Does recolonization of wolves affect moose browsing damage on young Scots pine?. Gicquel M, Sand H, Månsson J, Wallgren M, Wikenros C.Forest Ecology and Management. 2020 Oct


Ungulates frequently cause damage to human livelihoods, such as agriculture, livestock or forestry. In Sweden, forestry is the dominating land use and is a very important source of income. moose (Alces alces) browsing commonly causes damage to young forest stands, mainly Scots pine (Pinus sylvestris). Factors known to affect the level of moose browsing damage are moose density, forage availability, site productivity, tree species composition, snow depth, and infrastructure. One hypothesis is that the recent recolonization of wolves (Canis lupus) in Sweden may lead to a decrease in browsing damage levels, through an effect of wolf predation on moose density or moose behaviour. We used data from annual moose browsing damage surveys, long-term wolf monitoring, moose harvest statistics, habitat composition, snow depth, and road network to investigate the effect of wolf recolonization on moose browsing damage on Scots pine. Contrary to predicted, wolf territory establishment and duration showed an increase in the level of moose damage on young Scots pine. But, the effect size was small and it is questionable if it can be considered as biologically relevant. Overall, other factors were more important than wolves in explaining browsing damage on pine by moose. Presence and cover of deciduous species increased the occurrence of moose browsing damage on pine but reduced the level of damage. Decreasing snow depth and increasing road density both resulted in a lower level of damage. We suggest that the strong human impact on all trophic levels on the Swedish forest ecosystem through harvest and intense forestry practices is likely to override wolves’ effects on density and behaviour of moose, as well as their potential effects on preferred browsing species for moose.

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