A new report, "Browsing Damage - What is Happening in the Forest and What Happens in the Statistics?", published by the Swedish Forest Agency, provides new insights on the ongoing debate surrounding moose management and its impact on Sweden's forests.
Co-authored by Agriculture, Forestry, and Ecosystem Services (AFE) researcher Oskar Franklin and scientists from Sweden, the report highlights the complex relationship between moose populations, pine tree densities, and browsing damage from both statistical and biological perspectives.
Key Findings
The report challenges the prevailing conclusion that increasing pine tree densities is the most effective way to reduce browsing damage and suggests that moose density plays a more significant role. The study uses an extensive database and an updated calculation model and demonstrates that moose density has a greater impact on browsing damage than pine density.
Data and Methodology
The analysis is based on 718 observations of browsing damage from the Moose Browsing Inventory (MBI) collected between 2015 and 2024 across Sweden's moose management areas (MMA, or ÄFO in Swedish). By comparing these observations with spatially matched estimates of moose densities, the study reveals a noticeable browsing damage reduction as moose density dropped and pine density increased over the years.
However, the report advises careful interpretations of averaged data from multiple MMAs, emphasizing the role of local factors such as climate, vegetation, and the presence of other deer species, which can significantly influence outcomes.
Key Insights
- Only a few counties showed a statistically significant relationship between browsing damage and both moose and pine densities, suggesting that other localized factors such as climate, vegetation, and the presence of other deer species influence the browsing damage.
- The relationship between moose density and browsing damage is not strictly proportional. While the number of pines damaged by each moose declines as moose density rises (due to repeated browsing of already-damaged trees), the total number of damaged pines continues to grow-albeit at a slower rate as moose density increases.
- An ecological mechanisms model explained 50% of the variation in browsing damage across MMAs and years, highlighting the need for nuanced, data-driven approaches to moose management.
Policy and Management Implications
The report emphasizes the importance of balancing "top-down" management approaches (focused on controlling moose populations) with "bottom-up" considerations (like fostering pine growth) to mitigate browsing damage. It calls for moose management strategies to be rooted in robust scientific data and emphasizes the need for continued research and practical experimentation.
Authorities, researchers, forest owners, and hunters are encouraged to collaborate closely to ensure moose management practices are leading to more sustainable forest and wildlife management practices in Sweden.
