For the first time, a team of scientists from KU Leuven, UAntwerp and Ghent University have mapped the temperatures of all European forest tracts. The results show that the summer temperatures in certain forests can cool down by as much as 10°C compared to the surrounding area. This cooling function is important in the battle against climate change. You can check the cooling effect of the forest in your neighbourhood online.
On a hot summer day, forests can feel a lot cooler than the surrounding area, but the exact difference in temperature has been difficult to quantify. An international team of researchers, led by PhD student Stef Haesen and Professor Koenraad Van Meerbeek from KU Leuven, Belgium, has been measuring the temperature of each European forest.
This is a real scientific and technical breakthrough that will undoubtedly improve predictions about distribution of forest species.
Mini weather stations on the forest floor
Using a dataset of more than 1200 small weather stations across all European forests, the researchers quantified the difference in temperature between the forest understory and the surrounding area. "This network of sensors on the forest floor is unique as it accurately captures the true temperature under the forest canopy, both for big and small forests," explains Haesen. "This information is crucial to analyse the impact of climate change on and in forests."
Right: the new high-resolution temperature data;
The new map is more detailed and shows the cooling function of the 'Meerdaalwoud' in the centre of Belgium.
Forests as thermal insulation
The data show that the maximum summer temperature in forests is on average 2°C lower than in surrounding areas, but the difference can be as high as 10°C. Similarly, minimum temperatures in winter can be 2°C higher, and in some forests even up to 12°C. "With their foliage and branches in the canopy, trees create a thermal insulating layer above the forest floor. In addition, the transpiration during the photosynthesis process extracts heat from the air, lowering the temperature during summer even more," explains Professor Van Meerbeek. "Summer heat waves are thus strongly moderated below the tree canopy, which is increasingly important considering global warming."
Effect on climate change on and in forests
"This is a real scientific and technical breakthrough that will undoubtedly improve predictions about the distribution of forest species," Haesen adds. As the new map is very detailed, it reveals differences between and within forests: temperatures vary significantly depending on the local canopy cover, topography or tree species composition.
"If we want to know why certain forests grow in a specific place, we need information from within the forest. With this map, we can manage the forest climate in order to protect forests and their organisms against climate change and increased frequency of extreme weather events," says Professor Pieter De Frenne from Ghent University.
"This unique database and cooperation puts Flanders at the forefront of microclimate research, a discipline of critical importance considering the climate and biodiversity crisis," concludes postdoctoral researcher Jonas Lembrechts from UAntwerp.
