Bogle T FEMC2007

Examining the Length of the Planning Horizon in the Midst of Catastrophic Natural Disturbance and Uncertainty

Tim Bogle, Ministry of Forests and Range, P.O. Box 9512 Stn. Prov. Govt , Victoria, V8W 9C3, BC, Canada, Tim.Bogle@gov.bc.ca

In traditional timber supply analysis, the length of the planning horizon and the period length have been defined by rotation length and computer speed respectively. Where the forest estate has been in a stable state, the desire to model a number of harvest rotations and silviculture activity at a periodic interval that doesn’t overwhelm the available computer resources is ideal. However, what should a forest manager’s response be when the forest estate is in a high degree of flux due to catastrophic natural disturbance.

Currently, the chief forester of British Columbia has been temporarily increasing the allowable annual cut (AAC), in order to salvage dead and at risk pine trees due to an unprecedented catastrophic mountain pine beetle infestation. A case study in the interior of British Columbia will be used to show that during catastrophic natural disturbance, the traditional reference points of rotation length and period length should be significantly modified. It can be shown that certain key data elements possess enough uncertainty as to create only coarse medium term timber supply projections at best.

Several suggested principles are discussed in determining the adequate planning horizon. These include encapsulating the natural process in question, the term of the AAC decision, the uncertainty in the key data elements and how the AAC decision is implemented. In the BC context, the chief forester has little direct control over tactical implementation of the AAC decision (which stands are harvested). Therefore the planning horizon should be kept short to maintain a focus on damaged or susceptible pine stands to ensure that harvesting activity at elevated rates is focused in the forest with the highest risk of being damaged or rendered unharvestable.