Noise has complex effect on plants, study reports

Researchers haven’t given much thought to the effect of noise and noise pollution on plants.

But that could be about to change.

In northwestern New Mexico’s Rattlesnake Canyon, gnarled juniper trees and piñon pines dominate a landscape of high mesas and rough sandstone cliffs.

Tucked in among the trees are thousands of natural gas wells. About one-third of them are pressurized by ear-splitting compressors.

“They run 24 hours a day, 365 days a year, with the exception of periodic maintenance, so they are going all the time,” says Clinton Francis, of the National Evolutionary Synthesis Center in North Carolina.

Since 2005, he’s been studying how Rattlesnake Canyon’s birds respond to the compressors’ non-stop racket.

“Black-chinned hummingbirds, for example, tend to prefer and settle in really noisy landscapes, and western scrub jays tend to avoid these noisy areas,” Francis says.

So the noise in the canyon is changing the way the birds behave. And that got Francis wondering whether that’s having an effect on plants the birds interact with. Take piñon pine trees and scrub jays, for example.

“We know that jays are really important seed dispersers for piñon pine,” he says.

The jays bury the seeds to snack on later, but inevitably, some get forgotten and grow into new pine trees.

Francis already knew there were fewer pine seedlings at noisy sites. Was that because the noise was keeping the jays away from their pine nuts?

Francis set up motion-trigger cameras at both noisy and quiet sites, put out some pine seeds, and waited.

As he predicted, jays avoided the noisy sites, not stashing any nuts there.

“We only found them removing seeds on the quiet sites,” he says.

But that wasn’t the only thing the cameras saw. At the noisy sites, mice were gobbling up the seeds, leaving nothing behind to sprout.

So for the pine trees, it looked like the compressor noise was delivering a double whammy.

“We’re just not getting as many seeds going into the seed bank in noisy areas, and the ones that do might be consumed by the mice that are there.”

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