The Wonders of Wood
The Importance of Forest Products
In a Sustainable Society
By J.H. Crawford
This page is in draft form.
23 October 2001
Wood is a wonderful gift. It is one of the most useful naturally-occurring
engineering materials; some of the largest bridges ever built were constructed
entirely of wood (plus a small amount of iron fastening).
The world was once blessed with incredibly vast forest of enormous trees. Today,
many of the forests are gone entirely, and of those that remain, many are second-
and third-growth forests from which much of the topsoil has eroded and which no
longer produce pine trees a hundred meters tall and a dozen meters around.
The European exlorers of North America found forests that stretched from New England
to beyond the Great Lakes, forests so enormous that it was assumed they were
"inexhaustable." Today, virtually all of that forest has been cut, although to be
sure, a great deal of it has regrown, albeit with smaller and less useful trees.
Wood will undoubtedly play a vital role in the creation of a sustainable society,
but its enormous attraction for a myriad of uses means that consumption will have
to be reduced and production improved through ending clear-cutting, which devastates
the forest soil.
Properties
Wood has a number of remarkable, even singular properties that make it better suited
for many uses than any other material.
Useful Properties of Wood
An enormous variety of species provide for nearly every conceivable use, from feather-light
balsa wood for model airplanes to heavier-than-water lignum vitae, which was once used for
main propeller shaft bearings in steamships. Species such as ash can absorb tremenous amounts
of energy before breaking. Teak is nearly invulnerable to rot. Rosewood must be one of the
most beautiful materials ever found. And so it goes.
Wood in general has the following marveous properties:
- Wears well and does not fatigue
- Durable if kept dry
- Very strong for its weight
- Has roughly equal tensile and compression strength
- Has oriented strength (while an advantage, this does require more attention to design)
- Quite easily worked
- Can be steam-bent into tight curves
- Takes a fine finish
- Repairable
- Warm to the touch
- Beautiful
- Each piece is unique
- A reasonably good insulator for both electricity and heat
- Has appreciable bio-static properties, making unfinished wood the material of choice for chopping blocks
Unfortunate Properties of Wood
Wood also has some properties that are less wonderful:
- Wood burns, although it is not excessively flamable. It is also true that when a building made of
both steel and wood burns, one often sees heavy steel members turned into a sphaghetti that is
held up by the charred remains of wooden beams.
- When wood is burned, it releases large quantities of a wide variety of
pollutants, so much so that serious air pollution arises in areas where winter wood burning is widespread.
Modern stoves are not only more efficient
but may also be equipped with catalytic converters, which reduce
the output of polluting gasses.
- Most species rot if left in contact with the earth
- Unlike most man-made materials, wood cannot be cast, molded, or extruded.
- Has poor local strength, making high-strenth joints problematic to design and manufacture.
- Cannot be welded, and glued joints only have strength if properly designed.
- Sawdust is an irritant and probably a moderate carcinogen (comparatively simple sawdust control equipment solves this problem).
- Shrinks and swells with changes in humidity.
Uses of Wood
Wood is so widely used that a full accounting of the purposes to which it is applied
is probably impossible. The following are merely the most important
that have occurred to the author at his keyboard:
- Shipbuilding (even today, significant amounts of wood are used in building steel ships)
- Heavy construction, both temporary and permanent
- Light structures, especially houses
- Roofing
- Fence construction
- Residential decking
- Agricultural stakes
- Utility poles
- Railroad cross ties (concrete ties are rapidly supplanting this use)
- Furniture
Misuse of Wood
Wood is also widely abused. It is used in vast qualtities as a packaging material,
normally to be used once and discarded. It is used in the construction of countless
wooden pallets and to manufacture incredible amounts of cardboard of various types.
Wood is so widely used as a heating and cooking fuel that supplies of wood in many
poorer nations are under dire threat. (Fortunately, some countries are helping to
educate their citizens in the need to alter patterns of wood consumption and
reforestation now that populations have become so dense. The use of inexpensive
solar cookers has greatly reduced reliance on firewood in some tropical areas.
Wood is widely used in the production of "scrap" furniture. This is my name for
furniture made out of particle board with very thin wood (or plastic) veneers.
The furniture so made is normally shipped knocked-down (for cheaper freighting)
and assembled by the user. Because particle board contains large amounts of organic binders
to hold it together, it is much heavier than solid wood and therefore requires
more energy to ship. It also releases toxic gasses such as formaldehyde for the
first several years after manufacture. Worst of all, this furniture rarely lasts
ten years and is nearly impossible to repair, whatever damage may occur to it.
Good furniture made of solid wood (or solid wood with veneer) can last hundreds
of years if well made from good wood and reasonably cared for. In fact, most
of this old furniture is worth far more than its modern equivalents and will
probably outlast most furniture made today. When, as inevitably occurs,
it is damaged, furniture of solid wood is readily susceptible to high-grade repair
at fairly reasonable cost. The construction and maintenance of durable furniture
does require skilled craftsmen; parts of the process can be partially or fully
automated, but ultimately skill is required to assemble it.
We simply cannot afford to provide each member of society with seven or eight
complete sets of furniture during a lifetime. We must nurture old-growth forests
so that they will continue to produce relatively small amounts of very high
quality wood, some of which can be used to make durable furniture that will
last for generations.
Substituting for Wood
Many uses to which wood is put are amenable to substitution. The leading need
is for paper. While, some day, the "paperless office" may arrive, we will still
continue to use a considerable amount of paper for printing books, magazines,
and newspaper. Much of this use can be substituted by other fibres, such as
hemp. We can achieve a high level of recycling of most paper that is used for
temporary purposes, further reducing the demand for wood pulp.
For cardboard and wood packaging, we can substitute durable plastic packaging
that is used hundreds of times before itself being recycled. This practice is
already common in Europe.
Sustainable Wood
The great fiction is that we are already sustaining our forests. While it is
true that the large timber companies "plant two trees for every tree they cut down,"
that does not represent sustainable forestry by a long shot. The first problem is
that the timber companies find it far more economical to cut down every tree in the
forest in a single operation, rather than to pick an choose mature trees for havesting,
leaving all the younger trees to grow. The practice of clear cutting leads not only
to stream pollution from the high runoff that immediately results, it leads to an
enormous loss of topsoil, so that the forests will only grow a few crops of trees
before the topsoil is exhausted. Governments must regulate forest lands in ways that
assure their sustainability far into the future. This obviously means an end
to clear-cutting.
Coppacing is a relatively common practice in European wood lots. Trees are hardly ever
cut down; instead, limbs are regularly cut from the trees, leaving the trunk and
root system intact. This allows the trees to quickly re-grow limbs from the trunk,
resulting in a high and sustainable yield of firewood. (The wood so produced is
not generally suitable for uses except as fuel.)
Tropical hardwoods
The hardwood rain forests are graced by some of the most magnificent trees ever
seen, and many of these species are nearly unique in their properties. The wood
is usually fine-grained, making it ideal for furniture. Most of it is highly
resistant to rot. It is usually free of knots and other defects and is available
in very large pieces when needed.
The cutting of rain forests is widely regarded as one of the most serious threats
to the maintenance of biodiversity. Some encouraging work has shown that,
to the indigenous people, the rain forest may actually be more valuable intact as a
producer of income than the timber prodced by cutting down the forest. The problem
is that to the governments concerned, the wood has immediate, high cash value.
Since most of the nations in question are starved for cash, there is a high incentive
to simply cut down the forests and sell the timber. Unfortunately, the rain forest
seems never to grow back because the soil composition is radically changed by cutting
down the forest, and practically nothing will grow in the brick-hard earth that
results. We simply must find ways to protect the remaining rain forests, perhaps
while continuing to remove selected mature trees, possibly by helicopter, to avoid
damaging the comparatively fagile ecosystems in which these trees grow.
Summary
In short, our forests have the potential to become a sustainable resource at
comparatively high levels, but clearly below the rate at which we are consuming
wood today.
Copyright © 2001 J. Crawford. This page may be freely
reproduced provided that J.H. Crawford is acknowledged as the author, his
copyright is maintained, and the full text is reproduced.
By publication of this work, J. Crawford places in the
public domain any original ideas contained in the work.
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