A giant tree in Utah is making noise, and researchers say it may be the sound of millions of leaves moving through a shared root system.
Pando is a single male quaking aspen, Populus tremuloides, made up of 47,000 stems with the same DNA across 40 hectares. It weighs about 6,000 metric tons, making it the largest living organism on Earth by mass. It may also be about 12,000 years old.
Recent recordings have let people hear it in a new way.
“The findings are tantalizing,” Friends of Pando founder Lance Oditt said when the project was unveiled in 2023. “While it started as art, we see enormous potential for use in science. Wind, converted to vibration (sound) and traveling the root system, could also reveal the inner workings of Pando’s vast hidden hydraulic system in a non-destructive manner.”
Sound artist Jeff Rice placed a hydrophone inside a hollow at the base of a branch and fed it down to the tree’s roots.
“Hydrophones don’t just need water to work,” Rice said. “They can pick up vibrations from surfaces like roots as well, and when I put on my headphones, I was instantly surprised. Something was happening. There was a faint sound.”
During a thunderstorm, the sound grew louder, and the device recorded a low rumbling.
“What you’re hearing, I think, is the sound of millions of leaves in the forest, vibrating the tree and passing down through the branches, down into the earth,” Rice said when he presented the recordings to the 184th Meeting of the Acoustical Society of America.
The hydrophone also picked up thumps from tapping on a branch about 27 metres away, even though the sound could not be heard through the air at that distance.
That supports the theory that Pando’s root system is interconnected, although the article says a proper experimental setup would be needed to confirm the sound was not travelling through the soil.
Shared root systems are common in colonial quaking aspens, but Pando’s size and age make it unusual. Quaking aspens can reproduce through seeds, but they rarely grow that way because pollination is rare when large aspen stands are clones of the same individual and usually only one sex.
Friends of Pando invited Rice as an artist in residence to help better understand the organism. Oditt hopes sound can be used to map Pando’s roots.
“The sounds are beautiful and interesting, but from a practical standpoint, natural sounds can be used to document the health of an environment,” Rice said. “They are a record of the local biodiversity, and they provide a baseline that can be measured against environmental change.”
Rice also recorded Pando’s leaves, bark and the surrounding ecosystem.
“Friends of Pando plans to use the data gathered as the basis for additional studies on water movement, how branch arrays are related to one another, insect colonies, and root depth, all of which we know little about today,” Oditt said.
The article says Pando is deteriorating, and researchers are worried about its future and the forest life it supports. It says human activities, including clearing and killing predators that keep herbivore numbers down, are contributing to the decline.
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