Man-made noise 'harms plant growth'

The noise of cars, machines and other forms of human activity could be affecting growth of wild flowers and trees, as well as animals nearby.

Man-made noise may be harmful to some plants because of the long-term impact it has on animals that pollinate flowers and disperse seeds, scientists found in tests near the noisy gas wells of New Mexico, which have compressors running 24 hours a day.

The study, published in Proceedings of the Royal Society B, investigated the noise preferences of different animals that feed on the seeds of the pinon pine tree. It found that certain species, such as western scrub jays, tended to avoid noise, while other seed-eaters, such as mice, appeared to prefer foraging in noisy areas.

Clinton Francis, lead researcher at the National Evolutionary Synthesis Centre in North Carolina, said this difference in noise tolerance would affect the likely germination of pinon seeds because the natural instinct of jays is to hide many of the seeds they collect by burying them.

This means some inevitably survive to germinate in the next season, which is less likely in mice-infested noisy areas. "Fewer seedlings in noisy areas might eventually mean fewer mature trees, but because pinon pines are so slow-growing the shift could have gone undetected for years," Dr Francis said.