Harvest Retention Survivorship of Endangered Whitebark Pine Trees
Date
2021
Authors
Murray, Michael P.
Berg, Jenny
Huggard, David J.
Journal Title
Journal ISSN
Volume Title
Publisher
Forests
Abstract
Whitebark pine (Pinus albicaulis Engelm.) is a widely distributed high-elevation species in
western North America that is threatened primarily by an introduced disease and other disturbances.
In British Columbia, this tree is a component of harvested forests, yet knowledge of post-harvest
survivorship and factors that promote successful retention is lacking. Our objectives are to describe
the temporal attrition of retained mature whitebark pine trees and to identify factors that likely
influence survivorship during the critical initial post-harvest period. We assessed five separate
harvest units in southeastern British Columbia. Dendrochronological investigation revealed that
retained trees experienced high annual mortality rates (3–16%) across harvest sites during the initial
five-year post-harvest period. By eight years post-harvest, retention survivorship ranged from
17–80%. After eight years post-harvest, mortality rates drastically declined. The preponderance
of fallen stems oriented towards the northeast suggests that storm system events arriving from
the Pacific Ocean are the most significant drivers of blowdown. We estimate that survivorship is
positively associated with shorter tree heights and longer crown lengths, a lack of disease cankers, a
greater presence of rodent wounding, and higher numbers of surrounding retained trees. We found
little effect based on slope and aspect. As these trees are an endangered species, harvest operations
should be practiced cautiously in associated forests. We recommend carefully selecting retention
trees, ensuring an adequate number of neighbor trees, and orienting retention patches to avoid
predominant storm wind directions.
Description
Keywords
whitebark pine, Pinus albicaulis, harvest retention, post-harvest mortality, forest conservation, windthrow
Citation
Murray, M. P., Berg, J., & Huggard, D. J. (2021). Harvest Retention Survivorship of Endangered Whitebark Pine Trees. Forests, 12(6), 1-14. https://doi.org/10.3390/f12060654.