The use of growth models in forest planning: the tree that hides the forest

Climate Pressures on Forest Models

Forest growth models form the backbone of Canada's sustainable forest management, providing projections of tree volume accumulation used to set annual allowable cuts across vast public lands. These models underpin decisions on how much timber can be harvested without depleting future supplies or harming biodiversity.

Climate change has introduced rapid shifts that traditional empirical models struggle to capture. Rising temperatures, altered precipitation, increased wildfire frequency, and insect outbreaks like mountain pine beetle have altered growth rates, mortality, and regeneration patterns in boreal and temperate forests. Provincial inventories now incorporate ongoing research to update models with climate-sensitive parameters, but gaps persist in representing regeneration dynamics after disturbances.

The stakes are concrete and immediate. In 2024-2025 reports, Natural Resources Canada noted investments exceeding $800 million in wildfire resilience amid escalating disturbances that reduce productive forest area. Overharvesting based on optimistic growth assumptions could accelerate carbon emissions from forests, undermining Canada's climate commitments, while conservative adjustments might constrain timber supply for industries employing tens of thousands in rural areas.

Non-obvious tensions include the trade-off between precision in individual stand predictions and landscape-level reliability—focusing too narrowly on tree-level growth risks missing broader ecosystem shifts. Provinces like British Columbia and Ontario have revised planning manuals and yield tables to address these, yet debates continue over balancing timber production against carbon storage values, especially as old-growth protections and Indigenous co-management gain prominence. Economic analyses suggest protecting certain intact forests could yield billions in societal benefits from carbon and other services, challenging conventional logging economics.