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•Tropical forests
Tropical forests: a term indicating various forest types
ø A the surface of our planet, the principal climates (moderated climate, equatorial climate...) have a major role on the distribution of the great vegetable formations or biomes. Apart from the areas with more extreme climate (deserts or semi-deserts, Arctic areas and high mountains), the forests constitute the main part of the biomes present. In 1995, the F.A.O. (Organization of the United Nations for the food and agriculture) estimated that the forests covered more than 3 500 million hectares, that is to say more of the quarter of the emerged grounds (equivalent in the American continent). The tropical forests cover approximately 1 700 million hectares, the equivalent of South America.
ø The term of "tropical forest" indicates all the wooded zones located between the tropics of Cancer and the Capricorn. We distinguish various great types of tropical forests whose principal ones are the wet dense forests or sempervirentes equatorial, the dry forests, the high forests, the mangroves or savannas raised.
ø Before returning more in detail on the wet dense forests, habitat of many species of primates, here some general information on the other types of tropical forests, where also various monkeys live:
      · The dry forests is under the influence of a rainfall going of 1000 to 1 500 mm per year, with one clear dry period. They are located in the areas soudano-Guinean and Zambian, on the West coast of Madagascar, in the Indochinese peninsula or in tropical America. We distinguish the dry forests dense, rare, and the clear dry forests, most frequent. The trees, with null and void sheets, rarely exceed 20 m in height. The underwoods count many shrubs. These forests frequently undergo fires.
      · The forests of mountain are often misty. The development on the trees of plants epiphytes (lichens, foams, broméliacees...) there is very important. With altitude, the size of the trees and sheets are reduced. Then the relay is taken by trees with persistent sheets, like conifers. Lastly, on the raised heights, the forest disappears, replaced by herbaceous formations and buissonnantes.
      · The mangroves are brackish water forests (mixture fresh salted water), in zone subjected to the tides. They are dominated by the mangroves. Many species of trees present various systems to gain on water: roots which go down from the branches to anchor itself in the mud, air roots which are weighed down with their growth to go down again towards the ground, germination of the fruits on the tree with production a root in form of blade of knife, floating fruit... The mangroves are an environment biologically very active.
      · Raised or shrubby savannas are sometimes not easily distinguishable certain clear forests. Often they persist only thanks to the fires, often lighted for hunting or agriculture. This practice brought the selection of trees resistant to fire, equipped with a very thick bark.
ø The terms of primary or secondary forest are sometimes used: they can apply to all types of forests, tropical or not. Theoretically, a primary forest is an old forest having evolved without influence of the man. This forest type remains not very frequent, archaeology having shown the old presence of the man within great forest belts like Amazonia or the Congo basin.
The forest can recolonised some zones deforested by the man, in particular for agriculture. This new forest consists of species pionnieres for fast growth. We then speak about secondary forest. After several centuries, it can become similar to a primary forest.

Wet dense forests
ø Surface and localization
This map shows the distribution of the wet tropical forests. These forests represent approximately 6 % of the total surface of the emerged grounds, covering nearly 1 100 million km², while being spread out over a tape from 800 to 4 000 km around the equator. 50% of all these forests are in the Amazonian basin. The African wet tropical forests represent 18% and those of the Southeast Asia 32%.
ø Climatic Data
This type of forest can develop only with high temperatures and constant (between 23°C with 27°C, with a maximum thermal amplitude of 4°C), precipitations of at least 1500 mm per year (maximun in Colombia with 10.000mm/an) and a moisture of the air from at least 70%. Lastly, the rate of evaporation must be lower than precipitation. The dry season should not be marked too much.
ø ground
The ground is very poor, often strongly sandy and with a very weak layer of humus. In this type of forest, thanks in particular to the temperatures and moistures raised, the development on the level of the ground of organizations such as mushrooms or bacteria is important. These organizations are responsible for the rapid degradation of organic waste: no storage in the ground of the nutrients, which available and are very quickly reabsorbed by the plants. This cycle very court of the nutritive elements explains this very poor ground. Also, after deforestation, this ground is very quickly unusable, in particular for agriculture!
ø biological diversity
      · These forests are characterized by their very important biodiversity. With them only, they count 80 % of the insects, 84 % of the reptiles, 91 % of the Amphibians, 90 % of the primates, about two thirds of the plants with flowers. They would count nearly 50 000 species of trees! But many species are still unknown and the inventories are far from being finished.
      ·The wet tropical forest is an environment largely dominated by the vegetable world. Only green there is seen! To observe animauxs demand time and practice.
      · These forests are also characterized by animal and vegetable species certainly many but represented per few individuals. Thus, on one hectare of drill Peruvian, 283 species of trees were seen on only 600 trees present. In comparison, the French forests do not contain in general more than 5 different species.
      ·Another particuliarity of this type of forest: there are important bonds between animals and plants. Thus, the majority of the vegetable species have need for an animal, often member of a quite precise species, to be pollinated or to see its disseminated fruits. Conversely, certain animal species, in majority of the insects, are pledged with a vegetable species, even with a tree. Thus, the disappearance of an animal or vegetable species can have serious consequences for one or more other species.
      · This strong biological diversity would be partly explained by the history of these tropical wet forests. Thus, various climatic changes, like the last glaciation there is approximately 18-20 000 years, brought to a reduction and a fragmentation of this forest, replaced by a raised savanna. It could only survive fragmented in small islands, maintained in precise points by the presence of favorable climatic conditions. Each small island of wet forest then evolved independently of the close small island, with differentiation of its own animal and vegetable species; from where an increase in the number of species. With the return of more favorable conditions, the wet forest again extended, allowing the junction of the various small islands and the vicinity of all these species in larger forest blocks.
      · This phenomenon of extention of the wet tropical forest is always of setting. This explains the presence of certain zones of savanna "wedged" by the wet forest. Lastly, certain zones of savanna persist only by the action of the man, who in particular by the fires which it lights, limit the natural reconquest of the wet forest. In addiction to that, comes the deforestation (see "threats on the tropical forests")
ø the forest structure
      · In the wet tropical forest, the trees which constitute the canopée (the "roof" of the forest) is of big size, up to 40 m and more, sometimes old several hundreds of years. These trees prevent the light from arriving on the ground. The young trees and shrubs are thus very few in a rather open underwood in general.
      ·On the other hand, as soon as a large tree falls, while often entrainant of others in its fall, it creates for itself one perforated or windfallen wood. Will be then favoured the pionneer species, greedy in light and the herbaceous ones. To circulate in these windfallen woods becomes difficult then and this environment is hostile with the development of new trees. It will need favorable conditions to make it possible to a future giant to grow, like the regular passage of animals opening a passage in this tide the herbaceous ones.
      · Ground at the top of canopée, the environmental conditions change: more and more of light, wind more marked at the top, less constant temperatures, variation of moisture... As many factors which support the creation of many ecological niches staging ground with canopée. Thus, a great part of the animal species do not live on the ground but with various heights, in the trees. This diversity of ecological niches explains also the biological richness of these forests.

Why the tropical forests are vital for us?
ø the role of the tropical forests in the environmental protection is multiple: safeguarding of biological diversity, regulation of the mode of water, maintenance of the grounds, storage of carbon... They are also sources of food, of drugs, habitat of certain human populations or fundamental element of the saving and the culture in many companies.
ø On the level of the regulation of the climate, the tropical forests play an essential part while contributing to thermal balance at the surface of the sphere and by regularizing the cycle of precipitations.
ø They also limit the impact of the pouring rain, by slowing down the streaming and by attenuating the erosion of the grounds. The floods devastator which recently struck China and Bangladesh are directly related to the deforestation of the basins slopes.
ø These forests also can, thanks to their properties of retention, reduce the risks of dryness like those of flood.
Without tropical forests, the survival of the man on planet seems even more difficult!

Tropical forests: threats and future.
ø Two principal threats come upon the tropical forests: the deforestation and the climatic changes.
      · In 15 years, from 1980 to 1995, 200 million hectares of forest, nearly four times France, were deforested in Asia, in Africa, in Latin America, Asia being the more touched continent . Certain countries are more concerned than others. In Ivory Coast, deforestation was fast and intensed: there remain nothing any more but 2,2 million hectares of forests on an original surface of 15 million hectares; whereas in Surinam the forest still occupies almost the totality of the territory. Among the three large solid masses of primary wet tropical forests of planet, that of the Basin of Congo (180 million hectares) underwent a degradation limited (0,6 % per annum) contrary to that of Brazilian Amazonia which lost a surface equal to that of France. The primary forest of Borneo east in the process of disappearance.
      · The principal causes of the deforestation are varied: search for arable lands, requirement out of sawlog or conversion, firewood into industrial plantations, stopping, fire...
      · Wood remains the principal source of energy in the countries of the south. In 2010, the annual world requirements out of firewood could reach 3 billion cubic meters. The demand for wood-energy, strongly dependent on the demography and the low level of development, should continue to grow in the tropical areas, where it represents already 80 % of consumption of wood and nearly 90 % of the domestic power consumption.
    · According to F.A.O.'S, from here 2010, the demand for wood-material should increase by 40 % while passing from 3,5 to 5 billion cubic meters, with strong disparities according to areas'. For wood tropical, China and Japan are the largest world importers with 55 % of the barks.
    · Certain climatic models relating to the "total reheating" of planet see an average increase in the temperature of 4° during the XXI° century. However, this would be accompanied by an increase in evaporation in approximately 30% but with only 12% in rain in more for tropical Africa. Such conditions would be unfavourable in particular with the wet dense forests, which would see their surface then being reduced and to split up, already known phenomenon from the past.
ø Of the tracks for the future
    · The integral protection of the tropical forests cannot be a solution usable everywhere. The durable and reasoned management of the forest resource, by integrating the needs for the present generations and future seem the way of wisdom.
    · Various axes are possible:
- a rational use of the forest resources;
- improvement of the processes of energy production starting from wood and the promotion of the renewable alternative sources of energy, in particular to answer the needs of energy;
- forest plantations for approvionnement out of wood-material with the provison of not increasing the deforestation. In constant increase since the middle of the XXe century, the plantations should cover one third of world consumption in 2010.
- the development of plantations associating forest species and agricultural production could bring a response to the arable lack of land.
- improvement of the processes of harvest, transformation and conditioning to fight against the wasting of the raw material.
    · But it is recognized in a general way, that one of the brakes to the development of the durable control programs of these tropical forests are the lacks of knowledge on these forests (their divesity, their evolution, their relations with the man.) and of competences, in particular in the countries in the process of development. The increase in knowledge by research and the formation thus become a priority.
    · The tropical forests are the object of important  political stakes, and sometimes exploited for the needs for countries known as rich or from the north. However, the tropical forests are located primarily in countries in the process of development and still ensure a part of the incomes of millions of people. Sixty million people depend entirely on these forests and 12 million lives there permanently. Also, their management will have to be done with the whole of these populations. It is also a stake for the future.

African tropical forests within the African forests
ø the Republic of Congo is one of the countries of equatorial Africa which presents the most important percentage of the territory covered by the forest. Thus, in 1996, the latter represented 67.8 more % of the estimated forest cover 8000 years ago, against 33.9 % on average in Africa. In addition, the Republic of Congo is to the junction of two great essential forest environments:
    · Wet dense forests of the African Western plains, present at Gabon and Cameroun and represented in the Republic of Congo by the solid masses of Mayombe and Chaillu;
    · The zone of the basin "Congo", wet forests of low altitude, which extends in DRC, representing the forest solid mass most important of the African continent.
ø These Congolese ecosystems, in spite of an increasing human pressure, are still relatively intact and their protection present a less emergency criterion. This offers the possibility of reflective actions, really relevant and not conceived in the urgency. The total protection of the equatorial African forest cannot thus be done without considering the Republic of Congo.

To know more
Rainforest Network Action : an English site, to have all last information concerning the tropical forests. http://membres.lycos.fr/amazonyy/forettropicale.htm
http://fr.wikipedia.org/wiki/For%C3%AAt_tropicale_humide
Initiative Congo basin: initial evaluation