11.1.1 Global demands
The world's woodlands and forests have always changed in response to alterations in climate and the impact of animals, especially the grazers and disease organisms. The major difference in the present Flandrian interglacial is the overwhelming impact of humans, whose world population rose from under two billion in 1900 to over six billion in 2000, after having been comparatively negligible in Neolithic times. Accurate estimation of annual global wood consumption is difficult but it was at least 3.36 billion m3 in 1996, of which some 55% was used as fuel, largely in developing countries. The other 45% went for industrial use, largely as saw logs but also as chemical raw material. Sugar produced by trees in photosynthesis can be converted into a host of complex chemicals, then combined into a cellular structure with a high strength to weight ratio. Lignin, cellulose, resins, turpentine, wood alcohol and many other products are all derived from trees.
Twenty per cent of the world population lives in developed economies where consumption is high and the fertility rate (average number of children per woman) low; the remaining 80% exist in the so-called developing economies where consumption is low and the fertility rate may be as high as seven. Average use of wood per person per year in 1990 was around 2.3 m3 in the USA, nearly four times the 1996 global average of 0.58 m3. The world's resources could not cope with an unlimited continuation of the population increase seen in the twentieth century. Instead, future factors are expected to result in an annual demand for timber which will be stable, but much higher than it is now. Recent predictions (Sutton, 1999, 2000) are that a large rise in consumption levels in the developing economies will be accompanied by a fall in population increase as occurred in the existing developed economies. This is expected to result in a stabilization of the world population at around ten billion by 2050. Total demand for timber will thus enlarge; it will also increase on a per capita basis as timber is substituted for ever-diminishing fossil fuels. A small but significant proportion could well come from the efficient harvesting and use of urban timber, a process now well underway in parts of the USA, where many people became disgusted by the way in which urban trees were used as landfill or just burnt in a convenient spot (Sherrill, 2003).
If this scenario becomes reality, timber production will have to increase on a massive scale. Total world forest area will have to be greatly increased, as will productivity per unit area. Sutton (2000) predicts that by the year 3000 the total annual wood harvest will have increased to nearly 28 billion m3, mainly from plantation forests. His views are interesting and although even short-term prediction is difficult, what he puts forward seems to be within the realm of technical possibility; one hopes that the human population will in the future become sufficiently disciplined to plan accordingly.
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