The forest really does hum with life.
Though often too low or too high for human ears to detect, insects and animals signal each other with vibrations. Even trees and plants fizz with the sound of tiny air bubbles bursting in their plumbing.
And there is evidence that insects and plants “hear” each other’s sounds. Bees buzz at just the right frequency to release pollen from tomatoes and other flowering plants. And bark beetles may pick up the air bubble pops inside a plant, a hint that trees are experiencing drought stress.
Sound is so fundamental to life that some scientists now think there’s a kernel of truth to folklore that holds humans can commune with plants. And plants may use sound to communicate with one another.
If even bacteria can signal one another with vibrations, why not plants, said Monica Gagliano, a plant physiologist at the University of Western Australia in Crawley.
“Sound is overwhelming, it’s everywhere. Surely life would have used it to its advantage in all forms,” she told OurAmazingPlanet.
Gagliano and her colleagues recently showed corn seedling’s roots lean toward a 220-Hertz purr, and the roots emit clicks of a similar tune. Chili seedlings quicken their growth when a nasty sweet fennel plant is nearby, sealed off from the chilies in a box that only transmits sound, not scent, another study from the group revealed. The fennel releases chemicals that slow other plants’ growth, so the researchers think the chili plants grow faster in anticipation of the chemicals — but only because they hear the plant, not because they smell it. Both the fennel and chilies were also in a sound-isolated box.
“We have identified that plants respond to sound and they make their own sounds,” Gagliano said. “The obvious purpose of sound might be for communicating with others.”
Gagliano imagines that root-to-root alerts could transform a forest into an organic switchboard. “Considering that entire forests are all interconnected by networks of fungi, maybe plants are using fungi the way we use the Internet and sending acoustic signals through this Web. From here, who knows,” she said.