Wood economy

The existence of a wood economy, or more correctly, a forest economy (since in many countries a bamboo economy predominates), is a prominent matter in many developing countries, as well as in many other nations with temperate climate and especially in those with low temperatures. These are generally the countries with greater forested areas. The uses of wood in furniture, buildings, bridges, and as a source of energy are widely known. Additionally, wood from trees and bushes, can be employed in a wide variety, including those produced from wood pulp, as cellulose in paper, celluloid in early photographic film, cellophane, and rayon (a substitute for silk).

At the end of their normal usage, wood products can be burnt to obtain thermal energy, or can be used as a fertilizer. The potential environmental damage that a wood economy could occasion include (problems of reduction the biodiversity due to monoculture forestry - the intensive cultivation of very few types of trees); and CO₂ emissions. However, forests can aid in reduction of atmospheric carbon dioxide and therefore decrease global warming.^[1]

Introduction[edit | edit source]

History of use of wood[edit | edit source]

The wood economy is historically the starting point of the civilizations worldwide, since eras preceding the Paleolithic and the Neolithic. It necessarily preceded ages of metals by many centuries, as the melting of metals was possible only through the discovery of techniques to light fire (usually obtained by the scraping of two very dry wooden rods) and the building of many simple machines and rudimentary tools, as canes, club handles, bows, arrows, lances. One of the most ancient handmade articles ever found is one smoothed pricked of wood (Clacton Spear) 250,000 years old (third interglacial period), that was buried under sediments in England, at Clacton-on-Sea..^[2][3]

Successive civilizations such as the Egyptians and Sumerians built sophisticated objects of furniture. Many types of furniture in ivory and valuable woods have survived to our time practically intact, because secluded in inviolated secret tombs, they were protected from decay also by the dry environment of desert.^[4] Many buildings and parts of these (above all roofs) contained elements in wood (often of oak) forming structural supports and covering; means of transport such as boats, ships; and later (with the invention of the wheel) wagons and carriages, winches, flour mills powered by water, etc.

Dimensions and geography of wood economy[edit | edit source]

The main source of the lumber used in the world are forests, which can be classified in virgin, semivirgin and plantation. It is known that much timber is removed for firewood by the local populations in many countries, especially in third world, but this amount can only estimated, with wide margins of uncertainty.

In 1998, the worldwide production of wood, officially that not used as firewood (known as "roundwood"), was about 1.5 billions of cubic meters (m³), amounting to around 45% of the wood cultivated in the world. Cut logs and branches destined to become elements for the construction of buildings account for approximately 55% of the World's industrial wood production. 25% becomes wood pulp (including wood powder and truccioli) mainly destined for the production of paper and paperboard; a further 20% approximately became panels in plywood and valuable wood for furnitures and objects of common use (FAO 1998).^[5] The World's largest producer and consumer of this wood "officially accounted" is the USA, although the country that possesses the greatest area of forests is Russia.

In the seventies, the countries with the biggest forest surface were: Soviet Union (approximately 8,800,000 km²), Brazil (5,150,000 km²), Canada (4,400,000 km²), USA (3,000,000 km²), Indonesia (1,200,000 km²) and Democratic Republic of Congo (1,000,000 km²). Other countries with important production and consumption of wood usually have a low density of population in relation to their territorial extension, here we can include countries as Argentina, Chile, Finland, Poland, Sweden, Ukraine.

By 2001 the rainforest areas of Brazil were reduced by a fifth (respect of 1970), to around 4,000,000 km²; the ground cleared was mainly destined for cattle pasture - Brazil is the world's largest exporter of beef with almost 200,000,000 head of cattle.^[6] Also the booming ethanol economy that in Brazil is based upon sugar cane cultivation, is reducing forests size. Canadian forest was reduced to by almost 30% to 3,101,340 km² over the same period.^[7]

Importance in fighting greenhouse effect[edit | edit source]

Regarding the problem of climate change, it is known that burning forests increase CO₂ in atmosphere, while intact virgin forest or plantations act as sinks for CO₂, for these reasons wood economy fights greenhouse effect. The amount of CO₂ absorbed depends on the type of trees, lands and the climate of the place where trees naturally grow or are planted. Moreover, should be told that by night plants do not execute photosynthesis, and produce CO₂, eliminated the successive day. Paradoxically in summer oxygen created by photosynthesis in forests near to cities and urban parks, interacts with urban air pollution (from cars, etc.) and is transformed by solar beams in ozone (molecule of three oxygen atoms), that while in high atmosphere constitutes a filter against ultraviolet beams, in the low atmosphere is a pollutant, able to provoke respiratory disturbances.^[8][9]

In a low-carbon economy, forestry operations will be focused on low-impact practices and regrowth. Forest managers will make sure that they do not disturb soil based carbon reserves too much. Specialized tree farms will be the main source of material for many products. Quick maturing tree varieties will be grown on short rotations in order to maximize output.^[10]

Wood economy per nation/continental area[edit | edit source]

Wood economy in Australia[edit | edit source]

• Eucalyptus: these are seven hundred tree species from Australia, that grow very fast in tropical, sub-tropical and semi-arid climates, and are very resistant to forest fires (with their tree cortex) and to drought. Its essential oil is used in pharmacology, its wood for building, and the small branches as firewood and for paper and cardboard pulp.

Wood economy in Brazil[edit | edit source]

Brazil has a long tradition in the harvesting of several types of trees with specific uses. Since the sixties imported species of pine tree and eucalyptus have been grown mostly for the industry of paper pulp and plywood. Currently high-level research is being conducted, to apply the enzymes of sugar cane fermentation to cellulose in wood, in order to obtain methanol, but the cost is much higher when compared with ethanol derived from corn costs.^[11]

• Brazilwood: has a dense, orange-red heartwood that takes a high red shine (brasa=ember), and it is the premier wood used for making bows for string instruments from the violin family. This trees soon became the biggest source of red dye, and they were such a large part of the economy and export of that country, that slowly it was known as Brazil.^[12]
• Hevea brasiliensis: is the biggest source of the best latex, that is used to manufacture many objects in rubber, as an example gloves, condoms, anti-allergic mattresses and tires (vulcanized rubber). Latex has the ability to adjust to the exact shape of the body part, an advantage over polyurethane or polyethylene gloves.

Wood economy in Canada & USA[edit | edit source]

There is a close relation in the forestry economy between these countries, they have many tree genus in common, and Canada is the main producer of wood and wooden items destined to the USA, the biggest consumer of wood and its byproducts in the world. The water systems of the Great Lakes, Erie canal, Hudson river and Saint Lawrence Seaway to the east coast and Mississippi to central plains and Louisiana allows transportation of logs at very low costs. In the west coast the basin of the Columbia River has plenty of forests with excellent timber.

Canada[edit | edit source]

The agency Canada Wood Council calculates that by the year 1999 in Canada, the forest sector employed 850,000 workers (1 job every 17), making around $74 billion of value in goods and services. For many years products derived from trees in Canadian forests had been the most important export items of the country. In 2001, exports around the world totaled some $44.1 billion – the single largest contributor to Canadian trade balance.^[7][13]

Canada is the world leader in sustainable forestry management practices. Only 120 million ha (28% of Canadian forests) are currently managed for timber production while an estimated 32 million ha are protected from harvesting by the current legislation.^[14]

USA[edit | edit source]

• Cherry: has a hardwood prized for its high quality in grain, width, color, and rich warm glow.^[15] The first trees were carried to the lands surrounding Rome (Latium) from Armenia.^[16] In the United States, most cherry trees are grown in Washington, Pennsylvania, West Virginia, California and Oregon..^[17] When cherry tree flower, they make several among the most appreciated landscapes in Japan.
• Cedar: this genus are coniferas of the pinaceae family, originating from high mountain areas from Carpathians, Lebanon, Turkey to Himalaya. Their scented wood make them suitable for chests and closet lining. Cedar oil and wood is known to be a natural repellent to moths.^[18] Actually are planted in western and southern USA, mostly for ornamental purposes, but also for the production of pencils (specially incense-cedar).
• Douglas-fir: is a native tree of the United States west coast, with records in fast grow and the reaching of high statures in brief time. It has the ability to grow in mountains till the height of 1,800 meters. Their wood is used for construction, for homebuilt aircraft, for paper pulp, and also as firewood.
• Hybrid poplar is being investigated by Oak Ridge National Laboratory in Tennessee^[19][20] for genetic engineering in order to obtain a tree with a higher content of cellulose and a lower content in lignin, in such a way that the extraction of bioethanol (useful as a fuel) could be easier and less expensive.
• Walnut: It is a prized furniture and carving hardwood because of its colour, hardness, grain and durability. Walnut wood has been the timber of choice for gun makers for centuries, including the Lee Enfield rifle. It remains one the most popular choices for rifle and shotgun stocks.^[21]

Wood economy in the Caribbean & Central America[edit | edit source]

• Mahogany: has a straight grain, usually free of voids and pockets. The most prized species come from Cuba and Honduras. It has a reddish-brown color, which darkens over time, and displays a beautiful reddish sheen when polished. It has excellent workability, is available in big boards, and is very durable. Mahogany is used in the making of many musical instruments, as drums, acoustic and electric guitars' back and side, and luxury headphones.

Wood economy in Europe[edit | edit source]

Italy[edit | edit source]

The species that are ideal for the many uses in this type of economy are those employed by arboriculture, which are very well known for their features and the need for certain types of ground and climates.

• Fraxinus: being a lightweight wood is easy to transport, as firewood burns easily, grows in damp environments like those present in river flooding areas, stands pollution of water and air.
• Larix: in Italy, it grows at high altitudes around mountain tops, its timber stand sudden climatic change, from icy winds to high temperatures in sunny afternoon summers, it is excellent for use in the building of exposed structures as bridges, roofs, etc.
• Stone pine: "Mediterranean pine" could be the noble emblem of many coastal areas in Italy, originally giant forests of pines extended from the mouth of the Tiber river until Liguria and Provence in France, over soils with high salinity, not very apt for agriculture. Its trees produce a vast amount of dry branches that can be burnt, cones (used for Christmas decoration) and needle-like foliage that can be burnt, or used as mulch. Oils and resins can be used in scents and ointments. The pinoli are useful elements in Italian cooking (along with basil are tritured to make pesto sauce). Currently, "progress" has brought to a severe reduction of these magnificent tree extensions, and in many places, cheap beach buildings, car-parking, and semi-abandoned areas have taken their place.
• Poplar: in Italy is the most important species for tree plantations, is used for several purposes as plywood manufacture, packing boxes, paper, matches, etc. It needs good quality grounds with good drainage, but can be used to protect the cultivations if disposed in windbreak lines. More than 70% of Italian poplar cultivations are located in the pianura Padana. Constantly the extension of the cultivation is being reduced, from 650 km² in the 80's to the current 350 km². The yield of poplars is about 1,500 t/km² of wood every year.^[22] The production from poplars is around 45-50% of the total Italian wood production.
  • In the history of art poplar was the wood of choice for painting surfaces as panels, as in Renaissance (The Mona Lisa by Leonardo da Vinci). Because of this reason, many of the products with the highest added value, extremely expensive, are made with wood from the humble but durable poplar.
  • Because of the presence of tannic acid, the poplar cortex was often used in Europe for the tanning of leather.

Portugal[edit | edit source]

• Oak for cork: are trees with slow growth, but long life, are cultivated in warm hill areas (min. temp. > -5°Celsius) in all the west area of Mediterranean shores. Popular for bulletin boards. Even if the production as stoppers for wine bottles is diminishing in favor of nylon stoppers, for the sake of energy saving granules of cork can be mixed into concrete. These composites have low thermal conductivity, low density, and good energy absorption (earthquake resistant). Some of the property ranges of the composites are density (400–1500 kg/m³), compressive strength (1–26 MPa) and flexural strength (0.5–4.0 MPa).^[23] Because of this cork can be used as thermal isolation in buildings (as well in its natural form and as a mixture), useful also as sound insulation. In the shoe industry cork is used as soles and insoles. In the world there are 20,000 km² of cork oak plantations, and every year are extracted around 300,000 tons of cork, 50% in Portugal, 15,000 in Italy (12,000 in the island of Sardinia). The advantage of this natural industry is that the extraction of cork from layers outer to the cortex does not kills the tree.

Wood economy in Scandinavia & Russia[edit | edit source]

• Birch: is a genus with many species of trees from Scandinavia and Russia, excellent for acid grounds. They act as pioneer species in the frozen border between taiga and tundra, are very resistant to periods of drought and icy conditions. The species Betula nana has been identified as the ideal tree for the acid grounds of the sides of sloped mountains, also in southern Europe, with soils poor in nutrients, where these trees can be used to restraint landslides. From birch tree can be extracted Xylitol, a natural sweetener.

Nessuna di queste specie sottrae terreni pregiati o particolarmente fertili all'agricoltura, ma, al contrario, contribuiscono a proteggere i suoli coltivati dall'erosione e dai venti. Nonostante questa caratteristica positiva in Italia, da secoli si assiste alla progressiva riduzione della presenza degli alberi nei terreni circostanti le colture con la conseguenza che l'eccesso di acqua meteorica non viene adeguatemente trattenuto e si possano verificare, quando succedono piogge abbondanti, catastrofiche alluvioni.

Uses of wood[edit | edit source]

Combustion[edit | edit source]

Mean energy density of Wood, was calculated at around 6–17 Megajoule/Kilogram.

Charcoal[edit | edit source]

Direct burning[edit | edit source]

The most intuitive use for wood, is that for burning in traditional fireplaces, even if combustion of wood is linked to the production of micro-environmental pollutants, as carbon dioxide (CO₂), carbon monoxide (CO) (an invisible gas able to provoke irreversible saturation of blood's hemoglobine), as well as nanoparticles. .^[24]

In Italy poplar has been proposed as tree cultivation to be transformed in biofuels, interesting because of the excellent ratio between the low energy needed to cultivate, cut, and transport these trees, and the high amount of energy that can be extracted from its wood, because of poplar's capture of atmospheric carbon dioxide and their fast-growing. As an example, Populus euroamericana clone "I-214", grows so fast that is able to reach 14 inches (35 cm) in diameter and heights of 100 feet (30 m) in ten years.

For many centuries there had been used many types of traditional ovens in order to take benefit from the heat generated by wood combustion, that actually had been developed to more efficient and clean machines: advanced fireplaces (with heat exchangers), wood-fired ovens, wood-burning stoves and pellet stoves, that are able to filter and separate pollutants (centrifugating ashes with rotative filters), thus eliminating many emissions, also allowing to recover a higher quantity of heat that usually went away with the chimney fumes.

Wood gasogen[edit | edit source]

Wood gas generator (gasogen): is a bulky and heavy device (but technically simple) that transforms burning wood in a mix of molecular hydrogen (H₂), carbon monoxide (CO), carbon dioxide (CO₂), molecular nitrogen (N₂) and water vapor (H₂O). This gas mixture, known as "poor gas" or "syngas" is obtained after the combustion of dry wood in a reductive environment (low in oxygen) with a limited amount of atmospheric air, at temperatures of 900° Celsius, through an internal combustion engine..^[25]

In the time between World War I and World War II included, because of the lack of oil, in many countries, like Italy, France, Great Britain and Sweden, several gasoline-powered cars were modified, with the addition of a wood gas generator (a "gasogen"), a device powered by wood, coal, or burnable waste, able to produce (and purify) gas that immediately, in the same vehicle, could power a slightly modified ICE engine of a standard car (low-compression engine). Carburetor had to be changed with an air-gas mixer). There were several setbacks, as the great reduction of maximum speed and the need to drive using low gears and wisely dosing the amount of air. In modern cars, modified with a wood gas generator, gas emissions (CO, CO₂ and NOx) are lower to those of the same vehicle running with gasoline (keeping the same catalytic converter).

Methanol[edit | edit source]

Methanol, also known as formic alcohol (H₃C-OH), is the simplest alcohol (an hydroxyl radical bonded to a molecule of methane), which behaves as a liquid at 25°C, is very toxic (lethal) and corrosive, and in organic chemistry basic books is often called "the spirit of wood", since it can be obtained from wood fermentation. Rarely, when unwise wine-makers mix small chunks of wood and leaves with grapes, methanol can be found as a pollutant of the blend of water, ethanol and other substances derived from grape's fermentation.

Best way to obtain methanol from wood is through syngas (CO, CO₂, H₂) produced by the anhydrous pyrolysis of wood, a method discovered by ancient Egyptians.

Methanol can be used as an oxygen-rich additive for gasoline, but usually, it is much cheaper to produce it from methane or from syngas, and it is the most important base material for industrial chemistry, where it is often used to make more complex molecules, through reactions of halogenation and later by chemical addition reaction.

Gas turbine[edit | edit source]

Construction[edit | edit source]

Wood is relatively light in weight, because its specific weight is less than 500 kg/m³, this is an advantage, when compared against 2,000-2,500 kg/m³ for armed concrete or 7,800 kg/m³ for steel.

Wood is strong, because the efficiency of wood for structural purposes has qualities that are similar to steel.

Material	E/f
Concrete	(Rck300, fck 25 M-Pascal)		1250
Structural steel	Fe430 (ft = 430 MPa)		480
Glued laminated timber	(BS 11 ÷ BS 18)		470
Aluminium	(alloy 7020, ft 355 MPa)		200

Briges, levees, microhydro, piers[edit | edit source]

Wood is used to build bridges (as the Magere bridge in Amsterdam), as well as water and air mills, and microhydro generators for electricity.

Housing[edit | edit source]

Hardwood is used as a material in wooden houses, and other structures with a broad range of dimensions. In traditional homes is preferred for ceilings, doors, floorings and windows. Wooden frames were traditionally used for home ceilings, but they risk collapse during fires.

The development of energy efficient houses including the "passive house" has revamped the importance of wood in construction, because wood provides acoustic and thermal insulation, with much better results than concrete.

Earthquake resistant buildings[edit | edit source]

In Japan, ancient buildings, of relatively high elevation, like pagodas, historically had shown to be able to resist earthquakes of high intensity, thanks to the traditional building techniques, employing elastic joints, and to the excellent ability of wooden frames to elastically deform and absorb severe accelerations and compressive shocks.

In 2006, Italian scientists from CNR patented^[26] a building system that they called "SOFIE",^[27] a seven-storey wooden building, 24 meters high, built by the "Istituto per la valorizzazione del legno e delle specie arboree" (Ivalsa) of San Michele all'Adige. In 2007 it was tested with the hardest Japanese antiseismic test for civil structures: the simulation of Kobe's earthquake (7,2 Richter scale), with the building placed over an enormous oscillating platform belonging to the NIED-Institute, located in Tsukuba science park, near the city of Miki in Japan. This Italian project employed very thin and flexible panels in glued laminated timber, and according to CNR researchers could be brought to the construction of much more safe houses in seismic areas.^[28]

Vehicles[edit | edit source]

Airplanes[edit | edit source]

• Until World War II, due of a lack of metals (like aluminum and iron), there were several airplanes built with a structure of metal Warren girder covered with laminated plywood and balsa wood, like the British Hawker Hurricane and de Havilland Mosquito, the second one was a very fast a successful tactical bomber, pathfinder and reconnaisance aircraft, and with two engines it flew faster than the average Nazi Germany fighter plane. The lack of durability poised by wood was not a problem since combat airplanes usually did not had a useful life of more than 100 missions (or days).

<!-=== Manifactures ===

Tools[edit | edit source]

Furniture[edit | edit source]

Nel settore dell'arredamento il legno si utilizza tipicamente per costruire armadi, tavoli, sedie, di qualità e durata molto spesso superiori a quelle in plastica e metallo. Il loro aspetto e testura risulta particolarmente gradevole sia alla vista che al tatto, che nei i modelli a basso prezzo destinati all'assemblaggio fai da te (ad esempio quelli dell'IKEA) danno piacevoli sensazioni affini al calore del focolaio domestico.

I modelli di mobili di alto livello qualitativo, costruiti con legni pregiati ed elaborati design, danno un tocco di raffinatezza sia all' ambito domestico, che agli uffici, scuole, universita'. ecc.

Musical instruments[edit | edit source]

Toys[edit | edit source]

Wood statues[edit | edit source]

Paper[edit | edit source]

Other uses[edit | edit source]

Ashes from wood burning[edit | edit source]

• it:Bucato: uno degli utilizzi tradizionali, è quello della cenere di legna come sbiancante "ranno", ricco di carbonato di sodio. Attualmente esiste un prodotto di questo tipo a base di sapone di Marsiglia e cenere. Inoltre la tavoletta dove si sfregavano i panni durante il lavaggio era in legno.
• it:Fertilizer: la cenere (deprecabilmente) molto utilizzata nei paesi del terzo mondo, dove si procede al taglio della foresta (per il recupero dei legni pregiati, anche se questa procedura non si esegue sempre) e successivamente si da fuoco all'area disboscata. Molto ricca di alcuni elementi minerali che promuovono la crescita d'erba, nell'America del Sud le estensioni bruciate nella tala y quema vengono utilizzate per l'allevamento di bufali, vacche ed altri bovini. In terreni dove la pluviosità é bassa, questa pratica provoca la salinizzazione del terreno, che diventa piuttosto arido.

Vantaggi e svantaggi[edit | edit source]

Vantaggi[edit | edit source]

• Ambientalmente si ha la massima compatibilità, non si hanno i tremendi impatti ambientali e paesaggistici dell'industria estrattiva del carbone, oppure le perdite di petrolio in mare, che causano gravi danni alla pesca ed al turismo.
• Assorbimento di anidride carbonica (CO₂) dall'atmosfera, con conseguente riduzione dell'effetto serra a livello globale. Possibilità di vendere le "quote di assorbimento" in base a quanto stabilito dal protocollo di Kyoto.
• Aumento dell'occupazione nelle nazioni che mantengono le foreste, in Italia soprattutto in zone che nell'ultimo secolo si sono spopolate, come le Appennini o le Alpi, oppure le zone collinari del centro e del nord, che spesso coincidono con le comunità montane dal momento che l'economia forestale si serve intensivamente di guardie, di tagliatori, trasportatori, mobilifici, ecc. Non si contribuisce ad incrementare la ricchezza degli sceicchi e la vastità dei loro arsenali.
• Basso costo del trasporto, dal momento che i tronchi possono galleggiare nei fiumi (come i tronchi di quercia in Canada) oppure essere trasportati in vari tipi di imbarcazioni e navi.
• Fonte energetica totalmente rinnovabile, specialmente se gestita adeguatamente, ad esempio allestendo nursery degli alberi e vigilando attentamente l'estensione arborea con guardie forestali.
• Miglioramento del bilancia dei pagamenti con l'estero, per il mancato esborso dovuto alla riduzione della quota di energia che viene importata.
• Prevenzione delle alluvioni e dell'erosione dei suoli, con conseguente miglioramento delle rese agricole. Le alluvioni spesso causano danno al patrimonio artistico e monumentale delle città, come accade per l'alluvione di Firenze del 4 novembre 1966.

Svantaggi[edit | edit source]

• Fragilità dell'economia a legna: se tagliando il bosco per i fini più diversi, si dovesse superare la capacità di una foresta di rigenerarsi, in pochi decenni si arriva all'estinzione della stessa, condizione verificatasi in molte società in diverse epoche storiche. Ad esempio se una foresta "coltivata" ha alberi che crescono ad una dimensione sfruttabile in 25 anni, non si può tagliare più del 4% della foresta ogni anno, ed allo stesso modo bisogna ripiantare con alberi della stessa qualità un'area di pari estensione. Vigilare l'estensione della foresta tramite la fotografia aerea è uno dei compiti principali delle guardie forestali.

History of crisis in wood economies[edit | edit source]

Classic Greece[edit | edit source]

Uno degli esempi storici più noti della crisi dell'economia a legna è quello che si verificò nella Grecia Classica, in particolare nelle regioni dell'Attica, Beozia e Peloponneso dove il taglio indiscriminato degli alberi per diversi usi, associato a siccità ed incendi portò alla mancanza di legna per costruire aratri, lance, navi, scudi, ecc. e quindi ad un lento ma inesorabile declino della potenza militare e navale della grecia penisolare in favore dell'Epiro e del Regno di Macedonia, terre più fertili perché piovose, fatti culminanti durante il IV secolo a.C., epoca di Filippo II di Macedonia ed Alessandro Magno.

L'arma segreta del soldato peltasta macedone di Filippo nella battaglia di Cheronea (338 a.C.) ed in quelle successive che portarono a conquistare l'Asia Minore, Babilonia, la Persia e l'Egitto, era la sarissa, un tipo di lancia oplitica, molto piu lunga (5-7 m.) rispetto a quelle del resto della grecia, ottenuta dal lungo, resistente ma leggero legno del corniolo.^[29]

Rapa Nui[edit | edit source]

Rapa Nui, meglio conosciuta come Isola di Pasqua, è il tipico esempio di come l'espansione geometrica di una popolazione porta alla fine di una risorsa rinnovabile, proprio perché ad un certo punto l'assoluta necessità rende lo sfruttamento eccessivo, ed impedisce che la risorsa si rinnovi. Si calcola che dopo l'anno 1000 a Rapa Nui siano state tagliate 10 milioni di palme, portando ad erosione delle terre fertili, ed a desertificazione attorno al XV secolo (forse favorita da un'infestazione di ratti), che ridusse la popolazione da 15.000 a 2.500 anime. Senza legname, niente barche, niente lance, nè reti e dunque niente pesce e proteine, ed alla fine la società diventa preda della fame, della guerra civile (nel 1600-1700), si immerge nella superstizione più fanatica, ed infine si arriva alla disgregazione ed al caos sociale, con distruzione dei simboli tradizionali (Moai abbattuti) ed estinzione della civiltà, anche in assenza di nemici esterni.

Notes and references[edit | edit source]

Bibliography[edit | edit source]

English[edit | edit source]

• Diamond, Jared. 2005. Collapse. How Societies Choose to Fail or Succeed. New York: Viking. ISBN 0-14-303655-6.
• "Construction of a Simplified Wood Gas Generator for Fueling Internal Combustion Engines in a Petroleum Emergency"

Italian[edit | edit source]

• Conti, L., Lamera C. "Tecnologie dalle Origini al 2000", Arnoldo Mondadori Editore, 1981. ISBN
• Appunti del corso di formazione "Energie Alternative e Risparmio Energetico", presso Ordine degli Ingegneri di Padova, De Carli M 2006
• Frank Rosillo-Calle, Biomasse. Manuale per un uso sostenibile, Franco Muzzio editore, ISBN 9788874131600
• Rapporto "Lo sviluppo delle rinnovabili in Italia tra necessità e opportunità", Enea 2005
• Rapporto "Utilizzo energetico della biomassa", Opet (Organizations for the Promotion of Energy Technologies), 2001

See also[edit | edit source]

• Autarchy
• Biofuels
• Biomass
• Hardwood
• Hydrogen economy
• Forest Stewardship Council
• Low-carbon economy
• Lumber
• Wood

External links[edit | edit source]

English[edit | edit source]

• Fast Growing Trees
• Forestry Encyclopedia - Forests and Forestry in the Americas
• Canadian Forests - Quick Facts
• Canadian Forests - Information Reseources
• UNECE - FAO - Timber Committee - European Forestry Commission
• WOODGAS: Biomass Energy Foundation (BEF) website

Italian[edit | edit source]

• Distillazione gassificata dal legno, con produzione di metano, idrogeno e monossido di carbonio
• Forest Sterwardship Council - Italia
• Federlegno - Arredo
• Jolly_Mec_Catalogo_Termojolly_IT.pdf Jolly Mec: l'economia della legna, l'efficacia dell'impianto
• Holzenergie: sfruttare resti delle lavorazioni forestali e del legno
• Thermojolly: economia e fascino della legna - Da caminetti supertecnologici molto più calore