PNGAF MAGAZINE ISSUE #9 JW2 of 9th Nov 2022. What are PNG Woods?

AUSTRALIAN FORESTERS in PAPUA NEW GUINEA 1922-1975

PNGAF MAGAZINE ISSUE # 9J W2 of 9th Nov 2022 WHAT ARE PNG WOODS? Editor R B McCarthy1 2022

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District Forester TPNG 1963-1975

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Legend Cover Page.

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Hardwood cell structure. Source Bottle Wood in Australia ISBN 0074510479.

Example of a PNG hardwood species. a. Pometia pinata (taun) wood description FRI Lae. b. Pometia pinata (taun)standing tree format FRI Lae. c. Pometia pinata (taun) forest setting. Cloudy Bay TA. Photo credit Dick McCarthy.

Softwood cell structure. Source Bootle Wood in Australia ISBN 0074510479.

Example of a PNG Softwood species. a. Cross section Araucaria hunsteinii Bulolo 1970. Source New Horizons. b. Araucaria hunsteinii (green klinkii pine) Bulolo, standing tree form.

Photo credit Neville Howcroft. c. Araucaria hunsteinii (green klinkii pine) Bulolo Su Su forest setting. Photo credit John Davidson. d. Araucaria hunsteinii (green klinkii pine) Bulolo. Forest setting Bulolo Valley. Photo credit John Davidson.

PNG Woods. Austimber Display 2004. Photo credit Dick McCarthy. .

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TABLE OF CONTENTS “FORWOOD” ORIGINS OF WOOD TREE STRUCTURE SOFTWOODS and HARDWOODS HOW A TREE GROWS GROWTH RINGS REACTION WOOD VISUAL CHARACTERISTICS of WOOD Texture, Grain, Figure HARD VERSUS SOFT CHEMISTRY OF WOOD Silica Greasy nature Extractives Odour and Taste

page 4 page 4 page 5 page 6 page 7 page 10 page 14 page 15

COLOUR

page 19

FACTORS AFFECTING WOOD MECHANICAL PROPERTIES

page 21

page 16 page 17

Wood Density Moisture Content Specific Gravity Hardness Strength Groups Brittleheart Rates of Growth Percentage of Latewood Position in Tree Natural Durability Temperature Effect of Knots Overgrowth of Injury Grain Distortion Compression Failures Blue Stain Pinhole Borer Damage Lyctid Damage Marine Borers Termite Damage Decay – Fungi - White, Brown, Soft Rot Gum Veins Shakes, Splits, Checks REFERENCES

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ACRONYMS

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“FORWOOD” Wood 2 • • •

is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. is an organic material – a natural composite of cellulose fibres that are strong in tension and embedded in a matrix of lignin that resists compression. is a heterogeneous, hygroscopic, cellular, and anisotropic 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%).

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.

Wood is renewable. It has a variety of species and colours, workability, highly versatile, relatively light in weight, yet has good strength in both tension and compression. It provides rigidity, toughness, buoyancy, and insulating properties. It can be bent or twisted into special shapes, and it is readily worked, fastened, and finished. The finished surface is pleasant to the touch and the visual patterns provided can be of great beauty Despite its wide range of application and the profligate use made of it when it is abundant, wood, like most other materials, should not be applied without thought for the conditions under which it will serve or for the inherent properties that will determine its suitability. A natural substance, wood reflects the conditions under which it was grown through the variations in its properties, which vary in different directions. There are marked variations from one species to another.

Consequently, there is a continuing challenge in the development of wood technology to recognize the inherent nature of wood and to understand the implications of it at every stage, from the harvesting of the trees to their final conversion to the end uses.

ORIGINS OF WOOD. Botanically wood comes from plants which belong to the Spermatophya – a division of seedbearing plants which is subdivided into Gymnospermae and Angiospermae.

A spermatophyte (lit. 'seed-bearing plants'; from Ancient Greek (spérmatos) 'seed', and (phytón) 'plant') is any plant that produces seeds, hence the alternative name seed plant.

Spermatophytes are a subset of the embryophytes or land plants.

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PNGAF MAG # 94C! P11-20 OF 20TH March 2022.

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Seed-bearing plants are a subclade of the vascular plants (tracheophytes) and were traditionally divided into angiosperms, or flowering plants, and gymnosperms, which includes the gnetophytes, cycads, ginkgo, and conifers The extant spermatophytes form five divisions, the first four of which are traditionally grouped as gymnosperms, plants that have unenclosed, "naked seeds": • • • •

Cycadophyta, the cycads, a subtropical and tropical group of plants, Ginkgophyta, which includes a single living species of tree in the genus Ginko, Pinophyta, the conifers, which are cone-bearing trees and shrubs, and Gnetophyta, the gnetophytes, various woody plants in the relict genera Ephedra, Gnetum, and Welwitschia.

The fifth extant division is the flowering plants, also known as angiosperms or magnoliophytes, the largest and most diverse group of spermatophytes: - Angiosperms, the flowering plants, possess seeds enclosed in a fruit, unlike gymnosperms.

TREE STRUCTURE 3

The plant vascular system is comprised of two main types of tissue: the xylem and the phloem. The xylem distributes water and dissolved minerals upward through the plant, from the roots to the leaves and provides physical support. The phloem carries food downward from the leaves to the roots. The word xylem is derived from the Ancient Greek word ξύλον (xylon), meaning "wood"; the best-known xylem tissue is wood, though it is found throughout the plant.

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Qld Dept of Forestry/Dept Education/TRADAC 1982-85. ForEd Project 1982-1985.

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SOFTWOODS and HARDWOODS In the plant kingdom, hardwoods are angiosperms (flowering plants – broad leaved plants) and softwoods are gymnosperms (cone-bearing plants usually with needle like leaves).

Softwoods4 (make long fibred pulp) have a simple wood structure where most of the wood consist of tracheids – long narrow cells up to 7 mm long. Tracheids functions include – conducting water and nutrients up from the roots, supporting the tree and providing physical support and strength.

In coniferous or softwood species 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.

Hardwoods (make short fibred pulp) have a more complex wood structure. Vessels are long hollow pipes consisting of wide short cells stacked one above the other. These hollow vessels carry water and nutrients up from the roots. Fibres are the strength giving cells. They are short (about 1 mm long and usually thick walls). Their only function is to support the tree. They are the most numerous cells.

In discussing such woods, it is customary to divide them into two large classes, ringporous and diffuse-porous.

The main physical characteristic of wood fibres is their strong tension that is created both by its natural strength, and the way the fibres are embedded in a matrix that very effectively resists compression. Wood plays an important supporting role in a living tree – it enables all woody plants a strong structure on which they can grow and reach more sunlight than surrounding plant life, to elevate their fruit from the easy reach of animals and off course, it conveys the nutrients and water between roots and canopy.

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Source Qld Forestry ForEd Project 1982-1985.

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Wood fibres are the cellulosic elements that are extracted from the wood of trees and used to make materials in the modern composite pulp and paper industry due to their specific characteristics (including paper products as paper, paperboard, tissue, cardboard etc, and feedstock to produce purified cellulose and its derivatives, such as cellophane and cellulose acetate.).

HOW A TREE GROWS5 .

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Source Qld Forestry ForEd Project 1982-1985

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A thin layer of living cells between the bark and the wood, called the cambium subdivides every year to form new wood on the inner side and phloem or bast on the outside.

As the inner diameter of the tree increases, the old bark splits and new bark is formed by the bast. Cambial cells are weak and thin walled. In the growing season when they are moisture laden, the bark can be easily peeled. In winter months, the cells stiffen and bind the bark firmly. The new wood cells on the inside develop into two specialised types – living cells which store food for the tree and non-living cells which conduct sap up the tree and provide support for it. These two types make up the sapwood layer.

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Source Qld Forestry ForEd Project 1982-1985.

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Each year a new ring of sapwood is built up on the outside of the previous year’s growth. At the same time, the oldest sapwood nearer the centre is no longer used to conduct water; it is chemically converted into the heartwood that forms the structural spine of the tree. The area of heartwood increases annually, while the sapwood remains around the same thickness during the trees’ life.

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Good Wood – basic woodworking. A Jackson & D Day iSBN 0007129491

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GROWTH RINGS A diagram 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.

Source Wikipedia.

Where the differences between the four seasons are distinct, e.g., temperate regions, 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 tropical zones), 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. Source Wikipedia.

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Cross-section of an oak log showing growth rings. Source Wikipedia.

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.

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. Upon the whole, however, as a tree gets larger in diameter the width of the growth rings decreases.

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.

Source Wikipedia.

Heartwood 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.

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.

Sapwood 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.

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The life of a Slash Pine (Pinus elliottii.).

Photos left to right Standing plantation tree.

Branch containing needles, current season male cones, next seasons female cones and last seasons opened female cones. Mature bark.

1904 slash pine tree is born.

1909 Sapling

1914 tree pushed sideways creating reaction wood.

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1924 now narrow growth rings, requires thinning.8

1927, surrounding tree harvested. Now with ample nutrient and sunlight available, tree can now grow rapidly again.

1930. a fire through the forest causes partial scarring.

1942. Narrow growth rings reflect a prolonged dry spell.

1957. Another series of narrow growth rings presumed to be caused by diseases and/or insect /fungal damage to roots or leaves.

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Source Qld Forestry ForEd Project 1982-1985.

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REACTION WOOD The wood of greatest commercial value comes from the straight main stem of the tree. Wood from branches, apart from not being sufficiently straight, has considerable growth stresses in it due the formation of reaction wood.

Reaction wood is formed when the tree is subject to prolonged structural stress, such as leaning trunks or continual exposure to strong winds. It is associated with eccentric growth of wood, with more tissue being formed on the upper side of the leaning stem or branch of hardwoods (called tension wood) and on the lower side of softwoods (called compression wood).

In many tropical hardwoods, tension wood is a feature mainly emanating from leaning or crooked stems. Its presence is revealed during sawing by one most characteristic feature, namely the extreme wooliness or furriness of the sawn longitudinal surfaces.

In tropical softwoods, compression wood may cause drying problems, but difficulties in conversion are less severe than the tension wood of hardwoods.

Spiral Grain The helical orientation of the grain can be caused by environmental factors as persistent strong wind but more often a genetic factor. (Important check for tree breeders).

Knots A knot on a tree trunk.

Source Qld Forestry ForEd Project 1982-1985 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. Their bases may become overgrown and enclosed by subsequent layers of trunk wood, forming a type of imperfection known as a knot.

Subsequent growth of wood may completely conceal the stubs which will however remain as knots.

Since in most uses of wood, knots are defects that weaken the timber and interfere with its ease of working and other properties. Knots affect the technical properties of the wood, usually reducing tension strength, but may be exploited for visual effect.

Wood knot in vertical section.

Source Qld Forestry ForEd Project 1982-1985

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VISUAL CHARACTERISTICS of WOOD These features of wood, (texture, grain, and figure), play an important part in determining wood’s suitability for decorative use.

Texture Wood is described as fine or coarse, even, or uneven. It is determined by the size and arrangement of the cells, and by variations in density as a result from earlywood and latewood.

Grain The grain of wood refers to the general direction of growth of the woody tissue. It is indicated by the way it tends to separate when a piece of wood is split. It can be straight, spiral, sloping, interlocked, curly, wavy, or rippled.

Figure With wood, this describes the ornamental markings seen on the dressed surface and produced by the arrangement of the various wood tissues and variations in colour. Descriptions of figure include fiddleback, ribbon, striped, silver, burl, bird’s eye.

Myrtle Beech Nothofagus cunninghamii Burl. Photo credit Dick McCarthy.

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HARD VERSUS SOFT. (It is common to classify wood as either softwood or hardwood) The wood from conifers (e.g., pine) is called softwood. Softwoods are gymnosperms (conebearing plants usually with needle like leaves).

Hoop Pine (Araucaria cunninghamii) Left - a large hoop pine tree.

Bottom right characteristic bark.

Top right top of tree showing needle like leaves and maturing female cones9.

The wood from dicotyledons (usually broad-leaved trees, e.g. oak) is called hardwood.

Hardwoods are angiosperms (flowering plants – broad leaved plants.

Spotted Gum (Eucalyptus maculata) Left - a stand of spotted gum trees in SW Qld. Bottom right spotted bark of larger trees Top right - the foliage, flowers, and capsules of the trees.10 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.

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Source Qld Forestry ForEd Project 1982-1985 Photo from A Gardeners Guide to Eucalypts by I Holiday & G Watton Rigby Brisbane 1980.

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CHEMISTRY OF WOOD 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, phosphorous, 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%.

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 25% of wood dry matter and responsible for many of its properties. Lignin confers the hydrophobic properties reflecting the fact that it is based on aromatic rings.

Chemical structure of lignin.

Source Wikipedia.

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.

Silica.

Silica is the main mineral inclusion which affects sawing properties. A number of tropical hardwoods contain appreciable amounts of silica.eg Anisoptera thurifera, Burckella obovata, Teysmannodendron bogoriense, Maranthes corymbosa.

Greasy Nature Some wood is distinctly greasy or oily to the touch. This is due to an excessive content of fatty or waxy substances. This property can cause difficulties with gluing, painting, and varnishing. Similarly, the greasiness of a wood can influence its actual end use where the property may be used as an advantage. E.g., dance floors.

Extractives Aside from the structural polymers, i.e., cellulose, hemicellulose and lignin, 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 17

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, fragrance, 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 the paper industry. Some extractives are surface-active substances and unavoidably affect the surface properties of paper, such as water adsorption, friction, and strength. Extractives also account for paper smell, which is important when making food contact materials.

Odour and Taste Odour in wood is caused by the presence of infiltration products in the heartwood. They may be pleasant or disagreeable. Many timbers have a distinctive characteristic odour when freshly sawn.e.g., Wau Beech (Elmerrillia papuana), Scented Maple (Flindersia laevicarpa) and Camphorwood (Cinnamomum spp.). Aromatic compounds with persistent and agreeable odours are common in certain families e.g., Lauraceae.

Odour can influence a wood’s end use. The choice of woods for food containers is restricted to those timbers without pronounced odour or taste to avoid tainting or contamination of food. However, odour is a property which may be desirable for such uses as linen boxes.

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COLOUR The basic structural components of wood (cellulose, lignin, and hemi-cellulose) do not give it colour. The colour which give species their individual aesthetic appeal are complex organic compounds such as flavones and quinones which are more concentrated in the heartwood than the sapwood, hence the common colour distinction between them.

When subject to long-term exposure to sunlight, these compounds undergo chemical change: blond woods acquire a yellowish tint and red ones become brown. This is termed weathering.

Such changes are limited to the surface layers of wood and the original colour can be regained by sanding or planing the surface.

Colours of PNG Woods

11 Description of PNG WOODS above.

Cover

Amberoi Pterocymbium beccari

Water Gum

Erima

Beech

Syzygium spp.

Octomeles sumatrana

Nothofagus spp.

Hopea

Malas

Calophyllum

Mersawa

Taun

Hopea spp.

Homalium foetidum

Calophyllum spp.

Anisoptera thurifera

Pometia pinnata

Red Brown Terminalia

Kamarere

Yellow Terminalia

PNG walnut

PNG Vitex

Eucalyptus deglupta

Terminalia spp.

Dracontomelon mangiferum

Vitex cofassus

Kapiak

High Mt Podocarp

PNG Oak

PNG Quandong

PNG beech

Artocarpus spp.

Dacrycarpus imbricatus

Lithocarpus spp.

Elaeocarpus spp.

Nothofagus perryi

PNG Walnut

PNG Rosewood

White cheesewood

White Tulip oak

Taun (red brown)

Dracontomelon dao

Pterocarpus indicus

Alstonia scholaris

Pterygota horsfildi

Pometia pinnata

Terminalia spp.

Kwila Instia spp.

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PNG Woods comprises an incredible variety of timber species with hues from white, yellow to golden brown and black that are used for furniture manufacture, flooring, boat building, chopsticks, turnery and for other structural engineering tasks. The timbers’ subtle colours, textures and feel are qualities that make one species attractive to some consumers, while the uniqueness of some may make another species virtually as valuable as gold.

PNG Face Mask. Photo credit Dick McCarthy.

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FACTORS AFFECTING WOOD MECHANICAL PROPERTIES The main factors affecting the mechanical properties of wood (significant in building construction) include density, brittleheart, rate of growth, percentage of latewood, position in tree, moisture content, temperature, duration of loading, effect of knots, grain distortions, blue stain, pin hole borer damage, decay, gum veins, shakes, splits, and checks.

Wood Density Wood density is defined as the weight of wood in kilograms which would occupy a volume of one cubic metre at a given moisture content.

The density of seasoned wood (air dry density) is given at the average figure of 12 % moisture content.

Age, diameter, height, radial (trunk) growth, geographical location, site and growing conditions, silvicultural treatment, and seed source all to some degree influence wood density. 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. In general, the denser a species, the greater the mechanical properties of its clear material.

Moisture Content Water occurs in living wood in three locations, 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 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. Drying produces a decided increase in the strength of wood, particularly in small specimens.

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Specific Gravity The single most revealing property of wood as an indicator of wood quality is specific gravity as both pulp yield and lumber strength are determined by it.

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Source Qld Forestry ForEd Project 1982-1985

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Specific gravity is the ratio of the mass of a substance to the mass of an equal volume of water. Upon drying, wood shrinks and its density increases. Variation of specific gravity within the bole of a tree can occur in either the horizontal or vertical direction.

Hardness The Janka hardness test was created by Austrian-born American researcher Gabriel Janka (1864–1932). It measures the resistance of a sample of wood to denting and wear. A common use of Janka hardness ratings is to determine whether a species is suitable for use as flooring.

Strength Groups PNG woods have been classified according to the Australian System of Strength Groups (devised and reviewed by CSIRO and State Forest Services).

Property

S1

S2

S3

S4

S5

S6

S7

Basic density

900

760

640

540

450

375

320

103

86

73

62

52

43

36

16300

14200

12400

10700

9100

7900

6900

52

43

36

31

26

22

18

13.1

11.0

9.1

7.7

6.6

5.5

4.6

Kg/cubic m3 Modulus of rupture megapascals Module of elasticity megapascals Maximum crushing strength megapascals Maximum shear strength Megapascals Modulus of rupture is the measure of the maximum compressive or tensile strengths in the wood fibres at the point of fracture. It is a direct measurement of the strength of wood in bending.

Module of elasticity is a measure of the stiffness or rigidity of wood. E.g., for a beam, the modulus of elasticity is a measure of its resistance to deflection.

Compression parallel to grain (maximum crushing strength) is a measure of the maximum stress sustained by wood under a load applied slowly parallel to the grain. It indicates the relative suitability of timber for columns.

Shear is a measure of the ability of wood to resist slipping of one part upon another alongside grain.

Creep is long term deformation under load. A wood member loaded continuously for ten years could only carry about sixty percent of what it can easily sustain for a few minutes.

Timber being of a non-crystalline nature is less subject to fatigue failure than metals but it is not immune.

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Brittleheart (Heart in hardwoods, Pith in softwoods)

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The pith in softwoods (heart in hardwoods) forms at the centre of the tree. This wood may be a lot weaker and lower in density than surrounding wood fibre. Wood near the centre of the tree may have suffered high compressive stress in the initial stages of growth and may be abnormally low in impact or shock resistance and liable to abrupt failure at comparatively small deflections. Grading rules address the occurrence of brittleheart and reject its use.

Rates of Growth Wood from trees of moderate growth is likely to have some superiority over very fast or very slow grown material.

Percentage of Latewood Some species of pronounced seasonal growth habits have thicker walled cells in the wood formed late in the growing season and such wood is denser and stronger than that formed at the beginning of the season.

Position in the tree.

Acacia tray depicting early wood (light colour) and late wood (darker colour) across the stem. Photo credit Dick McCarthy.

Wood from the butt section of a tree is expected to be more dense and stronger than wood from the top of the tree.

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Source Qld Forestry ForEd Project 1982-1985

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Natural Durability The wood of timber species is classified according to a durability classification based on the resistance of sound untreated heartwood (of hardwoods) to attack by wood destroying fungi, borers, and insects. The sapwood of all species is regarded as non-durable.

CSIRO Forest Products Durability Classification Class 1

Very durable

Suitable for long `term use in structures exposed to the weather, and in contact with the ground.

Class 2

Durable

Suitable for use in the ground and for unprotected exterior use under normal conditions.

Class 3

Moderately durable

Class 4

Non-durable

Suitable for protected exterior work and for interior use.

Not suitable for use in contact with ground.

Not suitable for exterior use unless treated with preservative.

“Graveyard” timber durability trials CSIRO/TPNG Forests Kerevat ENB PNG 1967 & Bob Willis TA. Photo credit Ian Whyte.

Temperature Above normal temperatures tend to lower the strength properties of wood and lower temperatures make it stronger.

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Effect of Knots13

Knots can have a major effect on mechanical properties since they interrupt the continuity and change the direction of the wood tissue. Knots are formed by longitudinal sawing of tree trunks through areas where branches were attached to the trunk. The slope in grain around knots can be very severe and thus reduce the strength properties of the piece of wood.

Overgrowths of Injury14

Formed in the living tree when branches fall off or the tree is damaged by fire, insects, or animals. New woody tissue grows into the damaged area. Similarly, to knot effect, the grain at overgrowth is discontinuous, and thus reducing the strength of the piece of wood.

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Source Qld Forestry ForEd Project 1982-1985 Source Qld Forestry ForEd Project 1982-1985

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Grain Distortion15 Besides grain distortion caused by knots, there are other types of grain distortion as spiral grain, diagonal grain, interlocked grain, and curly grain.

Sloping grain may be due to spiralling in the trunk of the tree although it can also be caused by not sawing parallel to the log longitudinal axis.

Compression Failures16

Localized creases in the wood arising from severe stresses due to high winds, or the felling operation, can cause a serious reduction of tensile strength and impact resistance, leading to a brittle fracture.

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Source Qld Forestry ForEd Project 1982-1985 Source Qld Forestry ForEd Project 1982-1985

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Blue Stain17

The sapwood of many species is very susceptible to discoloration by blue stain fungi in warm humid weather. Unless a very severe attack, little impact on mechanical properties.

Pin Hole Borer Damage18 The ambrosia or pin hole borer can cause a serious weakening in strength if there is a large concentration of holes.

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Source Qld Forestry ForEd Project 1982-1985 Source Qld Forestry ForEd Project 1982-1985

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The characteristic effects of ambrosia beetle damage on wood is depicted by the tunnels and associated staining. The effect of damage is largely on appearance, sawn recovery and in severe cases on strength.

Lyctid damage to susceptible timber19

The recognition signs of lyctid powder-post beetle attack. Unchecked attach can result in a hollowing out of the wood with resulting loss of strength.

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Source Qld Forestry ForEd Project 1982-1985

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Marine Borers20

Marine borers cause extensive damage to wood which has been underwater for any length of time. A wood boring mollusc (teredo – shipworm) causes these large holes.

Termite damage21

Subterranean termites bridging of ant caps. The bridging of ant caps by termites makes recognition of attack easy. The strength of damaged timber is greatly reduced.

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Source Qld Forestry ForEd Project 1982-1985 Source Qld Forestry ForEd Project 1982-1985

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Drywood termite damage by West Indian drywood termites is evidenced by the presence of frass. Wood strength is greatly reduced by the tunnel effect as shown.

Pine beam attacked by West Indian drywood termite22

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Source Qld Forestry ForEd Project 1982-1985

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Decay Wood, in which decay fungi have become well established has little strength, particularly regarding impact resistance.

Fungi as agents of damage23. Here fruiting bodies of a fungus on a piece of rotting wood.

White Rot24. White rot fungo require moist wood and attack is mostly on the inside. This fungi feeds on the brownish lignin leaving the white cellulose. White rot seriously affects wood strength.

23 24

Source Qld Forestry ForEd Project 1982-1985 Source Qld Forestry ForEd Project 1982-1985

31

Brown rot25. For attack by brown rot, wood must be wet at least intermittently. The fungus feeds on the cellulose leaving the lignin, hence the brownish colour. Affected wood eventually breaks up into cubical pieces which crumble to brown powder. Brown rot seriously affects the strength of wood. It may be difficult to detect because it occurs inside the wood.

Soft rot.26 Soft rot tolerates much greater moisture conditions and are found in damp locations. The wood is degraded inwards form the surface. Affected wood is usually soft but becomes hard and brittle when dried. The fungi feed mostly on cellulose and hence the wood becomes darker in colour. The strength of wood is seriously affected.

25 26

Source Qld Forestry ForEd Project 1982-1985 Source Qld Forestry ForEd Project 1982-1985

32

Gum Veins27

Because of the discontinuity of tissue which they represent, gum veins reduce strength. Gum veins most frequent in eucalypts, the formation of which is a natural protective response to injury such as fire.

Shakes, Splits and Checks28 These forms of fibre separation reduce resistance to share stress. They should not be present in quantity at joints.

Cross shakes are usually formed when the wind forces on a standing tree are such that they cause a compression failure in the wood fibres or alternatively when the tree is felled and lands awkwardly.

27 28

Source Qld Forestry ForEd Project 1982-1985 Source Qld Forestry ForEd Project 1982-1985

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Checks are usually formed when timber dries out and growth stresses that were in the tree are relieved in the sawn timber. Checks do not usually affect strength but can be unacceptable in flooring because of appearance.

A forthcoming PNGAF Mag addresses the PNG wood scientists who studied the physical, chemical, and biological properties of wood to find ways of processing the raw material into different products such as pulp, paper, construction timber and into products such as chipboard, fibre board and laminated beams. They describe and categorise different wood species by chemical and physical attributes as durability, treatability, density, moisture movement, workability, availability, typical uses, and production methods.

Wood is a renewable but expensive commodity. Wood scientists find ways to use every scrap of the raw material.

E.g., Chipboard was invented when people noticed piles of sawdust going to waste at sawmills. Wood Scientists ‘invented’ a new type of wood by mixing the sawdust with modern wood glues, making sure nothing went to waste.

E.g., Paper is a vital part of the modern world. Wood Scientists use their skills and training to find new ways and processes to produce paper-based products.

E.g., They also work in other fields such as primary processing (timber treating), plywood manufacture, fibre and particle board manufacture and saw-milling, secondary processing (furniture, joinery, building and timber construction) and other (research, marketing, labour, and training).

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REFERENCES Bootle K R 1983. Wood in Australia ISBN 0074510479 Dept. of Forests Forest Products Research Centre 1970. Properties and Uses of Papua and New Guinea Timbers Revision 1970, Port Moresby.

Dept of Forests 1973. NEW HORIZONS Forestry in Papua New Guinea Brisbane ISBN 0 701681845 Jacaranda Press., Brisbane. Pp. 1-70, plus six maps. # (1). # An updated account of forestry in Papua New Guinea with particular reference to resources, commercial timbers, and marketing.

Eddowes P 1977. Commercial Timbers of Papua New Guinea Their Properties and Uses First published in 1961 Forest Products Research Centre Director Office of Forests Papua New Guinea.

FPRC. 1970. Properties and Uses of Papua and New Guinea Timbers. Second trade note.

Department of Forests, Division of Utilization, FPRC, Hohola. Pp. 1-44. (1).

Jane F W 1956. The Structure of Wood. Reprinted 1970. ISBN0713609125.

Jackson A & Day D 1998 GOOD WOOD – basic woodworking. ISBN 0007129491 Lefteri C 2003 WOOD - Materials for Inspirational Design ISBN 2880466458 Queensland ForEd Project 1982-1985. Qld Dept of Forestry, Qld Dept of Education & Timber Research & Development Advisory Council.

Stacpoole J 1992. What timber will I use? ISBN 064628181X Wallis N K 1970. AUSTRALIAN TIMBER HANDBOOK Third Edition. ISBN 0207120536

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ACRONYMS AAD ACT ACIAR ACLMP ACP ADB ADD AEC AFAP ADB AFLEGT AFPNG AFS AFTA AIF AMF ANBG ANGAU ANU APEC APMF APPM ARD ASEAN ASIO ASOPA ATIBT ATL ATO AusAID BA BCOF BDV “Beer Time” BFC BGD BNGD BUC C cm CALM CBD CDM CEFACT CEPT CERFLOR CFA

Australian Antarctic Division Australian Capital Territory Australian Centre for International Agricultural Research AusAid funded World Bank Land Mobilisation program.

African, Caribbean and Pacific States Asian Development Bank Air Dry Density Administrators Executive Committee Australian Foundation for the Peoples of Asia & the Pacific Ltd. African Development Bank African Forest Law Enforcement, Governance and Trade Association of Foresters of PNG Australian Forestry School Asean Free Trade Area Australian Infantry Forces Australian Military Forces Australian National Botanical Gardens Australian New Guinea Administrative Unit Australian National University Asia-Pacific Economic Cooperation Australian Paper Manufacturers Forestry Pty Ltd Australia Paper and Pulp Manufacturers Afforestation, Reforestation and avoided Deforestation Association of South East Asian Nations Australian Security Intelligence Organisation Australian School of Pacific Administration Association Technique Internationale des Bois Tropicaux Accelerated Tariff Liberalization African Timber Organization Australian Aid Agency basal area British Commonwealth Occupational Force 1945-52 Brussels Definition of Value Any time.

Bulolo Forestry College Bulolo Gold Dredging Company British New Guinea Development (Company Limited) Bulolo University College Commonwealth centimetre Western Australian Department of Conservation and Land Management Convention on Biological Diversity Clean Development Mechanism United Nations Centre for Trade Facilitation and Electronic Business Common Effective Preferential Tariff Certificate of Origin of Forest Raw Material, Brazil Commonwealth Forestry Association 36

CFE CGTM CIF CIFOR CITES C&I CNGT CO2 COC COP CPF CRE CRE

CSIRO CHAH C&I C&L CSD CTE DASF DBH/ dbh DEPT DESA DIES DIY DPI DOF DSB EC ECE ECOSOC EEA EFI EIA EMAS EMS ENB e.g.

ENGO Etc EU EVSL FAO F &TB FIM

Community forestry enterprise Cintra for Global Trade Model cost, insurance, freight Centre for International Forestry Research Convention on International Trade in Endangered Species of Wild Fauna and Flora Criteria and indicators Commonwealth New Guinea Timbers Bulolo carbon dioxide chain of custody Conference of Parties Collaborative Partnership on Forests Commander Royal Engineers CRE is a term inherited by RAE from RE and is the term for the Commanding Officer of a RAE unit which is headed by a Lt Col. Although the officer is called the CRE the name is also used for the name of his unit.

E.g., CRE Aust Forestry Group or 1(NG Forests).

Commonwealth Scientific & Industrial Research Organisation Council of Heads of Australasian Herbaria Criteria and Indicators Certification and Labelling Commission on Sustainable Development (United Nations) Committee on Trade and Environment Dept of Agriculture, Stock and Fisheries Diameter at breast height Department United Nations Department of Economic and Social Affairs Department of Information and Extension Services Do-it-yourself Department of Primary Industry Department of Forests Dispute Settlement Body European Commission ECA Export credit agency Economic Commission for Europe Economic and Social Council of the United Nations European Economic Area European Forest Institute Environmental Investigation Agency Eco-Management and Audit Scheme of European Union Environmental Management System East New Britain Province.

For example Environmental Non-governmental Organisation et cetera (more of the same) European Union Early Voluntary Liberalisation Food and Agriculture Organisation Forest and Timber Bureau Canberra Forest Information System 37

FMA FPRC FRA FRG FRI Forkol FSP/PNG FCCC FD FDI FIELD FLEGT FLEG FLONAS FOB FPRC FSC FTAA GAB Gbhob Gubab GIS G8 GATT GDP GEF GFTN GFPM GHG GIS GMO GNP GPA GSP GTZ ha IBRD IEA IFA IFY IADB IBAMA ICA ICCI IDB IEA IEC IFC IFF

Forest Management Agreement Forest Products Research Centre Hohola Forest Resource Assessment Forest Red Gum Forest Research Institute Lae Bulolo Forestry College Foundation of the Peoples of the South Pacific See UNFCCC Forest department Foreign direct investment The Foundation for International Environmental Law and Development Forest Law Enforcement, Governance and Trade Forest Law Enforcement and Governance National Forest logging concessions, Brazil free on board Forest Products Research centre Hohola Dept of Forests PNG Forest Stewardship Council Free Trade Area of the Americas Girth above buttress Girth breast height over bark Girth under bark above buttress Geographic Information Systems Group of Eight (leading economies) General Agreement on Tariffs and Trade Gross Domestic Product Global Environment Facility Global Forest and Trade Network Global Forest Products Model greenhouse gas Geographical information system genetically modified organism Gross National Product Plurilateral Government Procurement Agreement Generalized System of Preferences Deutsche Gesellschaft für Technische Zusammenarbeit hectare International Bank for Reconstruction and Development International Energy Agency Institute of Foresters of Australia International Year of the Forest Inter-American Development Bank Amazon Environmental Institute, Brazil International Commodity Agreement International Conference on C&I for Sustainable Forest Management Inter-American Development Bank International Environmental Agreement International Electrical Commission International Finance Corporation Intergovernmental Forum on Forests 38

IHPA IIED IMF INGO IPC IPCC IPF ISO ITC ITTA ITTC ITTO IUCN IWPA JICA L of N LRRS LCA LEEC LEI LULUCF m3 MCCAF MHA MM MUS MEA MFN MIGA MOU MTTC n.a.

NAA NARI NB NAFTA NGO NHLA NRRP NT NTB NTCC NTFP NTM NWFP NDS NFCAP NGM no.

NG

International Hardwood Products Association International Institute for Environment and Development International Monetary Fund International Non-Governmental Organisations Integrated Programme for Commodities Intergovernmental Panel on Climate Change Intergovernmental Panel on Forests International Organization for Standardisation International Trade Centre International Tropical Timber Agreement International Tropical Timber Council International Tropical Timber Organization The World Conservation Union International Wood Products Association Japanese International Cooperation Agency League of Nations Land Resource Soils Survey (branch of CSIRO) Life Cycle Analysis London Economic and Environmental Centre Indonesian Ecolabelling Institute Land Use, Land Use Change and Forests cubic metre McCarthy & Associates (Forestry) Pty. Ltd. Member of House of Assembly PNG Military Medal Malayan Uniform System Multilateral Environmental Agreement Most Favoured Nation Multilateral Investment Guarantee Agency Memorandum of Understanding Malaysian Timber Certification Council not available National Archives Australia National Agriculture Research Institute New Britain North American Free Trade Agreement Non-Governmental Organisation National Hardwood Lumber Association Natural Resources and Rights Program National Treatment non-tariff barrier National Timber Certification Council non-timber forest product non-tariff measures non-wood forest product Northern District Sawmills PNG National Forestry and Conservation Action Plan New Guinea Mainland number New Guinea 39

NGF NGIB NGI NGO NGVR NZ NSW NTSC OECD OTO OIC OISCA OTML P or p PEFC PIB PIR PNG PNGAA PNGAF PNGFA PNGFIA PNGRIS PNGUT POM P&C PEFC PGA PPM PPP QLD QF RAE RPC RRA RIIA RIL RFE RTA RWE SAP SPS SFM SGS SMS SP SPWP sq m TAG

New Guinea Forces (relates to plant collection of Lae Herbarium) New Guinea Infantry Battalion New Guinea Islands Non-Government Organisation New Guinea Volunteer Rifles New Zealand New South Wales National Tree Seed Centre PNG Bulolo Organization for Economic Co-operation and Development Office of Trade and Investment Ombudsman Officer in Charge Organisation for Industrial, Spiritual and Cultural Advancement International Japan.

Ok Tedi Mining Ltd page Pan European Forest Certification Scheme Papuan Infantry Battalion Pacific Islands Regiment Papua New Guinea Papua New Guinea Australia Association Papua New Guinea Australian Foresters Magazine Series Papua New Guinea Forest Authority PNG Forest Industries Association Papua New Guinea Resource Information System PNG University of Technology Port Moresby Principles and Criteria Pan-European Forest Certification Framework Plurilateral Agreement on Government Procurement production and processing method Polluter Pays Principle (other meaning Purchasing Power Parity) Queensland Queensland Forestry Royal Australian Engineers/Australian Army Royal Papuan Constabulary Rapid Resource Appraisal Royal Institute of International Affairs reduced impact logging Russia Far East Regional Trade Agreement roundwood equivalent structural adjustment programme Sanitary and Phytosanitary Measures Sustainable Forest Management Société General de Surveillance Selective Management System Malaysia South Pacific Secondary Processed Wood Products square metres Trade Advisory Group of ITTO 40

TSS TBT TFF TFRK TNC TRADC TRAINS TREM TRIM TRIP UK UN Unasylva UNCCD UNCED UNCSD UNCTAD UNESCO UNDP UNECE UNEP UNFCCC UNFF USTR UNE UNEP UNI UNITECH UNRE UPNG UQ US USA USD TPNG TUBL TA TA TRP Vol VSF WA WB WCMC WCO WSSD WTO WWF

Tropical Shelterwood System Technical Barriers to Trade Tropical Forest Foundation traditional forest-related knowledge Transnational corporation Timber Research & Development Advisory Council Qld. Trade-Basic Indicators of UNCTAD trade-related environmental measures Trade Related Investment Measures Trade-Related Aspects of Intellectual Property Rights United Kingdom United Nations Journal of FAO of UN United Nations Programme to Combat Desertification United Nations Conference on Environment and Development United Nations Committee on Sustainable Development United Nations Conference on Trade and Development United Nations Economic and Social Council United Nations Development Programme United Nations Economic Commission for Europe United Nations Environment Programme Framework Convention on Climate Change of United Nations United Nations Forum on Forests US, Office of the US Trade Representative University of New England Armidale NSW United Nations Environment Program University University of Technology Lae PNG University of Natural Resources and Environment University of Papua New Guinea University of Queensland United States United States of America United States dollar Territory of Papua and New Guinea Territory United Brewery Ltd Timber Area Timber Authority Timber Rights Purchase volume Victorian School of Forestry Western Australia World Bank World Conservation Monitoring Centre World Customs Organisation World Summit for Sustainable Development World Trade Organization World Wide Fund for Nature

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