Older trees tell younger spruces when eclipses will happen, study shows

Telegraph

30-04-2025

Older trees send messages to younger spruces before an eclipse, scientists have found.
Spruces start syncing their electrical activity 14 hours before the astronomical phenomenon begins, a study of trees in the Italian Dolomites discovered.
Italian and Australian scientists detected bioelectrical waves travelling between the trees, suggesting that the 'ancestral memories' about an eclipse were being transmitted between them.
Researchers picked up on the phenomenon while using sensors to monitor the bioelectrical patterns of spruce trees in the Costa Bocche forest near Paneveggio.
'What we found was quite incredible and in a way unexpected,' said Prof Monica Gagliano from Southern Cross University in Australia.
'We had an eclipse event passing through the site while we were recording and monitoring the trees and we observed something that we see in animals but have never seen before in plants, a synchronisation behaviour.
'All the trees that we were monitoring ended up having the same behaviour and the same bioelectrical signature coming out during the eclipse event.
'Older trees were the ones that started the signal first, 14 hours before the eclipse even arrived and they were the ones to send a message to all the others, especially the young ones that potentially never experienced an event of this kind and allowed everyone to synchronise as one.'
She added: 'We went from individual trees to see the activity of the forest as one entity and then everyone came back and did whatever they wanted after the eclipse was done.'
Most species are sensitive to light, having evolved to take advantage of the 24-hour cycle of day and night which drives circadian clocks inside cells.
Animals can also adapt their behaviour to astronomical events, with many marine animals, particularly corals and invertebrates like worms, synchronising their spawning with the full moon.
During an eclipse, birds stop singing, cattle return to their sheds and horses cluster together, shaking their heads and tails. But these animal changes are driven by the fall in light.
Researchers say the trees cannot be sensing changes in light, so have theorised they may be picking up tiny gravitational changes, or even have memory of previous eclipses. Older trees exhibited the most anticipatory activity.
Prof Alessandro Chiolerio, of the Italian Institute of Technology, said: 'There are two options we could not totally exclude: they could sense gravitational perturbations connected to the astronomical event; or they could have a memory of previous eclipses, occurring with a periodicity of 18 years.'
All cells in living organisms communicate and coordinate using tiny currents of electricity which is collectively known as an 'electrome'.
For the study the team placed electrodes in two trees of about 70 years old, one in full sun and one in the shade as well as a 20-year-old tree in full shade. They also attached the sensors to five tree stumps.
They found the activity of all three trees – and even the stumps – became significantly more synchronised around the eclipse – both before and during the one-hour event, with the two older trees having a much clearer early response. It lasted for about 17 hours after the event.
Scientists do not know why the trees appear to sync but believe it could be to reassure each other during periods of change. Many animals huddle together collectively during eclipses.
Long distance signalling between plants has already been recorded in scientific literature, with trees in forests often using fungal and root networks to transmit information about threats, a phenomenon dubbed the Wood Wide Web.
This 'underground internet' for trees enables them to transfer water, nutrients and chemical signals.
Prof Gagliano added: 'This is a very remarkable example of the Wood Wide Web in action.
'This signal was coming from the older trees to the younger ones which, without being warned of an event like an eclipse, might have been suffering from hydraulic dysfunction which meant they could have dehydrated and died of thirst.
'It reinforces that old trees cannot simply be replaced by replanting but they need to be protected because they hold ancestral memories that allow for resilience and adaptation in a state of climate change.'