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Development of a productivity index for Douglas-fir
Authors: L. KnowlesPublication: New Zealand Journal of Forestry, Volume N.Z.J.For. 2005, Issue N.Z.J.For. 50(2) 2005, pp 19-22, Aug 2005
Publisher: New Zealand Institute of Forestry
Abstract: Site index is a commonly used method for indicating productivity of a range of plantation species throughout the world. For Douglas-fir in New Zealand, basal area 'level' (as represented by site basal area potential, or SBAP) is also a key component in determining volume yield, and therefore also needs to be considered. A productivity index combining SI and SBAP shows promise for comparing yields across a range of sites. The index has been standardised to a specific regime, involving thinning to waste by 15m MTH to 500 stems/ha, and then growing the stand to age 40 years. Because of this, it has been named the '500 Index'. Its development is described, and sensitivity of the index to minor variations in the underlying assumptions is presented.