Effects on Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) in the sapling stage from ungulate browsing

Sammanfattning: Ecosystem services from forestry are highly valuable and may be limited by ungulate browsing. Thus, I investigated the impact and seasonality of browsing on Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) using seasonal exclosures. Slightly more than 10 % of the pine trees were browsed at the top shoot, compared to spruce where top shoot browsing was almost non-existent. Pines that had a browsed top shoot had a significantly lower height to width ratio. Further, for pine there was a significant difference between the seasonal browsing in height to width ratio, where the exclosure that prevented ungulate browsing all year around had the highest ratio while the exclosure that was open for browsing all year around had the lowest ratio. Results also showed, for both pine and spruce, that height, width, and number of shoots seemed to be more affected by different sites than from ungulate browsing. For a tree individual, both species also showed that there were strong correlations between both height and diameter and number of shoots. To sum up, this study showed that top shoot browsing limits height to width ratio in pine and might also limit growth. It also showed that the browsing distribution between species can be very uneven, since spruce was hardly not browsed at all. Furthermore, the study also showed that different sites can have a strong impact on growth.