Mountain Spruce Forests As Hotspots for Extremes: Impacts, Resilience and Management Priorities (MountEx)

Spruce mountain forests, which are crucial for protection against natural hazards and for providing other important ecosystem services, are increasingly threatened by climate change. The MountEx project identifies vulnerable forests, develops adaptation strategies, and optimizes operational planning in forest management. This contributes to improved decision support for management priorities and strategies with regard to future extreme disturbances in spruce-dominated mountain forests.

Spruce-dominated mountain forests account for more than 50 percent of the alpine forests in Switzerland. They provide habitat for a wide range of species and deliver important ecosystem services such as carbon sequestration, water retention, and soil protection. They are also a source of timber, an important recreational area, and help protect settlements by acting as a natural barrier against hazards such as avalanches and rockfall. However, with climate change, extreme weather events and disturbances are increasing in both frequency and intensity, placing mountain spruce forests under growing pressure—and their decline could have serious consequences for ecosystems, the economy, and human health. Effective and forward-looking management strategies are therefore urgently needed to strengthen forest resilience, protect biodiversity, and secure the vital ecosystem services these forests provide.

The MountEx project aims to provide the knowledge, strategies, and tools needed to guide the effective management of mountain spruce forests under the influence of previously unthinkable extreme disturbances. Collaborating closely with local foresters and cantonal authorities, the project focuses on three key research questions:   

1. Identifying Predisposition and Risk: How can we integrate spatial data and models on forest structure, site conditions, and potential natural hazards to create interactive maps that identify multiple risks under extreme disturbances?
2. Evaluating Management Options: What are the most effective proactive (pre-disturbance) and reactive (post-disturbance) management strategies for mitigating risks to ecosystem services?
3. Enhancing Operational Planning: How can we improve operational planning and the economic assessment of management strategies in the context of extreme disturbances?

Upon project completion at the end of 2025, MountEx will have delivered several valuable outputs that support the sustainable management of spruce-dominated mountain forests:

• Predisposition Maps: A set of spatially continuous maps that highlight those forest areas that are particularly susceptible to bark beetle infestations, windthrow, and snow breakage. The maps will incorporate numerous forest structure parameters and site factors, including the protective role of forests against rockfall and avalanches. The aim is to support a holistic approach to forest management prioritization, enabling targeted interventions.
• Best-Practice Guides: A series of management recommendations to enhance mountain spruce-dominated forest stand resistance and resilience.
• Optimization Method: A novel method that subdivides forest areas into management units. The potential costs and benefits of silvicultural intervention on forest resilience and the economy are assessed for each unit, supporting cost-effective and sustainable forest management.
• MountEx Dashboard: A user-friendly and interactive web application that integrates all of MountEx’s insights into a single platform to help stakeholders and practitioners make informed decisions.

By developing these valuable tools and strategies, the MountEx project is working to ensure spruce-dominated mountain forests can withstand and recover from extreme disturbances, securing the health of Switzerland’s mountain ecosystems – and the essential services they provide – against a future in which extreme events are increasingly commonplace.

The MountEx project is part of WSL’s Extremes Research Program, which aims to equip Swiss stakeholders with the resources needed to meet the challenges of future extreme events.