Trees are useful in many respects:
- Trees, protectors of fauna and of flora
In forest, trees shelter the whole ecosystem which assures the diversity of species and produces invaluable chemical principles. They are the centre of important biocoenosis, constituted by bacteria living in roots, by organisms breaking down leaves, by feeding many insects, by birds nesting in crevices, small rodents using fruits, etc.
- Trees, health sources
Trees are rich in principles themselves which medicine could exploit at all times. Let us name the aspirin, extracted from the willow bark, the taxine, cardio-active alkaloid extracted from the yew tree and the cinchona, extracted from bark, which stops malaria. More generally, forests are admitted to be essential for the balance of the ecosystem for their capacity to regenerate the oxygen, thanks to photosynthesis. These are like factories which extract the carbon of air (famous CO and CO2 of our exhausts) and to recycle it, according to an irremovable alchemy: the solar energy, picked up by leaves, speeds up the reaction which separates the coal of the oxygen. The oxygen evaporates, while the carbon strengthens the backbone of the tree. Its trunk is made to a great extent of carbon, which escapes again there slowly at the time of the putrefaction of the wood or when it is burnt. There is only the dried out wood which "fossilizes" the carbon definitely. But this wealth in carbon fibres is worth to the trees to be exploited, with consequences, often reported in the tropical countries (Amazon, Indonesia, Malaysia), on the rocking of the ecosystem.
- Trees with wood
Under tempered climate, trees with wood are on one hand conifers, pines, firs, which quickly grow and give a wood of medium quality (because of resinous channels), on the other hand hardwoods, the white poplar (Populus alba), trembles him (P. tremula), birch (Betula pendula), Hornbeam (Carpinus betulus), beech (Fagus sylvatica) or else oaks as pubescent oak, (Quercus pubescens), the sessile oak ,(Q. petraea). These are still the village elm (Ulmus procera), the norway maple(Acer platanoides) or the Bigleaf Linden (Tilia platyphyllos). The fruit trees, wild cherry tree, cherry tree, are not cultivated for the wood, but are nevertheless appreciated in cabinetmaking (compact wood, of hot colour). The walnut also gives a very hard wood. In the tropical countries, the mahogany tree and the ebony are searched because of their hard and lasting wood, with damage which is known in the countries where regulation is deficient. A precious tree working of which is very regulated is the sandalwood, in India, odorous wood statues of which (with sacred character) and of the soap are made.
- Timber, joinery, wood fuel
Traditional timber are the oak, the chestnut, the spruce. They do not deteriorate and the chestnut has a reputation to push back the flies. So, the spiders do not weave their web there! The oak was searched in France to fabricate ships. Colbert became aware that to endow France of a powerful Navy, it was necessary to prepare the writing woods for a long time for advance. So was born the management of forests as that of Tronçais (in the Southeast of Bourges). Long before, Philippe-Augustus had judged necessary to manage the logging of the big trees necessary to the building of cathedrals. The breadth of naves (of cathedral of course) was directly linked to the maximum length of timber! Let us stay in transport: carriages, first cars and first planes were made of light wood.
Then came the oil and its substitution derivatives (isn't the oil a carbon broken down, after compression millenniums under rock?). Textile industries made with fibres of barks (by yew tree notably) had disappeared before the arrival of the Dacron and other nylons. Windows in PVC replace the wood. But quality musical instruments are always made of wood. Finally, the heating and cooking for many inhabitants are made neither with gas nor with oil, but with wood fuel which the women and the children have to search far from villages, because of its rarefaction. Hardwood is preferred over softwood because it creates less smoke and burns longer.
- Paper trees
The first paper of the Chineses was made of mulberry bark ("in paper"), while the Indians of North America used the bark of the birch ("in paper"). While Europe knew only the "vellum" (calf-skin, lamb). The paper, introduced from China in the XIIIth century by the Arabs, is first based on old rags. In the XIXth century, the growing need for paper (including newspaper) encourages researchers to develop a method that exploits the woody fibers of the wood. The eucalyptus and resinous (subject to eliminating the resin), because they grow fast, are mostly exploited for the paper mill. Wood ships are treated with solvents which remove the resinous material and lignite of the wood, leaving only fibres of pure cellulose. The most ancient technique in chemical solvents is the soda technique, perfected in 1851 and which uses a solution of caustic soda (of soda hydroxide) as solvent.
- Wood of small crafts
The former trades have hosted rural areas up to the mid-twentieth century, loggers, longshoremen, renderers, merains chop, chop of échalats, turners-Boisselier, chair makers, Cerclier (barrels), coopers, draymen, charcoal burners (charcoal), fagotiers, shoemakers worked the wood or prepared it. The oak bark produced tannin and cork.
- Environmental cultures
Trees do not grow only in forests. The man could use them to arrange the territory up: the dunes of the Landes were fixed, first with herbs (the marram grass), then with maritime pines at the end of the XVIIIth century. In the second Empire, an engineer imagined process of viabilisation of insalubrious marshes of the Landes. The loamy layer (alios) which kept the water and prevented the penetration of roots is broken down, drained. Then seeds of pines are seeded among plants as which decomposition acts as litter. The success of operation is incontestable, in spite of uniformity, monotony of the landscape, fire hazards, and fragility of pines in the violent winds. Trees serve of windcheater (poplars planted in Provence), of slope stabilizers (willows in Brittany, before land consolidation), of stabilizers of banks (willows, alders).
- Urban trees
The tree in city asserts perspectives (alignment of plane trees, of hackberries or of elms in Provence) and gives shadow to places. Avoid the trees which sucker abundantly from roots (because they would distort roadways), as the Balsam Poplar. Avoid too planting the female poplar in city, because seeds are endowed with hair abundant, like cotton-wool, which the wind takes, at the beginning of the summer, and pours out in white carpets. Also, one plants species of tree of heaven endowed with few male flowers, because they smell bad. The Ginkgo resists pollution well, but ovules with maturity (that it would be possible to take for fruits because of their bowl form) smell particularly pestilential if they are rotting on the ground: avoid planting female trees. Graveyards are traditionally livened up with yew trees, because they represent longevity and because the toxicity of their leaves proscription the access to the stock (to the campaign).
- Garden trees
Trees imported well in advance were fluently used in alignment of paths in parks: chestnut trees, plane trees. Le Nôtre, who was "Jardineur" of the king, drew the very nice parks of "classical" epoch. The trees which support pruning entered the composition of gardens: lindens, charms, yew trees, and boxwood for groves. By 1760, an English passenger, Chambers, describes gardens, which would be called "environmental", of Japan : rivers, rip-raps, waterfalls squeeze in among willows and insulated alders (think of Kew Gardens, next to London). The Romanticism and the fashion antiquarian of the XIXth century are going to top up other surprises: pyramids, ruins, cenotaphs (desert of Retz, park Monceau in Paris, garden of Buttes-Chaumont in Paris). Bélanger, "architect of gardens", draws Bagatelle, west of Paris, while Alexander Brongniard, the architect of the Stock Exchange, conceives the Eastern graveyard (current graveyard of Père-Lachaise) as a garden: tombs are shaded by trees in pot which are taken in the shelter for winter.
- Fruit trees
The classical fruit trees produce the fruits of the summer market: apples, peaches, plums, apricots. These trees result from successive hybridizations, which allowed to improve abundance and quality of fruits, to the detriment of their production length. Out of this season, oranges come to us (that it is possible to keep up to Christmas, in cool places, for example, in the caves of Cappadoce, in Turkey), lemons, grapefruits of the Mediterranean regions, as well as mangos, dates, coconut, and other exotic fruits (to the which it is possible to link the cocoa, which pods contain the seeds of cocoa). The end of the summer brings figs, nuts and hazelnuts, before the horse chestnuts which announce the winter. Like fruits, we can quote the olive of mediterranean countries, the avocado and the fruit of the breadfruit of the tropical regions.