Ecology Researchers use drones to monitor the health of forests
Scientists are using drones to detect stressed trees in Swiss forests. This new monitoring method is intended to reveal how individual tree species react to heat and water shortages.
19.01.2026, 08:01
SDA
Increasing heat and drought pose major challenges for forests. In order to increase their resilience, forestry experts need to know how individual tree species react to a lack of water, as the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) explained in a press release on Monday.
Until now, such studies have been costly and usually only possible for individual trees. Studies using drones should change this.
In order to detect drought stress from the air, a WSL research team used drones with so-called multispectral cameras. These can also record areas of the light spectrum that are invisible to the human eye.
The cameras record a special pigment that trees produce in dry conditions to protect their leaves from excessive sunlight. "This allows us to recognize whether a tree is under acute stress even before damage is visible to the eye," WSL geographer Petra D'Odorico is quoted as saying in the communiqué.
Trees for the future
D'Orica's research team has now presented the method to experts in the latest issue of the journal "Agricultural and Forest Meteorology". The method was tested for the first time in a mixed forest in Hölstein BL during the hot summer of 2023.
The team observed different reactions to the drought. "For example, we observed that oak trees recover more quickly from a hot previous day than other tree species," explains D'Odorico. Conifers showed a different behavior: they only show signs of drought stress with a delay, but can then suddenly die.
The new method could help researchers to monitor forests on a large scale in the future and find out which tree species are best able to cope with climate change. In the meantime, D'Odorico is also investigating non-native trees such as the Lebanon cedar and the Oriental beech. The aim is to identify species that could be used to replace native trees in regions that are particularly affected by climate change.
