Future Yields – how ungulate browsing affects forest development and revenue
KEY POINTS- Ungulates may limit sapling growth and damage future production stems
- Ungulates may influence future stand compositions
- We lack quantitative predictions of how browsing limits future yields in forestry.
Project overview
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Short summary
Ungulate browsing can affect stand composition, forest growth and furure revenue from forestry. In Future Yields, we study how plant-ungulate interactions may limit forestry and monitoring methods for assessing impacts.
In Sweden, damage caused by moose browsing on young Scots pine is a particular concern. Browsing damage is surveyed regularly, mainly through the Moose Browsing Inventory (ÄBIN), but individual surveys do not show how damage accumulates during the young stand phase or what it means for future timber production and revenue. In Future Yields, we investigate these relationships through repeated field surveys, exclosure experiments and simulations of forest development.
We follow young stands in 14 reference areas along a latitudinal gradient, encompassing variation in forage availability and the density and species composition of ungulate communities. By surveying the same stands over several years, we investigate how browsing damage accumulates, how browsing changes tree species composition, and how this relates to the amount and spatial distribution of forage. We also assess how the selection of stands, the number of sample plots and differences between observers affect the reliability of Äbin.
We compare pine growth inside and outside exclosures that exclude ungulates, in both young stands and older stands that have reached the thinning phase. We examine different types of damage, including browsing of side shoots, which may affect growth but is not recorded by Äbin. We also investigate how pre-commercial and commercial thinning, whenh damaged stems may be removed, influence the long-term consequences of browsing. The results are used in Heureka to project future timber production and financial returns under different conditions.
The project is expected to provide more reliable methods for measuring and interpreting browsing damage. We test whether targets for annual damage are consistent with goals for the proportion of undamaged pines remaining. By linking measured damage to subsequent forest development, the project can contribute to more accurate estimates of the costs of wildlife damage to forestry and better-informed trade-offs between timber production and the benefits provided by ungulates, including hunting. This provides evidence for trade-offs within Sweden's environmental objective Sustainable Forests and Sustainable Development Goal 15, where forest production, biodiversity and other ecosystem services need to be considered.