Timber Density Research Articles

Utilisation potential of plantation-grownEucalyptus nitens

Summary 20-year-old plantation-grown Eucalyptus nitens Maiden (shining gum) trees were examined for the production of structural and appearance products from sawn timber. Log characteristics were examined and measurements made of peripheral longitudinal strain. Basic density and mechanical strength characteristics of sawn timber were determined. Four commercial drying schedules were applied to 25 mm and 50 mm thick back—and quarter-sawn products. Measurements for twist spring, bow, width and thickness were made on the 50 mm boards before and after seasoning, and all boards were machined and graded to Australian Standard (AS) 2082 “Visually stress-graded hardwood for structural purposes”. The logs contained a high proportion of sapwood, and the basic density of the wood was lower than that reported for heartwood of mature E. nitens, though the moduli of rupture and elasticity, and crushing strength were comparable. The method of sawing only influenced the amount of bow in freshly sawn products. Drying redu...

The Effect of Timber Density and Type of Adhesive on the Strength of Finger-joints in S.A. Pine andEucalyptus grandis

SYNOPSIS It is universally accepted that a finger-joint is a strength reducing feature in timber members that are subjected to tensile stresses. This weakening effect is most pronounced in high density timber such as high grade S.A. Pine and the Eucalyptus species. This study compares the strength of finger-joints manufactured with phenol resorcinol formaldehyde (p.r.f.) to those manufactured with two different epoxy mixtures. The epoxy resins had to provide a stronger finger-joint without sacrificing any of the positive qualities of p.r.f. such as stiffness, durability and minimal creep. All the test specimens were manufactured according to the glue manufacturer's instruction sheet on a normal production line as it was felt that test specimens manufactured under laboratory conditions would give a false impression of the strengths that could be expected from commercially prepared finger-joints.

Productivity and management of western Queensland's rangelands.

This article provides a brief description of the environment of western Queensland, and details of management practices employed by graziers to economically produce meat and wool. Changes in pasture composition occasioned by grazing pressure and difference? in annual rainfall are given. Whereas Mitchell grasslands are stable, and only affected in the short-term by the usual vagaries ofweather and stock-imposed stres?, mulga rangelands are unstable, and in a continual state of flux. Stock management, timber density and weather are each, separately or combined, liable to effect changes in floristics and consequently in animal productivity. While Mitchell grass and mulga rangelands together cotnprise the bulk of Queensland rangelands, other rangelands are also discussed including those dominated by spinifex, eucalypt woodlands, gidgee and chenopod shrublands.

The Relationship Between Quality and Quantity in Spruce Timber Production Report of a Meeting of the Border Group of the Institute Held at Ayr, 8–9 December 1977

In northern England and southern Scotland 240,000 hectares or two-thirds of the productive woodland area are spruce, mainly Sitka spruce. A continuing theme for the Border Group has been the relation between quality and quantity of timber production in spruce, particularly Sitka spruce. It is generally accepted that the aim for Sitka spruce should be to produce a good general purpose timber. The most recent meeting discussed the results of a sawmill conversion of logs from Sitka spruce stands grown under different silvicultural regimes. Sitka spruce is intrinsically one of the lighter and weaker timbers and, to ensure that at least 80 per cent of the sawn timber is suitable for structural grades, crops should be grown within current standard silvicultural regimes with particular attention paid to the moulding of the first 6 to 8 metres of the stem which provides more than half the sawn timber. The trees should be light-branched and have the highest possible timber density. Attention must be given from planting to the thicket stage and through to final felling to the production of crops grown uniformly within their yield classes. In the higher yield classes pruning up to 5 metres may be necessary on final crop trees to maintain the strength and grade of timber rather than to provide ‘clears’. More information is required on the log sizes required for maximum sawmill recovery of chosen end products. A regional sales grading system of sawlogs should be introduced.

The Effect of Planting Espacement and Pruning on Growth, Yield and Timber Density ofEucalyptus grandis

SUMMARY Results of a comprehensive planting espacement and pruning experiment in Eucalyptus grandis on a low quality site are described. The climatic conditions during the growing period of the experiment are compared with the average conditions at this site and are shown to have been very unfavourable. The height growth was slightly above that for site quality VII (van Laar). It was found that mortality was independent of planting espacement or pruning treatment throughout the growing cycle. The conclusion was made that mean annual increment culminates at about 10 years of age on this site. Higher stand densities yielded a greater volume of timber, but this greater volume was entirely confined to the smaller tip-diameter classes, no increase in timber of more than 12,5 cm tip diameter having occurred. Pruning of the living crown reduced tree size, but not total volume per ha. Pole volumes and pole acceptability, however, were reduced by pruning. It was found that timber specific gravity was indirectly related to diameter, and that this relationship was not affected by espacement or pruning. Economic calculations show that it pays to plant more trees per acre if the greatest total volume yield is the object of management, and that the additional profit is proportional to the extra trees planted and to the capital invested. However, black wattle cultivation is clearly more profitable than growing E. grandis on this site.

FIELD TRIALS OF GEOGRAPHICAL RACES OFPINUS PINASTERIN SOUTH AFRICA

SUMMARY This paper was presented to the Fifth British Empire Forestry Conference in London, 1947, and is reprinted here with the kind permission ot the Director of Forestry. Replicated field trials with stocks of Pinus pinaster Soland., from known localities in Europe and North Africa, were established in South Africa from 1934 to 1936. The objects were to determine differences due to geographical races and to ascertain which stocks were most desirable for afforestation. The trials are described and data derived from an interim enumeration are analysed. Some data from a few older stands of known origin are also referred to. The investigation indicates that six races are represented in South Africa, namely, Corsican, Esterel, Landes, Luccan, Moroccan and Portuguese. The Portuguese race is proving superior to all others in rate of growth and density of timber and its use in preference to all others for afforestation in this country is confirmed.