A Hungarian–Finnish-Austrian research group’s laser scanner experiment revealed what happens to the foliage of trees during the night. The results stunned everyone. András Zlinszky, the researcher at the Balaton Limnological Institute of MTA’s Centre for Ecological Research served as the group’s biologist.

A new method for measuring the sleeping movements of trees has been devised by an international research group of Finnish, Austrian and Hungarian scientists. With the help of a laser scanner, they made a very precise and detailed model of the examined tree, repeating the process on an hourly basis during the entire night. It turned out that the branches and leaves of the trees drooped by as much as 10 centimetres during the night.

“We measured a small but systematic change,” said Eetu Puttonen of the Finnish Geodetic Institute and leader of the experiment. “The leafy branches of 5-meter birch trees gradually drooped by 8 to 10 centimetres by night. Their lowest position was right before sunrise and after dawn, it took a couple of hours for them to return to their original position. Whether the branches were “woken up” by the rays of the Sun or by their own inner rhythm independent of the Sun still remains to be seen.”

“Наука и жизнь”