Secondary defense responses of White spruce (Picea glauca) and arctic lupine (Lupinus arcticus) to changes in herbivory and soil nutrient concentrations ...

• Main Author: Sharam, Gregory John-David
• Format: Text
• Language: English
• Published: University of British Columbia 2009
• Subjects: Arctic
• Online Access: https://dx.doi.org/10.14288/1.0087634; https://doi.library.ubc.ca/10.14288/1.0087634

White spruce (Picea glauca, Voss) contains an antifeedant (camphor) which deters snowshoe hares (Lepus americanus Erxleben), a generalist herbivore, from feeding on it. Spruce was used as a model species to test the sometimes conflicting predictions of the Optimal Defense, and the Carbon: Nutrient Balance (CNB) theories of plant defense. The Optimal Defense theory predicts that plants will produce inducible defenses, this concentration being a function of the intensity of herbivore attack, and soil fertility. The CNB theory predicts that changes to the carbon: nutrient ratio will alter the relative amount of available carbon in the plant, and thus, the amount of defensive investment. Twig samples of white spruce were collected from small (0.5-1 m tall), medium (2-3m), and large (6-10m) trees growing in areas which have had Herbivore Exclusion, Fertilization, and Herbivore Exclusion + Fertilization treatments for 9 years. Twig samples were also collected from a group of medium-sized trees on Control and ...