Abstract :
[en] Norway recently adopted a “quality norm” system to assess the status of wild reindeer. Each of the 24 management areas are assessed based on three parameters, one of which is human impact on habitats, currently a major threat. Further work is needed to identify anthropogenic drivers and identify/implement targeted action plans (“tiltaksplaner”) to ensure that each area meets quality standards sufficient to maintain viable populations for future generations.
Prioritizing the most effective mitigation measures is a demanding task that requires solid knowledge of key reindeer areas and migration corridors, the cumulative impact of various types of disturbances, and the relative importance of each impact factor. A robust knowledge base is also essential to avoid suboptimal solutions and to support constructive dialogue that reduces the potential for conflict among stakeholders.
This report supports the action plan processes in the Setesdal Ryfylke (SR) wild reindeer area by providing a quantitative, spatially explicit, and high-resolution knowledge base to assess the expected effect of one of the proposed mitigation measures.
Reindeer use of the southern parts of SR has changed dramatically since the 1990s. After the Brokke–Suleskard road was constructed in 1992, crossings over the road have gradually decreased—likely due to increased traffic and human activity on surrounding trails. This has led to a significant reduction in land use south of the road, with some areas no longer used at all. As part of the action plan work, Agder County is considering placing Brokke–Suleskard road (Route 450) in a tunnel to reduce its barrier effect and facilitate increased reindeer use of the area.
The report presents the results of scenario analyses to assess how three different tunnel alternatives and future use of the current road could affect reindeer in SR. To provide a comprehensive answer, the report first presents a complete statistical overview of habitat quality—both current and historical—barriers to reindeer movement, key areas and migration corridors, the total impact from different types of disturbances, and the relative importance of each impact factor—both throughout SR and in the focus area. The results build upon models developed for all wild reindeer areas and on earlier scenario analyses in SR (Panzacchi et al., 2022; van Moorter et al. 2023; Dorber et al. 2023; Dashboard: https://www.nina.no/apps/villrein.habitattap; WebApp: https://www.nina.no/Naturmangfold/Hjortedyr/reindeermapsnorway).
The results focus on females - the most vulnerable part of the population - and show that:
• In summer, GPS-collared females stay in areas north of the road, the largest continuous area with remaining functional habitat in SR.
• As soon as the road is closed in autumn—or just before, when traffic and disturbances are significantly reduced—the females begin grazing near the road. In winter, they continue to use the area, which functions as viable winter habitat. All females retreat north of the road before April 20, well before the road reopens on May 21. There may be suitable calving areas south of the road, but connectivity to current summer pastures may be weak.
• Roads with high traffic primarily act as barriers to reindeer, so tunnel construction can be an effective measure to reopen lost corridors between key grazing areas. For Route 450, the situation is complex, and the effect of building a tunnel greatly depends on how the area above and around the planned tunnel is going to be used.
• Route 450 has high traffic volume during summer, creating a barrier effect that prevents road crossings. Additionally, the road is used for recreation, and also connected to trails, cabins, tourist attractions, hydropower stations - and is in an area with a significant number of grazing sheep. The resulting cumulative impact causes diffuse habitat degradation over a relatively large “zone of influence” both north and south of the road, keeping reindeer at a distance.
• Furthermore, although there are currently good winter areas and potential calving areas south of the road, the extent of summer pastures south of the road is relatively limited. Previously, summer habitat was more widespread in SR, especially in the west, but also adjacent to and up to 10–15 km south of Route 450. Although some patches of suitable summer habitat still exist further south, these are small and scattered in the southernmost part of the reindeer range – limiting the amount of habitat that could potentially be regained with the tunnel.
• The area adjacent to and south of the road is more attractive in autumn and winter, as females occasionally cross the road even before it is closed, once traffic is significantly reduced.
• The tunnel will first and foremost promote an earlier use of the area in late summer/autumn and increase the chance of using the area during summer — although this depends on how the area above the tunnel will be managed.
• If the tunnel is built without any changes to tourist cabins, trails, or other disturbance factors, the estimated summer habitat gain is about 2.3 km² (equivalent to 322 football fields), mostly within a few kilometers around the current road alignment. The model does not predict a substantially increased use of the area further south, due to disturbance and low suitability.
• Constructing the tunnel in combination with other planned mitigation measures (relocation of Øyuvsbu, Storsteinhytta, and related infrastructure) yields the greatest benefit, with a gain of 31 km² of well connected summer habitat—equivalent to 4,384 football fields—spread over a larger area east of Rosskrefppfjorden and along the current road.
• The best alternative is a 17 km long tunnel without a road or trails on top. The 17 km tunnel would enable to re-establish the most important potential corridors. The effects of the 9 and 11 km tunnels are quite similar, as they both would enable re-establishing some of the potential corridors, but at the same time stop a bit too close to other potential corridors.
• The tunnel’s effectiveness depends heavily on how the area above and around it will be used. Any activity that increases traffic and disturbance will reduce the likelihood of reindeer approaching the area, in the worst case countering the positive effect of removing the barrier.
• Retaining a reduced-traffic road over the tunnel involves a risk, as it may be difficult to limit recreational use of the areas around the road. For the tunnel to have the desired effect, the overlying road should either be removed entirely or the car traffic significantly reduced.
• Establishing hiking trails over the tunnel also carries risks. The location and number of trails is still to be discussed, and the expected tourist volume unknown. In the worst case, depending on tourist volume, the extent of disturbance could result in a net negative effect.
In conclusion, building the tunnel, without trails or roads over it, would be a good measure as part of a broader plan to reduce disturbances in the area. There is no guarantee that reindeer will return to previously lost grazing areas. We therefore suggest to be ambitious, take a holistic view from the reindeer’s perspective, and aim to obtain an area free from all possi-ble disturbance. The goal is “grazing peace.” We suggest to:
- Assess various measures in SR, as well as any development plans, in a holistic context.
- Take a broader perspective on all good and also former grazing areas in SR, and explore the possibility of mitigation measures to help restore or increase the use and connectivity of these areas (including to the west). Statistical analyses may support the process.
- Set precise, long-term, and measurable management goals for reindeer habitat use in SR. E.g.: (i) females shall use the area around and south of the road earlier in the fall; (i) females shall use the area also in summer; (iii) calving areas south of the road shall be used again
- Increase knowledge and consider mitigating the main impact factors, including sheep grazing.
