The Significance of Windthrow for Pinus radiata Management in the Nelson District

Authors: R.E. Irvine
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 1970, Issue N.Z.J.For. 15(1) 1970, pp 57-68, May 1970
Publisher: New Zealand Institute of Forestry

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Abstract: Golden Downs Forest, Nelson, suffered extensive blowdown in stands of mature radiata pine (Pinus radiata) during an exceptionally severe gale in April 1968. This followed conclusive evidence of appreciable cumulative volume loss due to intermittent and scattered small-scale windthrow.
This paper describes the history of wind damage and the site limitations in terms of soil, tree rooting and climatic factors. Wind turbulence, when accompanied by rain, is held to be a major contributor to windthrow. Between 1964 and 1968, the loss from windthrow was about 5 million cu. ft, of which half was salvaged. Despite the fact that radiata pine was the species affected, it will be retained as the major species, but management will be modified. It is intended to reduce the rotation to about 30 years to limit the recurrence of serious blow-downs. Wider initial spacing and heavy early thinnings of young stands are proposed, the object being to produce within the rotation trees averaging 23 in. d.b.h.

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