison dries contrary to the equatorial , but also an increase of the thermal Amplitude annual as the Atmospheric pressure which is weaker in the zones close to the equator.

Ecology

The fight for the light

Because of the dense forest, the light penetrates there with difficulty.

Grounds

Even if this Biome is richest and most complex of planet, the ground of the rain forest does not remain about it less fragile, thin and poor since the nutritive elements are captive vegetation. Any broken up element indeed is re-used quickly and given in circulation or is involved in subterranean water.

Symbioses

Épiphytes

Vegetation

With him only, this ecosystem contains 70% of the known plant species. Its Vegetation, characterized by the vertical stratification, is largely dominated by the flowering plants, especially species and the trees. One can find between 80 and 200 species of Arbre S per hectare in the ripe tropical forests. However, we will find only seldom two individuals of the same species in one hectare. One or two species will be able to alone dominate only in the specific sectors the such marshes.

The Feuille S in general have very lengthened ends which make it possible to accelerate the drainage because the stagnant water gene the respiratory functions and assimilatrices of the tree and supports the plants épiphyte S. There is few bud S because a bad season ago to surmount. When they exist, they are protected by secondary hairs, Mucilage or sheets.

Canopée

The Canopée of the wet tropical forest is an ecosystem with it only. It is composed of trees being able to reach heights from 30 to 50 meters. The emergent trees do not form a dense layer: they are exposed to high temperatures, winds sometimes violent one and a not very wet air. Canopée the higher is constantly occupied by various species of animals, including one great number passes the essence of their life there.

The mangrove

The Mangrove does not belong to the wet tropical forest itself, but it allows a transition between the latter and the oceans, it undergoes the same climate but its biome is different semi-watery and salted bus.

Roles

It would seem that, overall, the tropical forests store (slightly) more carbon than they do not reject any and would take part of this fact in the reduction of gases in greenhouse effect. In practice, the fall of surfaces (often by denshering) obliterates a little this assessment. One can however note interesting attempts at plantations with large scales of forests intended to be carbon wells (by keeping in memory the ecological poverty of this type of medium).

The forest ensures the safeguarding of the biodiversity, plays a big role in the cycle of water. It allows also a forestry development for the needs for the homme.
the pharmacopeia uses molecules resulting from the forest.

Deforestation

According to FAO, the Déforestation relates to each year more than 13 million hectares. All the Equatorial forests of the sphere are concerned.

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