The heartbeat of a tree: Scientists discover plants pulsate throughout the night

It might seem as though trees spend most of their lives standing still – but, according to new research, they do a lot more moving than you’d think, according to Daily Mail.

Scientists have discovered the subtle ‘heartbeat’ of trees and shrubs, using terrestrial laser scanning to measure the overnight movement of branches and leaves.

While only some trees in the study were shown to follow a ‘sleep cycle,’ in which their branches lowered at night and returned to their daytime position hours later, the researchers found that all of the trees displayed minute, periodic pulses.

The discovery suggests trees are pumping water, the experts say. 

 In the study, researchers investigated the overnight movement of 21 species of trees using a high-precision three-dimensional surveying technique known as terrestrial laser scanning.

It’s long been known that trees in the legume family have a distinct ‘sleep cycle,’ and move their leaves overnight.

More recently, scientists found that other trees lower their branches at night as well, with some dropping 10 centimeters before returning to normal in the morning.

As this happens very gradually, the phenomenon is difficult to spot with the naked eye.

Now, in a surprise discovery, scientists have found that numerous types of trees exhibit periodic movements.

‘We detected a previously unknown periodic movement of up to one centimetre in cycles of two to six hours,’ said postdoc András Zlinszky.

‘The movement has to be connected to variations in water pressure within the plants, and this effectively means that the tree is pumping.

‘Water transport is not just a steady-state flow, as we previously assumed.’

According to the researchers, all of the trees experienced minute branch movement, though only seven species showed ‘sleep motion.’

And, these sleep periods weren’t always 12 hours; some had shorter or longer periods, while others showed slow, continuous movement in one direction.

Disease and other factors likely contribute to their motion, the researchers note.

The researchers noted the most dramatic movement in the tree, which moved through three up-and-down cycles over the course of a night.

Trees’ short-term movement is linked to changes in water pressure.

According to the team, the barely detectable movements of trees and other plants could serve as an important signal of their health.

‘We believe that detection of anomalies of overnight movement could become an efficient diagnostic tool to reveal stress or disease in crops,’ said Anders S Barfod, Associate Professor .

‘This would open up for early intervention, which is not only cost efficient but also more environmentally friendly.’

N.H.Kh

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