The retention system:reconciling variable retention with the principles of silvicultural systems

The philosophy of ecosystem management seeks a balance between protecting natural systems and using them to meet societal demands. The objectives of silvicultural systems listed in standard texts focus on the sustained production of timber and maintenance of quality growing stock. These objectives need updating for situations where the broader goal is to sustain ecosystem function and productivity. The "retention system" recently adopted in British Columbia is a silvicultural system designed to implement the "variable retention" (VR) approach to harvesting. With VR, trees are retained to meet ecological objectives such as maintaining structural heterogeneity and protecting biological legacies. The contribution of retained trees to yield or regeneration may be low or even negative. Among the challenges in implementing the retention system is the adjustment of yield expectations and target stand projections to account for the expected health and vigour of the future stand. Key words: silvicultural system, retention system, variable retention, ecosystem management