Even in the wilderness, humans are making a ruckus.In 63 percent of America’s protected places — including parks, monuments and designated wilderness areas — sounds made by human activity are doubling the volume of background noise. And in 21 percent of protected places, this racket can make things 10 times noisier.
Enough clatter from cars, planes and suburban sprawl is seeping into wild places to diminish animals’ ability to hear mating calls and approaching predators, a team of researchers based in Colorado reports in the May 5 Science. Human noise doesn’t always have to be loud to override natural sounds, though. Some places are so quiet to begin with that even the smallest amount of human noise can dominate, the researchers found.
“The world is changing, and protected areas are getting louder — the last strongholds of diversity,” says Jesse Barber, an ecologist at Boise State University in Idaho. Studies like this one that show the impact of human-related noise across the entire country instead of in a single park are important, he says, because “this is the scale at which conservation occurs.”
Researchers measured the reach of human noise by tapping into a National Park Service dataset containing long-term audio recordings from 492 sites across the United States. At each site, the scientists linked the sound volume in decibels (averaged over weeks of recording and adjusted to prioritize the frequencies that human ears are most sensitive to) to the presence or absence of dozens of possible features. Such factors include whether the terrain was mountainous or flat, if there was a river nearby, and how close the site was to a highway or a farm.
Machine learning algorithms then predicted the volume in areas without audio monitors, based on the features of that place — and figured out how much of the noise in any given location came from human sources compared with natural ones.
The answer: quite a lot, even in the wilderness. In 12 percent of designated wilderness areas, for instance, human-made noises increase the median sound level 3 decibels above the predicted natural levels of noise. That means the area over which a bird’s squawk would register in human ears would be cut in half in those places.
The more stringent the protections on the land, the lower the noise pollution, says study coauthor Rachel Buxton, an ecologist at Colorado State University in Fort Collins. For example, some categories of land protection allow mining and timber harvesting in limited amounts, which can boost noise levels. Areas labeled as wilderness ban such activity almost entirely, though do permit livestock grazing. Overall, protected areas were 35 percent less noisy than nearby spots that weren’t protected in any way.
上海419论坛洗浴中心
Land managed by the federal government also tended to be less impacted by human noise than land under local control. That might come as a surprise to anyone who’s faced a traffic jam trying to find a parking spot in Yosemite or Shenandoah national parks on a summer weekend. But unlike other U.S. land management agencies, the National Park Service “considers natural sounds to be a natural resource,” Buxton says.
Many national parks have instituted restrictions on airplanes flying overhead, for instance, and implemented public transit to decrease park traffic. So while the area around the visitor center might feel like an amusement park, chirping birds and gurgling streams can dominate the soundscape deeper in the park. This study suggests those noise control efforts might be making a difference.
Still, even a little extra noise can take a toll on the surrounding ecosystem. A humming highway can drown out birds’ mating calls or prevent predators from hearing rustling prey (SN: 2/21/15, p. 22). And species don’t need ears to be affected — the effects of excess noise “can really trickle through a community,” Buxton says. Plants often depend on birds to spread their seeds, or on bees to get pollinated. If noise changes those animals’ behavior, then the plants can face consequences, too.
“Noise is not strictly an urban phenomenon,” says Clint Francis, an ecologist at California Polytechnic State University in San Luis Obispo. There’s hope for wild areas, though. “Solutions to noise are often readily available,” he says. Quieter car engines and different types of road surfaces can all help reduce traffic noise, for example.
Quieter wild places can benefit humans, too. “When you’re in a park and you’re appreciating some sight, like the Grand Canyon, you also experience the sound of the river going by, the sound of the birds in the trees,” Buxton says. “It totally enhances your experience.”
相关文章China calls for peace, order to be restored in Gabon while West expresses concerns over self-interest
After media reported that a group of senior military officers in Gabon seized power on Wednesday, some Western countries condemned the military coup. The coup in Gabon, which comes a month after Nigers President Mohamed Bazoum was taken hostage by the troops of presidential guard, showed that the overall influence of Western countries, which have […]
Friendship between Chinese and American people deserves to be told more positively: owner of Iowa Sino-US Friendship House
Editors Note: "The Chinese people value friendship. We never forget our old friends, nor your historic contributions to promoting the growth of China-US relations and enhancing friendship between the two peoples," Chinese President Xi Jinping said during the meeting with former US secretary of state Henry Kissinger in Beijing, on July 20, 2023, the Xinhua […]
Some Americans should look beyond disassembling phones: Global Times editorialAlthough some mainstream US media and the US government maintain a "reserved" style of silence, Huaweis latest flagship mobile phone, Mate 60 Pro, continues to send shockwaves in the US public opinion field. Bloomberg commissioned a professional organization to disassemble the new phone, looking for clues about how far Chinas technology has gone. Some simply […]
‘Super Golden Week’ is more than just about the economy: Global Times editorialThe "Super Golden Week," which combines the Mid-Autumn Festival and the National Day holidays, officially begins, as rail transportation of the holiday started on Wednesday. Before this, the festive atmosphere of the two combined holidays had been fully "preheated" in all parts of the country. On social media and in daily life, the destination of […]
还没有评论，来说两句吧...