Even high-altitude forests in Switzerland are now weakened by frequent droughts, making natural hazards more dangerous
Due to global warming, Swiss forests are now at a tipping point where summer droughts are overwhelming trees' tolerance and resilience, scientists have shown. That bodes ill for people in the valleys because forests form their first line of defense against avalanches, rockfalls, landslides and floods.
Frequent droughts in high-altitude forests in Switzerland are weakening these ecosystems, making natural hazards more dangerous. Global warming is overwhelming trees' tolerance and resilience, posing risks for people in valleys, where forests act as the first line of defense against avalanches, rockfalls, landslides, and floods.
A new study reveals that even at altitudes of 2,200 meters (7,220 feet), the number of trees per stand has decreased due to the decline or death of large, dominant trees. This progressive decline of protective forests ultimately endangers natural hazard mitigation. Despite historically being more vulnerable to summer drought in low-altitude belts, recent warming at intermediate and high altitudes has made trees thirstier, increasing drought frequency.
The study analyzed Swiss national forest inventory data from 1983 to 2022, focusing on protective forest stands in areas unaffected by fires or interventions. The percentage of declining stands increased over time in every belt, but most notably in lower-altitude belts like the colline and montane. In the highest belts (subalpine inferior and superior), the percentage of declining stands decreased until the mid-1990s, then sharply rose to 18.8% by 2022.
Tree density also decreased across all belts. The loss of large trees weakens protection against natural hazards, and there is a pressing need for adaptive forestry strategies in response to these changing conditions.
Written by urgent.news from Phys.org's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
