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

anglais. 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.

anglais. Effects on growth in pine and spruce from ungulate browsing Forest products have a high economic value. Thus, forest owners have a high interest in maximizing productivity and preventing outer damage to occur on production trees, such as Scots pine (Pinus sylvestris) and Norway spruce (Picea abies). One example of outer damage is ungulate browsing. However, not enough research has been made to fully understand what effect different seasonal browsing might have on growth. Previous research has mostly looked at the effects from winter browsing, while research on summer browsing have not been fully investigated. Therefore, research on the effects on growth from browsing in different seasons needs to be done. In this study, four exclosures were established in ten different cutting areas. These four exclosures in each site were different experimental treatments for seasonal browsing. One exclosure were open all year around, one was closed all year around, one was closed during the winter and the last was closed during the summer. In each exclosure there were individuals of both pine and spruce that we took measurements on. In this project, site seemed to have a great impact on sapling growth. For both pine and spruce, there were a significant difference in height, width, and number of shoots between sites. This might be due to different conditions (soil type, topography, competition from other vegetation, etc.) between sites. This difference in site properties together with other factors seemed to affect growth more than ungulate browsing did. For a tree individual, both species also showed that there were strong correlations between both height and diameter, and number of shoots. The study also showed that the browsing distribution between species can be very uneven, since slightly more than 10 % of the pine trees had a browsed top shoot while spruce was hardly not browsed at all. 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. Further, the pine trees that had been browsed in the top shoot had a significantly lower height to width ratio. Because of the increasing browsing damage in the Swedish forestry, further research within this topic will be needed. In addition to this study, the effects of browsing on lateral shoots, the effects from browsing on deciduous trees etc., will be important issues that needs to be further investigated for the future, to be able to create a sustainable co-management of game and forestry. Bachelor thesis for the bachelor´s degree in Biology 15 hp 2019 Department of Biology, Lund University Supervisor: Fredrik Widemo Department of Wildlife, Fish and Environment, Swedish University of Agricultural Sciences Co-supervisor: Bengt Hansson Department of Biology, Lund University