Old-growth forests and timber supply : a case study from the boreal forest

Abstract

Historically in Canada, old-growth forest preservation concerns, research, and analyses have centred on the stately coniferous forests of British Columbia (e.g., Clayoquot Sound). Within the past decade, however, the forests of Ontario have also come under scrutiny for their old-growth values. The Timmins Forest, a Sustainable Forest License, provides the background for this case study of Ontario’s old-growth forests. Old-growth is defined conceptually as an integral landscape element, differentiated at the stand level by age The principal objectives of this study were to develop and examine the temporal impact of various timber harvest scenarios on the old-growth component of the forest. To support this analysis, silvicultural options for the creation of old-growth structures at the stand level were outlined for the boreal species under examination. One hundred-year simulation scenarios were run on a forest model called HSG. HSG operates by tracking the spatial identity of individual forest stands through time. As age and time increments are simulated, HSG updates stand successional changes and inventories, applies harvests, and allocates and schedules silvicultural treatments. Indicators for analysis included long-run sustained yield versus growing stock, and the percentage of the landscape in the old-growth condition per species. The scenarios ranged in design from no harvests, no silviculture, to the use of “old-growth windows” (where stands were protected from harvest) to the use of intensive silviculture. Results show that old-growth supply is maximized across the boreal species when a program of no harvests is undertaken. Protecting stands from harvest for a specified number of years provided the least amount of long-run sustained yield over time. Intensive silviculture increased harvest levels at the expense of old growth. The Benchmark Scenario provided the best option for the provision of both inventories of old-growth and long-run sustained yield. Forest resource managers have the basic simulation tools necessary to measure and manage for old growth, but need to perform additional analyses such as cost-benefit-analysis to evaluate the role of old growth in the landscape context. Clarification and refinement of such methodologies and simulation tools will lead to the improvement of forest policies designed to create and manage sustainable forest management programs.