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An assessment of critical assumptions supporting the timber supply modelling for mountain-pine-beetle-induced allowable annual cut uplift in thePrince George Timber Supply Area

John Pousette, Chris Hawkins

Abstract


To address the mountain pine beetle epidemic, the allowable annual cut (AAC) for the Prince George Timber Supply Area (TSA) has been increased by 5.7 million m3 to 14.944 million m3. Timber supply model forecasts supporting AAC uplift decisions show a significant mid-term timber supply falldown. Timber supply modelling undertaken for the Prince George TSA in support of the recent AAC decision has not incorporated mortality in stands less than 60 years old, has generally considered the shelf life of beetlekilled wood to be 5 years for use as dimension lumber and 5 additional years for use as products of reduced fibre quality, and has assumed that pine timber makes up at least 78% of the total harvest in the short term. Current research suggests that certain of these assumptions may be optimistic. Refinements to these important timber supply analysis assumptions may result in a mid-term timber supply falldown that is deeper and longer than originally forecast. If the current outbreak continues unabated, stands in which lodgepole pine represents over 70% of the volume will provide enough mature growth to satisfy the new AAC for a further 14 years. It may be that the current increased AAC will not be realized for this period of time because of economic and environmental reasons. Greater value may be gained by not harvesting pine-dominated stands that contain significant stand structure or advance regeneration. Retention of these stands could mitigate the negative effects to the environment, hydrology, and wildlife while increasing the volume available in the latter part of the mid-term. Barriers to forest licensees focussing harvest in these stands include current mill requirements, existing traditional operating areas, previously approved cutting permits, stumpage appraisal, accessibility, and other economic considerations.

Keywords


allowable annual cut; immature pine mortality; mountain pine beetle; timber shelf life; timber supply analysis; timber supply modelling

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