Factors affecting bark-stripping by red deer (Cervus elaphus)
the importance of landscape structure and forage availability
Bark-stripping by red deer (Cervus elaphus) cause extensive damage to economically valuable spruce trees (Picea abies) in Swedish forests. The underlying causes for bark-stripping are not fully understood, and the frequency and severity of damage unpredictably differ between regions. In this study, I investigated if landscape structure (e.g. agricultural dominated landscape opposed to forest dominated landscape), forage availability, population density and disturbance (e.g. roads and settlements) affect bark-stripping frequency. The study was carried out in two Swedish regions, Skåne and Södermanland/Östergötland and included 180 spruce stands. Bark-stripping frequency was explained by proportion agricultural land in the area, forage availability and the distance to agricultural land. Areas with a high proportion agricultural land had significantly more damage than forested areas. Areas with high abundance of available winter forage had significantly less damage than areas that lacked alternate forage. Disturbance by roads and settlements did however not seem to influence the amount of bark-stripping. There was a significant difference in bark-stripping frequency between the regions. Skåne had 87 % damaged trees, while Södermanland/Östergötland only had 18 % damaged trees. The damage frequency was higher in Skåne despite a lower population size. Furthermore damage did not differ between study sites in Skåne even at different densities. Because bark-stripping seems to be dependent on landscape structure and forage availability, habitat management rather than increased red deer culling may be a possible way to reduce damage.