According to the man use of trees , we can classify them into:
- Trees for fruit production: One of the main uses of trees is addressed to fruit production. Although humans can use the fruits of wild plants, we must stress the importance of trees grown for the production and consumption of fruits.
These are models who have been chosen by man from nature. Man has learnt how to improve their resistance to the environment, or to the attack of pests and diseases. He has increased their production capacity, their appearance or their nutritional values.
- Trees for timber production: Historically men have used wood from trees for their own use. Since the discovery of fire, the wood of trees has been an invaluable resource for Humanity. In the Paleolithic, hunters prepared their weapons with the hardest woods.
In Europe, they generally make use of them collecting strong and durable wood, such as that of oaks (Quercus ilex) and beeches (Fagus sylvatica).
New techniques have been develop to boost food production. Photo of apple orchard with the trees planted in rows.
- Exotic trees for timber production: in Africa they would would use even more durable and resistant wood trees, which today are regarded as exotic, such as African Ebony (Diospyros spp), the iroko tree (Chlorophora excelsa) or paduak (Pterocarpus soyauxii) .
In South America we would have others like curupay (Anadenanthera macrocarpa) or ziricote (Cordia dodecandra), the lenga (Nothofagus dombeyi), the freijo (Cordia Goeldiana), the bocote (ordi elaeagnoides), the caranchana (Cabralea cangerana) or the guatambu (Balfourodendron riedelianum)
In North America the hardest wood will be provided by a number of trees having such a high density that they sink in the water. These include ebony (Diospyros ebenum), mountain mahogany (Cercocarpus betuloides) or desert ironwood (Olney tesota). The latter has been used since ancient times for the manufacture of knife handles.
Without reaching the hardness of these trees some other ones can be considered very hard: the American cat's claw acacia (Acacia greggii), the persimmon tree (Diospyros virginiana) the caria or hickory (Carya ovata), Engelmann oak (Quercus engelmannii), the California live oak (Quercus agrifolia), or the black locust (Robinia pseudoacacia).
In Asia it is worth mentioning the mabolo or velvet apple (Diospyros discolor) or the Indian ebony, one of the rarest and most expensive woods in the present with the strength and hardness of all the varieties of ebony.
It grows in Philippines, Southeast Asia and Celebes. The East Indian rosewood (Dalbergia latifolia) is twice harder than the oak. It grows in deciduous forests of India. In the south west of Australia we can find the jarrah (Eucalyptus marginiata) with a hardness much higher than an oak. The koa (Acacia koa) is unique in the islands of Hawaii and provides a very high quality wood.
Trees for the production of firewood or charcoal: Fire is used to protect us from the cold and from animals and to cook food. Felling of the forest also allowed him to deforest land where food can be obtained. This type of deforestation was very limited and the forest was able to recover by itself when crops were abandoned.
The use of wood from forests for production of charcoal should also be mentioned . Charcoal is formed by piling wood and covering it with branches and soil. Later, the stack is fired and it burns for several days until it produces coal. Men have been using charcoal since the discovery of fire as they took advantage of the remnants of the bonfire to have it at hand .
Charcoal gives much more heat than firewood, so it has been used since antiquity to forge weapons. By means of charcoal man from the Iron Age was able to mold and manufacture the iron axes, swords, knives and other weapons or instruments. Subsequently it was used in the metallurgical industry until it was replaced by coal. At present,this type of coal is used as the main source of energy in developing countries.
In the western world is mainly used as absorbent in the manufacture of gunpowder.
- Trees for the production of tools, houses and means of transport: As civilizations became more complex, the consumption of wood increased.
We learned to build our tools, our weapons, our homes and our means of transportation. In the Middle Ages, common bog (Buxus serpervirens) was virtually wiped out in some areas or transformed into a singe bush because is was very used to make bows.
The construction of houses and boats, along with the transformation of forests into grazing land or the production of charcoal have been the major causes of deforestation in many forests of the world.
In Europe, huge fleets in countries like Spain, England or Flanders led to deforestation in many forested areas. is said that when the Romans arrived in Spain, a squirrel could cross from North to South by jumping from a tree crown to another tree crown. At present, forests in many parts of the world have been reduced to mountainous areas.
Some tools (axes,saws ,plows, etc) made with birch wood (Vos Museum- Norway)
- Trees for the production of industrial products: wood , besides water, contains cellulose.Cellulose is a carbohydrate. it is the main component of plants that, together with lignin, constitutes cell walls . Lignin acts as a plastic cement that binds the cellulose fibers. Cellulose is subjected to a series of industrial processes to produce a series of products useful to man.
The pulp for paper is obtained by removing the lignin from the pulp and bleaching it properly. By neutralizing the acid in the pulp and adding carbon disulfide steam, a liquid paste is obtained with which very thin sheets or wires can be produced.
This product is used to produce rayon or cellophane. Cellulose, mixed with sulfuric acid and nitric acid, produces nitrates which are used, for example, for the manufacture of explosives or plastics.
Besides cellulose, trees contain many components that are used by industry. Among them, we can mention resins which are the main substances that are secreted when trees suffer a wound or tear. In its natural state, tree resins are used as coagulants and protective substances to heal the wounds, to prevent the sap outflow or to hinder foreign pathogens to go into the inner tissues. Man uses this property to obtain resins by making cuts into the trunks.
We must distinguish between natural resins produced by trees from synthetic resins such as polyurethane or polyester. The main producers of resin trees are conifers that produce oleoresins, ie oily resin in which the resin is mixed with essential oils.
This type of resin paste is less doughy than the rest.Pines stand out among the major producing conifers . By making a cut in their trunks, we can gather an oily paste called turpentine, which is distilled to produce turpentine (also called oil of turpentine or white spirit). Turpentine is mainly used as a solvent and secant in industrial paints.
From the distillation of turpentine a residual resin is also obtained, a substance which has many applications in industry today: for paper pulp, hairsprays , glues, soaps, car tires, gum, and pharmaceutical products.
Among the best known turpentines we must mention Cyprus turpentine which is not obtained from any pine, but a kind of lentisc, called terebinth or turpentine tree (Pistacia terebinthus). This is a small tree - in most cases, a shrub - living in Mediterranean areas.. This resin has not only industrial properties but is also used for healing purposes in the treatment of gout, arthritis and sciatica. It has even been used to cure cancer.
Canada balsam is another type of resin which is obtained from balsam fir (Abies balsamea). . This tree grows in the Northeast of the Southeastern United States and Canada, where it is widely used as a Christmas plant. Glue to attach glass , liquid to prepare samples for microscopy and other products are obtained from it.
Lactoresins are very important group among the resins. They are called so because they derive from the latex or secretions, very similar to milk , produced by the trunk secretions of certain trees. Among the main lactoresins is rubber. Previously all rubber was obtained from rubber plant (Ficus elastica).It is now often produced synthetically.
Scots pine (Pinus silvestris - photograph- ) and Aleppo pine(Pinus halepensis) are the main producers of turpentine in Europe.In America it is mainly produced from ponderosa pine (Pinus ponderosa) taeda pine (Pinus taeda) or longleaf pine (Pinus palustris). In Asia, from the Chinese red pine (Pinus massoniana) or the Sumatran pine (Pinus merkusii)
- Trees for the obtention of medicines and natural remedies: From trees we extract products that are used for the manufacture of medicines.
The pharmaceutical industry obtains the majority of drugs through chemical processes. However, many products that now can can be produced in the laboratory are based on old components from plants that were already used in a natural way in the past .
Aspirin is the trade name for acetylsalicylic acid, a component obtained synthetically in 1853 by Charles Frederic Gerhardt It derives from salicin which comes from the willow (Salix sp.). , before the aspirin was invented, people used the leaves of the willow to make preparations for fighting the same aches that this medicine is used for: pain, inflammation, fever and platelet aggregation.
The importance of taxol, a derivative obtained from the Pacific yew (Taxus brevifolia) in the treatment of cancer and especially in regard to breast cancer, has been approved by the U.S. FDA.
The lentiscus mastic is a resin used by dentists to produce dental cement. Before applying it to modern medicine, mastic was already widely used as chewing gum to favor smell and fortify gums. Among the major medical applications of turpentine , obtained from pine resin, is its ability to stimulate the production of urine or eliminate intestinal worms.
Used externally it is used as an astringent for the treatment of wounds or scratches. Mixed with animal fat, it makes a paste that can be done to remedy cold or bronchitis. In fact the formula of the product "Vicks vaporub" contains this product among its ingredients.
Undoubtedly many more natural remedies are derived from flowers, bark, leaves, resins or latex from the trees. The birch tree is considered one of the best diuretics for their ability to prevent fluid retention.
The Carob seed is very rich in mucilages and its ideal in case of constipation. The horse chestnut tree is one of the best remedies for toning the arteries and capillaries , therefore it is recommended in the problems of varicose veins, hemorrhoids or celulitis.
It is well known the use of eucalyptus or elderberries as effective remedies for treating cold, flu, and asthma and other respiratory problems. And what to say about the flowers and bracts of lime tree in the preparation of the so renowned herbal tea , in the treatment of insomnia, stress, tachycardia, and other problems of the nerves.
In this way we could go on mentioning many more trees with proven medicinal properties throughout the world and many other ones which are going subjected to recent studies . Within the rainforest there are many more who we do not know and probably contain principles of healing for many diseases that afflict us.