Learn something new every day – Trees “sleep”

In the only reported study to look at tree siestas, researchers set up lasers that measured the movements of two silver birch trees (Betula pendula) at night. One tree was in Finland and the other in Austria, and both were monitored from dusk until morning on dry, windless nights in September. This was close to the solar equinox, when daylight and nighttime are about equal…

The silver birches’ branches and leaves sagged at night; they reached their lowest position a few hours before sunrise, and then perked up again during the wee hours of the morning, the researchers found.

The silver birches’ branches and leaves sagged at night; they reached their lowest position a few hours before sunrise, and then perked up again during the wee hours of the morning, the researchers found.

“Our results show that the whole tree droops during night, which can be seen as position change in leaves and branches,” study lead author Eetu Puttonen, a researcher at the Finnish Geospatial Research Institute, said in a statement. “The changes are not too large, only up to 10 centimeters [4 inches] for trees with a height of about 5 meters [16 feet].”

Quoting from Live Science for this one. There’s more in the article.

This reminded me of the walking palm tree articles I’d come across before. There’s debate on the truth of that. A BBC travel report quotes a paleobotanist who claims he’s seen how they do it. It could also just be an illusion based on how the trees grow so many roots outward into the ground and as new ones grow in and others die, it’s going to look like the tree “moved” a little when it hasn’t actually. Whichever is right, tour guides will still say they walk because it impresses the tourists.

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