National park plants could indicate climate change

By Katie Demeria

Shenandoah National Park is home to two plants that, though globally common, are considered rare in Virginia. And they might be able to reveal the impacts of climate change.

Botanists with the park will spend the summer monitoring the three-toothed cinquefoil and Appalachian fir clubmoss that grow on the park’s rock outcrops. Both are considered imperiled in the commonwealth, according to botanist Wendy Cass.

The plants usually grow in the north, so those found in Shenandoah National Park are in the southernmost areas of their region.

“Because the communities are so restricted and at the very edge of their geographic range, they’re going to be more sensitive to any kind of stress, whether it be lack of rain or changes in temperature,” Cass said.

If it gets warmer here, Cass pointed out, the plants will be more likely to retreat to the north.

“We’re trying to use them as an indicator of stress to a larger system,” she said. “If you suddenly see all your rare plants at the southern edge of your range dying off on the rock outcrops, then you know there’s some big change afoot that could impact things on a much wider scale.”

The two main stressors possibly impacting the plants would be either climate change or acid deposition from acid rain.

The monitoring began in 2010 with a graduate student working for Cass. He selected monitoring points, documenting their positions and photographing the plants.

Now, Cass and her team will go back out to those exact positions to recreate the photos exactly as he took them, matching up to a precise grid through which they can compare the plants then and now. In three to four more years, she said, they will repeat the process.

“So you’re getting these little points in time to watch the change,” she said.

The rock outcrops on which the plants are growing are also quite special, Cass said. She described them as the “most botanically valuable in Shenandoah National Park.”

Four globally rare plant communities are found only on rock outcrops in the park, one of which is endemic, meaning it is found nowhere else in the world.

“These high elevation greenstone outcrop bearing communities make up less than one tenth of one percent of the park’s vegetation, so they’re extremely restricted,” Cass said. “They’re the rarest and most sensitive plant communities.”

Studying extremely sensitive plants in this capacity will help the team develop a real understanding of global warming. Cass said she is oftentimes asked how climate change is impacting the park.

“It’s a very complicated question to answer because there are so many different things that could potentially impact a plant that you come across, maybe it was eaten by insects, maybe somebody sat on it, maybe it was just hot,” she said.

The rock outcrops she and her team will be monitoring are out of the way, so are likely not going to be bothered. It will present a clearer image of widespread changes.

“It may be one small indicator of climate change amidst many others,” Cass said.

Contact staff writer Katie Demeria at 540-465-5137 ext. 155, or kdemeria@nvdaily.com