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Predicting forest fires and researching the consequences

Several forest fires occur in Switzerland every year. Researchers from the WSL Institute collect event data and develop methods and approaches to assess fire risks. They also examine the effects forest fires have on hillside erosion and on the development of biodiversity.

Waldbrand in Leuk
Forest Fire of Leuk, august 2003.
Foto: P. Guyot

Waldbrandfläche Leuk - Weidenröschen
The willow-herb often spreads after forest fires.

Low rainfall periods or extreme droughts combined with extensive forest management are nowadays factors that increase the risk of forest fires. Modern extensive forest use causes combustible biomass and dead wood to accumulate on the forest’s soil. As a result, fires may spread with higher intensity during long, dry spells. Humans cause 90 percent of all forest fires in Switzerland through arson and carelessness.

Forest fires also increasing north of the Alps

In Switzerland, forest fires occur most frequently on the southern side of the Alps: in Tessin and in the south-facing valleys of the Grisons. Typically, the fires occur in the spring. During this time, the driest spells occur and deciduous trees do not yet bear a leafy canopy that protects the ground from the dehydrating sunrays.

There are much fewer forest fires in the central Alpine valleys. Nevertheless, 10 to 15 forest fires occur each year, especially in the Valais. Most of these fires are registered in the summer semester when the warm temperatures dry out pine forests in particular. Prolonged dry periods with high temperatures have caused the risk of forest fires in Switzerland to increase in the past 30 years. Forests north of the Alps are also becoming more and more affected.

Implementing scientific results

WSL scientists commit themselves to better understand the consequences of forest fires and to improve outreach for forest practitioners about these consequences and about fire prediction.

Predicting forest fires
  • How accurately can forest fires be predicted?
  • Are there orecasting methods of general validity?
  • How should forest fire management be approached in the future?

The consequences of forest fires
  • How soon does life return to a destroyed forest area?
  • What influence do fires have on biodiversity?
  • What consequential dangers can forest fires present?

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