Temperature records are compiled from selected sites, in the open, up to 2 metres off the ground. The equipment, in a ventilated box out of the sun, records the ambient air temperature. It is from thousands of these sites that we calculate how fast the climate is heating.
But everyone who goes outside on a hot day knows how the temperature can be several degrees lower under trees, and much cooler in a dense wood. This matters enormously to a vast quantity of creatures and plants that live close to the ground in the world’s woodland and forests, the most biodiverse places on Earth.
Most species thrive in what is for them an optimum temperature range, so the stable temperatures of the forest floor provide a cushion against the effect of climate heating. Destroying the protective canopy provided by big trees, even with selective logging, can be catastrophic for this sheltered community. The forest floor dries out and the temperatures surge, changing the habitat overnight.
Scientists studying 3,000 sites over 80 years say these changes happen too fast for some species to adapt, wiping them out, while allowing others to move in. With increasing heatwaves they plead for foresters to take this into account during their operations and help preserve biodiversity.
