Air Quality in American National Parks and Big Cities Is Roughly the Same

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National parks usually have more vegetation, wildlife, and open spaces than urban areas, but the two don't look much different when it comes to air quality. As City Lab reports, a new study published in Science Advances found that U.S. national parks and the nation's largest cities have comparable ozone levels.

For their research, scientists from Iowa State University and Cornell University looked at air pollution data collected over 24 years from 33 national parks and the 20 most populous metro areas in the U.S. Their results show that average ozone concentrations were "statistically indistinguishable" between the two groups from 1990 to 2014.

On their own, the statistics look grim for America's protected areas, but they're actually a sign that environmental protection measures are working. Prior to the 1990s, major cities had higher ozone concentrations than national parks. At the start of the decade, the federal government passed the Clean Air Act (CAA) Amendments in an effort to fight urban air pollution, and ozone levels have been declining ever since.

The average ozone in national parks did increase in the 1990s, but then in 1999 the EPA enacted the Regional Haze Rule, which specifically aims to improve air quality and visibility in national parks. Ozone levels in national parks are now back to the levels they were at in 1990.

Ground-level ozone doesn't just make America's national parks harder to see: It can also damage plants and make it difficult for human visitors to breathe. Vehicles, especially gas-guzzling trucks and SUVs, are some of the biggest producers of the pollutant.

[h/t City Lab]

The Tree That Inspired Dr. Seuss's The Lorax Has Fallen Over

Rhododendrites, Wikimedia Commons // CC BY-SA 4.0
Rhododendrites, Wikimedia Commons // CC BY-SA 4.0

The Truffula trees at the center of The Lorax may have been a product of Dr. Seuss's imagination, but it's believed they were inspired by a real-life tree in La Jolla, California. Nearly 50 years after the environmental parable was published, Smithsonian reports that the iconic Monterey cypress has fallen.

The tree had grown for 80 to 100 years in what is today Ellen Browning Scripps Park in Southern California. It was clearly visible from the observation tower where Theodor Geisel, a.k.a. Dr. Seuss, lived in La Jolla following World War II.

While the children's book author and illustrator never stated that the tree inspired his work, locals started referring to it as "The Lorax Tree." The resemblance it bears to Seuss's Truffula is undeniable: Both have skinny trunks with whimsical curves and thick, fluffy canopies of foliage concentrated at the top.

In The Lorax, the Truffula trees are threatened by the Once-ler, who wants to chop them down and turn them into garments called Thneeds. The title character "speaks for the trees" and conveys the book's environmentalist message.

Unlike the Truffula, La Jolla's Monterey cypress appeared to be in no danger until it recently toppled over. Arborists aren't sure what caused the collapse, as they hadn't noticed any prior health issues with the tree except for some termites. The past year's uncharacteristically wet winter and the effect it had on the surrounding soil may have played a role, so experts are looking into that possibility.

Most of the tree has been removed from the area, and the city plans to plant another tree in its place. There are also plans to salvage and repurpose the trunk from the fallen tree, though they haven't been made official.

[h/t Smithsonian]

Tourists Are Picking Apart Britain's Oldest Tree

Paul Hermans, Wikimedia Commons // CC BY-SA 3.0

The Fortingall Yew in the Fortingall churchyard in Perthshire, Scotland has seen a lot. Since it started growing at least 2000 years ago, it's been present for the Roman settlement of Scotland, the shift from paganism to Christianity, and the country's induction into the United Kingdom. But after standing for millennia, the ancient tree is facing its greatest threat yet. Tourists are removing twigs and branches from the tree to take home as souvenirs, and the tree is under so much stress that it's spontaneously changing sexes, Atlas Obscura reports.

Because of how the tree grows, it's hard to date the Fortingall Yew precisely. It comprises several separate trunks that have hollowed out over the years, making it easier for the tree to support itself in its old age. Based on historical measurements and 19th-century ring counts, the yew has been around for at least two millennia, but it could date back as far as 5000 years. That makes it the oldest tree in Britain and one of the oldest living things in Europe.

That impressive title means the tree gets a lot of visitors, not all of whom are concerned with extending its lifespan even longer. A stone and iron wall built in the Victorian era encloses the tree, but that hasn't stopped people from climbing over it to break off pieces or leave behind keepsakes like beads and ribbons.

As the abuse adds up, the tree has responded in concerning ways. It sprouted red berries this spring, a sign that the tree is transitioning to a different sex for the first time in its life. Yew trees are either male or female, and sex changes among the species are incredibly rare and misunderstood. Some botanists believe it's a reaction to stress. The change may be a survival mechanism intended to increase the specimen's chances of reproducing.

Scientists aren't sure why this particular yew, which was formerly male, sprouted berries on its upper branches, an exclusively female characteristic, but they've collected the berries to study them. The seeds from the berries will be preserved as part of a project to protect the genetic diversity of yew trees across the globe.

In the mean time, caretakers of the Fortingall Yew are imploring visitors to be respectful of the tree and keep their hands to themselves.

[h/t Atlas Obscura]

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