Forest structural attributes after windthrow and consequences of salvage logging

In the eastern boreal forest of Quebec (Canada) windthrow is a major natural disturbance, given the long fire cycle interval. Understanding windthrow is essential to ecosystem-based forest management. Dead wood, live trees, and pit-and-mound microtopography are major post-windthrow attributes with known ecological importance. So far, these structural post-windthrow attributes have not been described for this ecosystem. In addition, ecological consequences of salvage logging after windthrow remain unknown, with no specific salvage standard being applied to maintain such attributes and biological legacies. In this study, comparisons were made between salvaged and unsalvaged windthrow to identify which post-windthrow attributes were more greatly affected by harvest operations and to clarify management options. Downed coarse woody debris (downed CWD), snags, live trees, and pits and mounds were characterized. We showed that downed CWD and snags diminished after salvage operations, with a more uniform distribution among decay classes. Pit and mound density was reduced after salvage logging compared to unsalvaged windthrow, with pits being smaller in the salvaged plots. From an ecosystem management perspective, retention patches with dead wood and standing living trees should be kept in salvaged cut-blocks. To minimize salvage operation effects on microtopography, machinery trails should be reduced to a minimum. Also, a certain proportion of windthrow should be exempted from logging operations.

► We describe post-windthrow forest structural attributes.
► We compare forest structural attributes after unsalvaged and salvaged windthrow.
► Dead wood, living trees and microtopography were reduced after salvaged logging.
► Retention patches with dead wood should be kept in salvaged cut-blocks.
► A certain proportion of windthrow should be exempted from logging operations.