Wood

Wood is a structural tissue/material found as

Wood samples
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
Pine Spruce Larch Juniper
sometimes defined as only the secondary
xylem in the stems of trees,[1] 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
Aspen Hornbeam Birch Alder
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
Beech Oak Elm Cherry
other plant materials with comparable
properties, and to material engineered from
wood, woodchips, or fibers.

Wood has been used for thousands of years

for fuel, as a construction material, for Pear Maple Linden Ash

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.[2] As an
abundant, carbon-neutral[3] 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.[2]
Dominant uses were for furniture and building construction.[4]

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.[5][6]
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.[7]

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.[8]

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, Diagram of secondary growth in a
leading to growth rings; these can usually be most clearly seen on tree showing idealized vertical and
the end of a log, but are also visible on the other surfaces. If the horizontal sections. A new layer of
distinctiveness between seasons is annual (as is the case in wood is added in each growing
season, thickening the stem,
equatorial regions, e.g. Singapore), these growth rings are referred
existing branches and roots, to form
to as annual rings. Where there is little seasonal difference growth a growth ring.
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.[9] 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,[10] but may be exploited for visual effect. In a
longitudinally sawn plank, a knot will appear as a roughly circular
A knot on a tree trunk "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 Wood knot in vertical
along the neutral plane of a beam and increase the strength by section
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-fou
from either edge are not serious defects.

— Samuel J. Record, The Mechanical Properties of Wood[11]

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[12]) 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.[13]

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. A section of a yew branch showing
Thin sapwood is characteristic of such species as chestnut, black 27 annual growth rings, pale
locust, mulberry, osage-orange, and sassafras, while in maple, ash, sapwood, dark heartwood, and pith
(center dark spot). The dark radial
hickory, hackberry, beech, and pine, thick sapwood is the rule.[14]
lines are small knots.
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[15]) is the younger, outermost wood; in the growing tree it is living wood,[16] 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. Cross-section of an oak log showing
growth rings
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
The wood of coast redwood is
dramatic color variation does not imply a significant difference in
distinctively red.
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
Equilibrium moisture content in
to render it softer and more pliable. A similar effect occurs in the wood.
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.[11]

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%).[17]
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.[18] 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.[19]

In ring-porous species, such as ash, black locust, catalpa, chestnut, elm, Magnified cross-section of
black walnut, showing the
hickory, mulberry, and oak,[19] the larger vessels or pores (as cross
vessels, rays (white lines)
sections of vessels are called) are localized in the part of the growth ring and annual rings: this is
formed in spring, thus forming a region of more or less open and porous intermediate between
tissue. The rest of the ring, produced in summer, is made up of smaller diffuse-porous and ring-
vessels and a much greater proportion of wood fibers. These fibers are the porous, with vessel size
elements which give strength and toughness to wood, while the vessels are declining gradually
a source of weakness.[20]

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,[19] basswood,[21] birch,[19] buckeye, maple, willow, and the Populus species such as aspen,
cottonwood and poplar.[19] Some species, such as walnut and cherry, are on the border between the two
classes, forming an intermediate group.[21]

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
Earlywood and latewood in
In ring-porous woods, each season's
a softwood; radial view,
growth rings closely spaced
growth is always well defined, because the
in Rocky Mountain large pores formed early in the season abut
Douglas-fir 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. Earlywood and latewood in
a ring-porous wood (ash) in
In ring-porous woods of good growth, it is usually the latewood in which a Fraxinus excelsior;
the thick-walled, strength-giving fibers are most abundant. As the breadth tangential view, wide growth
of ring diminishes, this latewood is reduced so that very slow growth rings
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.[11]
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."[22]

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."[22]

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),[23] as both pulp
Trunks of the coconut palm, a
yield and lumber strength are determined by it. Specific gravity is monocot, in Java. From this
the ratio of the mass of a substance to the mass of an equal volume perspective these look not much
of water; density is the ratio of a mass of a quantity of a substance different from trunks of a dicot or
to the volume of that quantity and is expressed in mass per unit conifer
3
substance, e.g., grams per milliliter (g/cm 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).[23]

The U.S. Forest Products Laboratory lists a variety of ways to define specific gravity (G) and density (ρ)
for wood:[24]

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[25] 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).[26]

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).[23] 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:[27][28]
 Compressive
Common Moisture Density Flexural strength
Scientific name strength
name content (kg/m3) (megapascals)
(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

Fraxinus
Blue Ash Green 530 24.8 66
quadrangulata
Fraxinus
Blue Ash 12.00% 580 48.1 95
quadrangulata

Fraxinus
Green Ash Green 530 29 66
pennsylvanica

Fraxinus
Green Ash 12.00% 560 48.8 97
pennsylvanica
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

Populus
Bigtooth Aspen Green 360 17.2 37
grandidentata

Populus
Bigtooth Aspen 12.00% 390 36.5 63
grandidentata
Quaking Aspen Populus tremuloides Green 350 14.8 35

Quaking Aspen Populus tremuloides 12.00% 380 29.3 58

American
Tilia americana Green 320 15.3 34
Basswood

American
Tilia americana 12.00% 370 32.6 60
Basswood

American
Fagus grandifolia Green 560 24.5 59
Beech
American
Fagus grandifolia 12.00% 640 50.3 103
Beech

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

Betula
Yellow Birch Green 550 23.3 57
alleghaniensis
Betula
Yellow Birch 12.00% 620 56.3 114
alleghaniensis

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
Castanea dentata Green 400 17 39
Chestnut

American
Castanea dentata 12.00% 430 36.7 59
Chestnut
Balsam Poplar
Populus balsamifera Green 310 11.7 27
Cottonwood

Balsam Poplar
Populus balsamifera 12.00% 340 27.7 47
Cottonwood

Black
Populus trichocarpa Green 310 15.2 34
Cottonwood
Black
Populus trichocarpa 12.00% 350 31 59
Cottonwood

Eastern
Populus deltoides Green 370 15.7 37
Cottonwood

Eastern
Populus deltoides 12.00% 400 33.9 59
Cottonwood
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
Carya cordiformis Green 600 31.5 71
Hickory
Bitternut
Carya cordiformis 12.00% 660 62.3 118
Hickory

Nutmeg
Carya myristiciformis Green 560 27.4 63
Hickory

Nutmeg
Carya myristiciformis 12.00% 600 47.6 114
Hickory
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
Carya tomentosa Green 640 30.9 77
Hickory

Mockernut
Carya tomentosa 12.00% 720 61.6 132
Hickory
Pignut Hickory Carya glabra Green 660 33.2 81
Pignut Hickory Carya glabra 12.00% 750 63.4 139
Shagbark
Carya ovata Green 640 31.6 76
Hickory

Shagbark
Carya ovata 12.00% 720 63.5 139
Hickory

Shellbark
Carya laciniosa Green 620 27 72
Hickory
Shellbark
Carya laciniosa 12.00% 690 55.2 125
Hickory

Honeylocust Gleditsia triacanthos Green 600 30.5 70

Honeylocust Gleditsia triacanthos 12.00% 600 51.7 101

Robinia
Black Locust Green 660 46.9 95
pseudoacacia

Robinia
Black Locust 12.00% 690 70.2 134
pseudoacacia

Cucumber Tree
Magnolia acuminata Green 440 21.6 51
Magnolia
Cucumber Tree
Magnolia acuminata 12.00% 480 43.5 85
Magnolia

Southern
Magnolia grandiflora Green 460 18.6 47
Magnolia

Southern
Magnolia grandiflora 12.00% 500 37.6 77
Magnolia
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
Quercus pagoda Green 610 31.9 74
Red Oak

Cherrybark
Quercus pagoda 12.00% 680 60.3 125
Red Oak

Laurel Red Quercus

Green 560 21.9 54
Oak hemisphaerica
Laurel Red Quercus
12.00% 630 48.1 87
Oak hemisphaerica
Northern Red
Quercus rubra Green 560 23.7 57
Oak
Northern Red
Quercus rubra 12.00% 630 46.6 99
Oak

Pin Red Oak Quercus palustris Green 580 25.4 57

Pin Red Oak Quercus palustris 12.00% 630 47 97

Scarlet Red
Quercus coccinea Green 600 28.2 72
Oak

Scarlet Red
Quercus coccinea 12.00% 670 57.4 120
Oak

Southern Red
Quercus falcata Green 520 20.9 48
Oak
Southern Red
Quercus falcata 12.00% 590 42 75
Oak

Water Red Oak Quercus nigra Green 560 25.8 61

Water Red Oak Quercus nigra 12.00% 630 46.7 106

Willow Red
Quercus phellos Green 560 20.7 51
Oak

Willow Red
Quercus phellos 12.00% 690 48.5 100
Oak

Quercus
Bur White Oak Green 580 22.7 50
macrocarpa
Quercus
Bur White Oak 12.00% 640 41.8 71
macrocarpa

Chestnut White
Quercus montana Green 570 24.3 55
Oak

Chestnut White
Quercus montana 12.00% 660 47.1 92
Oak
Live White Oak Quercus virginiana Green 800 37.4 82

Live White Oak Quercus virginiana 12.00% 880 61.4 127

Overcup White
Quercus lyrata Green 570 23.2 55
Oak
Overcup White
Quercus lyrata 12.00% 630 42.7 87
Oak

Post White
Quercus stellata Green 600 24 56
Oak

Post White
Quercus stellata 12.00% 670 45.3 91
Oak
Swamp
Chestnut White Quercus michauxii Green 600 24.4 59
Oak

Swamp
Chestnut White Quercus michauxii 12.00% 670 50.1 96
Oak

Swamp White
Quercus bicolor Green 640 30.1 68
Oak
Swamp White
Quercus bicolor 12.00% 720 59.3 122
Oak
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

Liquidambar
Sweetgum Green 460 21 49
styraciflua

Liquidambar
Sweetgum 12.00% 520 43.6 86
styraciflua
American Platanus
Green 460 20.1 45
Sycamore occidentalis

American Platanus
12.00% 490 37.1 69
Sycamore occidentalis

Notholithocarpus
Tanoak Green 580 32.1 72
densiflorus
Notholithocarpus
Tanoak 12.00% 580 32.1 72
densiflorus

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

Liriodendron
Yellow Poplar Green 400 18.3 41
tulipifera

Liriodendron
Yellow Poplar 12.00% 420 38.2 70
tulipifera

Baldcypress Taxodium distichum Green 420 24.7 46

Baldcypress Taxodium distichum 12.00% 460 43.9 73

Atlantic White Chamaecyparis

Green 310 16.5 32
Cedar thyoides

Atlantic White Chamaecyparis

12.00% 320 32.4 47
Cedar thyoides
Eastern
Juniperus virginiana Green 440 24.6 48
Redcedar

Eastern
Juniperus virginiana 12.00% 470 41.5 61
Redcedar

Calocedrus
Incense Cedar Green 350 21.7 43
decurrens
Calocedrus
Incense Cedar 12.00% 370 35.9 55
decurrens
Northern White
Thuja occidentalis Green 290 13.7 29
Cedar
Northern White
Thuja occidentalis 12.00% 310 27.3 45
Cedar

Port Orford Chamaecyparis

Green 390 21.6 45
Cedar lawsoniana

Port Orford Chamaecyparis

12.00% 430 43.1 88
Cedar lawsoniana
Western
Thuja plicata Green 310 19.1 35.9
Redcedar

Western
Thuja plicata 12.00% 320 31.4 51.7
Redcedar

Cupressus
Yellow Cedar Green 420 21 44
nootkatensis
Cupressus
Yellow Cedar 12.00% 440 43.5 77
nootkatensis

Pseudotsuga
Coast Douglas
menziesii var. Green 450 26.1 53
Fir
menziesii

Pseudotsuga
Coast Douglas
menziesii var. 12.00% 480 49.9 85
Fir
menziesii
Interior West Pseudotsuga
Green 460 26.7 53
Douglas Fir Menziesii

Interior West Pseudotsuga

12.00% 500 51.2 87
Douglas Fir Menziesii

Interior North Pseudotsuga

Green 450 23.9 51
Douglas Fir menziesii var. glauca
Interior North Pseudotsuga
12.00% 480 47.6 90
Douglas Fir menziesii var. glauca

Interior South Pseudotsuga

Green 430 21.4 47
Douglas Fir lindleyana

Interior South Pseudotsuga

12.00% 460 43 82
Douglas Fir lindleyana
Balsam Fir Abies balsamea Green 330 18.1 38

Balsam Fir Abies balsamea 12.00% 350 36.4 63

California Red
Abies magnifica Green 360 19 40
Fir
California Red
Abies magnifica 12.00% 380 37.6 72.4
Fir

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
Abies amabilis Green 400 21.6 44
Fir
Pacific Silver
Abies amabilis 12.00% 430 44.2 75
Fir
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
Tsuga canadensis Green 380 21.2 44
Hemlock

Eastern
Tsuga canadensis 12.00% 400 37.3 61
Hemlock
Mountain
Tsuga mertensiana Green 420 19.9 43
Hemlock

Mountain
Tsuga mertensiana 12.00% 450 44.4 79
Hemlock

Western
Tsuga heterophylla Green 420 23.2 46
Hemlock
Western
Tsuga heterophylla 12.00% 450 49 78
Hemlock

Western Larch Larix occidentalis Green 480 25.9 53

Western Larch Larix occidentalis 12.00% 520 52.5 90

Eastern White
Pinus strobus Green 340 16.8 34
Pine

Eastern White
Pinus strobus 12.00% 350 33.1 59
Pine

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
Pinus contorta Green 380 18 38
Pine

Lodgepole
Pinus contorta 12.00% 410 37 65
Pine

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
Pinus ponderosa Green 380 16.9 35
Pine
Ponderosa
Pinus ponderosa 12.00% 400 36.7 65
Pine

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
Pinus monticola Green 360 16.8 32
Pine

Western White
Pinus monticola 12.00% 380 34.7 67
Pine

Redwood Old Sequoia

Green 380 29 52
Growth sempervirens
Redwood Old Sequoia
12.00% 400 42.4 69
Growth sempervirens

Redwood New Sequoia

Green 340 21.4 41
Growth sempervirens

Redwood New Sequoia

12.00% 350 36 54
Growth sempervirens
Black Spruce Picea mariana Green 380 19.6 42

Black Spruce Picea mariana 12.00% 460 41.1 74

Engelmann
Picea engelmannii Green 330 15 32
Spruce
Engelmann
Picea engelmannii 12.00% 350 30.9 64
Spruce

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
Larix laricina Green 490 24 50
Spruce

Tamarack
Larix laricina 12.00% 530 49.4 80
Spruce
Bamboo properties:[29][28]
 Compressive
Common Moisture Density Flexural strength
Scientific name strength
name content (kg/m3) (megapascals)
(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
Bambusa bambos 9.5 710 61 143
bamboo

Indian thorny
Bambusa bambos 43.05 37.15
bamboo
Nodding
Bambusa nutans 8 890 75 52.9
Bamboo

Nodding
Bambusa nutans 87 46 52.4
Bamboo

Nodding
Bambusa nutans 12 85 67.5
Bamboo
Nodding
Bambusa nutans 88.3 44.7 88
Bamboo

Nodding
Bambusa nutans 14 47.9 216
Bamboo

Clumping Bambusa
45.8
Bamboo pervariabilis
Clumping Bambusa
5 79 80
Bamboo pervariabilis

Clumping Bambusa
20 35 37
Bamboo pervariabilis

Burmese Bambusa
95.1 32.1 28.3
bamboo polymorpha
Bambusa spinosa air dry 57 51.77

Indian timber
Bambusa tulda 73.6 40.7 51.1
bamboo
Indian timber
Bambusa tulda 11.9 68 66.7
bamboo

Indian timber
Bambusa tulda 8.6 910 79 194
bamboo

Dendrocalamus
dragon bamboo 8 740 70 193
giganteus
Hamilton's Dendrocalamus
8.5 590 70 89
bamboo hamiltonii

Dendrocalamus
White bamboo 102 40.5 26.3
membranaceus

String Bamboo Gigantochloa apus 54.3 24.1 102

String Bamboo Gigantochloa apus 15.1 37.95 87.5

Java Black Gigantochloa

54 23.8 92.3
Bamboo atroviolacea
Java Black Gigantochloa
15 35.7 94.1
Bamboo atroviolacea
Giant Atter Gigantochloa atter 72.3 26.4 98

Giant Atter Gigantochloa atter 14.4 31.95 122.7

Gigantochloa
8 960 71 154
macrostachya
American
Guadua
Narrow-Leaved 42 53.5
angustifolia
Bamboo

American
Guadua
Narrow-Leaved 63.6 144.8
angustifolia
Bamboo

American
Guadua
Narrow-Leaved 86.3 46
angustifolia
Bamboo
American
Guadua
Narrow-Leaved 77.5 82
angustifolia
Bamboo

American
Guadua
Narrow-Leaved 15 56 87
angustifolia
Bamboo

American
Guadua
Narrow-Leaved 63.3
angustifolia
Bamboo
American
Guadua
Narrow-Leaved 28
angustifolia
Bamboo

American
Guadua
Narrow-Leaved 56.2
angustifolia
Bamboo

American
Guadua
Narrow-Leaved 38
angustifolia
Bamboo
Melocanna
Berry Bamboo 12.8 69.9 57.6
baccifera

Japanese Phyllostachys
51
timber bamboo bambusoides

Japanese Phyllostachys
8 730 63
timber bamboo bambusoides
Japanese Phyllostachys
64 44
timber bamboo bambusoides

Japanese Phyllostachys
61 40
timber bamboo bambusoides

Japanese Phyllostachys
9 71
timber bamboo bambusoides
Japanese Phyllostachys
9 74
timber bamboo bambusoides

Japanese Phyllostachys
12 54
timber bamboo bambusoides
 Tortoise shell Phyllostachys
44.6
bamboo edulis
Tortoise shell Phyllostachys
75 67
bamboo edulis

Tortoise shell Phyllostachys

15 71
bamboo edulis

Tortoise shell Phyllostachys

6 108
bamboo edulis
Tortoise shell Phyllostachys
0.2 147
bamboo edulis

Tortoise shell Phyllostachys

5 117 51
bamboo edulis

Tortoise shell Phyllostachys

30 44 55
bamboo edulis
Tortoise shell Phyllostachys
12.5 603 60.3
bamboo edulis

Tortoise shell Phyllostachys

10.3 530 83
bamboo edulis

Phyllostachys
Early Bamboo 28.5 827 79.3
praecox
Thyrsostachys
Oliveri 53 46.9 61.9
oliveri

Thyrsostachys
Oliveri 7.8 58 90
oliveri

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.[30] 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.[31] 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 Chemical structure of lignin, which makes up
hydrophobic properties reflecting the fact that it is about 25% of wood dry matter and is responsible
based on aromatic rings. These three components are for many of its properties.
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.[32]

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.[33] 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.[34] Unlike the structural constituents, the composition of extractives varies
over wide ranges and depends on many factors.[35] 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.[33] 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.[36] 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.[37]

These compounds contribute to various physical and chemical properties of the wood, such as wood
color, fragnance, durability, acoustic properties, hygroscopicity, adhesion, and drying.[36] 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.[33] 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.[34] 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.[38] 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.[39] Forchem tall oil refinery in Rauma,
Finland
Most extractives can be categorized into three groups: aliphatic
compounds, terpenes and phenolic compounds.[33] 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.[34] The most common
wood sterol is sitosterol, and less commonly sitostanol, citrostadienol, campesterol or
cholesterol.[33]
The main terpenes occurring in the softwood include mono-, sesqui- and diterpenes.[34]
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).[33][34]
The mono- and sesquiterpenes of the softwood are responsible for the typical smell of pine
forest.[33] Many monoterpenoids, such as β-myrcene, are used in the preparation of flavors
and fragrances.[34] 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.[40] 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.[41][42]
Phenolic compounds are especially found in the hardwood and the bark.[34] 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.[34] 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.[33] 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.[36] Flavonoids are very diverse, widely
distributed in the plant kingdom and have numerous biological activities and roles.[34]

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
Main global producers of roundwood
production, respectively; Africa and Europe have similar shares of by type.
20–21 percent, while Oceania produces the remaining 2
percent.[43]

Fuel
Wood has a long history of being used as fuel,[44] 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.

World production of roundwood by

Pulpwood type
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.[46] 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
Map of importers and exporters of
residential and commercial forest products including wood in
buildings as structural and 2021
aesthetic materials.

In buildings made of other

The Saitta House, Dyker
materials, wood will still be found
Heights, Brooklyn, New
York built in 1899 is made as a supporting material, especially
of and decorated in in roof construction, in interior
wood.[45] 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 The churches of Kizhi, Russia are
construction. among a handful of World Heritage
Sites built entirely of wood, without
metal joints. See Kizhi Pogost for
Flooring more details.
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.
Wood can be cut into straight planks
and made into a wood flooring.
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.[47]
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.[47] Approximately 100 million
cubic meters of wood was consumed for this purpose in 1991.[4] 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.[48] 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.[49]

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 Prayer Bead with the Adoration of
the Magi and the Crucifixion, Gothic
constructed of wood in the past. For example, cricket bats are
boxwood miniature
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.[50]

See also

Trees portal

Acetylated wood Mineral bonded wood wool board

Ancient Chinese wooden architecture Mjøstårnet
Ash burner Natural building
Burl Parquetry
Carpentry Pallet crafts
Certified wood Pellet fuel
Conservation and restoration of Petrified wood
waterlogged wood Pine tar
Conservation and restoration of wooden Plyscraper
artifacts Pulpwood
Driftwood
Reclaimed lumber
Dunnage Sawdust brandy
Forestry
Sawdust
Fossil wood
Thermally modified wood
Furfurylated wood Timber framing
Green building and wood
Timber pilings
Helsinki Central Library Oodi Timber recycling
International Wood Products Journal
Tinder
List of tallest wooden buildings Wood ash
List of woods
Wood degradation
Log building Wood drying
Log cabin
Wood economy
Log house
Wood lagging
 Wood preservation Woodturning
Wood stabilization Woodworm
Wood warping Xylology
Wood wool Xylophagy
Wood-decay fungus Xylotheque
Wooden box Xylotomy
Wood-plastic composite Yakisugi

Sources
This article incorporates text from a free content work. Licensed under CC BY-SA IGO 3.0 (license
statement/permission (https://commons.wikimedia.org/wiki/File:World_Food_and_Agriculture_-_Statisti
cal_Yearbook_2023.pdf)). Text taken from World Food and Agriculture – Statistical Yearbook 2023​ (http
s://www.fao.org/documents/card/en?details=cc8166en), FAO.

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Hoadley, R. Bruce (2000). Understanding Wood: A Craftsman's Guide to Wood Technology.
Taunton Press. ISBN 978-1-56158-358-4.

External links
The Wood in Culture Association (https://web.archive.org/web/20160527073656/http://www.
woodinculture.fi/en/) (archived 27 May 2016)
The Wood Explorer: A comprehensive database of commercial wood species (http://www.th
ewoodexplorer.com/) (Archived (https://web.archive.org/web/20150407062512/http://www.th
ewoodexplorer.com/) April 7, 2015, at the Wayback Machine)
APA – The Engineered Wood Association (https://web.archive.org/web/20110414041302/htt
p://www.apawood.org/level_b.cfm?content=prd_main) (archived 14 April 2011)
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