From 15 to 30% it also plays a function of very important protection (see illustration opposite); - timbered islands, if timbering is natural or “ near to nature ” is also regarded as good refuges for certain species because of a less disturbance. In the case of true islands, the criteria of insulation take a positive direction then, like in the case of the Inselberg S; on a case-by-case basis to study relative with the context
- the percentage of the forest in protected area (by type, stage of the succession and category of protection in % total forest surface);
- the rate of forest cover (by type) already converted or in the course of conversion with other uses (including truck driver);
- Surface and percentage of forests touched by a anthropic and/or natural disturbance;
- Complexity and heterogeneity of the forest structure;
- Many species tributary of the forest;
- Percentage of indigenous gasolines and percentage of these gasolines which would be threatened. Attention, it is an indicator relating to the biogeographic context. There are for example only 3 indigenous gasolines in all Iceland, against 7.780 indexed in 2005 in only Brazil (subspecies not included/understood). Moreover, the tropical forests comprise many gasolines, but some are dominant; In Center and West Africa, in South Asia and South-east and Central America, one naturally finds a very great diversity of species of trees (until nearly 300 different species per ha), whereas in moderated, boreal or sub-Saharan zone, the ten most frequent species of trees (in volume) relate to at least 50% of the forest biomass (in volume of tree).
Les rarest species of the trees, especially those whose commercial value is high are often in danger of extinction for part of their line. FAO estimates that on average, 5% of the indigenous species of a country are vulnerable, in danger or critical danger of extinction. - State of conservation of the species tributary of the forest.
- the indicators of the genetic variation are excluded from this examination because they normally require complex analyzes of laboratory (Namkoong and Al , 1996; but to also see Jennings and Al , 2001);
- Presence, mass, volume, quality (wood hard, tender, resinous, leafy) and distribution of the Deadwood, Middle Age of the trees, presence of large carnivores, beaver S or a great high content in mushrooms thus take new significances, sometimes opposed to those which were taught at the previous century in schools of sylviculture.
- the state of pollution of the forest (How for example to evaluate the quality of the forest which in the closed areas of Bélarus is restored naturally, but on grounds having received approximately 70% radioactive repercussions of the Catastrophe of Tchernobyl.
Legal classification
There exist classifications of the forests, with for example in France;
In Germany, it is:
- Markwald
- Landesherrlichkeit
- Säkularisierung
- Privatwald
- Hauberg
- Waldinteressentenschaft
- Kommunalwald
- Kirchenwald
- Landeswald
- Bundeswald
Management and exploitation of the forests
The forest was formerly exploited for wood, the Charcoal, the gathering, the pasture and hunting. Wood was generally discharged using horses, of oxen, buffaloes or of Indian elephants. In Central Europe, on the slopes, it sometimes was descended crossed on sledges (Schlitte). Generally, in fact the torrents and river transported the trunks to the rivers in rafts or by simple Flottage. Formerly, the trunks were cut by the Bûcheron S, then output by pit sawyers, before being carried to back of man or by horses to the ways. At the recent times, in fact sawmills actuated by the force of water allowed the cut of board in the forest or in the vicinity, before the trucks do not transport the trees to more distant sawmills starting from second half of the 20th century. In a general way the number of loggers and sawyers did not cease being reduced to the profit mechanization.
The modern Sylviculture aims to maintain or increase the potential of production of a forest, while preserving a balance sylvo-hunting when the game is a major economic resource and that the animals are numerous (In France, it is frequent that at least 50% income of a forest owner come from the products of hunting to big game.
Forest regeneration, i.e. the reproduction of the trees is done according to two approaches:
- by rejections (or suckers); this method exploits the capacity of many gasolines of leafy trees to be rejected starting from a stock. It is especially used for the Taillis.
- by seeds ; this method requires, at least for some gasolines a level of sufficient illumination of the ground, which justifies cuts of breaks for the ones and broad cuts for others.
One speaks about natural regeneration when the forester selects and preserves seed-bearer trees “ ” at the time of the cuts, so that the seeds present in the ground and fallen from seed-bearer can germinate and regenerate the forest. It is an effective and inexpensive solution when the gasolines present are well adapted to the biogeographic context and that the herbivores are not too numerous. For certain gasolines (oak by ex), whose fructification are not regular, the times of regeneration can be lengthened. It there has natural regeneration and continues with the approaches of the type Prosilva, promoting management step by step or in bouquets, without Coupe shaves.
Artificial regeneration corresponds to the situation where seedlings come from sowings made in Pépinière, or of grageonnages external with the piece, starting from selected seeds or trees (certified source), with the risk of loss of impact strength and biodiversity, even of introduction pathogenic not present into the forest. It is a mode of regeneration adapted to the mechanization of the forest management, which was strongly developed at the 20th century in the countries of north, but also in Australia and in certain tropical forests. The long-term benefit of this method are discussed, in particular for possible medical, landscape and environmental consequences on the forest.
The traditional mining methods in moderate forests are the following ones:
- simple Coppice : the rejections regularly are cut (the whole of the rejections resulting from a stock is called one cépée), which produces trees low-size, usable like stake or firewood (for the Châtaignier and the Acacia), used mainly today for the heating, but which fed formerly from industries like the glassmaking, the porcelain and the iron and steel industry.
- Coppice under grove : it is a forest exploited mainly in coppice, but to also provide sawlog, one lets come from the trees of franc-foot, i.e. resulting from sowing, various ages.
- regular Grove : in this type of forest all the trees result from sowing and have the same age, which gives to the adulthood Groves “cathedrals”. This type of treatment is relatively modern, and goes back in France from the time to Colbert which wanted to develop the production of wood for the frame of navy and in particular the masts. A famous example is the grove of oaks of Tronçais in the Allier.
- gardened Grove : it is a grove in which one finds trees at all the developmental stages. One exploits it by regularly taking part of the trees considered as ripe, but by preserving the protection of forest cover permanently. It is the traditional method, which was best preserved in mountain because it protects the grounds, the forest microclimate and limit at best the erosion and the landslides. It is also the forestry principle of Prosilva which associates a dimension Biodiversité to him (the grove heterogeneous and is mixed, out of gasolines and age groups, by preserving dead and senescent trees, considered necessary to the balance ecological forester).
According to the treatment used, and the gasolines, the time of “revolution”, i.e. the time run out between sowing and the cut, are variable but generally long, from 60 to 100 years for the coniferous trees (grown can be crossed as from 40 years), 150 years and more for the leafy trees (80-100 years for the red Chêne of America). Sylviculture is a business of several generations; only the populiculture (Poplar S) with one duration of revolution of approximately 20 years approaches agriculture.
A very small share of the nonprimary forests are not managed for the production of wood (ex: natural reserves, integral biological reserve, National parks, forests of protection, forests urban, or are the subject of a management restauratoire at end of protection of the water resource or grounds). The ecologist Japanese Akira Miyawaki was pioneer as regards Forêt of protection restored starting from local gasolines.
Recognized functions of the forest
The forest fulfills three essential functions: ecological, economic and social.
Ecological function
- Tank of Biodiversity and habitats, as well as genetic resources and phytopharmacological, they for this reason studied and are sometimes classified in reserves biological, natural, national parks, etc).
- Functions écopaysagères: “cores” or “nodes” of the ecological Network, and sometimes biological Corridor for the Forest gallery, the forests linear, the Mangrove S, and the quickset hedges which can to it be attached.
- Protection against some Risk S natural (Avalanche S, Flood S, dryness, turning into a desert and elements of ecological Impact strength…).
- Quality of the air: in addition to the forest produces a significant part of oxygen in air on the continents, it has an extraordinary capacity to fix dust (like certain pollutants not dégradables), thanks in particular to foams, the lichens, the dew and the ground.
- Protection of the grounds (fight against erosion): the forest is a place of restoration of the ground if she is not overexploited.
-
cf Forest of the Moors in France or the green belt of the Algerian south. - Function macro and micro climatic, thanks to the evapotranspiration and with the protection of canopée which attenuate the thermal shocks considerably, and dehydration due to the wind.
- Well of carbon, by fixing of carbonic gas in wood and the ground, at least for the moderated forests not subjected to the Fire S and for the tropical forests in phase of growth.
-
cf plantations made in Amazonia qualified “carbon well”. - Function aménitaire.
- the natural forest edges, eminently complex, have important functions écotoniales, in particular for the riverine forests and the mangroves.
Economic function
Wood counts for a big part of GDP of ten tropical or Scandinavian countries. Forest employment (except abstract employment and processing industry) still paid nearly 10 million people in 2005, but; - forest employment declines regularly relative with the tonnage extracted the forests which did not cease to him increasing, and this since the invention from the Tronçonneuse. It decreases on average by 1% per annum in the world (- 10% of 1990 to 2000), especially in Asia and Europe, whereas it increased slightly elsewhere. FAO charges this decline to the increases in productivity of the sector, and - for Eastern Europe - to the reorganization of the planned economies.
- the average costs of the wood in the rough decreases : The average increase in the paid prices (barks or tree) was from 11 to 15% in the years 2000-2005 (source FAO, FRA 2005), but always remained lower than inflation; there is thus lowers average costs (in particular for tropical wood) on a world level, which does not exclude downstream and for the consumer from big rises from the Wood-energy where it becomes rare or after the " shocks pétroliers" and of wood écocertifiés or écosociocertifiés for which the offer remains much higher than the request, for FSC in particular.
- the informal sector remains very badly known . Via the sale of game in particular, it is important.
- an important part of the taking away and benefit is illegal , threatening of the gasolines and the theoretically protected and/or threatened species. The populations autochtones suffer from the Corruption and the pressures of the owners. 10 to 15 billion euros per annum would be thus bleached in the world, including close 3 billion € in the EU, coming from six areas where the production of wood is an important issue. Twenty Member States of the EU in 2006 are still suspectés to import illegal wood (Finland, Sweden and the United Kingdom at the head). The “network TRAFFIC ” of WWF and UICN on the International business of the Wild Species estimates that the legal and illegal trade of species would reach 15 billion euros of annual sales turnover (just behind the traffic of weapons and drug). A study of the British government estimated that the prohibition of illegal wood in Europe is possible and credible, with the existing tools and of control effective, with the profit of the legal and durable dies now confronted with an unfair competition. Tens of ONG whose Greenpeace and WWF since a score of years denounce illegal wood and promote credible and transparent écocertifications, as described by the group of ONG FERN, in an evaluation published in 2001.
- Of new functions emergent; social, agrosylvicole, tourist, teaching, scientific and of protection environmental ( In 2005,11% of the forests of the world are declared by the states " assigned to the conservation of biological diversity " , this rate is in increase , but always does not correspond to a reality of ground). The function Puits of carbon seems to have to take importance. The economic importance of these new functions is badly evaluated, but could locally report more than the exploitation of wood.
Production of wood
- Firewood and Firewood, most important Use from the world but primarily in Africa and South America (and behind the destruction of the forest to extend the arable lands or of breeding);
- Wood of industry: pulpwood (Pulp paper), unwinding Plating, fiberboards, Packing;
- Sawlog: Frame, wood of mine, Cross-piece S of Railroad, Furnishing;
- Derived from wood.
Nonwoody forest products (PFNL)
According to FAO the PFNL are: “ is products of biological origin, others that wood, derived from the forests, other wooded grounds and trees except forests.
the PFNL can be collected in nature, or produced in forest plantations or perimeters of agroforestery, or by trees except forest.
Examples of PFNL include/understand products used as food and food additives (edible nuts, mushrooms, fruits, grasses, spices and condiments, plants aromatic, game meat), fibers (used in the construction industry, the pieces of furniture, clothing or the ustensils), resins, gums, and crop product and animal used for medicinal, cosmetic goals or culturels' .”
Here some example of PFNL:
- Mushroom S;
- Game S;
- Fruits of wood;
- Plant S medicinal and tinctorial;
- Tourism related to the forest.
- Fruit S
http://www.fao.org/forestry/site/nwfp/fr/
Functions social, symbolic systems and cultural
Approximately 8000 years ago that with the assistance of fire, our ancestors started with déforester the northern hemisphere (while starting with China) however the forest remained present in many tales, myths and legends, in almost all civilizations.
The spiritual and cultural value of the real or mythical forest is not disputed. The name of Brocéliande still evokes of it the druids and the magic. Nemeton was the Celtic word which meant at the same time sanctuary , and forest . Well after one forgot the Forest of Dodone Greeks, one continues to compare the pillars of the Gothic cathedrals with the trunks of a forest whose branches would be the arcs which support the vault. At last Century, many German loggers murmured a small prayer of excuse to the tree which they were going to cut. In India, the Sannyâsâ are withdrawn and are collected in forest, as some did it Ermite S Europeans. In China, the wooded tops almost always sheltered a temple. In Japan, the forest that reflect or symbolize in miniature certain gardens is crowned, as indicates it the Torii which marks sometimes its entry, like that of a temple. The tree of life is omnipresent in the myths founders of the forest countries, but also of the déforestés countries, with a tree of knowledge with ambiguous connotation in the Bible.
The forest is often symbolically interpreted like connecting sky and ground, by the branches, the trunks and its roots.
The forest is also the field of the Man wild, present in many myths of Western Europe or Asia; the wild man who is like the tree present in the heraldic European one
The forest also makes fear; place of Nature where one loses oneself, place where one loses the children, where one meet the wolf, where gods, spirits and wild animals live, where the night is done blacker, last refuge of the wolves and the pursued bears. They is the places where out it law, goods (Robin of Wood) or malicious hid, although sometimes exclusively reserved for royal huntings.
In Europe, as from the century of the lights and the French royal model, one got busy to humanize them, to name them and to split up them for better controlling them by squaring them of alleys and tailboards, then they were planted and “rationally” managed.
C' is locally a place of memory with the royal forests, the Forêt of war).
C' is finally and especially the place of life of the people of the forest, Amerindians, African, and of Southeast Asia in particular, where they survived. Secular place of initiation, refuge of the spirits, place of life and adventure for many people… places aménitaire of relaxation and discovered nature for others, the forest is recognized for all these functions by certain national laws and the écosociolabels FSC).
The majority of the populations and elected officials say themselves very attached to the idea of protection of remarkable trees, the forest and/or forest which protects, for reasons much broader than for the services than it returns like spaces relaxation and leisures or like place of family gathering of fruits and mushrooms.
Forest habitat of the Man; feeder and hunting
More than 500 million human live in forest or with its accesses and depend on it directly. Even when she is not inhabited any more, she remains a traditional place of gathering and hunting (with the large animals especially, which disappeared or regressed in the cultivated and inhabited plains). For approximately 150 million indigenous S pertaining to hundreds of tribes and people autochtones, the biodiversity of the forest is still the vital source of water, materials, of plants, fruits, animals and edible mushrooms or useful (drugs, ornaments.). The “meat of bush” locally remains the 1st source of protein in many tropical countries, although she is threatened by the increase of the pressure of hunting, the increasingly powerful weapons, and the means of transport such as the quad.
In the rich and moderate countries, hunting remains also important, the incomes huntings approaching or often exceed 50% of the total forest income in countries such as France. But the “big game” when it is too abundant, in particular following an important agrainage and with the disappearance of its predatory natural, can cause damage rather important for slow down or block forest regeneration.
A true management hunting would also require to take into account the problems medical (Peste porcine, CWD, diseases conveyed by the Tique S, appearance of the AIDS or virus hemoragic, standard Ebola, etc), in particular in the absence of Prédateur S.
More locally, of the new problems are posed with the contamination of the game (wild boar in particular) by poisons resulting from Séquelles of war or fallen down with the rains which washed the cloud of Tchernobyl.
The tropical forests produce the essence of the meat of bush, with pressures of huntings which rarefied or makes disappear the game on vast zones.
The question of pollution by the lead of hunting, related to the Toxicité of the ammunition (shot and balls) arises there less than in the wetlands, but it seems to be able to be underestimated.
Enemies of the forest
Natural enemies
The forester fears especially the fire and of the devastating insects the such caterpillar Processionnaire of the pine, that of the oak, some xylophagous, of the Bactérie S or the Champignon S (ex: Graphiose of the Elm, Disease of ink of the Chestnut). The attacks which take the appearance of epidemic S and Pullulation S generally follow a weakening of the trees of to events of the type Sécheresse, Tempête, Pollution, drainage, fragmentation, etc It seems that in the extreme mediums (polar, sub-Saharan), the pullulations belong to natural and regulating cycles, in forests of which the number of gasolines is reduced, and more exposed to the climatic shocks.
In the northern hemisphere, rodent mammals (ex: mulots, field vole of the fields), the rabbits and of the species-game (stags, deer, roe-deers, wapitis, etc) are locally regarded as " nuisibles" by the forrestiers because they graze the starts-up and corrode the barks. In Mediterranean forest, the Chèvre S are a frightening enemy of the trees.
Figures: According to the provided figures by the states with FAO; in 2000-2005, on average, 104 million hectares of forest was annually devastated by fires, insects and diseases, drynesses, storms, great colds or floods. This figure is underestimated because certain countries (African in particular) did not join together or not provided statistics, whereas the satellite imagery shows extensive damage by fire in Africa.
From a historical point of view, the Man had an ambiguous relation with the forest and in particular with the primary, sometimes protective forest or not developing to with it visible impact lasting of the millenia (in tropical zone, normis on certain islands), and often destructor in European, Asian moderate zone and in the Middle East, since several thousands of years. The primary forest continues to move back, and in Rio, as in Johannesburg the elected officials present did not succeed in validating the project of a world Convention for the forest , which remained only one declaration of intent, whose value and the legal consequences are much lower than those of the conventions on the biodiversity or the climate.
Climatic accidents
The periods of Dryness, like 1976, or of strong heat wave (2003) can cause the drying of the sheets which fall then prematurely. One can also note burns of the bark exposed to the sun (beeches).
The effects can be felt years afterwards. The dryness generally worsens the effects of other the devastating agents, the such fires or insects. Thus, in 1976, the fires accentuated by the dryness burned more than 800 km ² in France.
In wintry time, the Gel is not generally to fear, except the extreme cases, as in 1956 in France or in 1985, when 30.000 maritime pines landais froze. The late frosts, are, they, vermin for the young seedlings. The Neige can be dangerous under certain conditions, when it forms sleeves around the branches, which end up breaking under the accumulated weight.
The storms, like that of December 1999 in Western Europe, cause the uprooting and the demolition of the trees, which form the “windfallen wood” or their break by the medium of the trunk, leaving places the “candlesticks from there” and on the ground the “windbreaks”. In France, the storm of 1999 thus cut down 146 million m ³ of wood.
Action of the man
It is old in Europe, where large the Défrichement S dates from the Antiquité (in the Mediterranean regions) and from the Moyen-âge, but continue to make place with certain equipment, highway, urbanization, tanks hydro-electric, installations for the winter sports, etc At present, in fact especially the tropical forests suffer from this phenomenon of deforestation, either for reasons of economic development, as in Amazonia, Southeast Asia or Siberia, or by overexploitation of the tropical Ressource S in wood.
En 2006, although there is still no international convention on the Forest (the principal failure of Rio), more than 100 countries had instituted a national forest program, generally including a shutter protection (although the programmes treat still primarily the development of the exploitation of wood) and sometimes a shutter conservation (or restoration) of the grounds, water, biological diversity and other richnesses and services environmental.
These programs when they exist are respected little in the very poor countries or those undergoing of the civil disorders or surges of refugees of adjoining countries.
Il would remain in 2006 approximately 4 billion hectares more or less wooded on planet, that is to say approximately 30% of the emerged surfaces. From 1990 to 2005,3% of the forest disappeared, (- 0,2% per annum) according to FAO.
From 2000 to 2005,57 countries announced announced an increase in their rate of timbering (but often acts of industrial plantations (eucalyptus, poplars, coniferous tree, palm trees with oil) of little interest for the biodiversity). 83 countries recognized that their forest moved back. The net loss would be of 7,3 million ha/an (either 20.000 hectares/day).
The 10 countries richest in forests alone account for 80% of the primary forests of the ground, of which the Indonesia, the Mexico, the New Guinea-News-Guinea and the Brésil. It is also those which underwent the most intense deforestation and rapid of 2000 to 2005, in spite of plantations of commercial secondary forests.
The East Asia which had lost the majority of its forest recorded the principal increase following the hundreds in million in trees planted in China (but they are young timberings and not forests with the ecological direction of the term) and these increases do not compensate for high rates of deforestation of other zones. Broadly deforestation still accelerated in Southeast Asia between 2000 and 2005. It is however in Africa and Latin America/the Caribbean that the forest moves back more; Africa accounts for 16% more of the total wooded surface, but it lost more than 9% of its forests between 1990 and 2005, while Europe and North America into important massively of the exotic wood could increase their forest surfaces in same time. New Scientist published a study on the 50 most wooded countries: 22 presented in 2006 a clear reafforestation. The situation with the Brazil and in Indonesia is alarming, while China creates the surprise: since 2002, one replanted there a surface equivalent to that of Cafifornie.
La deforestation is also a cause of appearance and diffusion of emergent diseases.
The pollutants related to the human activity are numerous: Sulfur dioxide which causes famous “the acid rains” to which was allotted the deterioration of the forests noted in Europe in the years 1970 - 80, but which much also had with the Sécheresse and with the Pesticide S conveyed by the air and/or solubilized by the rains, the oxides of nitrogen, the hydrofluoric Acid , emitted locally by certain industries in particular in certain alpine valleys, particles emitted by the combustion of coal and the oil fuels, the Ozone… with also in mountain and in the cold zones the Sel of snow clearance. In addition the foams and the Lichen S very effectively trap the particles of the air, of which they are nourished. By this skew, they alas fix also heavy metals increasingly present in the air, as well as others Polluant S (at the point to die about it sometimes, which in fact, according to the sensitivity of species of goods biological indicators). The mushrooms which make the richness of the forest ground show also capable of bioconcentrer of many pollutants (heavy metals of which Plomb, Cadmium and mercury, but also Radionucléide S, which can then be concentrated by the Food chain).
The forest at all times was also a place privileged for the Chasse; The ammunition with lead (Shot and balls) there were dispersed by thousands of tons each year, often drawn at the same places; close to the water points, banks of rivers, on the spot of agrainage, the tailboards or bulk-headings or starting from arranged stations of shooting. The forest grounds are often naturally slightly acid with very acid in zones tropical or boreal, which facilitates the dispersion and biodisponibility of this lead enriched by arsenic and antimony, as of the mercury which was used a long time by the starters.
In certain countries, muds of purification plant are regularly dispersed in forests, sometimes in the form of pulverization, which can contribute to the dispersion of certain contaminants.
With the first experiments of trees GMO
(poplars primarily, tested for example in France and with the Canada in medium not-confined), some fear a genetic rapid pollution and an impact on fauna and the forest ground via the Toxine BT emitted by these trees, their roots or their pollens, or in certain cases because of the encouraged use of weeding.
See also: Acid rain
After-effects of War
At all times, the forests were strategic from the point of view Militaire. They are been used as marine wood reserve of and Charpente, but especially of shelter or target to all the armies, maquis and resistance S, of the million Réfugié S being protected there still today in the countries in conflicts. Sometimes they were plundered or destroyed within the framework of the strategy of the “burned ground”. To Vietnam and Laos, the defoliant, the Napalm and the ammunition at submunitions left still persistent traces (degraded dioxanes, heavy metals, grounds, active mines, etc).
The Bois grapeshot of the forest Frenchwomen lost her technical merits and financial, but it can also be polluted by lead or other heavy metals.
At the 20th century, in particular in France in the Red zone, of vast forests known as “of war” were artificially planted on agricultural sites made uncultivable by the after-effects of war and locally to Germany or France on sites seriously polluted by of accidents related to the production of factory or arms factories producing upstream the chemical poisons or the metals used in the Munition S (lead, cadmium, zinc, copper, mercury, etc). Forests as that of Verdun still contain considerable quantities of not exploded ammunition, of which some chemical (charged with “poison gas”).
Forest fires
They are generally lit by the man, voluntarily (pyromaniacs, shepherds…) or involuntarily (negligence). The fire-stick farming , often employed by the aboriginals Australian, deeply modified the fauna and flora of Australia. This practice consisted in burning vast grounds to facilitate hunting involved the disappearance of its mégafaune… In spite of means of monitoring and of fight increasingly powerful, their number and their gravity do not cease growing in tropical zone (Indonesia, Brésil.) but also in Europe and North America or Australia.
Taking catastrophic proportions in certain areas (in particular around the the Mediterranean), they lead to the installation of very important means of fight, whose effectiveness is variable. All the forest gasolines are combustible, but certain rich person in volatile products support combustion and the extension of the fire, others resist better (thanks to phenomena of protection like the creation of cork), or are regenerated more quickly.
In France, on average 200 km ² of forest burn annually (for the years 2000). Some estimate that the fires are not a serious threat for the forests but rather an economic problem; in addition to the shortfall in products of exploitation (Sawlog and firewood), the prevention and the fire control cost on average 125 million euros per annum. Nevertheless fires with repetition on already parcelled out zones can start serious phenomena of erosion and impoverishment of the soil. Certain species (terrestrial tortoise for example suffered much from it).
It is difficult to draw an assessment from the action of the man on the forests: he does not summarize himself with harmful actions, because if the States did not stop deforestation nor not been able to agree to write and sign an international convention for the protection of the forests in Rio in 1992 or Johannesbourg in 2003, of many local programmes of studies and restoration of forests exist in the world, of which the model forests Canadian.
In Western Europe, the shape and the surface of the contemporary European forests result primarily from the action of the man, and it is usually allowed in the foresters whom they are managed in a durable way. Contrary to an idea spread, the surface of the French forest, after having strongly decreased until the end of the Middle Ages réaugmenté, including since the years 1900 (from approximately + 30%), but often thanks to commercial plantations of coniferous tree and poplars, less rich on the level of the Biodiversité and with a passing of the wetlands. The profit in surface did not slow down or did not compensate for the retreat of the birds, insects, Lichens and typically forest flowers, nor the massive retreat of the Bocage and the scattered trees since the years 1950. The trees tend in addition to being exploited increasingly young and the plantations are varied genetically little. Except locally, following the storms, the large Deadwood remains too rare to allow the survival of many species of invertebrates saproxylophages.
Forest and oxygen
A metaphor often qualifies the forest of “lung of planet”. In spite of the functions many and essential even “vital” that it fills, the forest cannot be directly compared with a Poumon (the lung does not produce a Oxygène and it is the Plancton which produces the essence of planetary oxygen available in the air and solubilized in water). Nevertheless, the forest has essential functions micro - and macro-climatic and for the quality of the atmosphere, in thermo-hygrometrical term of balance and purity of the air in particular. From a certain point of view, a little with the manner of the lung, but on another scale, it is a kind of écotone complex and functional between the atmosphere and the ground, related to the cycle of carbon in particular, but also with all the biogeochemical cycles important.
Forests and Well of carbon
The carbon assessment of a forest ecosystem is very difficult to estimate, and it varies considerably according to the biogeographic zones , the times, the history of the site, the stage of growth of the forest, the Risque S of Incendie, Sécheresse and Inondation, and many other factors such as the action of insects défoliateurs or other parasites of the trees. Of course, to become to it trees is another factor to be considered: firewood, paper-cellulose, sawlog, or deadwood will have impacts very different in term from emission of Carbon dioxide.
Moreover, certain forests can, at least temporarily to have a null assessment (mature tropical forest) or negative (in zone of recurring fires, or at the beginning of phase of growth), while indirectly contributing to enrich the rivers in nutrients (phosphorus, potassium, calcium, iron, etc and by the phenomena of acidification, humification, decolmatation and mineralization and structuring of the grounds) by thus offering a constant source by Nutriment S for the marine plankton downstream, plankton which produces 80 % of the oxygen that we breathe and which constitutes an important carbon well.
In theory, the Photosynthèse consumes Carbon dioxide and produced Dioxygène and Organic matter. Oxygen is consumed at the time of the Respiration plants themselves, animals of the forest and hidden biomass forest ground, like by the natural fires and moindrement by the natural oxidation of the chemical elements made available by the formation process of the grounds.
In phase of growth, after ten year of negative assessment if it is about a regeneration starting from a naked ground, the biomass increases regularly, mainly in the form of Cellulose and of Lignine. It stores also carbon in the form of Nécromasse and of biomass animal, microbial and fungic. In tropical zone, the majority of the forests push on poor grounds and acids where the humus is not formed and where nécromasse quickly is recycled or mineralized. The tropical forest in growth stores carbon, but it ends (after several centuries, even more than 1000 years) up arriving at a balance between primary production and decomposition of the deadwood. At this stage the forest seems to produce oxygen as much than than it consumes. Moreover, the emissions of methane related to the wood fermentation immersed or resulting from the activity of the Termite S still complex calculations of the emissions of Gaz to greenhouse effect.
In moderate or cold zone, it goes from there differently with respectively the forest grounds (including the Tourbière S associated with certain forests) and the Pergélisol S which, in circumpolar zone, can store considerable quantities of carbon (in the form of Hydrate of methane).
Lastly, it to become and the lifespan of the methane emitted by the forest ecosystems are not yet well included/understood. It could be over-estimated or underestimated.
Forest and health
Very early, certain trees were considered to cleanse the air (Sapin, spruce, woodland Pin, Eucalyptus planted around the hospitals and of the places of cure), or on the contrary, to more rarely corrupt it (not to sleep under a Noyer). Walk in forest was recommended, and of course-health are still frequently installed there, just as in the wooded city parks.
Les forest plays an important role as regards physical and physico-chemical, and probably biological purification of the air and water. The products of the forest and all the parts of the trees were used to produce drugs and many medicines traditional. A sylvan Sylvothérapie and cures were developed in certain countries with 19th and beginning of the 20th century to make benefit certain patients (tuberculous in particular) from the forest air enriched out of oxygen (three times more oxygen produced by the moderate forest than in meadow), out of Ozone (in particular in seaside and in the forests of coniferous tree) and in Phytoncide S (famous molecules bactéricdes and fungicides, of which Terpène S) and by the purity of the air. It was recently shown that the biochemical activity is developed much in canopée than in the herbaceous layer.
Après Pasteur, various measurements quoted per G. pleasure compared various airs and showed that the forest air contained less microbes than the urban air (50 microbes per m3 of air, against 1000 in the Montsouris park of bets, 88.000 on the fields élysées, 575.000 on the grand boulevards and 4.000.000 in the department stores in Paris according to Georges Plaissance)
The patrimonial forest and community property
Everywhere in the world, one locates or classifies trees because worthy and remarkable or for their landscape or ecological interest or of protection. It becomes delicate to manage the forests only for the cut of wood. For the artists and the tourists, as for the scientists and industrial, they conceal treasures which it is advisable to bequeath to the future generations.
A quarter of France lives in the shade of the trees. Some are thousand-year-old and knew Gaulle hairy, the old worships. Townsmen and rural wish the conservation of a significant number of old tree. The first reserve of the forest of Fontainebleau was required by artists, and not by foresters.