THE ELECTRIC FOREST--TREES RESPOND TO A SOLAR ECLIPSE: Solar Eclipses Aren't Just For Homo Sapiens.

THE ELECTRIC FOREST--TREES RESPOND TO A SOLAR ECLIPSE: Solar eclipses aren't just for homo sapiens. Researchers have long known that birds, insects, and many mammals pay attention when the Moon slides in front of the sun. Now we can add trees to the list.

The study's location in the Dolomite Mountains of Italy. Photo credit: Monica Gagliano

A paper just published in the journal Royal Society Open Science reports the extraordinary reaction of an Italian mountain forest to a partial eclipse on Oct. 25, 2022. Electrical signals inside spruce trees began to pulse in unison, with older trees seeming to anticipate the eclipse before it happened.

This is unconventional research, and it may challenge what some readers think about trees. However, it is serious work conducted by experts in plant communication and published in a peer-reviewed journal of the Royal Society.

The paper reports how scientists led by Alessandro Chiolerio of the Italian Institute of Technology and Monica Gagliano of Southern Cross University attached electrodes to three Norway spruce trees and five tree stumps. Their device is like an EKG for trees. The trees were different ages, ranging from 20 to 70 years old, allowing the team to compare how age might influence bioelectrical responsiveness to the eclipse.

Electrodes connected to the spruce trees during the eclipse. Photo credit: Monica Gagliano

As the eclipse approached, electrical signals from different trees began to align; their waveforms became more similar in shape and timing. This synchronization peaked during the eclipse and gradually diminished afterward. The older trees started showing electrical changes earlier, hours before the eclipse began, while the youngest tree responded later and more weakly. The tree stumps also exhibited a bioelectrical response, albeit less pronounced than in the standing trees.

The researchers interpreted this as a coordinated "organism-like" response to a large-scale environmental event, possibly involving communication or shared signaling pathways. 

The idea that trees may "talk" to one another is key to the burgeoning field of plant communication. A growing body of research (especially since the 1990s) suggests that trees form symbiotic relationships with fungi, creating vast underground networks called the "Wood Wide Web." Through these networks, trees exchange nutrients, water, and even chemical signals. They also reportedly recognize their own young and give preferential treatment to kin. Even tree stumps may retain connections to this network.

"Basically, we are watching the famous 'Wood Wide Web' in action!" says Gagliano.

Although the researchers successfully detected electrical activity in the trees, they have no idea what was being said--if anything. Perhaps it was simply a basic response to changes in temperature or light levels (about 1/3rd of the sun was covered during the eclipse). The researchers don't yet speak the "language" of arboreal electricity, so they can't decipher what they overheard. Repeating the experiment in different forests during more eclipses may be revealing.

Stay tuned for updates from the forest.

Recommended reading: Two good introductory books on plant communication and networking are "Finding the Mother Tree" by Suzanne Simard and "The Light Eaters" by Zoe Schlanger.