The morphology and chemistry of two willow species in relation to moose winter browsing

Abstract

This study examines the interaction between moose (Alces alces gigas) and winter dormant willows (Salix alaxensis and Salix pulchra) in Alaska, emphasizing the impact of moose browsing on the forage produced by willow. In a two year field study, plant responses were examined with clipping treatments designed to simulate browsing by moose. The plant responses examined included biomass production, plant architecture, and concentration of plant tannins. Forage selection by moose in the study area is also addressed. Results suggest that a plant response of increased growth, decreased chemical defense, and redistribution of new biomass may explain the pattern of repeated browsing of plants by moose. The responses of clipped plants indicate that moose improve the quality of their willow hosts by browsing and repeated browsing negatively affects carbon reserves of willows. Among and within plant variation in tannin content was also examined among 5. alaxensis trees. Observations are related to within and among tree measurements of growth rate.