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9.8 Posts and Poles
Authors: P M Carpenter, G B WalfordPublication: NZIF Forestry Handbook, Volume Section 9 – Utilisation of forest products, pp 8, Dec 2023
Publisher: New Zealand Institute of Forestry
Abstract: Corsican pine, Douglas-fir, and European larch have been important species in the production of softwood poles in New Zealand for the past 40 years. Corsican pine has been the dominant species, also utilised for posts, with the bulk of production originating from stands planted between 1926 and 1936. The low level of management of Corsican pine left largely untended stands producing suitably straight, small-branched trees, ideal for an expanding pole market in later years. In addition, the wide acceptance of copper chrome arsenate (CCA) preservative treatment, ahead of creosote or pentachlorophenate-in-oil (PCP in oil), also favoured the use of relatively permeable Corsican pine ahead of Douglas-fir and larch. The main resource of Corsican pine has now all but disappeared, with the rate of depletion hastened by its use for sawn timber, pulp, and the export log trade. However, the main contributing factor to its virtual disappearance was its elimination from the planting programme in New Zealand by the early 1970s, as a result of its susceptibility to the needle blight Dothistroma pini. The 1982 Roundwood Workshop recognised the imminent shortage of suitable pole material, and examined the suitability of various other species, including radiata pine. Despite the advent of early heavy thinning for radiata pine, forest management practice was far from homogeneous. Some supplies of poles would therefore be available in the future from stands that had been kept at relatively high stockings, again, more by accident than design.