Effects of Thinning and Nitrogen Fertilization on Sugars and Terpenes in Douglas-Fir Vascular Tissues: Implications for Black Bear Foraging

Authors

Bruce A. Kimball, USDA/APHIS/NWRCFollow
Eric C. Turnblom, University of Washington
Dale L. Nolte, USDA-APHIS-Wildlife ServicesFollow
Doreen L. Griffin, Physical Science Technician, USDA/APHIS/NWRC
Richard M. Engeman, Research Biometrician at the USDA/APHIS/NWRCFollow

Date of this Version

May 1998

Comments

Published by Forest Science 44(4)1998.

Abstract

The chemical constituents of coniferous vascular tissues play a role in bear forage selection. In particular, bear foraging preferences are related to the concentrations of simple sugars (nonstructural carbohydrates) and terpenes in the forage. Analyses of vascular tissue samples from trees collected in test plots indicted that both thinning and fertilization caused the sugar concentration of vascular tissues in the lower bole to increase. However, these treatments had no effect on the concentrations of hydrocarbon monoterpenes, oxygenated monoterpenes, or sesquiterpenes. These results may explain the observations that black bears prefer to forage in thinned and fertilized stands.