Prior land-use influences wood properties of Pinus radiata in New South Wales

Three pairs of sites in the Oberon area of NSW were sampled to determine the effect of prior land-use (pasture or plantation) on a range of wood properties for Pinus radiata D. Don. Paired sites were matched as closely as possible for climate and soil type. Ten trees at each site were sampled at ages 19 or 20, and outerwood basic density, fibre length, fibre coarseness, and wood pH were determined using breast-height cores. In addition, pith-to-bark profiles for air-dry density and microfibril angle were mapped for each sample. Consistent differences in wood and fibre properties were found between the paired ex-pasture and second-rotation sites. Overall, the ex-pasture sites produced lower-density wood with shorter fibres, lower fibre coarseness, higher pH, and higher microfibril angle leading to a decrease in calculated modulus of elasticity. However, when results were examined across all pairs of sites, large differences were also apparent within forest areas, with some ex-pasture sites producing better-quality wood than some second-rotation sites. Despite differences in growth patterns with prior land-use, the age of change from juvenile to mature-type wood was the same for the two site types. In the growth rings closest to the pith, wood density was similar for the ex-pasture and second-rotation sites. However, from Ring 6 onwards density was consistently higher for the second-rotation sites. There was little effect of site type on patterns of change for microfibril angle. The major effect of site type would appear to come from an increase in the volume of juvenile corewood on the ex-pasture sites.