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Abstract

Silvicultural treatments that are aimed at increasing plantation growth rate may also impact directly or indirectly on wood
properties. We examined this impact in a fertiliser × clone trial in northwestern Tasmania, Australia. Nitrogen (N) and
phosphorus (P) fertilisers were applied at planting to three Eucalyptus nitens (Deane et Maiden) Maiden clones and
one F1 hybrid clone of E. nitens and E. globulus Labill. in a factorial design with each clone exposed to two levels of
nitrogen (0 and 23 kg N/ha) and two levels of phosphorus (0 and 21 kg P/ha) spot-applied close to each seedling. The
trial comprised four replicates per treatment with 5 × 5 tree clonal plots. Height was measured at ages one and two years,
and diameter at breast height over bark at age 11 years. Increment cores at breast height were obtained from one fastand
one slow-growing ramet within each clonal plot to determine corewood basic density, near infrared-predicted kraft
pulp yield, cellulose content, and extractives content. No significant interactions among main treatments were detected
for any of the growth- or wood-property traits. Nitrogen application increased cellulose content (p < 0.05). Phosphorus
application significantly increased diameter (p < 0.01), but resulted in lower wood density (p < 0.001). Within clonal plots,
large trees had lower wood density (p < 0.001) and a higher extractives content (p = 0.004) than the corresponding small
trees. Pulpwood production per hectare (calculated from plot volume, mean whole-tree adjusted density and mean plot
kraft pulp yield) indicated that: (i) the choice of germplasm had a much larger effect on plantation profitability than did the
starter fertiliser application; and (ii) that failure to account for adverse changes in wood properties in calculating pulp fibre
production would result in over-estimation of the gain in pulp production due to starter phosphorus application by up to 0.6
t/ha or 20% per 12 year rotation.

Item Type:	Article
Authors/Creators:	Stackpole, DJ and Joyce, K and Potts, BM and Harwood, CE
Keywords:	clone; Eucalyptus nitens; pulp yield; pulp productivity; wood density; growth; co-variation; nutrition
Journal or Publication Title:	New Zealand Journal of Forestry Science
ISSN:	0048-0134
Additional Information:	BM Potts Copyright © 2010 New Zealand Forest Research Institute Limited,
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