Swiss high-altitude forests weaken under drought stress

Swiss protective forests, which serve as natural defenses against avalanches, landslides, and floods, are reaching a critical tipping point due to global warming. Research published in Frontiers in Forests and Global Change by Dr. Estelle Noyer and colleagues at Bern University of Applied Sciences indicates that summer droughts are now overwhelming tree resilience even at altitudes of 2,200 meters.

Data from the Swiss national forest inventory, spanning 1983 to 2022, reveals that the historical trend of high-altitude forests being shielded from drought has disappeared post-2017. In the colline belt, the share of declining stands rose from 11.1% in 1983 to 30.4% by 2022. While subalpine stands experienced a dip in decline during the early 2000s, they have since seen a sharp increase to 18.8%.

Frequent droughts are selectively killing large, dominant trees, reducing overall canopy density. The study concludes that current stands, while potentially containing more resilient species, remain vulnerable to consecutive drought events. Researchers suggest that foresters must prioritize diverse, multi-layered stands to maintain natural hazard protection. What to watch: Development of new adaptive forestry strategies and spatial data to mitigate forest decline in European mountain ranges.

Editor's note: The article is accurate and well-synthesized, effectively capturing the core study findings, methodology, and the specific impact on altitudinal forest resilience.

This article is AI-generated and fact-gated. Original reporting: Phys.org