Abstract Anthropogenic and natural disturbances change forest structure and subsequently habitat for wildlife in boreal ecosystems. Timber harvesting and wildfire can constrain availability of forage for species that often use older seral forest, like threatened woodland caribou (Rangifer tarandus caribou), or enhance forage availability for generalists like moose (Alces americanus) and omnivorous predators like bears (black bears: Ursus americanus, grizzly bears: Ursus arctos). However, few studies have assessed long-term changes in the availability of forage following natural and anthropogenic disturbance. We used forest growth models to project future stand conditions and characterized the effects of timber harvest and wildfire on corresponding availability of forage for caribou, moose, and bears. We initialized models with field data collected from 250 harvested and 259 burned stands (0–40 years since disturbance) across boreal and montane forests in Alberta, Canada. We compared the projected amount of forage to the availability of forage observed in 256 older stands ( 40 years since disturbance) that were used by caribou. The development trajectory of forage varied among disturbance type and ecosystem subtype. Within the first 50 to 60 years post-disturbance, forage for caribou, moose, and bears experienced the greatest rate of change. In some ecosystem subtypes, the availability of terrestrial lichens, winter forage for caribou, was similar to undisturbed stands 40 years following timber harvest or wildfire. Forage for moose and bears, comprised of large deciduous shrubs, was projected to reach a greater abundance in most cutblock and wildfire sites when compared to the undisturbed sites used by caribou. Our results suggest that for the first few decades following timber harvest and wildfire, there will be more forage for moose and bears and less for caribou. Those post-disturbance increases in forage could directly or indirectly (i.e. via apparent predation) result in greater risk for caribou.
Best et al. (Tue,) studied this question.