Journal of Chemical Ecology

, Volume 36, Issue 5, pp 461-466

First online:

Dynamics of the Volatile Defense of Winter “Dormant” Balsam Poplar (Populus balsamifera)

  • Thomas P. ClausenAffiliated withDepartment of Chemistry & Biochemistry, University of Alaska Fairbanks Email author 
  • , Janice ChenAffiliated withDepartment of Psychology, Stanford University
  • , John P. BryantAffiliated withInstitute of Arctic Biology, University of Alaska Fairbanks
  • , Frederick D. ProvenzaAffiliated withDepartment of Wildland Resources, Utah State University
  • , Juan VillalbaAffiliated withDepartment of Wildland Resources, Utah State University

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6-Hydroxycylohex-2-en-1-one (6-HCH) has been reported as a major chemical defense of the winter-dormant internodes of balsam poplar (Populus balsamifera) against feeding by herbivores such as the snowshoe hare (Lepus americanus). We report that the concentration of 6-HCH in the fall internodes is triggered by a single hard frost, and then undergoes an exponential decline through volatilization over the winter that results in barely detectable quantities by early spring. We conclude that the role of 6-HCH in the defense of mature balsam poplar is more complex than simply acting as a toxin. Rather, 6-HCH’s role as a defensive agent must evolve over the course of the winter from being a co-toxin to a cue for a conditioned flavor aversion (CFA) to finally having no role by late spring.


Balsam poplar Populus balsamifera Snowshoe hare 6-HCH Conditioned flavor aversion Salicortin Plant defense