As the tremors of millions of leaves echo through its roots, we can now hear the whisper of one of the largest and oldest living organisms on Earth. A monolithic forest known as Pando (Latin for “I spread”) has 47,000 trunks (all with the same DNA) growing from a common root system across a 100-acre (40-hectare) area in Utah.

Here, this lone quaking aspen (Populus tremuloides) slowly grew into a massive plant weighing 6,000 metric tons, making it the largest living organism on Earth.

This giant plant, with its tree-like trunks rising up to 24 metres (80 feet), has a lot to say after perhaps 12,000 years on Earth, and recordings released this year allow us to “hear” it like never before.

“The results are very promising,” said Lance Oditt, founder of Friends of Pando, when the project was unveiled in 2023.

“Although it started as art, we see great potential for use in science. Wind converted into vibration (sound) and traveling through the root system could also non-destructively reveal the inner workings of Pando’s vast hidden hydraulic system.”

Experimentally, sound engineer Jeff Rice placed a hydrophone in the gap at the base of a branch and aimed it toward the tree’s roots without expecting to hear much.

“Hydrophones need more than just water to work,” Rice says. “They can also detect vibrations from surfaces like roots, and when I put the headphones on, I was immediately amazed. Something was happening. There was a faint sound.”

This noise increased during the storm; the device recorded an eerily low rumble.

“I think you’re hearing the sound of millions of leaves in the forest vibrating on the tree and moving down the branches,” Rice said while presenting his recordings at the 184th meeting of the Acoustical Society of America, according to The Guardian.

The hydrophone also recorded the shocks when a branch was hit at a distance of 90 feet, but the sound could not be heard in the air at this distance. This supports the theory that the Pando root system is interconnected, but a suitable experimental setup is needed to verify that the sound does not travel through the soil.

Such shared root systems are typical of colonial aspens, but Pando’s size and age make it unique. Although quaking aspens can reproduce by seed, they rarely grow from seed because pollination is rare and large aspen stands are often monoecious, meaning they are clones of the same individual.

To try to better understand this strange, giant creature, the Friends of Pando invited Rice as a guest artist. Oditt hopes to use the sound to map Pando’s root ball.

“The sounds are beautiful and interesting, but from a practical perspective, natural sounds can be used to document environmental health,” Rice says. “They are a record of local biodiversity and provide a baseline against which changes in the environment can be measured.”

Rice also recorded Pando’s leaves, bark and surrounding ecosystem.

“Pando’s colleagues plan to use the data collected as a basis for additional studies of water movement, branch relationships, insect colonies and root depth, which we currently know very little about,” Oditt said.

Unfortunately, this majestic tree is deteriorating and researchers fear that Pando’s days, and all the forest life it supports, are numbered. Human activities, including deforestation and the killing of predators that has reduced the number of herbivores, are depleting this ancient creature.

All the more reason to listen to the Trembling Giant while it still has its secrets to share. The recording was presented at the 184th meeting of the Acoustical Society of America. A previous version of this article was published in May 2023.