A Comparison of Wood Properties of Coastal and Interior Provenances of Lodgepole Pine Pinus contorta Dougl. ex Loud

At the Millbuie Lodgepole pine intensive provenance plots incrementborings were extracted at similar fractional heights in treesof a central Interior and a southern Coastal provenance andthe properties of the same five growth-rings were compared.Scanning microphotometry was used to measure ring width, percent earlywood, and earlywood density. Tracheid length and width,nominal density, and latewood density were also determined.For each of these wood properties significant differences werefound between the average values for the two provenances. Inthe Coastal provenance nominal density was about 20 per centhigher than in the Interior provenance, the incidence of compressionwood was much higher, but tracheid length was about 20 per centshorter. The probable effects of these results on the propertiesof sawn timber and pulp are discussed. Average tree heightsand diameters were similar, and the earlier growth of the treeswas analysed. The relation between nominal density and ringwidth (vigour) was investigated, and a low correlation (r² of0·054 and 0·17) was found between the two quantities.Furthermore the regression lines show density decreasing slowlywith increased ring width. Both these results are in contrastwith published results for Sitka spruce.     

Factors Influencing Stem Breakage of Conifers in High Winds

Conifer stems of paraboloidal form are taken to bend along curvesproducing uniform strain in the outer wood. The total appliedbending moment arising from the displacement of the weightsof the stem and crown and from wind drag is compared with theresistive bending moment caused by the elasticity of the wood.Variation of wind speed within the canopy and vertical distributionof crown weight are taken into account. The top half of thecrown contributes most of the moment applied by wind drag. Criticalwind speeds are obtained for trees of various heights, tapersand crown weight/stem weight ratios. Critical tree heights arein keeping with those predicted by the Windthrow Hazard Classification.Trees of low taper are most liable to break.     

Theoretical Calculations of the Influence of Spacing on Stand Stability

Theoretical stability calculations for unthinned plantationsof Sitka spruce (Picea sitchensis) at spacings of 0.9, 1.4,1.8, 2.0, 2.4 and 3.0 m showed that for both static and dynamicloading the increase in the resistance to uprooting or stembreakage as a result of increasing the mean tree size outweighedthe greater drag force on the crown. Thus, increasing the spacingbeyond the currently accepted norm of 2 m would appear to improvestability. The results are sensitive to assumptions about the effect ofspacing on the relationship between the maximum turning momentand tree size, and on the effect of spacing on the wind-loadingof the crowns. Spaced-furrow ploughing is likely to have a moreadverse effect on the root anchorage of widely spaced standsthan on that of closely spaced stands and further work is requiredbefore it can be confidently asserted that wider spacings willimprove tree stability on ploughed, poorly drained soils.     

Treatment with vitamins A, D and E did not reduce weight loss in transported cattle

SUMMARY Two field trials using an injectable vitamin A, D and E solution conducted in the pastoral environment of northern Australia are described. It was found that treatment of lighter (< 150 kg) or heavier (> 372 kg) weight cattle did not reduce weight loss during road transport. These findings contradict anecdotal evidence of reduced weight loss during transport with the use of vitamins A, D and E. The lack of scientific basis for their use is discussed.     

Stability of Coniferous Tree Stems in Relation to Damage by Snow

In this work both conical and paraboloidal conifer stems aretaken to bend along curves calculated to produce uniform strainin the outer wood. Such curvature has been observed in windtunnel tests. From these curves for various displacements theresistive bending moment produced by the elasticity of the stemmay be calculated. The maximum value of this is related to thebreaking stress of the timber. The bending moments applied bythe weights of stem, crown and snowload are calculated by obtainingthe appropriate lever arms from the stem bending curves. Appliedand resistive bending moments are compared for 20m-high treesof various types. Densely grown trees of low taper are leaststable. Open grown trees with conical stems and high taper aremost stable. The effects on tree stability of wind, a leaningstem, an asymmetrical crown and basal bowing are also investigated.     

The effects of heavy thinning on stem quality and timber properties of silver birch (Betula pendula Roth)

A study was carried out into the effects of heavy thinning onstem quality and timber properties of silver birch (Betula pendulaRoth). Comparisons were made with lightly thinned and unthinnedbirch stands. Birch stands from the UK were also compared withsimilarly managed stands from Germany and Denmark. In general,trees from lightly thinned and unthinned stands had similarcharacteristics. Heavy thinning enhanced diameter incrementthrough greater ring width in comparison with the other treatments.The timber properties of basic density, grain angle and shrinkagecoefficients in the radial, tangential and longitudinal directions,however, were largely unaffected. More and bigger branches andgreater stem taper were found on trees from heavily thinnedstands, but these stems still met the current Finnish veneerbirch quality and dimension standards. Comparisons between birchstands, managed by heavy and light thinning, from the UK andGermany and Denmark revealed no meaningful differences in timberproperties. The results suggest that veneer dimension and qualitylogs could be produced in the UK in rotations as short as 40years on good sites if heavy thinning is adopted.     

Variation of Density and Growth Ring Width in Stems of Sitka and Norway Spruce

The variation with height and radial distance from the pithof basic density and ring width has been determined in stemsof 48-year-old Sitka and Norway spruce planted at two spacingsat Durris, Kincardineshire. The pattern of radial variationof density was broadly similar at all heights: high near thepith, falling to a minimum and then a gradual increase. Themean whole-stem densities were significantly different at thetwo spacings in Sitka but not in Norway spruce. Density at breastheight was inversely correlated with ring width, strongly inSitka but weakly in Norway spruce. The density/ ring width regressionequation for outer wood in Sitka spruce at age 48 differed fromthat at age 31. In Norway spruce a high correlation was foundbetween whole-stem density and the density of rings 16–25at breast height.     

An Assessment of the Static and Dynamic Factors Involved in Windthrow

Static parameters of the windthrow process were measured bywinching over ten Sitka spruce trees growing on a windthrow-susceptiblesite in the Scottish Borders. The critical wind speeds to causeuprooting were calculated using measured wind profiles and assumingstatic loading of the crown. Values obtained greatly exceededthe wind speeds recorded during a gale which caused damage.The ranking of stabilities of the ten samples was: Suppressedtrees >gt; sturdy dominants >gt; slender dominants. Recalculationusing measured damping ratios, and assuming that the gust frequencycoincided with the tree frequency to cause resonance, reducedthe values to within the range of the maximum recorded gust. Displacements of three sample trees, estimated from accelerometerdata, were compared with simultaneous wind speed recordings.Perfect resonance was not observed but large oscillations builtup over a period of 2–3 cycles. Estimates of the dynamicload factors varied from 0.5–5. The larger gusts tendedto be associated with the smaller factors. Increasing the dynamicload factor from 1 (equivalent to a static load) to 2 reducedthe critical wind speed by approximately 40 per cent. The influence of sway direction and canopy contact on the dampingratio of the three accelerometer trees was investigated. Theresults suggest that canopy contact comprises a greater portionof the damping ratio of small trees than that of dominants.