Drought pushes Swiss forests to their limits

Drought is pushing Swiss forests to their limits, with shallow-rooted species such as beech struggling to survive, SRF reports. Ansgar Kahmen, a biology professor at the University of Basel, said he was surprised by how quickly damage appeared in 2026.

Dead trees and dried leaves are now visible across Central European forests. Kahmen said the region’s forests had never been so stressed since meteorological records began, and that the dead trees point to a profound change underway.

For nearly a decade, the University of Basel has studied how climate change affects key Central European tree species at a test site near Hölstein in the canton of Basel-Landschaft. The experiment, which includes all the region’s important tree species, is unique in Europe.

The latest findings show that many species cannot adapt quickly enough to changing conditions. Trees with shallow roots are particularly vulnerable because they cannot reach water deeper in the soil during prolonged dry spells. Beech, still common in Swiss and Central European forests, is among the hardest hit.

Deeper-rooted species, including oak and the less common wild service tree, are better able to draw water from lower soil layers. If conditions exceed the limits of vulnerable species, Kahmen said, they could disappear from many Central European forests. “You can’t turn a beech into a cactus,” he said.

In an extreme scenario, forests could gradually become more open, with fewer trees per unit of land and lower water use by the ecosystem. Kahmen described a shift towards savannah as the far end of a long-term process.

A more likely possibility is that people will plant species from drier climates that can also withstand cold winters. Options under discussion include Oriental beech and North American Douglas fir. The findings suggest that Central European forests are already changing.