Innovations in cumulative impact studies and applications to aid conservation and sustainable management of Reindeer in Scandinavia

During the last century, human activities have reshaped landscapes at an unprecedented pace. Roads, railways, energy infrastructure, settlements, and tourism have transformed large areas, often fragmenting habitats and creating barriers to animal movement. At the same time, changing climate conditions are altering where suitable living conditions are found. Together, these pressures form a “perfect storm”, where species may be constrained to landscapes that no longer provide the conditions they need to survive. In the OneImpact project, we focused on reindeer, one of the most iconic species of Scandinavia. Reindeer play a key role in alpine and tundra ecosystems and are central to the livelihoods and cultural identity of Sami communities. Despite the relative remoteness of many reindeer ranges, they have not been spared from infrastructure development and increasing human activity. Understanding how these different pressures act together is therefore essential for sustainable land-use planning and reindeer management. In an interdisciplinary team of researchers with expertise ranging from ecology to computer science, we developed new methods and tools that make it possible to quantify the cumulative effects of multiple human activities on reindeer habitat. Rather than assessing individual developments in isolation, our approach captures how their combined effects reduce habitat quality, fragment landscapes, and disrupt movement corridors across entire regions. Applying these methods across Norway and Sweden revealed that the impacts of human infrastructure and activity often extend far beyond their immediate physical footprint. Transport infrastructure, hydropower development, wind turbines, buildings, and tourism activity all contribute to cumulative impacts, particularly in areas where multiple developments are concentrated. For example, in the Hardangervidda wild reindeer area, we found that while the effect of a single private cabin is small, the combined impact of clusters of cabins and tourist infrastructure can influence reindeer habitat over distances of 10–20 kilometres. This illustrates how cumulative effects can be much larger than the sum of individual developments. A central outcome of the project is the development of interactive maps and dashboards that visualise habitat loss, fragmentation, zones of influence, and key drivers of cumulative impact. These tools allow managers and decision-makers to explore how different stressors interact across the landscape and to compare alternative development or mitigation scenarios. They make otherwise invisible cumulative effects visible and provide a transparent basis for discussion and planning. The project has also demonstrated how these tools can be used to assess mitigation measures. In several wild reindeer areas, we analysed scenarios such as alternative placements of infrastructure, changes to hydropower and tourism facilities, and the closure of trails or resorts. A key insight from these analyses is that the effectiveness of local mitigation measures depends strongly on the broader landscape context: interventions can have limited effect if connectivity is already compromised elsewhere, while targeted measures in strategically important areas can yield disproportionate benefits. The scientific results of OneImpact are documented in a series of peer-reviewed publications and openly available software tools. An overview of the methods, results, maps, and publications is available through the Reindeer Web App: https://reindeermaps.nina.no/ Interactive dashboards summarising cumulative impacts for wild reindeer populations can be explored at: https://view.nina.no/QN Together, these outputs provide new ways of understanding how human activities collectively shape reindeer landscapes and offer practical tools to support more informed and sustainable decisions for the future of reindeer and the ecosystems and communities they depend on.

OneImpact has provided local and national management authorities with a data-driven and comprehensive quantification of the impacts and zones of influence of different anthropogenic land uses and infrastructures on wild and semi-domesticated reindeer. A central outcome of the project is the development of interactive dashboards that visualize and map cumulative impacts from anthropogenic infrastructures on wild reindeer habitat, highlighting both the amount of habitat loss and the relative contribution of key drivers. Comparable dashboards for semi-domesticated reindeer are currently under development. The project has contributed directly to local management and planning processes through the assessment of multiple mitigation interventions in different wild reindeer areas using scenario analysis. These assessments included evaluations of alternative placements of DNT cabins, as well as different tunnel options for a regional road. A key outcome from these applications has been the demonstrated ability of landscape network models to represent and communicate a true landscape perspective: not only by capturing effects beyond the immediate footprint of an intervention (off-site effects), but also by revealing how the effectiveness of local mitigation measures may be constrained by the broader landscape context. For the scientific community, OneImpact has delivered a general framework for cumulative impact assessment based on landscape networks, including network-based zonation methods for spatial planning. This framework has been documented through peer-reviewed publications, together with openly available software implementing the underlying algorithms. These methodological contributions represent an important advance for cumulative impact assessment by integrating habitat loss, fragmentation, and connectivity within a unified analytical approach. The project’s outcomes are expected to have long-term impacts on wild reindeer management through their contribution to the further development and application of national “Quality Norms” for reindeer. Beyond the focal species, OneImpact has already generated broader impacts by informing subsequent projects, such as GreenPlan, where the approach is generalized to green infrastructure planning across species and ecosystems. Internationally, the methodology has contributed to the development of spatial biodiversity indicators and a composite index for conservation prioritization in Switzerland, demonstrating the transferability of the project’s results beyond the Scandinavian context. These outcomes and impacts directly realize the project’s original objective of integrating habitat quality and connectivity into a unified, spatially explicit framework for cumulative impact assessment, and of translating this framework into decision-support tools with demonstrated relevance for management and policy.

Anthropogenic activities pose major challenges to sustainability. The cumulative impact of multiple stressors depends upon their interactions and spatio-temporal configurations with respect to each other and to ecosystem flows. Failure to adequately assess long-term cumulative impacts may lead to tipping points and undermine ecosystem functioning. We integrate advances in ecology and computer science to quantify cumulative impacts of any combination of stressors, occurring at specific places and times, on ecosystem performance. We extend the ecological niche concept by integrating movement flows and connectivity. We develop approaches to assess cumulative impacts simultaneously on habitat loss and fragmentation, and quantify the remaining amount of functional habitat. We will develop an open-source software to: calculate multi-stressor impacts, identify vulnerable areas, produce zonation maps, and perform scenario analyses to guide sustainable development. We test the approach on a sensitive key species posing major challenges to sustainable development: reindeer. We build upon decades of studies on > 1000 GPS-monitored reindeer individuals across Boreal, Alpine, sub-Arctic and high Arctic ecosystems in Norway and Sweden to synthesize knowledge, identify tolerance thresholds, and quantify the total impact of all stressors (climate, roads, railways, renewable energy, tourism, forestry, depredation, parasites etc.) on populations. We integrate the cumulative impact into a synthetic index quantifying the habitat functionality of each range, and produce zonation maps ranking sensitive areas for use in management. Finally, we analyse historic and future scenarios to unveil multi-stressor impacts so far, project it in time, and concretely assist sustainable development. To ensure practical relevance we integrate Traditional Ecological Knowledge and scenario analyses based on stakeholders' expertise and requirements within the same analytical framework.