Phytochemical deterrence of snowshoe hare browsing by adventitious shoots of four alaskan trees.

After snowshoe hares have severely browsed deciduous trees and shrubs, these woody plants produce adventitious shoots that are extremely unpalatable to them. The adventitious shoots of four common boreal forest trees contain significantly higher concentrations of terpene and phenolic resins than the mature-growth-form twigs of the same species. These resins are experimentally shown to be repellent to snowshoe hares and appear to explain the avoidance of adventitious shoots by hares. The production of adventitious shoots after intense hare browsing and the avoidance of these shoots by hares may play an important role in the 10-year hare cycle.