Beneath the tree: The sounds of a trembling giant

Abstract

The Pando aspen grove (Populus tremuloides) consists of more than 40000 genetically identical aspen stems spread across 106 acres in south-central Utah. While Pando resembles a forest, it is a single organism connected at the roots, making it the world's largest tree and one of the largest living things on the planet. First identified in 1976, Pando has not been studied as a bioacoustic subject. Focusing on recordings captured simultaneously above and below ground on July 12, 2022 during a thunderstorm, our presentation reveals a unique acoustic portrait of this botanical wonder. We compare audible sounds of Pando’s leaves with hydrophone recordings made in connection with the tree's root system. This dual soundscape shows that leaf motion causes vibrations that pass throughout the organism, from its branches to its base. The recordings suggest that the grove’s massive, interconnected root system is highly resonant with potential for future recordings and research.