Landscape disturbance alters the composition and diversity of the diet of moose, a generalist herbivore

Abstract

Human-caused landscape disturbance is one of the major threats to large herbivores, globally. Across central British Columbia (BC), Canada, industrial forest harvesting has resulted in rapid change to forest structure and composition. Concurrent with the increase in forest harvesting, moose (Alces alces) populations across central BC have declined, some dramatically. We studied moose diet across three seasons in two regional study areas that represented a range of logging intensity and rate of apparent starvation of moose. We used microhistological analysis of pellets to identify the proportional consumption of major plant groups that were known forage for moose across the study areas, as well as the diversity of the diet of moose. We used regression models to test whether the composition and diversity of moose diet in two study areas were consistent with the Niche Expansion Hypothesis or the Niche Shrinkage Hypothesis. In areas of increased density and size of clearcuts, moose consumed fewer shrubs and fir trees and their diet was more diverse. Where application of herbicides was common, moose consumed fewer forbs and their diet was more diverse. Both responses were consistent with the Niche Expansion Hypothesis. In areas of increased disturbance by wildfire, moose consumed less fir and more shrubs. Our results suggest that landscape disturbance in the form of extensive and rapid forest harvesting can influence the composition and diversity of the diet of moose.