Engineering the Woods

In the forest near Uster, more than five hundred spruce trees recently crashed to the ground. A century of quiet growth ended abruptly under the chainsaw, sacrificed to contain a bark beetle outbreak fueled by extraordinary heat and record low precipitation. It is a vivid illustration of the traditional Swiss approach to environmental trouble: when old plans falter, state intervention steps in with rapid corrections and generous public funds.

The Federal Council has made over 70 million Swiss francs available to adapt forests to changing climatic conditions. In Uster, local forester Ruben Menzi and his team are forced to make decisions that must hold up for a hundred years. Spruces draw water primarily from upper soil layers, leaving them vulnerable during extended dry spells.

Weakened by water shortages, the trees lose their ability to produce resin and trap invading insects. A single bark beetle, specifically the local Buchdrucker, can produce around 40 larvae, creating exponential population growth across a single trunk. Spruces currently make up about a quarter of Uster’s forest. Menzi aims to cut that proportion to five or ten percent, distributing risk across a wider variety of species, such as oak, winter linden, Norway maple, or wild service tree.

Yet ecological realities remain stubbornly localized. Data from the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) shows that nationwide beetle-damaged wood fell by 27 percent in 2025 to roughly 415,000 cubic meters. Regional damage varies widely, and spruces are not the only trees under pressure; local beeches have already dropped leaves prematurely to limit water loss. To determine which species can handle future conditions, the WSL is monitoring more than 55,000 test trees across 18 species on 56 sites around the country.

Nature could adjust on its own, but natural selection operates over several tree generations, spanning hundreds of years. Human society cannot afford that timeline. Forests serve immediate economic and practical functions, providing timber, recreational space, and protection against natural hazards. Replacing protective forests with artificial defense structures against avalanches and rockfalls would prove far more costly than targeted management. Swiss foresters are left directing the transition themselves, allowing natural regrowth where possible and planting alternative species where necessary, hoping their calculations endure into the next century.

Written by Sandy van Dongen sandy.vandongen@alpineweekly.com