
Wood is a structural tissue/material found as xylem in the stems and roots of trees and other woody plants. It is an organic material – a natural composite of cellulosic fibers that are strong in tension and embedded in a matrix of lignin that resists compression. Wood is sometimes defined as only the secondary xylem in the stems of trees, or more broadly to include the same type of tissue elsewhere, such as in the roots of trees or shrubs. In a living tree, it performs a mechanical-support function, enabling woody plants to grow large or to stand up by themselves. It also conveys water and nutrients among the leaves, other growing tissues, and the roots. Wood may also refer to other plant materials with comparable properties, and to material engineered from wood, woodchips, or fibers.
Wood samples |
Wood has been used for thousands of years for fuel, as a construction material, for making tools and weapons, furniture and paper. More recently it emerged as a feedstock for the production of purified cellulose and its derivatives, such as cellophane and cellulose acetate.
As of 2020, the growing stock of forests worldwide was about 557 billion cubic meters. As an abundant, carbon-neutral renewable resource, woody materials have been of intense interest as a source of renewable energy. In 2008, approximately 3.97 billion cubic meters of wood were harvested. Dominant uses were for furniture and building construction.
Wood is scientifically studied and researched through the discipline of wood science, which was initiated since the beginning of the 20th century.
History
A 2011 discovery in the Canadian province of New Brunswick yielded the earliest known plants to have grown wood, approximately 395 to 400 million years ago.
Wood can be dated by carbon dating and in some species by dendrochronology to determine when a wooden object was created.
People have used wood for thousands of years for many purposes, including as a fuel or as a construction material for making houses, tools, weapons, furniture, packaging, artworks, and paper. Known constructions using wood date back ten thousand years. Buildings like the longhouses in Neolithic Europe were made primarily of wood.
Recent use of wood has been enhanced by the addition of steel and bronze into construction.
The year-to-year variation in tree-ring widths and isotopic abundances gives clues to the prevailing climate at the time a tree was cut.
Physical properties
Growth rings
Wood, in the strict sense, is yielded by trees, which increase in diameter by the formation, between the existing wood and the inner bark, of new woody layers which envelop the entire stem, living branches, and roots. This process is known as secondary growth; it is the result of cell division in the vascular cambium, a lateral meristem, and subsequent expansion of the new cells. These cells then go on to form thickened secondary cell walls, composed mainly of cellulose, hemicellulose and lignin.
Where the differences between the seasons are distinct, e.g. New Zealand, growth can occur in a discrete annual or seasonal pattern, leading to growth rings; these can usually be most clearly seen on the end of a log, but are also visible on the other surfaces. If the distinctiveness between seasons is annual (as is the case in equatorial regions, e.g. Singapore), these growth rings are referred to as annual rings. Where there is little seasonal difference growth rings are likely to be indistinct or absent. If the bark of the tree has been removed in a particular area, the rings will likely be deformed as the plant overgrows the scar.
If there are differences within a growth ring, then the part of a growth ring nearest the center of the tree, and formed early in the growing season when growth is rapid, is usually composed of wider elements. It is usually lighter in color than that near the outer portion of the ring, and is known as earlywood or springwood. The outer portion formed later in the season is then known as the latewood or summerwood. There are major differences, depending on the kind of wood. If a tree grows all its life in the open and the conditions of soil and site remain unchanged, it will make its most rapid growth in youth, and gradually decline. The annual rings of growth are for many years quite wide, but later they become narrower and narrower. Since each succeeding ring is laid down on the outside of the wood previously formed, it follows that unless a tree materially increases its production of wood from year to year, the rings must necessarily become thinner as the trunk gets wider. As a tree reaches maturity its crown becomes more open and the annual wood production is lessened, thereby reducing still more the width of the growth rings. In the case of forest-grown trees so much depends upon the competition of the trees in their struggle for light and nourishment that periods of rapid and slow growth may alternate. Some trees, such as southern oaks, maintain the same width of ring for hundreds of years. On the whole, as a tree gets larger in diameter the width of the growth rings decreases.
Knots
As a tree grows, lower branches often die, and their bases may become overgrown and enclosed by subsequent layers of trunk wood, forming a type of imperfection known as a knot. The dead branch may not be attached to the trunk wood except at its base and can drop out after the tree has been sawn into boards. Knots affect the technical properties of the wood, usually reducing tension strength, but may be exploited for visual effect. In a longitudinally sawn plank, a knot will appear as a roughly circular "solid" (usually darker) piece of wood around which the grain of the rest of the wood "flows" (parts and rejoins). Within a knot, the direction of the wood (grain direction) is up to 90 degrees different from the grain direction of the regular wood.
In the tree a knot is either the base of a side branch or a dormant bud. A knot (when the base of a side branch) is conical in shape (hence the roughly circular cross-section) with the inner tip at the point in stem diameter at which the plant's vascular cambium was located when the branch formed as a bud.
In grading lumber and structural timber, knots are classified according to their form, size, soundness, and the firmness with which they are held in place. This firmness is affected by, among other factors, the length of time for which the branch was dead while the attaching stem continued to grow.
Knots materially affect cracking and warping, ease in working, and cleavability of timber. They are defects which weaken timber and lower its value for structural purposes where strength is an important consideration. The weakening effect is much more serious when timber is subjected to forces perpendicular to the grain and/or tension than when under load along the grain and/or compression. The extent to which knots affect the strength of a beam depends upon their position, size, number, and condition. A knot on the upper side is compressed, while one on the lower side is subjected to tension. If there is a season check in the knot, as is often the case, it will offer little resistance to this tensile stress. Small knots may be located along the neutral plane of a beam and increase the strength by preventing longitudinal shearing. Knots in a board or plank are least injurious when they extend through it at right angles to its broadest surface. Knots which occur near the ends of a beam do not weaken it. Sound knots which occur in the central portion one-fourth the height of the beam from either edge are not serious defects.
— Samuel J. Record, The Mechanical Properties of Wood
Knots do not necessarily influence the stiffness of structural timber; this will depend on the size and location. Stiffness and elastic strength are more dependent upon the sound wood than upon localized defects. The breaking strength is very susceptible to defects. Sound knots do not weaken wood when subject to compression parallel to the grain.
In some decorative applications, wood with knots may be desirable to add visual interest. In applications where wood is painted, such as skirting boards, fascia boards, door frames and furniture, resins present in the timber may continue to 'bleed' through to the surface of a knot for months or even years after manufacture and show as a yellow or brownish stain. A knot primer paint or solution (knotting), correctly applied during preparation, may do much to reduce this problem but it is difficult to control completely, especially when using mass-produced kiln-dried timber stocks.
Heartwood and sapwood
Heartwood (or duramen) is wood that as a result of a naturally occurring chemical transformation has become more resistant to decay. Heartwood formation is a genetically programmed process that occurs spontaneously. Some uncertainty exists as to whether the wood dies during heartwood formation, as it can still chemically react to decay organisms, but only once.
The term heartwood derives solely from its position and not from any vital importance to the tree. This is evidenced by the fact that a tree can thrive with its heart completely decayed. Some species begin to form heartwood very early in life, so having only a thin layer of live sapwood, while in others the change comes slowly. Thin sapwood is characteristic of such species as chestnut, black locust, mulberry, osage-orange, and sassafras, while in maple, ash, hickory, hackberry, beech, and pine, thick sapwood is the rule. Some others never form heartwood.
Heartwood is often visually distinct from the living sapwood and can be distinguished in a cross-section where the boundary will tend to follow the growth rings. For example, it is sometimes much darker. Other processes such as decay or insect invasion can also discolor wood, even in woody plants that do not form heartwood, which may lead to confusion.
Sapwood (or alburnum) is the younger, outermost wood; in the growing tree it is living wood, and its principal functions are to conduct water from the roots to the leaves and to store up and give back according to the season the reserves prepared in the leaves. By the time they become competent to conduct water, all xylem tracheids and vessels have lost their cytoplasm and the cells are therefore functionally dead. All wood in a tree is first formed as sapwood. The more leaves a tree bears and the more vigorous its growth, the larger the volume of sapwood required. Hence trees making rapid growth in the open have thicker sapwood for their size than trees of the same species growing in dense forests. Sometimes trees (of species that do form heartwood) grown in the open may become of considerable size, 30 cm (12 in) or more in diameter, before any heartwood begins to form, for example, in second growth hickory, or open-grown pines.
No definite relation exists between the annual rings of growth and the amount of sapwood. Within the same species the cross-sectional area of the sapwood is very roughly proportional to the size of the crown of the tree. If the rings are narrow, more of them are required than where they are wide. As the tree gets larger, the sapwood must necessarily become thinner or increase materially in volume. Sapwood is relatively thicker in the upper portion of the trunk of a tree than near the base, because the age and the diameter of the upper sections are less.
When a tree is very young it is covered with limbs almost, if not entirely, to the ground, but as it grows older some or all of them will eventually die and are either broken off or fall off. Subsequent growth of wood may completely conceal the stubs which will remain as knots. No matter how smooth and clear a log is on the outside, it is more or less knotty near the middle. Consequently, the sapwood of an old tree, and particularly of a forest-grown tree, will be freer from knots than the inner heartwood. Since in most uses of wood, knots are defects that weaken the timber and interfere with its ease of working and other properties, it follows that a given piece of sapwood, because of its position in the tree, may well be stronger than a piece of heartwood from the same tree.
Different pieces of wood cut from a large tree may differ decidedly, particularly if the tree is big and mature. In some trees, the wood laid on late in the life of a tree is softer, lighter, weaker, and more even textured than that produced earlier, but in other trees, the reverse applies. This may or may not correspond to heartwood and sapwood. In a large log the sapwood, because of the time in the life of the tree when it was grown, may be inferior in hardness, strength, and toughness to equally sound heartwood from the same log. In a smaller tree, the reverse may be true.
Color
In species which show a distinct difference between heartwood and sapwood the natural color of heartwood is usually darker than that of the sapwood, and very frequently the contrast is conspicuous (see section of yew log above). This is produced by deposits in the heartwood of chemical substances, so that a dramatic color variation does not imply a significant difference in the mechanical properties of heartwood and sapwood, although there may be a marked biochemical difference between the two.
Some experiments on very resinous longleaf pine specimens indicate an increase in strength, due to the resin which increases the strength when dry. Such resin-saturated heartwood is called "fat lighter". Structures built of fat lighter are almost impervious to rot and termites, and very flammable. Tree stumps of old longleaf pines are often dug, split into small pieces and sold as kindling for fires. Stumps thus dug may actually remain a century or more since being cut. Spruce impregnated with crude resin and dried is also greatly increased in strength thereby.
Since the latewood of a growth ring is usually darker in color than the earlywood, this fact may be used in visually judging the density, and therefore the hardness and strength of the material. This is particularly the case with coniferous woods. In ring-porous woods the vessels of the early wood often appear on a finished surface as darker than the denser latewood, though on cross sections of heartwood the reverse is commonly true. Otherwise the color of wood is no indication of strength.
Abnormal discoloration of wood often denotes a diseased condition, indicating unsoundness. The black check in western hemlock is the result of insect attacks. The reddish-brown streaks so common in hickory and certain other woods are mostly the result of injury by birds. The discoloration is merely an indication of an injury, and in all probability does not of itself affect the properties of the wood. Certain rot-producing fungi impart to wood characteristic colors which thus become symptomatic of weakness. Ordinary sap-staining is due to fungal growth, but does not necessarily produce a weakening effect.
Water content
Water occurs in living wood in three locations, namely:
- in the cell walls
- in the protoplasmic contents of the cells
- as free water in the cell cavities and spaces, especially of the xylem
In heartwood it occurs only in the first and last forms. Wood that is thoroughly air-dried (in equilibrium with the moisture content of the air) retains 8–16% of the water in the cell walls, and none, or practically none, in the other forms. Even oven-dried wood retains a small percentage of moisture, but for all except chemical purposes, may be considered absolutely dry.
The general effect of the water content upon the wood substance is to render it softer and more pliable. A similar effect occurs in the softening action of water on rawhide, paper, or cloth. Within certain limits, the greater the water content, the greater its softening effect. The moisture in wood can be measured by several different moisture meters.
Drying produces a decided increase in the strength of wood, particularly in small specimens. An extreme example is the case of a completely dry spruce block 5 cm in section, which will sustain a permanent load four times as great as a green (undried) block of the same size will.
The greatest strength increase due to drying is in the ultimate crushing strength, and strength at elastic limit in endwise compression; these are followed by the modulus of rupture, and stress at elastic limit in cross-bending, while the modulus of elasticity is least affected.
Structure
Wood is a heterogeneous, hygroscopic, cellular and anisotropic (or more specifically, orthotropic) material. It consists of cells, and the cell walls are composed of micro-fibrils of cellulose (40–50%) and hemicellulose (15–25%) impregnated with lignin (15–30%).
In coniferous or softwood species the wood cells are mostly of one kind, tracheids, and as a result the material is much more uniform in structure than that of most hardwoods. There are no vessels ("pores") in coniferous wood such as one sees so prominently in oak and ash, for example.
The structure of hardwoods is more complex. The water conducting capability is mostly taken care of by vessels: in some cases (oak, chestnut, ash) these are quite large and distinct, in others (buckeye, poplar, willow) too small to be seen without a hand lens. In discussing such woods it is customary to divide them into two large classes, ring-porous and diffuse-porous.
In ring-porous species, such as ash, black locust, catalpa, chestnut, elm, hickory, mulberry, and oak, the larger vessels or pores (as cross sections of vessels are called) are localized in the part of the growth ring formed in spring, thus forming a region of more or less open and porous tissue. The rest of the ring, produced in summer, is made up of smaller vessels and a much greater proportion of wood fibers. These fibers are the elements which give strength and toughness to wood, while the vessels are a source of weakness.
In diffuse-porous woods the pores are evenly sized so that the water conducting capability is scattered throughout the growth ring instead of being collected in a band or row. Examples of this kind of wood are alder,basswood,birch, buckeye, maple, willow, and the Populus species such as aspen, cottonwood and poplar. Some species, such as walnut and cherry, are on the border between the two classes, forming an intermediate group.
Earlywood and latewood
In softwood
In temperate softwoods, there often is a marked difference between latewood and earlywood. The latewood will be denser than that formed early in the season. When examined under a microscope, the cells of dense latewood are seen to be very thick-walled and with very small cell cavities, while those formed first in the season have thin walls and large cell cavities. The strength is in the walls, not the cavities. Hence the greater the proportion of latewood, the greater the density and strength. In choosing a piece of pine where strength or stiffness is the important consideration, the principal thing to observe is the comparative amounts of earlywood and latewood. The width of ring is not nearly so important as the proportion and nature of the latewood in the ring.
If a heavy piece of pine is compared with a lightweight piece it will be seen at once that the heavier one contains a larger proportion of latewood than the other, and is therefore showing more clearly demarcated growth rings. In white pines there is not much contrast between the different parts of the ring, and as a result the wood is very uniform in texture and is easy to work. In hard pines, on the other hand, the latewood is very dense and is deep-colored, presenting a very decided contrast to the soft, straw-colored earlywood.
It is not only the proportion of latewood, but also its quality, that counts. In specimens that show a very large proportion of latewood it may be noticeably more porous and weigh considerably less than the latewood in pieces that contain less latewood. One can judge comparative density, and therefore to some extent strength, by visual inspection.
No satisfactory explanation can as yet be given for the exact mechanisms determining the formation of earlywood and latewood. Several factors may be involved. In conifers, at least, rate of growth alone does not determine the proportion of the two portions of the ring, for in some cases the wood of slow growth is very hard and heavy, while in others the opposite is true. The quality of the site where the tree grows undoubtedly affects the character of the wood formed, though it is not possible to formulate a rule governing it. In general, where strength or ease of working is essential, woods of moderate to slow growth should be chosen.
In ring-porous woods
In ring-porous woods, each season's growth is always well defined, because the large pores formed early in the season abut on the denser tissue of the year before.
In the case of the ring-porous hardwoods, there seems to exist a pretty definite relation between the rate of growth of timber and its properties. This may be briefly summed up in the general statement that the more rapid the growth or the wider the rings of growth, the heavier, harder, stronger, and stiffer the wood. This, it must be remembered, applies only to ring-porous woods such as oak, ash, hickory, and others of the same group, and is, of course, subject to some exceptions and limitations.
In ring-porous woods of good growth, it is usually the latewood in which the thick-walled, strength-giving fibers are most abundant. As the breadth of ring diminishes, this latewood is reduced so that very slow growth produces comparatively light, porous wood composed of thin-walled vessels and wood parenchyma. In good oak, these large vessels of the earlywood occupy from six to ten percent of the volume of the log, while in inferior material they may make up 25% or more. The latewood of good oak is dark colored and firm, and consists mostly of thick-walled fibers which form one-half or more of the wood. In inferior oak, this latewood is much reduced both in quantity and quality. Such variation is very largely the result of rate of growth.
Wide-ringed wood is often called "second-growth", because the growth of the young timber in open stands after the old trees have been removed is more rapid than in trees in a closed forest, and in the manufacture of articles where strength is an important consideration such "second-growth" hardwood material is preferred. This is particularly the case in the choice of hickory for handles and spokes. Here not only strength, but toughness and resilience are important.
The results of a series of tests on hickory by the U.S. Forest Service show that:
- "The work or shock-resisting ability is greatest in wide-ringed wood that has from 5 to 14 rings per inch (rings 1.8-5 mm thick), is fairly constant from 14 to 38 rings per inch (rings 0.7–1.8 mm thick), and decreases rapidly from 38 to 47 rings per inch (rings 0.5–0.7 mm thick). The strength at maximum load is not so great with the most rapid-growing wood; it is maximum with from 14 to 20 rings per inch (rings 1.3–1.8 mm thick), and again becomes less as the wood becomes more closely ringed. The natural deduction is that wood of first-class mechanical value shows from 5 to 20 rings per inch (rings 1.3–5 mm thick) and that slower growth yields poorer stock. Thus the inspector or buyer of hickory should discriminate against timber that has more than 20 rings per inch (rings less than 1.3 mm thick). Exceptions exist, however, in the case of normal growth upon dry situations, in which the slow-growing material may be strong and tough."
The effect of rate of growth on the qualities of chestnut wood is summarized by the same authority as follows:
- "When the rings are wide, the transition from spring wood to summer wood is gradual, while in the narrow rings the spring wood passes into summer wood abruptly. The width of the spring wood changes but little with the width of the annual ring, so that the narrowing or broadening of the annual ring is always at the expense of the summer wood. The narrow vessels of the summer wood make it richer in wood substance than the spring wood composed of wide vessels. Therefore, rapid-growing specimens with wide rings have more wood substance than slow-growing trees with narrow rings. Since the more the wood substance the greater the weight, and the greater the weight the stronger the wood, chestnuts with wide rings must have stronger wood than chestnuts with narrow rings. This agrees with the accepted view that sprouts (which always have wide rings) yield better and stronger wood than seedling chestnuts, which grow more slowly in diameter."
In diffuse-porous woods
In the diffuse-porous woods, the demarcation between rings is not always so clear and in some cases is almost (if not entirely) invisible to the unaided eye. Conversely, when there is a clear demarcation there may not be a noticeable difference in structure within the growth ring.
In diffuse-porous woods, as has been stated, the vessels or pores are even-sized, so that the water conducting capability is scattered throughout the ring instead of collected in the earlywood. The effect of rate of growth is, therefore, not the same as in the ring-porous woods, approaching more nearly the conditions in the conifers. In general, it may be stated that such woods of medium growth afford stronger material than when very rapidly or very slowly grown. In many uses of wood, total strength is not the main consideration. If ease of working is prized, wood should be chosen with regard to its uniformity of texture and straightness of grain, which will in most cases occur when there is little contrast between the latewood of one season's growth and the earlywood of the next.
Monocots
Structural material that resembles ordinary, "dicot" or conifer timber in its gross handling characteristics is produced by a number of monocot plants, and these also are colloquially called wood. Of these, bamboo, botanically a member of the grass family, has considerable economic importance, larger culms being widely used as a building and construction material and in the manufacture of engineered flooring, panels and veneer. Another major plant group that produces material that often is called wood are the palms. Of much less importance are plants such as Pandanus, Dracaena and Cordyline. With all this material, the structure and composition of the processed raw material is quite different from ordinary wood.
Specific gravity
The single most revealing property of wood as an indicator of wood quality is specific gravity (Timell 1986), as both pulp yield and lumber strength are determined by it. Specific gravity is the ratio of the mass of a substance to the mass of an equal volume of water; density is the ratio of a mass of a quantity of a substance to the volume of that quantity and is expressed in mass per unit substance, e.g., grams per milliliter (g/cm3 or g/ml). The terms are essentially equivalent as long as the metric system is used. Upon drying, wood shrinks and its density increases. Minimum values are associated with green (water-saturated) wood and are referred to as basic specific gravity (Timell 1986).
The U.S. Forest Products Laboratory lists a variety of ways to define specific gravity (G) and density (ρ) for wood:
Symbol | Mass basis | Volume basis |
---|---|---|
G0 | Ovendry | Ovendry |
Gb (basic) | Ovendry | Green |
G12 | Ovendry | 12% MC |
Gx | Ovendry | x% MC |
ρ0 | Ovendry | Ovendry |
ρ12 | 12% MC | 12% MC |
ρx | x% MC | x% MC |
The FPL has adopted Gb and G12 for specific gravity, in accordance with the ASTM D2555 standard. These are scientifically useful, but don't represent any condition that could physically occur. The FPL Wood Handbook also provides formulas for approximately converting any of these measurements to any other.
Density
Wood density is determined by multiple growth and physiological factors compounded into "one fairly easily measured wood characteristic" (Elliott 1970).
Age, diameter, height, radial (trunk) growth, geographical location, site and growing conditions, silvicultural treatment, and seed source all to some degree influence wood density. Variation is to be expected. Within an individual tree, the variation in wood density is often as great as or even greater than that between different trees (Timell 1986). Variation of specific gravity within the bole of a tree can occur in either the horizontal or vertical direction.
Because the specific gravity as defined above uses an unrealistic condition, woodworkers tend to use the "average dried weight", which is a density based on mass at 12% moisture content and volume at the same (ρ12). This condition occurs when the wood is at equilibrium moisture content with air at about 65% relative humidity and temperature at 30 °C (86 °F). This density is expressed in units of kg/m3 or lbs/ft3.
Tables
The following tables list the mechanical properties of wood and lumber plant species, including bamboo. See also Mechanical properties of tonewoods for additional properties.
Wood properties:
Common name | Scientific name | Moisture content | Density (kg/m3) | Compressive strength (megapascals) | Flexural strength (megapascals) |
---|---|---|---|---|---|
Red Alder | Alnus rubra | Green | 370 | 20.4 | 45 |
Red Alder | Alnus rubra | 12.00% | 410 | 40.1 | 68 |
Black Ash | Fraxinus nigra | Green | 450 | 15.9 | 41 |
Black Ash | Fraxinus nigra | 12.00% | 490 | 41.2 | 87 |
Blue Ash | Fraxinus quadrangulata | Green | 530 | 24.8 | 66 |
Blue Ash | Fraxinus quadrangulata | 12.00% | 580 | 48.1 | 95 |
Green Ash | Fraxinus pennsylvanica | Green | 530 | 29 | 66 |
Green Ash | Fraxinus pennsylvanica | 12.00% | 560 | 48.8 | 97 |
Oregon Ash | Fraxinus latifolia | Green | 500 | 24.2 | 52 |
Oregon Ash | Fraxinus latifolia | 12.00% | 550 | 41.6 | 88 |
White Ash | Fraxinus americana | Green | 550 | 27.5 | 66 |
White Ash | Fraxinus americana | 12.00% | 600 | 51.1 | 103 |
Bigtooth Aspen | Populus grandidentata | Green | 360 | 17.2 | 37 |
Bigtooth Aspen | Populus grandidentata | 12.00% | 390 | 36.5 | 63 |
Quaking Aspen | Populus tremuloides | Green | 350 | 14.8 | 35 |
Quaking Aspen | Populus tremuloides | 12.00% | 380 | 29.3 | 58 |
American Basswood | Tilia americana | Green | 320 | 15.3 | 34 |
American Basswood | Tilia americana | 12.00% | 370 | 32.6 | 60 |
American Beech | Fagus grandifolia | Green | 560 | 24.5 | 59 |
American Beech | Fagus grandifolia | 12.00% | 640 | 50.3 | 103 |
Paper Birch | Betula papyrifera | Green | 480 | 16.3 | 44 |
Paper Birch | Betula papyrifera | 12.00% | 550 | 39.2 | 85 |
Sweet Birch | Betula lenta | Green | 600 | 25.8 | 65 |
Sweet Birch | Betula lenta | 12.00% | 650 | 58.9 | 117 |
Yellow Birch | Betula alleghaniensis | Green | 550 | 23.3 | 57 |
Yellow Birch | Betula alleghaniensis | 12.00% | 620 | 56.3 | 114 |
Butternut | Juglans cinerea | Green | 360 | 16.7 | 37 |
Butternut | Juglans cinerea | 12.00% | 380 | 36.2 | 56 |
Black Cherry | Prunus serotina | Green | 470 | 24.4 | 55 |
Blach Cherry | Prunus serotina | 12.00% | 500 | 49 | 85 |
American Chestnut | Castanea dentata | Green | 400 | 17 | 39 |
American Chestnut | Castanea dentata | 12.00% | 430 | 36.7 | 59 |
Balsam Poplar Cottonwood | Populus balsamifera | Green | 310 | 11.7 | 27 |
Balsam Poplar Cottonwood | Populus balsamifera | 12.00% | 340 | 27.7 | 47 |
Black Cottonwood | Populus trichocarpa | Green | 310 | 15.2 | 34 |
Black Cottonwood | Populus trichocarpa | 12.00% | 350 | 31 | 59 |
Eastern Cottonwood | Populus deltoides | Green | 370 | 15.7 | 37 |
Eastern Cottonwood | Populus deltoides | 12.00% | 400 | 33.9 | 59 |
American Elm | Ulmus americana | Green | 460 | 20.1 | 50 |
American Elm | Ulmus americana | 12.00% | 500 | 38.1 | 81 |
Rock Elm | Ulmus thomasii | Green | 570 | 26.1 | 66 |
Rock Elm | Ulmus thomasii | 12.00% | 630 | 48.6 | 102 |
Slippery Elm | Ulmus rubra | Green | 480 | 22.9 | 55 |
Slippery Elm | Ulmus rubra | 12.00% | 530 | 43.9 | 90 |
Hackberry | Celtis occidentalis | Green | 490 | 18.3 | 45 |
Hackberry | Celtis occidentalis | 12.00% | 530 | 37.5 | 76 |
Bitternut Hickory | Carya cordiformis | Green | 600 | 31.5 | 71 |
Bitternut Hickory | Carya cordiformis | 12.00% | 660 | 62.3 | 118 |
Nutmeg Hickory | Carya myristiciformis | Green | 560 | 27.4 | 63 |
Nutmeg Hickory | Carya myristiciformis | 12.00% | 600 | 47.6 | 114 |
Pecan Hickory | Carya illinoinensis | Green | 600 | 27.5 | 68 |
Pecan Hickory | Carya illinoinensis | 12.00% | 660 | 54.1 | 94 |
Water Hickory | Carya aquatica | Green | 610 | 32.1 | 74 |
Water Hickory | Carya aquatica | 12.00% | 620 | 59.3 | 123 |
Mockernut Hickory | Carya tomentosa | Green | 640 | 30.9 | 77 |
Mockernut Hickory | Carya tomentosa | 12.00% | 720 | 61.6 | 132 |
Pignut Hickory | Carya glabra | Green | 660 | 33.2 | 81 |
Pignut Hickory | Carya glabra | 12.00% | 750 | 63.4 | 139 |
Shagbark Hickory | Carya ovata | Green | 640 | 31.6 | 76 |
Shagbark Hickory | Carya ovata | 12.00% | 720 | 63.5 | 139 |
Shellbark Hickory | Carya laciniosa | Green | 620 | 27 | 72 |
Shellbark Hickory | Carya laciniosa | 12.00% | 690 | 55.2 | 125 |
Honeylocust | Gleditsia triacanthos | Green | 600 | 30.5 | 70 |
Honeylocust | Gleditsia triacanthos | 12.00% | 600 | 51.7 | 101 |
Black Locust | Robinia pseudoacacia | Green | 660 | 46.9 | 95 |
Black Locust | Robinia pseudoacacia | 12.00% | 690 | 70.2 | 134 |
Cucumber Tree Magnolia | Magnolia acuminata | Green | 440 | 21.6 | 51 |
Cucumber Tree Magnolia | Magnolia acuminata | 12.00% | 480 | 43.5 | 85 |
Southern Magnolia | Magnolia grandiflora | Green | 460 | 18.6 | 47 |
Southern Magnolia | Magnolia grandiflora | 12.00% | 500 | 37.6 | 77 |
Bigleaf Maple | Acer macrophyllum | Green | 440 | 22.3 | 51 |
Bigleaf Maple | Acer macrophyllum | 12.00% | 480 | 41 | 74 |
Black Maple | Acer nigrum | Green | 520 | 22.5 | 54 |
Black Maple | Acer nigrum | 12.00% | 570 | 46.1 | 92 |
Red Maple | Acer rubrum | Green | 490 | 22.6 | 53 |
Red Maple | Acer rubrum | 12.00% | 540 | 45.1 | 92 |
Silver Maple | Acer saccharinum | Green | 440 | 17.2 | 40 |
Silver Maple | Acer saccharinum | 12.00% | 470 | 36 | 61 |
Sugar Maple | Acer saccharum | Green | 560 | 27.7 | 65 |
Sugar Maple | Acer saccharum | 12.00% | 630 | 54 | 109 |
Black Red Oak | Quercus velutina | Green | 560 | 23.9 | 57 |
Black Red Oak | Quercus velutina | 12.00% | 610 | 45 | 96 |
Cherrybark Red Oak | Quercus pagoda | Green | 610 | 31.9 | 74 |
Cherrybark Red Oak | Quercus pagoda | 12.00% | 680 | 60.3 | 125 |
Laurel Red Oak | Quercus hemisphaerica | Green | 560 | 21.9 | 54 |
Laurel Red Oak | Quercus hemisphaerica | 12.00% | 630 | 48.1 | 87 |
Northern Red Oak | Quercus rubra | Green | 560 | 23.7 | 57 |
Northern Red Oak | Quercus rubra | 12.00% | 630 | 46.6 | 99 |
Pin Red Oak | Quercus palustris | Green | 580 | 25.4 | 57 |
Pin Red Oak | Quercus palustris | 12.00% | 630 | 47 | 97 |
Scarlet Red Oak | Quercus coccinea | Green | 600 | 28.2 | 72 |
Scarlet Red Oak | Quercus coccinea | 12.00% | 670 | 57.4 | 120 |
Southern Red Oak | Quercus falcata | Green | 520 | 20.9 | 48 |
Southern Red Oak | Quercus falcata | 12.00% | 590 | 42 | 75 |
Water Red Oak | Quercus nigra | Green | 560 | 25.8 | 61 |
Water Red Oak | Quercus nigra | 12.00% | 630 | 46.7 | 106 |
Willow Red Oak | Quercus phellos | Green | 560 | 20.7 | 51 |
Willow Red Oak | Quercus phellos | 12.00% | 690 | 48.5 | 100 |
Bur White Oak | Quercus macrocarpa | Green | 580 | 22.7 | 50 |
Bur White Oak | Quercus macrocarpa | 12.00% | 640 | 41.8 | 71 |
Chestnut White Oak | Quercus montana | Green | 570 | 24.3 | 55 |
Chestnut White Oak | Quercus montana | 12.00% | 660 | 47.1 | 92 |
Live White Oak | Quercus virginiana | Green | 800 | 37.4 | 82 |
Live White Oak | Quercus virginiana | 12.00% | 880 | 61.4 | 127 |
Overcup White Oak | Quercus lyrata | Green | 570 | 23.2 | 55 |
Overcup White Oak | Quercus lyrata | 12.00% | 630 | 42.7 | 87 |
Post White Oak | Quercus stellata | Green | 600 | 24 | 56 |
Post White Oak | Quercus stellata | 12.00% | 670 | 45.3 | 91 |
Swamp Chestnut White Oak | Quercus michauxii | Green | 600 | 24.4 | 59 |
Swamp Chestnut White Oak | Quercus michauxii | 12.00% | 670 | 50.1 | 96 |
Swamp White Oak | Quercus bicolor | Green | 640 | 30.1 | 68 |
Swamp White Oak | Quercus bicolor | 12.00% | 720 | 59.3 | 122 |
White Oak | Quercus alba | Green | 600 | 24.5 | 57 |
White Oak | Quercus alba | 12.00% | 680 | 51.3 | 105 |
Sassafras | Sassafras albidum | Green | 420 | 18.8 | 41 |
Sassafras | Sassafras albidum | 12.00% | 460 | 32.8 | 62 |
Sweetgum | Liquidambar styraciflua | Green | 460 | 21 | 49 |
Sweetgum | Liquidambar styraciflua | 12.00% | 520 | 43.6 | 86 |
American Sycamore | Platanus occidentalis | Green | 460 | 20.1 | 45 |
American Sycamore | Platanus occidentalis | 12.00% | 490 | 37.1 | 69 |
Tanoak | Notholithocarpus densiflorus | Green | 580 | 32.1 | 72 |
Tanoak | Notholithocarpus densiflorus | 12.00% | 580 | 32.1 | 72 |
Black Tupelo | Nyssa sylvatica | Green | 460 | 21 | 48 |
Black Tupelo | Nyssa sylvatica | 12.00% | 500 | 38.1 | 66 |
Water Tupelo | Nyssa aquatica | Green | 460 | 23.2 | 50 |
Water Tupelo | Nyssa aquatica | 12.00% | 500 | 40.8 | 66 |
Black Walnut | Juglans nigra | Green | 510 | 29.6 | 66 |
Black Walnut | Juglans nigra | 12.00% | 550 | 52.3 | 101 |
Black Willow | Salix nigra | Green | 360 | 14.1 | 33 |
Black Willow | Salix nigra | 12.00% | 390 | 28.3 | 54 |
Yellow Poplar | Liriodendron tulipifera | Green | 400 | 18.3 | 41 |
Yellow Poplar | Liriodendron tulipifera | 12.00% | 420 | 38.2 | 70 |
Baldcypress | Taxodium distichum | Green | 420 | 24.7 | 46 |
Baldcypress | Taxodium distichum | 12.00% | 460 | 43.9 | 73 |
Atlantic White Cedar | Chamaecyparis thyoides | Green | 310 | 16.5 | 32 |
Atlantic White Cedar | Chamaecyparis thyoides | 12.00% | 320 | 32.4 | 47 |
Eastern Redcedar | Juniperus virginiana | Green | 440 | 24.6 | 48 |
Eastern Redcedar | Juniperus virginiana | 12.00% | 470 | 41.5 | 61 |
Incense Cedar | Calocedrus decurrens | Green | 350 | 21.7 | 43 |
Incense Cedar | Calocedrus decurrens | 12.00% | 370 | 35.9 | 55 |
Northern White Cedar | Thuja occidentalis | Green | 290 | 13.7 | 29 |
Northern White Cedar | Thuja occidentalis | 12.00% | 310 | 27.3 | 45 |
Port Orford Cedar | Chamaecyparis lawsoniana | Green | 390 | 21.6 | 45 |
Port Orford Cedar | Chamaecyparis lawsoniana | 12.00% | 430 | 43.1 | 88 |
Western Redcedar | Thuja plicata | Green | 310 | 19.1 | 35.9 |
Western Redcedar | Thuja plicata | 12.00% | 320 | 31.4 | 51.7 |
Yellow Cedar | Cupressus nootkatensis | Green | 420 | 21 | 44 |
Yellow Cedar | Cupressus nootkatensis | 12.00% | 440 | 43.5 | 77 |
Coast Douglas Fir | Pseudotsuga menziesii var. menziesii | Green | 450 | 26.1 | 53 |
Coast Douglas Fir | Pseudotsuga menziesii var. menziesii | 12.00% | 480 | 49.9 | 85 |
Interior West Douglas Fir | Pseudotsuga Menziesii | Green | 460 | 26.7 | 53 |
Interior West Douglas Fir | Pseudotsuga Menziesii | 12.00% | 500 | 51.2 | 87 |
Interior North Douglas Fir | Pseudotsuga menziesii var. glauca | Green | 450 | 23.9 | 51 |
Interior North Douglas Fir | Pseudotsuga menziesii var. glauca | 12.00% | 480 | 47.6 | 90 |
Interior South Douglas Fir | Pseudotsuga lindleyana | Green | 430 | 21.4 | 47 |
Interior South Douglas Fir | Pseudotsuga lindleyana | 12.00% | 460 | 43 | 82 |
Balsam Fir | Abies balsamea | Green | 330 | 18.1 | 38 |
Balsam Fir | Abies balsamea | 12.00% | 350 | 36.4 | 63 |
California Red Fir | Abies magnifica | Green | 360 | 19 | 40 |
California Red Fir | Abies magnifica | 12.00% | 380 | 37.6 | 72.4 |
Grand Fir | Abies grandis | Green | 350 | 20.3 | 40 |
Grand Fir | Abies grandis | 12.00% | 370 | 36.5 | 61.4 |
Noble Fir | Abies procera | Green | 370 | 20.8 | 43 |
Noble Fir | Abies procera | 12.00% | 390 | 42.1 | 74 |
Pacific Silver Fir | Abies amabilis | Green | 400 | 21.6 | 44 |
Pacific Silver Fir | Abies amabilis | 12.00% | 430 | 44.2 | 75 |
Subalpine Fir | Abies lasiocarpa | Green | 310 | 15.9 | 34 |
Subalpine Fir | Abies lasiocarpa | 12.00% | 320 | 33.5 | 59 |
White Fir | Abies concolor | Green | 370 | 20 | 41 |
White Fir | Abies concolor | 12.00% | 390 | 40 | 68 |
Eastern Hemlock | Tsuga canadensis | Green | 380 | 21.2 | 44 |
Eastern Hemlock | Tsuga canadensis | 12.00% | 400 | 37.3 | 61 |
Mountain Hemlock | Tsuga mertensiana | Green | 420 | 19.9 | 43 |
Mountain Hemlock | Tsuga mertensiana | 12.00% | 450 | 44.4 | 79 |
Western Hemlock | Tsuga heterophylla | Green | 420 | 23.2 | 46 |
Western Hemlock | Tsuga heterophylla | 12.00% | 450 | 49 | 78 |
Western Larch | Larix occidentalis | Green | 480 | 25.9 | 53 |
Western Larch | Larix occidentalis | 12.00% | 520 | 52.5 | 90 |
Eastern White Pine | Pinus strobus | Green | 340 | 16.8 | 34 |
Eastern White Pine | Pinus strobus | 12.00% | 350 | 33.1 | 59 |
Jack Pine | Pinus banksiana | Green | 400 | 20.3 | 41 |
Jack Pine | Pinus banksiana | 12.00% | 430 | 39 | 68 |
Loblolly Pine | Pinus taeda | Green | 470 | 24.2 | 50 |
Loblolly Pine | Pinus taeda | 12.00% | 510 | 49.2 | 88 |
Lodgepole Pine | Pinus contorta | Green | 380 | 18 | 38 |
Lodgepole Pine | Pinus contorta | 12.00% | 410 | 37 | 65 |
Longleaf Pine | Pinus palustris | Green | 540 | 29.8 | 59 |
Longleaf Pine | Pinus palustris | 12.00% | 590 | 58.4 | 100 |
Pitch Pine | Pinus rigida | Green | 470 | 20.3 | 47 |
Pitch Pine | Pinus rigida | 12.00% | 520 | 41 | 74 |
Pond Pine | Pinus serotina | Green | 510 | 25.2 | 51 |
Pond Pine | Pinus serotina | 12.00% | 560 | 52 | 80 |
Ponderosa Pine | Pinus ponderosa | Green | 380 | 16.9 | 35 |
Ponderosa Pine | Pinus ponderosa | 12.00% | 400 | 36.7 | 65 |
Red Pine | Pinus resinosa | Green | 410 | 18.8 | 40 |
Red Pine | Pinus resinosa | 12.00% | 460 | 41.9 | 76 |
Sand Pine | Pinus clausa | Green | 460 | 23.7 | 52 |
Sand Pine | Pinus clausa | 12.00% | 480 | 47.7 | 80 |
Shortleaf Pine | Pinus echinata | Green | 470 | 24.3 | 51 |
Shortleaf Pine | Pinus echinata | 12.00% | 510 | 50.1 | 90 |
Slash Pine | Pinus elliottii | Green | 540 | 26.3 | 60 |
Slash Pine | Pinus elliottii | 12.00% | 590 | 56.1 | 112 |
Spruce Pine | Pinus glabra | Green | 410 | 19.6 | 41 |
Spruce Pine | Pinus glabra | 12.00% | 440 | 39 | 72 |
Sugar Pine | Pinus lambertiana | Green | 340 | 17 | 34 |
Sugar Pine | Pinus lambertiana | 12.00% | 360 | 30.8 | 57 |
Virginia Pine | Pinus virginiana | Green | 450 | 23.6 | 50 |
Virginia Pine | Pinus virginiana | 12.00% | 480 | 46.3 | 90 |
Western White Pine | Pinus monticola | Green | 360 | 16.8 | 32 |
Western White Pine | Pinus monticola | 12.00% | 380 | 34.7 | 67 |
Redwood Old Growth | Sequoia sempervirens | Green | 380 | 29 | 52 |
Redwood Old Growth | Sequoia sempervirens | 12.00% | 400 | 42.4 | 69 |
Redwood New Growth | Sequoia sempervirens | Green | 340 | 21.4 | 41 |
Redwood New Growth | Sequoia sempervirens | 12.00% | 350 | 36 | 54 |
Black Spruce | Picea mariana | Green | 380 | 19.6 | 42 |
Black Spruce | Picea mariana | 12.00% | 460 | 41.1 | 74 |
Engelmann Spruce | Picea engelmannii | Green | 330 | 15 | 32 |
Engelmann Spruce | Picea engelmannii | 12.00% | 350 | 30.9 | 64 |
Red Spruce | Picea rubens | Green | 370 | 18.8 | 41 |
Red Spruce | Picea rubens | 12.00% | 400 | 38.2 | 74 |
Sitka Spruce | Picea sitchensis | Green | 330 | 16.2 | 34 |
Sitka Spruce | Picea sitchensis | 12.00% | 360 | 35.7 | 65 |
White Spruce | Picea glauca | Green | 370 | 17.7 | 39 |
White Spruce | Picea glauca | 12.00% | 400 | 37.7 | 68 |
Tamarack Spruce | Larix laricina | Green | 490 | 24 | 50 |
Tamarack Spruce | Larix laricina | 12.00% | 530 | 49.4 | 80 |
Bamboo properties:
Common name | Scientific name | Moisture content | Density (kg/m3) | Compressive strength (megapascals) | Flexural strength (megapascals) |
---|---|---|---|---|---|
Balku bans | Bambusa balcooa | green | 45 | 73.7 | |
Balku bans | Bambusa balcooa | air dry | 54.15 | 81.1 | |
Balku bans | Bambusa balcooa | 8.5 | 820 | 69 | 151 |
Indian thorny bamboo | Bambusa bambos | 9.5 | 710 | 61 | 143 |
Indian thorny bamboo | Bambusa bambos | 43.05 | 37.15 | ||
Nodding Bamboo | 8 | 890 | 75 | 52.9 | |
Nodding Bamboo | 87 | 46 | 52.4 | ||
Nodding Bamboo | 12 | 85 | 67.5 | ||
Nodding Bamboo | 88.3 | 44.7 | 88 | ||
Nodding Bamboo | 14 | 47.9 | 216 | ||
Clumping Bamboo | 45.8 | ||||
Clumping Bamboo | 5 | 79 | 80 | ||
Clumping Bamboo | 20 | 35 | 37 | ||
Burmese bamboo | Bambusa polymorpha | 95.1 | 32.1 | 28.3 | |
Bambusa spinosa | air dry | 57 | 51.77 | ||
Indian timber bamboo | Bambusa tulda | 73.6 | 40.7 | 51.1 | |
Indian timber bamboo | Bambusa tulda | 11.9 | 68 | 66.7 | |
Indian timber bamboo | Bambusa tulda | 8.6 | 910 | 79 | 194 |
dragon bamboo | Dendrocalamus giganteus | 8 | 740 | 70 | 193 |
Hamilton's bamboo | Dendrocalamus hamiltonii | 8.5 | 590 | 70 | 89 |
White bamboo | 102 | 40.5 | 26.3 | ||
String Bamboo | 54.3 | 24.1 | 102 | ||
String Bamboo | 15.1 | 37.95 | 87.5 | ||
Java Black Bamboo | Gigantochloa atroviolacea | 54 | 23.8 | 92.3 | |
Java Black Bamboo | Gigantochloa atroviolacea | 15 | 35.7 | 94.1 | |
Giant Atter | Gigantochloa atter | 72.3 | 26.4 | 98 | |
Giant Atter | Gigantochloa atter | 14.4 | 31.95 | 122.7 | |
8 | 960 | 71 | 154 | ||
American Narrow-Leaved Bamboo | Guadua angustifolia | 42 | 53.5 | ||
American Narrow-Leaved Bamboo | Guadua angustifolia | 63.6 | 144.8 | ||
American Narrow-Leaved Bamboo | Guadua angustifolia | 86.3 | 46 | ||
American Narrow-Leaved Bamboo | Guadua angustifolia | 77.5 | 82 | ||
American Narrow-Leaved Bamboo | Guadua angustifolia | 15 | 56 | 87 | |
American Narrow-Leaved Bamboo | Guadua angustifolia | 63.3 | |||
American Narrow-Leaved Bamboo | Guadua angustifolia | 28 | |||
American Narrow-Leaved Bamboo | Guadua angustifolia | 56.2 | |||
American Narrow-Leaved Bamboo | Guadua angustifolia | 38 | |||
Berry Bamboo | Melocanna baccifera | 12.8 | 69.9 | 57.6 | |
Japanese timber bamboo | Phyllostachys bambusoides | 51 | |||
Japanese timber bamboo | Phyllostachys bambusoides | 8 | 730 | 63 | |
Japanese timber bamboo | Phyllostachys bambusoides | 64 | 44 | ||
Japanese timber bamboo | Phyllostachys bambusoides | 61 | 40 | ||
Japanese timber bamboo | Phyllostachys bambusoides | 9 | 71 | ||
Japanese timber bamboo | Phyllostachys bambusoides | 9 | 74 | ||
Japanese timber bamboo | Phyllostachys bambusoides | 12 | 54 | ||
Tortoise shell bamboo | Phyllostachys edulis | 44.6 | |||
Tortoise shell bamboo | Phyllostachys edulis | 75 | 67 | ||
Tortoise shell bamboo | Phyllostachys edulis | 15 | 71 | ||
Tortoise shell bamboo | Phyllostachys edulis | 6 | 108 | ||
Tortoise shell bamboo | Phyllostachys edulis | 0.2 | 147 | ||
Tortoise shell bamboo | Phyllostachys edulis | 5 | 117 | 51 | |
Tortoise shell bamboo | Phyllostachys edulis | 30 | 44 | 55 | |
Tortoise shell bamboo | Phyllostachys edulis | 12.5 | 603 | 60.3 | |
Tortoise shell bamboo | Phyllostachys edulis | 10.3 | 530 | 83 | |
Early Bamboo | 28.5 | 827 | 79.3 | ||
Oliveri | 53 | 46.9 | 61.9 | ||
Oliveri | 7.8 | 58 | 90 |
Hard versus soft
It is common to classify wood as either softwood or hardwood. The wood from conifers (e.g. pine) is called softwood, and the wood from dicotyledons (usually broad-leaved trees, e.g. oak) is called hardwood. These names are a bit misleading, as hardwoods are not necessarily hard, and softwoods are not necessarily soft. The well-known balsa (a hardwood) is actually softer than any commercial softwood. Conversely, some softwoods (e.g. yew) are harder than many hardwoods.
There is a strong relationship between the properties of wood and the properties of the particular tree that yielded it, at least for certain species. For example, in loblolly pine, wind exposure and stem position greatly affect the hardness of wood, as well as compression wood content. The density of wood varies with species. The density of a wood correlates with its strength (mechanical properties). For example, mahogany is a medium-dense hardwood that is excellent for fine furniture crafting, whereas balsa is light, making it useful for model building. One of the densest woods is black ironwood.
Chemistry
The chemical composition of wood varies from species to species, but is approximately 50% carbon, 42% oxygen, 6% hydrogen, 1% nitrogen, and 1% other elements (mainly calcium, potassium, sodium, magnesium, iron, and manganese) by weight. Wood also contains sulfur, chlorine, silicon, phosphorus, and other elements in small quantity.
Aside from water, wood has three main components. Cellulose, a crystalline polymer derived from glucose, constitutes about 41–43%. Next in abundance is hemicellulose, which is around 20% in deciduous trees but near 30% in conifers. It is mainly five-carbon sugars that are linked in an irregular manner, in contrast to the cellulose. Lignin is the third component at around 27% in coniferous wood vs. 23% in deciduous trees. Lignin confers the hydrophobic properties reflecting the fact that it is based on aromatic rings. These three components are interwoven, and direct covalent linkages exist between the lignin and the hemicellulose. A major focus of the paper industry is the separation of the lignin from the cellulose, from which paper is made.
In chemical terms, the difference between hardwood and softwood is reflected in the composition of the constituent lignin. Hardwood lignin is primarily derived from sinapyl alcohol and coniferyl alcohol. Softwood lignin is mainly derived from coniferyl alcohol.
Extractives
Aside from the structural polymers, i.e. cellulose, hemicellulose and lignin (lignocellulose), wood contains a large variety of non-structural constituents, composed of low molecular weight organic compounds, called extractives. These compounds are present in the extracellular space and can be extracted from the wood using different neutral solvents, such as acetone. Analogous content is present in the so-called exudate produced by trees in response to mechanical damage or after being attacked by insects or fungi. Unlike the structural constituents, the composition of extractives varies over wide ranges and depends on many factors. The amount and composition of extractives differs between tree species, various parts of the same tree, and depends on genetic factors and growth conditions, such as climate and geography. For example, slower growing trees and higher parts of trees have higher content of extractives. Generally, the softwood is richer in extractives than the hardwood. Their concentration increases from the cambium to the pith. Barks and branches also contain extractives. Although extractives represent a small fraction of the wood content, usually less than 10%, they are extraordinarily diverse and thus characterize the chemistry of the wood species. Most extractives are secondary metabolites and some of them serve as precursors to other chemicals. Wood extractives display different activities, some of them are produced in response to wounds, and some of them participate in natural defense against insects and fungi.
These compounds contribute to various physical and chemical properties of the wood, such as wood color, fragnance, durability, acoustic properties, hygroscopicity, adhesion, and drying. Considering these impacts, wood extractives also affect the properties of pulp and paper, and importantly cause many problems in paper industry. Some extractives are surface-active substances and unavoidably affect the surface properties of paper, such as water adsorption, friction and strength.Lipophilic extractives often give rise to sticky deposits during kraft pulping and may leave spots on paper. Extractives also account for paper smell, which is important when making food contact materials.
Most wood extractives are lipophilic and only a little part is water-soluble. The lipophilic portion of extractives, which is collectively referred as wood resin, contains fats and fatty acids, sterols and steryl esters, terpenes, terpenoids, resin acids, and waxes. The heating of resin, i.e. distillation, vaporizes the volatile terpenes and leaves the solid component – rosin. The concentrated liquid of volatile compounds extracted during steam distillation is called essential oil. Distillation of oleoresin obtained from many pines provides rosin and turpentine.
Most extractives can be categorized into three groups: aliphatic compounds, terpenes and phenolic compounds. The latter are more water-soluble and usually are absent in the resin.
- Aliphatic compounds include fatty acids, fatty alcohols and their esters with glycerol, fatty alcohols (waxes) and sterols (steryl esters). Hydrocarbons, such as alkanes, are also present in the wood. Suberin is a polyester, made of suberin acids and glycerol, mainly found in barks. Fats serve as a source of energy for the wood cells. The most common wood sterol is sitosterol, and less commonly sitostanol, citrostadienol, campesterol or cholesterol.
- The main terpenes occurring in the softwood include mono-, sesqui- and diterpenes. Meanwhile, the terpene composition of the hardwood is considerably different, consisting of triterpenoids, polyprenols and other higher terpenes. Examples of mono-, di- and sesquiterpenes are α- and β-pinenes, 3-carene, β-myrcene, limonene, thujaplicins, α- and β-phellandrenes, α-muurolene, δ-cadinene, α- and δ-cadinols, α- and β-cedrenes, juniperol, longifolene, cis-abienol, borneol, pinifolic acid, nootkatin, chanootin, phytol, geranyl-linalool, β-epimanool, manoyloxide, pimaral and pimarol. Resin acids are usually tricyclic terpenoids, examples of which are pimaric acid, sandaracopimaric acid, isopimaric acid, abietic acid, levopimaric acid, palustric acid, neoabietic acid and dehydroabietic acid. Bicyclic resin acids are also found, such as lambertianic acid, communic acid, mercusic acid and secodehydroabietic acid. Cycloartenol, betulin and squalene are triterpenoids purified from hardwood. Examples of wood polyterpenes are rubber (cis-polypren), gutta percha (trans-polypren), gutta-balatá (trans-polypren) and betulaprenols (acyclic polyterpenoids). The mono- and sesquiterpenes of the softwood are responsible for the typical smell of pine forest. Many monoterpenoids, such as β-myrcene, are used in the preparation of flavors and fragrances.Tropolones, such as hinokitiol and other thujaplicins, are present in decay-resistant trees and display fungicidal and insecticidal properties. Tropolones strongly bind metal ions and can cause digester corrosion in the process kraft pulping. Owing to their metal-binding and ionophoric properties, especially thujaplicins are used in physiology experiments. Different other in-vitro biological activities of thujaplicins have been studied, such as insecticidal, anti-browning, anti-viral, anti-bacterial, anti-fungal, anti-proliferative and anti-oxidant.
- Phenolic compounds are especially found in the hardwood and the bark. The most well-known wood phenolic constituents are stilbenes (e.g. pinosylvin), lignans (e.g. pinoresinol, conidendrin, plicatic acid, hydroxymatairesinol), norlignans (e.g. nyasol, puerosides A and B, hydroxysugiresinol, sequirin-C), tannins (e.g. gallic acid, ellagic acid), flavonoids (e.g. chrysin, taxifolin, catechin, genistein). Most of the phenolic compounds have fungicidal properties and protect the wood from fungal decay. Together with the neolignans the phenolic compounds influence on the color of the wood. Resin acids and phenolic compounds are the main toxic contaminants present in the untreated effluents from pulping.Polyphenolic compounds are one of the most abundant biomolecules produced by plants, such as flavonoids and tannins. Tannins are used in leather industry and have shown to exhibit different biological activities.Flavonoids are very diverse, widely distributed in the plant kingdom and have numerous biological activities and roles.
Uses
Production
Global production of roundwood rose from 3.5 billion m³ in 2000 to 4 billion m³ in 2021. In 2021, wood fuel was the main product with a 49 percent share of the total (2 billion m³), followed by coniferous industrial roundwood with 30 percent (1.2 billion m³) and non-coniferous industrial roundwood with 21 percent (0.9 billion m³). Asia and the Americas are the two main producing regions, accounting for 29 and 28 percent of the total roundwood production, respectively; Africa and Europe have similar shares of 20–21 percent, while Oceania produces the remaining 2 percent.
Fuel
Wood has a long history of being used as fuel, which continues to this day, mostly in rural areas of the world. Hardwood is preferred over softwood because it creates less smoke and burns longer. Adding a woodstove or fireplace to a home is often felt to add ambiance and warmth.
Pulpwood
Pulpwood is wood that is raised specifically for use in making paper.
Construction
Wood has been an important construction material since humans began building shelters, houses and boats. Nearly all boats were made out of wood until the late 19th century, and wood remains in common use today in boat construction. Elm in particular was used for this purpose as it resisted decay as long as it was kept wet (it also served for water pipe before the advent of more modern plumbing).
Wood to be used for construction work is commonly known as lumber in North America. Elsewhere, lumber usually refers to felled trees, and the word for sawn planks ready for use is timber. In medieval Europe oak was the wood of choice for all wood construction, including beams, walls, doors, and floors. Today a wider variety of woods is used: solid wood doors are often made from poplar, small-knotted pine, and Douglas fir.
New domestic housing in many parts of the world today is commonly made from timber-framed construction. Engineered wood products are becoming a bigger part of the construction industry. They may be used in both residential and commercial buildings as structural and aesthetic materials.
In buildings made of other materials, wood will still be found as a supporting material, especially in roof construction, in interior doors and their frames, and as exterior cladding.
Wood is also commonly used as shuttering material to form the mold into which concrete is poured during reinforced concrete construction.
Flooring
A solid wood floor is a floor laid with planks or battens created from a single piece of timber, usually a hardwood. Since wood is hydroscopic (it acquires and loses moisture from the ambient conditions around it) this potential instability effectively limits the length and width of the boards.
Solid hardwood flooring is usually cheaper than engineered timbers and damaged areas can be sanded down and refinished repeatedly, the number of times being limited only by the thickness of wood above the tongue.
Solid hardwood floors were originally used for structural purposes, being installed perpendicular to the wooden support beams of a building (the joists or bearers) and solid construction timber is still often used for sports floors as well as most traditional wood blocks, mosaics and parquetry.
Engineered products
Engineered wood products, glued building products "engineered" for application-specific performance requirements, are often used in construction and industrial applications. Glued engineered wood products are manufactured by bonding together wood strands, veneers, lumber or other forms of wood fiber with glue to form a larger, more efficient composite structural unit.
These products include glued laminated timber (glulam), wood structural panels (including plywood, oriented strand board and composite panels), laminated veneer lumber (LVL) and other structural composite lumber (SCL) products, parallel strand lumber, and I-joists. Approximately 100 million cubic meters of wood was consumed for this purpose in 1991. The trends suggest that particle board and fiber board will overtake plywood.
Wood unsuitable for construction in its native form may be broken down mechanically (into fibers or chips) or chemically (into cellulose) and used as a raw material for other building materials, such as engineered wood, as well as chipboard, hardboard, and medium-density fiberboard (MDF). Such wood derivatives are widely used: wood fibers are an important component of most paper, and cellulose is used as a component of some synthetic materials. Wood derivatives can be used for kinds of flooring, for example laminate flooring.
Furniture and utensils
Wood has always been used extensively for furniture, such as chairs and beds. It is also used for tool handles and cutlery, such as chopsticks, toothpicks, and other utensils, like the wooden spoon and pencil.
Other
Further developments include new lignin glue applications, recyclable food packaging, rubber tire replacement applications, anti-bacterial medical agents, and high strength fabrics or composites. As scientists and engineers further learn and develop new techniques to extract various components from wood, or alternatively to modify wood, for example by adding components to wood, new more advanced products will appear on the marketplace. Moisture content electronic monitoring can also enhance next generation wood protection.
Art
Wood has long been used as an artistic medium. It has been used to make sculptures and carvings for millennia. Examples include the totem poles carved by North American indigenous people from conifer trunks, often Western Red Cedar (Thuja plicata).
Other uses of wood in the arts include:
- Woodcut printmaking and engraving
- Wood can be a surface to paint on, such as in panel painting
- Many musical instruments are made mostly or entirely of wood
Sports and recreational equipment
Many types of sports equipment are made of wood, or were constructed of wood in the past. For example, cricket bats are typically made of white willow. The baseball bats which are legal for use in Major League Baseball are frequently made of ash wood or hickory, and in recent years have been constructed from maple even though that wood is somewhat more fragile. National Basketball Association courts have been traditionally made out of parquetry.
Many other types of sports and recreation equipment, such as skis, ice hockey sticks, lacrosse sticks and archery bows, were commonly made of wood in the past, but have since been replaced with more modern materials such as aluminium, titanium or composite materials such as fiberglass and carbon fiber. One noteworthy example of this trend is the family of golf clubs commonly known as the woods, the heads of which were traditionally made of persimmon wood in the early days of the game of golf, but are now generally made of metal or (especially in the case of drivers) carbon-fiber composites.
Bacterial degradation
Little is known about the bacteria that degrade cellulose. Symbiotic bacteria in Xylophaga may play a role in the degradation of sunken wood. Alphaproteobacteria, Flavobacteria, Actinomycetota, Clostridia, and Bacteroidota have been detected in wood submerged for over a year.
See also
- Acetylated wood
- Ancient Chinese wooden architecture
- Ash burner
- Burl
- Carpentry
- Certified wood
- Conservation and restoration of waterlogged wood
- Conservation and restoration of wooden artifacts
- Driftwood
- Dunnage
- Forestry
- Fossil wood
- Furfurylated wood
- Green building and wood
- Helsinki Central Library Oodi
- International Wood Products Journal
- List of tallest wooden buildings
- List of woods
- Log building
- Log cabin
- Log house
- Mineral bonded wood wool board
- Mjøstårnet
- Natural building
- Parquetry
- Pallet crafts
- Pellet fuel
- Petrified wood
- Pine tar
- Plyscraper
- Pulpwood
- Reclaimed lumber
- Sawdust brandy
- Sawdust
- Thermally modified wood
- Timber framing
- Timber pilings
- Timber recycling
- Tinder
- Wood ash
- Wood degradation
- Wood drying
- Wood economy
- Wood lagging
- Wood preservation
- Wood stabilization
- Wood warping
- Wood wool
- Wood-decay fungus
- Wooden box
- Wood-plastic composite
- Woodturning
- Woodworm
- Xylology
- Xylophagy
- Xylotheque
- Xylotomy
- Yakisugi
Sources
This article incorporates text from a free content work. Licensed under CC BY-SA IGO 3.0 (license statement/permission). Text taken from World Food and Agriculture – Statistical Yearbook 2023, FAO.
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External links
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Wood is a structural tissue material found as xylem in the stems and roots of trees and other woody plants It is an organic material a natural composite of cellulosic fibers that are strong in tension and embedded in a matrix of lignin that resists compression Wood is sometimes defined as only the secondary xylem in the stems of trees or more broadly to include the same type of tissue elsewhere such as in the roots of trees or shrubs In a living tree it performs a mechanical support function enabling woody plants to grow large or to stand up by themselves It also conveys water and nutrients among the leaves other growing tissues and the roots Wood may also refer to other plant materials with comparable properties and to material engineered from wood woodchips or fibers Wood samples Pine Spruce Larch Juniper Aspen Hornbeam Birch Alder Beech Oak Elm Cherry Pear Maple Linden Ash Wood has been used for thousands of years for fuel as a construction material for making tools and weapons furniture and paper More recently it emerged as a feedstock for the production of purified cellulose and its derivatives such as cellophane and cellulose acetate As of 2020 the growing stock of forests worldwide was about 557 billion cubic meters As an abundant carbon neutral renewable resource woody materials have been of intense interest as a source of renewable energy In 2008 approximately 3 97 billion cubic meters of wood were harvested Dominant uses were for furniture and building construction Wood is scientifically studied and researched through the discipline of wood science which was initiated since the beginning of the 20th century HistoryA 2011 discovery in the Canadian province of New Brunswick yielded the earliest known plants to have grown wood approximately 395 to 400 million years ago Wood can be dated by carbon dating and in some species by dendrochronology to determine when a wooden object was created People have used wood for thousands of years for many purposes including as a fuel or as a construction material for making houses tools weapons furniture packaging artworks and paper Known constructions using wood date back ten thousand years Buildings like the longhouses in Neolithic Europe were made primarily of wood Recent use of wood has been enhanced by the addition of steel and bronze into construction The year to year variation in tree ring widths and isotopic abundances gives clues to the prevailing climate at the time a tree was cut Physical propertiesDiagram of secondary growth in a tree showing idealized vertical and horizontal sections A new layer of wood is added in each growing season thickening the stem existing branches and roots to form a growth ring Growth rings Wood in the strict sense is yielded by trees which increase in diameter by the formation between the existing wood and the inner bark of new woody layers which envelop the entire stem living branches and roots This process is known as secondary growth it is the result of cell division in the vascular cambium a lateral meristem and subsequent expansion of the new cells These cells then go on to form thickened secondary cell walls composed mainly of cellulose hemicellulose and lignin Where the differences between the seasons are distinct e g New Zealand growth can occur in a discrete annual or seasonal pattern leading to growth rings these can usually be most clearly seen on the end of a log but are also visible on the other surfaces If the distinctiveness between seasons is annual as is the case in equatorial regions e g Singapore these growth rings are referred to as annual rings Where there is little seasonal difference growth rings are likely to be indistinct or absent If the bark of the tree has been removed in a particular area the rings will likely be deformed as the plant overgrows the scar If there are differences within a growth ring then the part of a growth ring nearest the center of the tree and formed early in the growing season when growth is rapid is usually composed of wider elements It is usually lighter in color than that near the outer portion of the ring and is known as earlywood or springwood The outer portion formed later in the season is then known as the latewood or summerwood There are major differences depending on the kind of wood If a tree grows all its life in the open and the conditions of soil and site remain unchanged it will make its most rapid growth in youth and gradually decline The annual rings of growth are for many years quite wide but later they become narrower and narrower Since each succeeding ring is laid down on the outside of the wood previously formed it follows that unless a tree materially increases its production of wood from year to year the rings must necessarily become thinner as the trunk gets wider As a tree reaches maturity its crown becomes more open and the annual wood production is lessened thereby reducing still more the width of the growth rings In the case of forest grown trees so much depends upon the competition of the trees in their struggle for light and nourishment that periods of rapid and slow growth may alternate Some trees such as southern oaks maintain the same width of ring for hundreds of years On the whole as a tree gets larger in diameter the width of the growth rings decreases Knots A knot on a tree trunk As a tree grows lower branches often die and their bases may become overgrown and enclosed by subsequent layers of trunk wood forming a type of imperfection known as a knot The dead branch may not be attached to the trunk wood except at its base and can drop out after the tree has been sawn into boards Knots affect the technical properties of the wood usually reducing tension strength but may be exploited for visual effect In a longitudinally sawn plank a knot will appear as a roughly circular solid usually darker piece of wood around which the grain of the rest of the wood flows parts and rejoins Within a knot the direction of the wood grain direction is up to 90 degrees different from the grain direction of the regular wood In the tree a knot is either the base of a side branch or a dormant bud A knot when the base of a side branch is conical in shape hence the roughly circular cross section with the inner tip at the point in stem diameter at which the plant s vascular cambium was located when the branch formed as a bud In grading lumber and structural timber knots are classified according to their form size soundness and the firmness with which they are held in place This firmness is affected by among other factors the length of time for which the branch was dead while the attaching stem continued to grow Wood knot in vertical sectionKnots materially affect cracking and warping ease in working and cleavability of timber They are defects which weaken timber and lower its value for structural purposes where strength is an important consideration The weakening effect is much more serious when timber is subjected to forces perpendicular to the grain and or tension than when under load along the grain and or compression The extent to which knots affect the strength of a beam depends upon their position size number and condition A knot on the upper side is compressed while one on the lower side is subjected to tension If there is a season check in the knot as is often the case it will offer little resistance to this tensile stress Small knots may be located along the neutral plane of a beam and increase the strength by preventing longitudinal shearing Knots in a board or plank are least injurious when they extend through it at right angles to its broadest surface Knots which occur near the ends of a beam do not weaken it Sound knots which occur in the central portion one fourth the height of the beam from either edge are not serious defects Samuel J Record The Mechanical Properties of Wood Knots do not necessarily influence the stiffness of structural timber this will depend on the size and location Stiffness and elastic strength are more dependent upon the sound wood than upon localized defects The breaking strength is very susceptible to defects Sound knots do not weaken wood when subject to compression parallel to the grain In some decorative applications wood with knots may be desirable to add visual interest In applications where wood is painted such as skirting boards fascia boards door frames and furniture resins present in the timber may continue to bleed through to the surface of a knot for months or even years after manufacture and show as a yellow or brownish stain A knot primer paint or solution knotting correctly applied during preparation may do much to reduce this problem but it is difficult to control completely especially when using mass produced kiln dried timber stocks Heartwood and sapwood A section of a yew branch showing 27 annual growth rings pale sapwood dark heartwood and pith center dark spot The dark radial lines are small knots Heartwood or duramen is wood that as a result of a naturally occurring chemical transformation has become more resistant to decay Heartwood formation is a genetically programmed process that occurs spontaneously Some uncertainty exists as to whether the wood dies during heartwood formation as it can still chemically react to decay organisms but only once The term heartwood derives solely from its position and not from any vital importance to the tree This is evidenced by the fact that a tree can thrive with its heart completely decayed Some species begin to form heartwood very early in life so having only a thin layer of live sapwood while in others the change comes slowly Thin sapwood is characteristic of such species as chestnut black locust mulberry osage orange and sassafras while in maple ash hickory hackberry beech and pine thick sapwood is the rule Some others never form heartwood Heartwood is often visually distinct from the living sapwood and can be distinguished in a cross section where the boundary will tend to follow the growth rings For example it is sometimes much darker Other processes such as decay or insect invasion can also discolor wood even in woody plants that do not form heartwood which may lead to confusion Sapwood or alburnum is the younger outermost wood in the growing tree it is living wood and its principal functions are to conduct water from the roots to the leaves and to store up and give back according to the season the reserves prepared in the leaves By the time they become competent to conduct water all xylem tracheids and vessels have lost their cytoplasm and the cells are therefore functionally dead All wood in a tree is first formed as sapwood The more leaves a tree bears and the more vigorous its growth the larger the volume of sapwood required Hence trees making rapid growth in the open have thicker sapwood for their size than trees of the same species growing in dense forests Sometimes trees of species that do form heartwood grown in the open may become of considerable size 30 cm 12 in or more in diameter before any heartwood begins to form for example in second growth hickory or open grown pines Cross section of an oak log showing growth rings No definite relation exists between the annual rings of growth and the amount of sapwood Within the same species the cross sectional area of the sapwood is very roughly proportional to the size of the crown of the tree If the rings are narrow more of them are required than where they are wide As the tree gets larger the sapwood must necessarily become thinner or increase materially in volume Sapwood is relatively thicker in the upper portion of the trunk of a tree than near the base because the age and the diameter of the upper sections are less When a tree is very young it is covered with limbs almost if not entirely to the ground but as it grows older some or all of them will eventually die and are either broken off or fall off Subsequent growth of wood may completely conceal the stubs which will remain as knots No matter how smooth and clear a log is on the outside it is more or less knotty near the middle Consequently the sapwood of an old tree and particularly of a forest grown tree will be freer from knots than the inner heartwood Since in most uses of wood knots are defects that weaken the timber and interfere with its ease of working and other properties it follows that a given piece of sapwood because of its position in the tree may well be stronger than a piece of heartwood from the same tree Different pieces of wood cut from a large tree may differ decidedly particularly if the tree is big and mature In some trees the wood laid on late in the life of a tree is softer lighter weaker and more even textured than that produced earlier but in other trees the reverse applies This may or may not correspond to heartwood and sapwood In a large log the sapwood because of the time in the life of the tree when it was grown may be inferior in hardness strength and toughness to equally sound heartwood from the same log In a smaller tree the reverse may be true Color The wood of coast redwood is distinctively red In species which show a distinct difference between heartwood and sapwood the natural color of heartwood is usually darker than that of the sapwood and very frequently the contrast is conspicuous see section of yew log above This is produced by deposits in the heartwood of chemical substances so that a dramatic color variation does not imply a significant difference in the mechanical properties of heartwood and sapwood although there may be a marked biochemical difference between the two Some experiments on very resinous longleaf pine specimens indicate an increase in strength due to the resin which increases the strength when dry Such resin saturated heartwood is called fat lighter Structures built of fat lighter are almost impervious to rot and termites and very flammable Tree stumps of old longleaf pines are often dug split into small pieces and sold as kindling for fires Stumps thus dug may actually remain a century or more since being cut Spruce impregnated with crude resin and dried is also greatly increased in strength thereby Since the latewood of a growth ring is usually darker in color than the earlywood this fact may be used in visually judging the density and therefore the hardness and strength of the material This is particularly the case with coniferous woods In ring porous woods the vessels of the early wood often appear on a finished surface as darker than the denser latewood though on cross sections of heartwood the reverse is commonly true Otherwise the color of wood is no indication of strength Abnormal discoloration of wood often denotes a diseased condition indicating unsoundness The black check in western hemlock is the result of insect attacks The reddish brown streaks so common in hickory and certain other woods are mostly the result of injury by birds The discoloration is merely an indication of an injury and in all probability does not of itself affect the properties of the wood Certain rot producing fungi impart to wood characteristic colors which thus become symptomatic of weakness Ordinary sap staining is due to fungal growth but does not necessarily produce a weakening effect Water content Water occurs in living wood in three locations namely in the cell walls in the protoplasmic contents of the cells as free water in the cell cavities and spaces especially of the xylemEquilibrium moisture content in wood In heartwood it occurs only in the first and last forms Wood that is thoroughly air dried in equilibrium with the moisture content of the air retains 8 16 of the water in the cell walls and none or practically none in the other forms Even oven dried wood retains a small percentage of moisture but for all except chemical purposes may be considered absolutely dry The general effect of the water content upon the wood substance is to render it softer and more pliable A similar effect occurs in the softening action of water on rawhide paper or cloth Within certain limits the greater the water content the greater its softening effect The moisture in wood can be measured by several different moisture meters Drying produces a decided increase in the strength of wood particularly in small specimens An extreme example is the case of a completely dry spruce block 5 cm in section which will sustain a permanent load four times as great as a green undried block of the same size will The greatest strength increase due to drying is in the ultimate crushing strength and strength at elastic limit in endwise compression these are followed by the modulus of rupture and stress at elastic limit in cross bending while the modulus of elasticity is least affected Structure Magnified cross section of black walnut showing the vessels rays white lines and annual rings this is intermediate between diffuse porous and ring porous with vessel size declining gradually Wood is a heterogeneous hygroscopic cellular and anisotropic or more specifically orthotropic material It consists of cells and the cell walls are composed of micro fibrils of cellulose 40 50 and hemicellulose 15 25 impregnated with lignin 15 30 In coniferous or softwood species the wood cells are mostly of one kind tracheids and as a result the material is much more uniform in structure than that of most hardwoods There are no vessels pores in coniferous wood such as one sees so prominently in oak and ash for example The structure of hardwoods is more complex The water conducting capability is mostly taken care of by vessels in some cases oak chestnut ash these are quite large and distinct in others buckeye poplar willow too small to be seen without a hand lens In discussing such woods it is customary to divide them into two large classes ring porous and diffuse porous In ring porous species such as ash black locust catalpa chestnut elm hickory mulberry and oak the larger vessels or pores as cross sections of vessels are called are localized in the part of the growth ring formed in spring thus forming a region of more or less open and porous tissue The rest of the ring produced in summer is made up of smaller vessels and a much greater proportion of wood fibers These fibers are the elements which give strength and toughness to wood while the vessels are a source of weakness In diffuse porous woods the pores are evenly sized so that the water conducting capability is scattered throughout the growth ring instead of being collected in a band or row Examples of this kind of wood are alder basswood birch buckeye maple willow and the Populus species such as aspen cottonwood and poplar Some species such as walnut and cherry are on the border between the two classes forming an intermediate group Earlywood and latewood In softwood Earlywood and latewood in a softwood radial view growth rings closely spaced in Rocky Mountain Douglas fir In temperate softwoods there often is a marked difference between latewood and earlywood The latewood will be denser than that formed early in the season When examined under a microscope the cells of dense latewood are seen to be very thick walled and with very small cell cavities while those formed first in the season have thin walls and large cell cavities The strength is in the walls not the cavities Hence the greater the proportion of latewood the greater the density and strength In choosing a piece of pine where strength or stiffness is the important consideration the principal thing to observe is the comparative amounts of earlywood and latewood The width of ring is not nearly so important as the proportion and nature of the latewood in the ring If a heavy piece of pine is compared with a lightweight piece it will be seen at once that the heavier one contains a larger proportion of latewood than the other and is therefore showing more clearly demarcated growth rings In white pines there is not much contrast between the different parts of the ring and as a result the wood is very uniform in texture and is easy to work In hard pines on the other hand the latewood is very dense and is deep colored presenting a very decided contrast to the soft straw colored earlywood It is not only the proportion of latewood but also its quality that counts In specimens that show a very large proportion of latewood it may be noticeably more porous and weigh considerably less than the latewood in pieces that contain less latewood One can judge comparative density and therefore to some extent strength by visual inspection No satisfactory explanation can as yet be given for the exact mechanisms determining the formation of earlywood and latewood Several factors may be involved In conifers at least rate of growth alone does not determine the proportion of the two portions of the ring for in some cases the wood of slow growth is very hard and heavy while in others the opposite is true The quality of the site where the tree grows undoubtedly affects the character of the wood formed though it is not possible to formulate a rule governing it In general where strength or ease of working is essential woods of moderate to slow growth should be chosen In ring porous woods Earlywood and latewood in a ring porous wood ash in a Fraxinus excelsior tangential view wide growth rings In ring porous woods each season s growth is always well defined because the large pores formed early in the season abut on the denser tissue of the year before In the case of the ring porous hardwoods there seems to exist a pretty definite relation between the rate of growth of timber and its properties This may be briefly summed up in the general statement that the more rapid the growth or the wider the rings of growth the heavier harder stronger and stiffer the wood This it must be remembered applies only to ring porous woods such as oak ash hickory and others of the same group and is of course subject to some exceptions and limitations In ring porous woods of good growth it is usually the latewood in which the thick walled strength giving fibers are most abundant As the breadth of ring diminishes this latewood is reduced so that very slow growth produces comparatively light porous wood composed of thin walled vessels and wood parenchyma In good oak these large vessels of the earlywood occupy from six to ten percent of the volume of the log while in inferior material they may make up 25 or more The latewood of good oak is dark colored and firm and consists mostly of thick walled fibers which form one half or more of the wood In inferior oak this latewood is much reduced both in quantity and quality Such variation is very largely the result of rate of growth Wide ringed wood is often called second growth because the growth of the young timber in open stands after the old trees have been removed is more rapid than in trees in a closed forest and in the manufacture of articles where strength is an important consideration such second growth hardwood material is preferred This is particularly the case in the choice of hickory for handles and spokes Here not only strength but toughness and resilience are important The results of a series of tests on hickory by the U S Forest Service show that The work or shock resisting ability is greatest in wide ringed wood that has from 5 to 14 rings per inch rings 1 8 5 mm thick is fairly constant from 14 to 38 rings per inch rings 0 7 1 8 mm thick and decreases rapidly from 38 to 47 rings per inch rings 0 5 0 7 mm thick The strength at maximum load is not so great with the most rapid growing wood it is maximum with from 14 to 20 rings per inch rings 1 3 1 8 mm thick and again becomes less as the wood becomes more closely ringed The natural deduction is that wood of first class mechanical value shows from 5 to 20 rings per inch rings 1 3 5 mm thick and that slower growth yields poorer stock Thus the inspector or buyer of hickory should discriminate against timber that has more than 20 rings per inch rings less than 1 3 mm thick Exceptions exist however in the case of normal growth upon dry situations in which the slow growing material may be strong and tough The effect of rate of growth on the qualities of chestnut wood is summarized by the same authority as follows When the rings are wide the transition from spring wood to summer wood is gradual while in the narrow rings the spring wood passes into summer wood abruptly The width of the spring wood changes but little with the width of the annual ring so that the narrowing or broadening of the annual ring is always at the expense of the summer wood The narrow vessels of the summer wood make it richer in wood substance than the spring wood composed of wide vessels Therefore rapid growing specimens with wide rings have more wood substance than slow growing trees with narrow rings Since the more the wood substance the greater the weight and the greater the weight the stronger the wood chestnuts with wide rings must have stronger wood than chestnuts with narrow rings This agrees with the accepted view that sprouts which always have wide rings yield better and stronger wood than seedling chestnuts which grow more slowly in diameter In diffuse porous woods In the diffuse porous woods the demarcation between rings is not always so clear and in some cases is almost if not entirely invisible to the unaided eye Conversely when there is a clear demarcation there may not be a noticeable difference in structure within the growth ring In diffuse porous woods as has been stated the vessels or pores are even sized so that the water conducting capability is scattered throughout the ring instead of collected in the earlywood The effect of rate of growth is therefore not the same as in the ring porous woods approaching more nearly the conditions in the conifers In general it may be stated that such woods of medium growth afford stronger material than when very rapidly or very slowly grown In many uses of wood total strength is not the main consideration If ease of working is prized wood should be chosen with regard to its uniformity of texture and straightness of grain which will in most cases occur when there is little contrast between the latewood of one season s growth and the earlywood of the next Monocots Trunks of the coconut palm a monocot in Java From this perspective these look not much different from trunks of a dicot or conifer Structural material that resembles ordinary dicot or conifer timber in its gross handling characteristics is produced by a number of monocot plants and these also are colloquially called wood Of these bamboo botanically a member of the grass family has considerable economic importance larger culms being widely used as a building and construction material and in the manufacture of engineered flooring panels and veneer Another major plant group that produces material that often is called wood are the palms Of much less importance are plants such as Pandanus Dracaena and Cordyline With all this material the structure and composition of the processed raw material is quite different from ordinary wood Specific gravity The single most revealing property of wood as an indicator of wood quality is specific gravity Timell 1986 as both pulp yield and lumber strength are determined by it Specific gravity is the ratio of the mass of a substance to the mass of an equal volume of water density is the ratio of a mass of a quantity of a substance to the volume of that quantity and is expressed in mass per unit substance e g grams per milliliter g cm3 or g ml The terms are essentially equivalent as long as the metric system is used Upon drying wood shrinks and its density increases Minimum values are associated with green water saturated wood and are referred to as basic specific gravity Timell 1986 The U S Forest Products Laboratory lists a variety of ways to define specific gravity G and density r for wood Symbol Mass basis Volume basisG0 Ovendry OvendryGb basic Ovendry GreenG12 Ovendry 12 MCGx Ovendry x MCr0 Ovendry Ovendryr12 12 MC 12 MCrx x MC x MC The FPL has adopted Gb and G12 for specific gravity in accordance with the ASTM D2555 standard These are scientifically useful but don t represent any condition that could physically occur The FPL Wood Handbook also provides formulas for approximately converting any of these measurements to any other Density Wood density is determined by multiple growth and physiological factors compounded into one fairly easily measured wood characteristic Elliott 1970 Age diameter height radial trunk growth geographical location site and growing conditions silvicultural treatment and seed source all to some degree influence wood density Variation is to be expected Within an individual tree the variation in wood density is often as great as or even greater than that between different trees Timell 1986 Variation of specific gravity within the bole of a tree can occur in either the horizontal or vertical direction Because the specific gravity as defined above uses an unrealistic condition woodworkers tend to use the average dried weight which is a density based on mass at 12 moisture content and volume at the same r12 This condition occurs when the wood is at equilibrium moisture content with air at about 65 relative humidity and temperature at 30 C 86 F This density is expressed in units of kg m3 or lbs ft3 Tables The following tables list the mechanical properties of wood and lumber plant species including bamboo See also Mechanical properties of tonewoods for additional properties Wood properties Common name Scientific name Moisture content Density kg m3 Compressive strength megapascals Flexural strength megapascals Red Alder Alnus rubra Green 370 20 4 45Red Alder Alnus rubra 12 00 410 40 1 68Black Ash Fraxinus nigra Green 450 15 9 41Black Ash Fraxinus nigra 12 00 490 41 2 87Blue Ash Fraxinus quadrangulata Green 530 24 8 66Blue Ash Fraxinus quadrangulata 12 00 580 48 1 95Green Ash Fraxinus pennsylvanica Green 530 29 66Green Ash Fraxinus pennsylvanica 12 00 560 48 8 97Oregon Ash Fraxinus latifolia Green 500 24 2 52Oregon Ash Fraxinus latifolia 12 00 550 41 6 88White Ash Fraxinus americana Green 550 27 5 66White Ash Fraxinus americana 12 00 600 51 1 103Bigtooth Aspen Populus grandidentata Green 360 17 2 37Bigtooth Aspen Populus grandidentata 12 00 390 36 5 63Quaking Aspen Populus tremuloides Green 350 14 8 35Quaking Aspen Populus tremuloides 12 00 380 29 3 58American Basswood Tilia americana Green 320 15 3 34American Basswood Tilia americana 12 00 370 32 6 60American Beech Fagus grandifolia Green 560 24 5 59American Beech Fagus grandifolia 12 00 640 50 3 103Paper Birch Betula papyrifera Green 480 16 3 44Paper Birch Betula papyrifera 12 00 550 39 2 85Sweet Birch Betula lenta Green 600 25 8 65Sweet Birch Betula lenta 12 00 650 58 9 117Yellow Birch Betula alleghaniensis Green 550 23 3 57Yellow Birch Betula alleghaniensis 12 00 620 56 3 114Butternut Juglans cinerea Green 360 16 7 37Butternut Juglans cinerea 12 00 380 36 2 56Black Cherry Prunus serotina Green 470 24 4 55Blach Cherry Prunus serotina 12 00 500 49 85American Chestnut Castanea dentata Green 400 17 39American Chestnut Castanea dentata 12 00 430 36 7 59Balsam Poplar Cottonwood Populus balsamifera Green 310 11 7 27Balsam Poplar Cottonwood Populus balsamifera 12 00 340 27 7 47Black Cottonwood Populus trichocarpa Green 310 15 2 34Black Cottonwood Populus trichocarpa 12 00 350 31 59Eastern Cottonwood Populus deltoides Green 370 15 7 37Eastern Cottonwood Populus deltoides 12 00 400 33 9 59American Elm Ulmus americana Green 460 20 1 50American Elm Ulmus americana 12 00 500 38 1 81Rock Elm Ulmus thomasii Green 570 26 1 66Rock Elm Ulmus thomasii 12 00 630 48 6 102Slippery Elm Ulmus rubra Green 480 22 9 55Slippery Elm Ulmus rubra 12 00 530 43 9 90Hackberry Celtis occidentalis Green 490 18 3 45Hackberry Celtis occidentalis 12 00 530 37 5 76Bitternut Hickory Carya cordiformis Green 600 31 5 71Bitternut Hickory Carya cordiformis 12 00 660 62 3 118Nutmeg Hickory Carya myristiciformis Green 560 27 4 63Nutmeg Hickory Carya myristiciformis 12 00 600 47 6 114Pecan Hickory Carya illinoinensis Green 600 27 5 68Pecan Hickory Carya illinoinensis 12 00 660 54 1 94Water Hickory Carya aquatica Green 610 32 1 74Water Hickory Carya aquatica 12 00 620 59 3 123Mockernut Hickory Carya tomentosa Green 640 30 9 77Mockernut Hickory Carya tomentosa 12 00 720 61 6 132Pignut Hickory Carya glabra Green 660 33 2 81Pignut Hickory Carya glabra 12 00 750 63 4 139Shagbark Hickory Carya ovata Green 640 31 6 76Shagbark Hickory Carya ovata 12 00 720 63 5 139Shellbark Hickory Carya laciniosa Green 620 27 72Shellbark Hickory Carya laciniosa 12 00 690 55 2 125Honeylocust Gleditsia triacanthos Green 600 30 5 70Honeylocust Gleditsia triacanthos 12 00 600 51 7 101Black Locust Robinia pseudoacacia Green 660 46 9 95Black Locust Robinia pseudoacacia 12 00 690 70 2 134Cucumber Tree Magnolia Magnolia acuminata Green 440 21 6 51Cucumber Tree Magnolia Magnolia acuminata 12 00 480 43 5 85Southern Magnolia Magnolia grandiflora Green 460 18 6 47Southern Magnolia Magnolia grandiflora 12 00 500 37 6 77Bigleaf Maple Acer macrophyllum Green 440 22 3 51Bigleaf Maple Acer macrophyllum 12 00 480 41 74Black Maple Acer nigrum Green 520 22 5 54Black Maple Acer nigrum 12 00 570 46 1 92Red Maple Acer rubrum Green 490 22 6 53Red Maple Acer rubrum 12 00 540 45 1 92Silver Maple Acer saccharinum Green 440 17 2 40Silver Maple Acer saccharinum 12 00 470 36 61Sugar Maple Acer saccharum Green 560 27 7 65Sugar Maple Acer saccharum 12 00 630 54 109Black Red Oak Quercus velutina Green 560 23 9 57Black Red Oak Quercus velutina 12 00 610 45 96Cherrybark Red Oak Quercus pagoda Green 610 31 9 74Cherrybark Red Oak Quercus pagoda 12 00 680 60 3 125Laurel Red Oak Quercus hemisphaerica Green 560 21 9 54Laurel Red Oak Quercus hemisphaerica 12 00 630 48 1 87Northern Red Oak Quercus rubra Green 560 23 7 57Northern Red Oak Quercus rubra 12 00 630 46 6 99Pin Red Oak Quercus palustris Green 580 25 4 57Pin Red Oak Quercus palustris 12 00 630 47 97Scarlet Red Oak Quercus coccinea Green 600 28 2 72Scarlet Red Oak Quercus coccinea 12 00 670 57 4 120Southern Red Oak Quercus falcata Green 520 20 9 48Southern Red Oak Quercus falcata 12 00 590 42 75Water Red Oak Quercus nigra Green 560 25 8 61Water Red Oak Quercus nigra 12 00 630 46 7 106Willow Red Oak Quercus phellos Green 560 20 7 51Willow Red Oak Quercus phellos 12 00 690 48 5 100Bur White Oak Quercus macrocarpa Green 580 22 7 50Bur White Oak Quercus macrocarpa 12 00 640 41 8 71Chestnut White Oak Quercus montana Green 570 24 3 55Chestnut White Oak Quercus montana 12 00 660 47 1 92Live White Oak Quercus virginiana Green 800 37 4 82Live White Oak Quercus virginiana 12 00 880 61 4 127Overcup White Oak Quercus lyrata Green 570 23 2 55Overcup White Oak Quercus lyrata 12 00 630 42 7 87Post White Oak Quercus stellata Green 600 24 56Post White Oak Quercus stellata 12 00 670 45 3 91Swamp Chestnut White Oak Quercus michauxii Green 600 24 4 59Swamp Chestnut White Oak Quercus michauxii 12 00 670 50 1 96Swamp White Oak Quercus bicolor Green 640 30 1 68Swamp White Oak Quercus bicolor 12 00 720 59 3 122White Oak Quercus alba Green 600 24 5 57White Oak Quercus alba 12 00 680 51 3 105Sassafras Sassafras albidum Green 420 18 8 41Sassafras Sassafras albidum 12 00 460 32 8 62Sweetgum Liquidambar styraciflua Green 460 21 49Sweetgum Liquidambar styraciflua 12 00 520 43 6 86American Sycamore Platanus occidentalis Green 460 20 1 45American Sycamore Platanus occidentalis 12 00 490 37 1 69Tanoak Notholithocarpus densiflorus Green 580 32 1 72Tanoak Notholithocarpus densiflorus 12 00 580 32 1 72Black Tupelo Nyssa sylvatica Green 460 21 48Black Tupelo Nyssa sylvatica 12 00 500 38 1 66Water Tupelo Nyssa aquatica Green 460 23 2 50Water Tupelo Nyssa aquatica 12 00 500 40 8 66Black Walnut Juglans nigra Green 510 29 6 66Black Walnut Juglans nigra 12 00 550 52 3 101Black Willow Salix nigra Green 360 14 1 33Black Willow Salix nigra 12 00 390 28 3 54Yellow Poplar Liriodendron tulipifera Green 400 18 3 41Yellow Poplar Liriodendron tulipifera 12 00 420 38 2 70Baldcypress Taxodium distichum Green 420 24 7 46Baldcypress Taxodium distichum 12 00 460 43 9 73Atlantic White Cedar Chamaecyparis thyoides Green 310 16 5 32Atlantic White Cedar Chamaecyparis thyoides 12 00 320 32 4 47Eastern Redcedar Juniperus virginiana Green 440 24 6 48Eastern Redcedar Juniperus virginiana 12 00 470 41 5 61Incense Cedar Calocedrus decurrens Green 350 21 7 43Incense Cedar Calocedrus decurrens 12 00 370 35 9 55Northern White Cedar Thuja occidentalis Green 290 13 7 29Northern White Cedar Thuja occidentalis 12 00 310 27 3 45Port Orford Cedar Chamaecyparis lawsoniana Green 390 21 6 45Port Orford Cedar Chamaecyparis lawsoniana 12 00 430 43 1 88Western Redcedar Thuja plicata Green 310 19 1 35 9Western Redcedar Thuja plicata 12 00 320 31 4 51 7Yellow Cedar Cupressus nootkatensis Green 420 21 44Yellow Cedar Cupressus nootkatensis 12 00 440 43 5 77Coast Douglas Fir Pseudotsuga menziesii var menziesii Green 450 26 1 53Coast Douglas Fir Pseudotsuga menziesii var menziesii 12 00 480 49 9 85Interior West Douglas Fir Pseudotsuga Menziesii Green 460 26 7 53Interior West Douglas Fir Pseudotsuga Menziesii 12 00 500 51 2 87Interior North Douglas Fir Pseudotsuga menziesii var glauca Green 450 23 9 51Interior North Douglas Fir Pseudotsuga menziesii var glauca 12 00 480 47 6 90Interior South Douglas Fir Pseudotsuga lindleyana Green 430 21 4 47Interior South Douglas Fir Pseudotsuga lindleyana 12 00 460 43 82Balsam Fir Abies balsamea Green 330 18 1 38Balsam Fir Abies balsamea 12 00 350 36 4 63California Red Fir Abies magnifica Green 360 19 40California Red Fir Abies magnifica 12 00 380 37 6 72 4Grand Fir Abies grandis Green 350 20 3 40Grand Fir Abies grandis 12 00 370 36 5 61 4Noble Fir Abies procera Green 370 20 8 43Noble Fir Abies procera 12 00 390 42 1 74Pacific Silver Fir Abies amabilis Green 400 21 6 44Pacific Silver Fir Abies amabilis 12 00 430 44 2 75Subalpine Fir Abies lasiocarpa Green 310 15 9 34Subalpine Fir Abies lasiocarpa 12 00 320 33 5 59White Fir Abies concolor Green 370 20 41White Fir Abies concolor 12 00 390 40 68Eastern Hemlock Tsuga canadensis Green 380 21 2 44Eastern Hemlock Tsuga canadensis 12 00 400 37 3 61Mountain Hemlock Tsuga mertensiana Green 420 19 9 43Mountain Hemlock Tsuga mertensiana 12 00 450 44 4 79Western Hemlock Tsuga heterophylla Green 420 23 2 46Western Hemlock Tsuga heterophylla 12 00 450 49 78Western Larch Larix occidentalis Green 480 25 9 53Western Larch Larix occidentalis 12 00 520 52 5 90Eastern White Pine Pinus strobus Green 340 16 8 34Eastern White Pine Pinus strobus 12 00 350 33 1 59Jack Pine Pinus banksiana Green 400 20 3 41Jack Pine Pinus banksiana 12 00 430 39 68Loblolly Pine Pinus taeda Green 470 24 2 50Loblolly Pine Pinus taeda 12 00 510 49 2 88Lodgepole Pine Pinus contorta Green 380 18 38Lodgepole Pine Pinus contorta 12 00 410 37 65Longleaf Pine Pinus palustris Green 540 29 8 59Longleaf Pine Pinus palustris 12 00 590 58 4 100Pitch Pine Pinus rigida Green 470 20 3 47Pitch Pine Pinus rigida 12 00 520 41 74Pond Pine Pinus serotina Green 510 25 2 51Pond Pine Pinus serotina 12 00 560 52 80Ponderosa Pine Pinus ponderosa Green 380 16 9 35Ponderosa Pine Pinus ponderosa 12 00 400 36 7 65Red Pine Pinus resinosa Green 410 18 8 40Red Pine Pinus resinosa 12 00 460 41 9 76Sand Pine Pinus clausa Green 460 23 7 52Sand Pine Pinus clausa 12 00 480 47 7 80Shortleaf Pine Pinus echinata Green 470 24 3 51Shortleaf Pine Pinus echinata 12 00 510 50 1 90Slash Pine Pinus elliottii Green 540 26 3 60Slash Pine Pinus elliottii 12 00 590 56 1 112Spruce Pine Pinus glabra Green 410 19 6 41Spruce Pine Pinus glabra 12 00 440 39 72Sugar Pine Pinus lambertiana Green 340 17 34Sugar Pine Pinus lambertiana 12 00 360 30 8 57Virginia Pine Pinus virginiana Green 450 23 6 50Virginia Pine Pinus virginiana 12 00 480 46 3 90Western White Pine Pinus monticola Green 360 16 8 32Western White Pine Pinus monticola 12 00 380 34 7 67Redwood Old Growth Sequoia sempervirens Green 380 29 52Redwood Old Growth Sequoia sempervirens 12 00 400 42 4 69Redwood New Growth Sequoia sempervirens Green 340 21 4 41Redwood New Growth Sequoia sempervirens 12 00 350 36 54Black Spruce Picea mariana Green 380 19 6 42Black Spruce Picea mariana 12 00 460 41 1 74Engelmann Spruce Picea engelmannii Green 330 15 32Engelmann Spruce Picea engelmannii 12 00 350 30 9 64Red Spruce Picea rubens Green 370 18 8 41Red Spruce Picea rubens 12 00 400 38 2 74Sitka Spruce Picea sitchensis Green 330 16 2 34Sitka Spruce Picea sitchensis 12 00 360 35 7 65White Spruce Picea glauca Green 370 17 7 39White Spruce Picea glauca 12 00 400 37 7 68Tamarack Spruce Larix laricina Green 490 24 50Tamarack Spruce Larix laricina 12 00 530 49 4 80 Bamboo properties Common name Scientific name Moisture content Density kg m3 Compressive strength megapascals Flexural strength megapascals Balku bans Bambusa balcooa green 45 73 7Balku bans Bambusa balcooa air dry 54 15 81 1Balku bans Bambusa balcooa 8 5 820 69 151Indian thorny bamboo Bambusa bambos 9 5 710 61 143Indian thorny bamboo Bambusa bambos 43 05 37 15Nodding Bamboo 8 890 75 52 9Nodding Bamboo 87 46 52 4Nodding Bamboo 12 85 67 5Nodding Bamboo 88 3 44 7 88Nodding Bamboo 14 47 9 216Clumping Bamboo 45 8Clumping Bamboo 5 79 80Clumping Bamboo 20 35 37Burmese bamboo Bambusa polymorpha 95 1 32 1 28 3Bambusa spinosa air dry 57 51 77Indian timber bamboo Bambusa tulda 73 6 40 7 51 1Indian timber bamboo Bambusa tulda 11 9 68 66 7Indian timber bamboo Bambusa tulda 8 6 910 79 194dragon bamboo Dendrocalamus giganteus 8 740 70 193Hamilton s bamboo Dendrocalamus hamiltonii 8 5 590 70 89White bamboo 102 40 5 26 3String Bamboo 54 3 24 1 102String Bamboo 15 1 37 95 87 5Java Black Bamboo Gigantochloa atroviolacea 54 23 8 92 3Java Black Bamboo Gigantochloa atroviolacea 15 35 7 94 1Giant Atter Gigantochloa atter 72 3 26 4 98Giant Atter Gigantochloa atter 14 4 31 95 122 78 960 71 154American Narrow Leaved Bamboo Guadua angustifolia 42 53 5American Narrow Leaved Bamboo Guadua angustifolia 63 6 144 8American Narrow Leaved Bamboo Guadua angustifolia 86 3 46American Narrow Leaved Bamboo Guadua angustifolia 77 5 82American Narrow Leaved Bamboo Guadua angustifolia 15 56 87American Narrow Leaved Bamboo Guadua angustifolia 63 3American Narrow Leaved Bamboo Guadua angustifolia 28American Narrow Leaved Bamboo Guadua angustifolia 56 2American Narrow Leaved Bamboo Guadua angustifolia 38Berry Bamboo Melocanna baccifera 12 8 69 9 57 6Japanese timber bamboo Phyllostachys bambusoides 51Japanese timber bamboo Phyllostachys bambusoides 8 730 63Japanese timber bamboo Phyllostachys bambusoides 64 44Japanese timber bamboo Phyllostachys bambusoides 61 40Japanese timber bamboo Phyllostachys bambusoides 9 71Japanese timber bamboo Phyllostachys bambusoides 9 74Japanese timber bamboo Phyllostachys bambusoides 12 54Tortoise shell bamboo Phyllostachys edulis 44 6Tortoise shell bamboo Phyllostachys edulis 75 67Tortoise shell bamboo Phyllostachys edulis 15 71Tortoise shell bamboo Phyllostachys edulis 6 108Tortoise shell bamboo Phyllostachys edulis 0 2 147Tortoise shell bamboo Phyllostachys edulis 5 117 51Tortoise shell bamboo Phyllostachys edulis 30 44 55Tortoise shell bamboo Phyllostachys edulis 12 5 603 60 3Tortoise shell bamboo Phyllostachys edulis 10 3 530 83Early Bamboo 28 5 827 79 3Oliveri 53 46 9 61 9Oliveri 7 8 58 90Hard versus softIt is common to classify wood as either softwood or hardwood The wood from conifers e g pine is called softwood and the wood from dicotyledons usually broad leaved trees e g oak is called hardwood These names are a bit misleading as hardwoods are not necessarily hard and softwoods are not necessarily soft The well known balsa a hardwood is actually softer than any commercial softwood Conversely some softwoods e g yew are harder than many hardwoods There is a strong relationship between the properties of wood and the properties of the particular tree that yielded it at least for certain species For example in loblolly pine wind exposure and stem position greatly affect the hardness of wood as well as compression wood content The density of wood varies with species The density of a wood correlates with its strength mechanical properties For example mahogany is a medium dense hardwood that is excellent for fine furniture crafting whereas balsa is light making it useful for model building One of the densest woods is black ironwood ChemistryChemical structure of lignin which makes up about 25 of wood dry matter and is responsible for many of its properties The chemical composition of wood varies from species to species but is approximately 50 carbon 42 oxygen 6 hydrogen 1 nitrogen and 1 other elements mainly calcium potassium sodium magnesium iron and manganese by weight Wood also contains sulfur chlorine silicon phosphorus and other elements in small quantity Aside from water wood has three main components Cellulose a crystalline polymer derived from glucose constitutes about 41 43 Next in abundance is hemicellulose which is around 20 in deciduous trees but near 30 in conifers It is mainly five carbon sugars that are linked in an irregular manner in contrast to the cellulose Lignin is the third component at around 27 in coniferous wood vs 23 in deciduous trees Lignin confers the hydrophobic properties reflecting the fact that it is based on aromatic rings These three components are interwoven and direct covalent linkages exist between the lignin and the hemicellulose A major focus of the paper industry is the separation of the lignin from the cellulose from which paper is made In chemical terms the difference between hardwood and softwood is reflected in the composition of the constituent lignin Hardwood lignin is primarily derived from sinapyl alcohol and coniferyl alcohol Softwood lignin is mainly derived from coniferyl alcohol Extractives Aside from the structural polymers i e cellulose hemicellulose and lignin lignocellulose wood contains a large variety of non structural constituents composed of low molecular weight organic compounds called extractives These compounds are present in the extracellular space and can be extracted from the wood using different neutral solvents such as acetone Analogous content is present in the so called exudate produced by trees in response to mechanical damage or after being attacked by insects or fungi Unlike the structural constituents the composition of extractives varies over wide ranges and depends on many factors The amount and composition of extractives differs between tree species various parts of the same tree and depends on genetic factors and growth conditions such as climate and geography For example slower growing trees and higher parts of trees have higher content of extractives Generally the softwood is richer in extractives than the hardwood Their concentration increases from the cambium to the pith Barks and branches also contain extractives Although extractives represent a small fraction of the wood content usually less than 10 they are extraordinarily diverse and thus characterize the chemistry of the wood species Most extractives are secondary metabolites and some of them serve as precursors to other chemicals Wood extractives display different activities some of them are produced in response to wounds and some of them participate in natural defense against insects and fungi Forchem tall oil refinery in Rauma Finland These compounds contribute to various physical and chemical properties of the wood such as wood color fragnance durability acoustic properties hygroscopicity adhesion and drying Considering these impacts wood extractives also affect the properties of pulp and paper and importantly cause many problems in paper industry Some extractives are surface active substances and unavoidably affect the surface properties of paper such as water adsorption friction and strength Lipophilic extractives often give rise to sticky deposits during kraft pulping and may leave spots on paper Extractives also account for paper smell which is important when making food contact materials Most wood extractives are lipophilic and only a little part is water soluble The lipophilic portion of extractives which is collectively referred as wood resin contains fats and fatty acids sterols and steryl esters terpenes terpenoids resin acids and waxes The heating of resin i e distillation vaporizes the volatile terpenes and leaves the solid component rosin The concentrated liquid of volatile compounds extracted during steam distillation is called essential oil Distillation of oleoresin obtained from many pines provides rosin and turpentine Most extractives can be categorized into three groups aliphatic compounds terpenes and phenolic compounds The latter are more water soluble and usually are absent in the resin Aliphatic compounds include fatty acids fatty alcohols and their esters with glycerol fatty alcohols waxes and sterols steryl esters Hydrocarbons such as alkanes are also present in the wood Suberin is a polyester made of suberin acids and glycerol mainly found in barks Fats serve as a source of energy for the wood cells The most common wood sterol is sitosterol and less commonly sitostanol citrostadienol campesterol or cholesterol The main terpenes occurring in the softwood include mono sesqui and diterpenes Meanwhile the terpene composition of the hardwood is considerably different consisting of triterpenoids polyprenols and other higher terpenes Examples of mono di and sesquiterpenes are a and b pinenes 3 carene b myrcene limonene thujaplicins a and b phellandrenes a muurolene d cadinene a and d cadinols a and b cedrenes juniperol longifolene cis abienol borneol pinifolic acid nootkatin chanootin phytol geranyl linalool b epimanool manoyloxide pimaral and pimarol Resin acids are usually tricyclic terpenoids examples of which are pimaric acid sandaracopimaric acid isopimaric acid abietic acid levopimaric acid palustric acid neoabietic acid and dehydroabietic acid Bicyclic resin acids are also found such as lambertianic acid communic acid mercusic acid and secodehydroabietic acid Cycloartenol betulin and squalene are triterpenoids purified from hardwood Examples of wood polyterpenes are rubber cis polypren gutta percha trans polypren gutta balata trans polypren and betulaprenols acyclic polyterpenoids The mono and sesquiterpenes of the softwood are responsible for the typical smell of pine forest Many monoterpenoids such as b myrcene are used in the preparation of flavors and fragrances Tropolones such as hinokitiol and other thujaplicins are present in decay resistant trees and display fungicidal and insecticidal properties Tropolones strongly bind metal ions and can cause digester corrosion in the process kraft pulping Owing to their metal binding and ionophoric properties especially thujaplicins are used in physiology experiments Different other in vitro biological activities of thujaplicins have been studied such as insecticidal anti browning anti viral anti bacterial anti fungal anti proliferative and anti oxidant Phenolic compounds are especially found in the hardwood and the bark The most well known wood phenolic constituents are stilbenes e g pinosylvin lignans e g pinoresinol conidendrin plicatic acid hydroxymatairesinol norlignans e g nyasol puerosides A and B hydroxysugiresinol sequirin C tannins e g gallic acid ellagic acid flavonoids e g chrysin taxifolin catechin genistein Most of the phenolic compounds have fungicidal properties and protect the wood from fungal decay Together with the neolignans the phenolic compounds influence on the color of the wood Resin acids and phenolic compounds are the main toxic contaminants present in the untreated effluents from pulping Polyphenolic compounds are one of the most abundant biomolecules produced by plants such as flavonoids and tannins Tannins are used in leather industry and have shown to exhibit different biological activities Flavonoids are very diverse widely distributed in the plant kingdom and have numerous biological activities and roles UsesMain global producers of roundwood by type World production of roundwood by typeProduction Global production of roundwood rose from 3 5 billion m in 2000 to 4 billion m in 2021 In 2021 wood fuel was the main product with a 49 percent share of the total 2 billion m followed by coniferous industrial roundwood with 30 percent 1 2 billion m and non coniferous industrial roundwood with 21 percent 0 9 billion m Asia and the Americas are the two main producing regions accounting for 29 and 28 percent of the total roundwood production respectively Africa and Europe have similar shares of 20 21 percent while Oceania produces the remaining 2 percent Fuel Wood has a long history of being used as fuel which continues to this day mostly in rural areas of the world Hardwood is preferred over softwood because it creates less smoke and burns longer Adding a woodstove or fireplace to a home is often felt to add ambiance and warmth Pulpwood Pulpwood is wood that is raised specifically for use in making paper Construction The Saitta House Dyker Heights Brooklyn New York built in 1899 is made of and decorated in wood Map of importers and exporters of forest products including wood in 2021 Wood has been an important construction material since humans began building shelters houses and boats Nearly all boats were made out of wood until the late 19th century and wood remains in common use today in boat construction Elm in particular was used for this purpose as it resisted decay as long as it was kept wet it also served for water pipe before the advent of more modern plumbing Wood to be used for construction work is commonly known as lumber in North America Elsewhere lumber usually refers to felled trees and the word for sawn planks ready for use is timber In medieval Europe oak was the wood of choice for all wood construction including beams walls doors and floors Today a wider variety of woods is used solid wood doors are often made from poplar small knotted pine and Douglas fir The churches of Kizhi Russia are among a handful of World Heritage Sites built entirely of wood without metal joints See Kizhi Pogost for more details New domestic housing in many parts of the world today is commonly made from timber framed construction Engineered wood products are becoming a bigger part of the construction industry They may be used in both residential and commercial buildings as structural and aesthetic materials In buildings made of other materials wood will still be found as a supporting material especially in roof construction in interior doors and their frames and as exterior cladding Wood is also commonly used as shuttering material to form the mold into which concrete is poured during reinforced concrete construction Flooring Wood can be cut into straight planks and made into a wood flooring A solid wood floor is a floor laid with planks or battens created from a single piece of timber usually a hardwood Since wood is hydroscopic it acquires and loses moisture from the ambient conditions around it this potential instability effectively limits the length and width of the boards Solid hardwood flooring is usually cheaper than engineered timbers and damaged areas can be sanded down and refinished repeatedly the number of times being limited only by the thickness of wood above the tongue Solid hardwood floors were originally used for structural purposes being installed perpendicular to the wooden support beams of a building the joists or bearers and solid construction timber is still often used for sports floors as well as most traditional wood blocks mosaics and parquetry Engineered products Engineered wood products glued building products engineered for application specific performance requirements are often used in construction and industrial applications Glued engineered wood products are manufactured by bonding together wood strands veneers lumber or other forms of wood fiber with glue to form a larger more efficient composite structural unit These products include glued laminated timber glulam wood structural panels including plywood oriented strand board and composite panels laminated veneer lumber LVL and other structural composite lumber SCL products parallel strand lumber and I joists Approximately 100 million cubic meters of wood was consumed for this purpose in 1991 The trends suggest that particle board and fiber board will overtake plywood Wood unsuitable for construction in its native form may be broken down mechanically into fibers or chips or chemically into cellulose and used as a raw material for other building materials such as engineered wood as well as chipboard hardboard and medium density fiberboard MDF Such wood derivatives are widely used wood fibers are an important component of most paper and cellulose is used as a component of some synthetic materials Wood derivatives can be used for kinds of flooring for example laminate flooring Furniture and utensils Wood has always been used extensively for furniture such as chairs and beds It is also used for tool handles and cutlery such as chopsticks toothpicks and other utensils like the wooden spoon and pencil Other Further developments include new lignin glue applications recyclable food packaging rubber tire replacement applications anti bacterial medical agents and high strength fabrics or composites As scientists and engineers further learn and develop new techniques to extract various components from wood or alternatively to modify wood for example by adding components to wood new more advanced products will appear on the marketplace Moisture content electronic monitoring can also enhance next generation wood protection Art Prayer Bead with the Adoration of the Magi and the Crucifixion Gothic boxwood miniature Wood has long been used as an artistic medium It has been used to make sculptures and carvings for millennia Examples include the totem poles carved by North American indigenous people from conifer trunks often Western Red Cedar Thuja plicata Other uses of wood in the arts include Woodcut printmaking and engraving Wood can be a surface to paint on such as in panel painting Many musical instruments are made mostly or entirely of woodSports and recreational equipment Many types of sports equipment are made of wood or were constructed of wood in the past For example cricket bats are typically made of white willow The baseball bats which are legal for use in Major League Baseball are frequently made of ash wood or hickory and in recent years have been constructed from maple even though that wood is somewhat more fragile National Basketball Association courts have been traditionally made out of parquetry Many other types of sports and recreation equipment such as skis ice hockey sticks lacrosse sticks and archery bows were commonly made of wood in the past but have since been replaced with more modern materials such as aluminium titanium or composite materials such as fiberglass and carbon fiber One noteworthy example of this trend is the family of golf clubs commonly known as the woods the heads of which were traditionally made of persimmon wood in the early days of the game of golf but are now generally made of metal or especially in the case of drivers carbon fiber composites Bacterial degradationLittle is known about the bacteria that degrade cellulose Symbiotic bacteria in Xylophaga may play a role in the degradation of sunken wood Alphaproteobacteria Flavobacteria Actinomycetota Clostridia and Bacteroidota have been detected in wood submerged for over a year See alsoTrees portalAcetylated wood Ancient Chinese wooden architecture Ash burner Burl Carpentry Certified wood Conservation and restoration of waterlogged wood Conservation and restoration of wooden artifacts Driftwood Dunnage Forestry Fossil wood Furfurylated wood Green building and wood Helsinki Central Library Oodi International Wood Products Journal List of tallest wooden buildings List of woods Log building Log cabin Log house Mineral bonded wood wool board Mjostarnet Natural building Parquetry Pallet crafts Pellet fuel Petrified wood Pine tar Plyscraper Pulpwood Reclaimed lumber Sawdust brandy Sawdust Thermally modified wood Timber framing Timber pilings Timber recycling Tinder Wood ash Wood degradation Wood drying Wood economy Wood lagging Wood preservation Wood stabilization Wood warping Wood wool Wood decay fungus Wooden box Wood plastic composite Woodturning Woodworm Xylology Xylophagy Xylotheque Xylotomy YakisugiSources This article incorporates text from a free content work Licensed under CC BY SA IGO 3 0 license statement permission Text taken from World Food and Agriculture Statistical Yearbook 2023 FAO ReferencesHickey M King C 2001 The Cambridge Illustrated Glossary of Botanical Terms Cambridge University Press FAO 2020 Global Forest Resources Assessment 2020 Main report Archived November 5 2022 at the Wayback Machine Rome The EPA Declared That Burning Wood is Carbon Neutral It s Actually a Lot More Complicated Archived from the original on June 30 2021 Retrieved June 3 2022 Horst H Nimz Uwe Schmitt Eckart Schwab Otto Wittmann Franz Wolf Wood in Ullmann s Encyclopedia of Industrial Chemistry 2005 Wiley VCH Weinheim doi 10 1002 14356007 a28 305 N B fossils show origins of wood CBC ca August 12 2011 Archived from the original on August 13 2011 Retrieved August 12 2011 Philippe Gerrienne et al August 12 2011 A Simple Type of Wood in Two Early Devonian Plants Science 333 6044 837 Bibcode 2011Sci 333 837G doi 10 1126 science 1208882 hdl 2268 97121 PMID 21836008 S2CID 23513139 permanent dead link Woods Sarah July 18 2016 A History of Wood from the Stone Age to the 21st Century EcoBUILDING A Publication of The 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of Northern Utah and Interior Alaska PDF Ecology 75 6 1736 1752 Bibcode 1994Ecol 75 1736S doi 10 2307 1939633 JSTOR 1939633 Archived from the original PDF on August 10 2017 Retrieved November 30 2018 Record Samuel James 1914 The Mechanical Properties of Wood Including a Discussion of the Factors Affecting the Mechanical Properties and Methods of Timber Testing J Wiley amp sons Incorporated Archived from the original on September 8 2023 Retrieved March 20 2023 Samuel James Record 1914 The mechanical properties of wood including a discussion of the factors affecting the mechanical properties and methods of timber testing J Wiley amp sons inc pp 44 U S Department of Agriculture Forest Products Laboratory The Wood Handbook Wood as an engineering material Archived March 15 2007 at the Wayback Machine General Technical Report 113 Madison WI Timell T E 1986 Compression wood in gymnosperms Springer Verlag Berlin 2150 p Wood Handbook Chapter 4 Moisture Relations and Physical Properties of Wood 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20 2023 Jean Pierre Barette Claude Hazard et Jerome Mayer 1996 Memotech Bois et Materiaux Associes Paris Editions Casteilla p 22 ISBN 978 2 7135 1645 0 W Boerjan J Ralph M Baucher June 2003 Lignin biosynthesis Annu Rev Plant Biol 54 1 519 549 doi 10 1146 annurev arplant 54 031902 134938 PMID 14503002 Ek Monica Gellerstedt Goran Henriksson Gunnar 2009 Chapter 7 Wood extractives Pulp and Paper Chemistry and Technology Volume 1 Wood Chemistry and Wood Biotechnology Berlin Walter de Gruyter ISBN 978 3 11 021339 3 Sjostrom Eero October 22 2013 Chapter 5 Extractives Wood Chemistry Fundamentals and Applications Second ed San Diego Elsevier Science ISBN 978 0 08 092589 9 Ansell Martin P 2015 Chapter 11 Preservation Protection and Modification of Wood Composites Woodhead Publishing Series in Composites Science and Engineering Number 54 Wood Composites Cambridge UK Woodhead Publishing ISBN 978 1 78242 454 3 Hon David N S Shiraishi Nubuo 2001 Chapter 6 Chemistry of Extractives Wood and Cellulosic Chemistry 2nd rev and expanded ed New York Marcel Dekker ISBN 0 8247 0024 4 Rowell Roger M 2013 Chater 3 Cell Wall Chemistry Handbook of Wood Chemistry and Wood Composites 2nd ed Boca Raton Taylor amp Francis ISBN 9781439853801 Mimms Agneta Michael J Kuckurek Jef A Pyiatte Elizabeth E Wright 1993 Kraft Pulping A Compilation of Notes TAPPI Press pp 6 7 ISBN 978 0 89852 322 5 Fiebach Klemens Grimm Dieter 2000 Resins Natural Ullmann s Encyclopedia of Industrial Chemistry doi 10 1002 14356007 a23 073 ISBN 978 3 527 30673 2 Sperelakis Nicholas Sperelakis Nick January 11 2012 Chapter 4 Ionophores in Planar Lipid Bilayers Cell physiology sourcebook essentials of membrane biophysics Fourth ed London UK ISBN 978 0 12 387738 3 Archived from the original on June 28 2020 Retrieved September 27 2020 a href wiki Template Cite book title Template Cite book cite book a CS1 maint location missing publisher link Saniewski Marian Horbowicz Marcin Kanlayanarat Sirichai September 10 2014 The Biological Activities of Troponoids and Their Use in Agriculture A Review Journal of Horticultural Research 22 1 5 19 doi 10 2478 johr 2014 0001 S2CID 33834249 Bentley Ronald 2008 A fresh look at natural tropolonoids Nat Prod Rep 25 1 118 138 doi 10 1039 b711474e PMID 18250899 World Food and Agriculture Statistical Yearbook 2023 FAO November 29 2023 doi 10 4060 cc8166en ISBN 978 92 5 138262 2 Sterrett Frances S October 12 1994 Alternative Fuels and the Environment CRC Press ISBN 978 0 87371 978 0 Archived from the original on December 30 2023 Retrieved October 6 2020 Saitta House Report Part 1 Archived December 16 2008 at the Wayback Machine DykerHeightsCivicAssociation com Binggeli Corky 2013 Materials for Interior Environments John Wiley amp Sons ISBN 978 1 118 42160 4 Archived from the original on December 30 2023 Retrieved October 6 2020 APA The Engineered Wood Association PDF apawood org Archived PDF from the original on June 27 2006 FPInnovations PDF forintek ca Archived from the original PDF on March 19 2009 System for remotely monitoring moisture content on wooden elements I Arakistain O Munne EP Patent EPO1382108 0 Christina Bienhold Petra Pop Ristova Frank Wenzhofer Thorsten Dittmar Antje Boetius January 2 2013 How Deep Sea Wood Falls Sustain Chemosynthetic Life PLOS ONE 8 1 e53590 Bibcode 2013PLoSO 853590B doi 10 1371 journal pone 0053590 PMC 3534711 PMID 23301092 Hoadley R Bruce 2000 Understanding Wood A Craftsman s Guide to Wood Technology Taunton Press ISBN 978 1 56158 358 4 External linksWikimedia Commons has media related to Wood The Wood in Culture Association archived 27 May 2016 The Wood Explorer A comprehensive database of commercial wood species Archived April 7 2015 at the Wayback Machine APA The Engineered Wood Association archived 14 April 2011 Portals ArthropodsEcologyEngineeringEnvironmentFungiIslandsPaintingTrainsTrees