Two decades of variable retention in British Columbia: A review of its implementation and effectiveness for biodiversity conservation
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Issue Date
2019-07-23
Authors
Beese, William J.
Deal, John
Dunsworth, B. Glen
Mitchell, Stephen J.
Philpott, Timothy J.
License
Subject
Abstract
Stand-level retention is an important component of sustainable forest management which aims to balance
ecological, social and economic objectives. Long-term retention of mature forest structures at the time of
harvesting (variable retention) is intended to produce future forest stands that more closely resemble conditions
that develop after natural disturbances, thereby maintaining greater diversity of habitats for a variety of organisms.
Structure includes features such as live and dead trees representing multiple canopy layers, undisturbed understory
vegetation and coarse woody debris. Over the past two decades, variable retention has become common on forest
lands in the temperate rainforests of coastal British Columbia (BC) and has been applied to a lesser extent in inland
forest types. Our review of studies in BC and in similar forest types in our region indicates that both aggregated
and dispersed retention can contribute to biodiversity conservation by providing short-term ‘life-boating’ habitat for
some species and by enhancing the structural characteristics of future stands. For example, greater abundance of
species present in the pre-harvest forest have been documented for vegetation, birds, carabid beetles, gastropods,
ectomycorrhizal fungi and soil fauna in retention cutblocks compared to clearcuts. There are, however, some
negative consequences for timber production such as wind damage to retained trees and reduced growth rates of
tree regeneration compared to clearcuts. The authors suggest an adaptive management approach for balancing
competing objectives when faced with uncertainty. This includes monitoring the implementation and effectiveness
of various strategies for achieving goals. Over two decades of experience applying variable retention harvesting to
industrial-scale management of forest lands in BC suggests that it is possible to balance production of wood with
biodiversity conservation.