Abstract

Topic: Diet choice and food availability

Impacts of forest management decisions on ericaceous shrub forage availability for moose

Adam Felton¹, Karin Öhman², Per-Ola Hedwall³, Laura Juvany Canovas³, Annika Maria Felton³

Swedish University of Agricultural Sciences, Inst för sydsvensk skogsvetenskap, Alnarp, SE
Department of Forest Resource Management, SLU, SE-901 83, Sweden
Southern Swedish Forest Research Centre, SLU, 234 22 Alnarp, Sweden

Abstract
Production forest management alternatives are often considered based on their potential to meet a variety of societal goals including biomass production, biodiversity conservation and climate change adaptation. In Sweden, where intensive silviculture occupies most productive forest area, these decisions have a dominant influence on the availability of forage for large wild herbivores of the family Cervidae. We set out to improve our understanding of how the adoption of seven forest management alternatives (baseline, prolonged rotation, no thinnings, intense thinnings, mixed forest, native alternatives to spruce, no management) would alter the cover of three ericaceous dwarf shrub species (cowberry, bilberry and heather), known to constitute a significant share of moose diets. To do so we used previously developed models that link national forest inventory data to dwarf-shrub percentage cover to infer their responses to canopy characteristics (tree species composition, basal area), soils, and past % cover. We integrated these models into the decision support system Heureka to project the cover of these plant species over 100 years in northern and southern Sweden in response to the alternative management strategies. We also used Heureka to optimize outcomes for each shrub species in response to combinations of the seven forest management alternatives, within three constraints for resultant net present value (100%, 90%, or 0% of max NPV). Our preliminary results show that promoting native alternatives to Norway spruce, or in some cases creating mixtures, has small positive effects on the cover of all three shrub species in the landscape. However, optimized management for the benefit of the shrubs indicates that the cover of bilberry and cowberry could be doubled relative to today’s cover in southern Sweden. Furthermore, although the benefits to bilberry and cowberry are highest when demands for forest biomass is 0%, substantial increases in cover can nevertheless be achieved at 90% NPV. We discuss these results, and unavoidable trade-offs among scenarios when trying to benefit all three ericaceous shrub species. We highlight the complex feedbacks and interactions that occur between forest management decisions and moose forage availability, particularly with respect to the ecological costs of dense and dark production forests.