Predictors of browsing damage on commercial forests – A study linking nationwide management data

•Predictors of winter damage differed from predictors of summer damage on Scots pine.•But dependent on spatial scale higher pine densities reduced both winter and summer damage.•Pine density predicted winter damage equally or better than deer density indices.•In multi-deer systems, all species need to be considered to interpret winter damage.•National predictors seem insufficient for regional management decisions. Population sizes and species distributions of wild ungulates in Europe have increased during the past decades, and continue to do so. As a result, browsing pressure in forests is increasing and concerns about the effects of increasingly common multi-species deer communities on forestry are rising. However, we currently lack an understanding of how the composition of deer communities affects browsing damage, particularly with respect to the role of species with different dietary requirements. Further, the relative importance of predictors of browsing damage in systems with multiple browsers remains elusive. Here, we used data from Swedish management, which is monitoring ungulates and their damage to forests, to test how deer densities, forage availability, and winter severity predict browsing damage on commercially important Scots pine (Pinus sylvestris) at national and regional scales. Moose (Alces alces) is the main browser of Scots pine, but competes with other deer over more preferred forage. During winter, a higher index of moose density was associated with higher browsing damage in northern Sweden, where there is low competition from other deer. In southern Sweden, competition from other deer is higher and a higher density index of roe deer (Capreolus capreolus) was associated with higher winter damage. However, there was no relationship between moose density and damage. We suggest that moose are forced to browse more pine due to interspecific competition over alternative forage resources in the south, yielding stronger relationships between densities of competing deer species and damage than between moose density and damage. Pine density, a proxy for forage availability, was an equally or more important determinant for browsing damage as deer density indices in most regions. Increasing pine density was associated with reduced browsing damage caused in winter in all regions and reduced damage caused in summer in central Sweden. Increased winter severity, as an index of snow depth, predicted increased winter damage in the northern region only