Rare Ecology Percolates in Pennsylvania Park

When the sky turned to ash in summers past above the Nottingham Serpentine Barrens, the locals knew that flames were again tearing through the lanky pine and prickly greenbriar.

The rare micro-ecosystem in southeast Pennsylvania actually promotes the growth of flammable plant life.

Wilma Breeding can still hear the exclamation resonate in her head from her childhood days in the 1940s.

“Whenever we smelled smoke and looked out and it was black all over, the neighbors would say, ‘Oh, Lord, the barrens are burning again,’ ” said Breeding, 68, secretary at Nottingham County Park. “They knew this stuff was so flammable ... that they had to get it under control.”

The serpentine barrens at Nottingham County Park are so named for the serpentinite rock found under a thin layer of soil. The rock, and thus the soil, is heavy in magnesium and light in calcium, meaning plant life that grows in more balanced soil does not grow well there.

The Nottingham Barrens are marked by scrawny pitch pine and the piercing prickers of smilax, or greenbriar -- “God’s barbed wire,” as park Supt. Bill DeCarme puts it. “If you have a desire to give blood and don’t want to go to the Red Cross, you can walk through smilax,” he said. “It’s that vicious.”

Serpentinite bedrock is found on every continent, and small islands of the ocean-floor rock dot the East Coast from Georgia to Newfoundland. The largest concentration is found in southeastern Pennsylvania and northern Maryland, says Roger Latham, a biologist who has been studying the barrens for 20 years. The Nottingham Barrens is part of eight sites within 12 miles of each other collectively called the Stateline Serpentine Barrens.

Ground-level serpentinite rock is the product of hundreds of millions of years of geology. The Nottingham Barrens’ rock was formed some 510 million years ago, after continents rammed together and thrust up a gigantic mountain range. After the mountains wore away, the serpentinite rock was exposed.

“What’s cool is the rock comes from way down under the ocean, and it’s rare that it’s found up on top of land,” Latham said.

The rock creates an ecological boundary, with leaf-bearing deciduous trees on one side and the pines, smilax and wild grasses on the other. The line is most obvious in the fall when even an untrained eye can see that the bright leafy colors stop cold where the magnesium-heavy soil takes over, DeCarme says.

“When you cross the boundary, suddenly the plants are completely different, a completely different set of species,” Latham said. “Many of the plants also grow in other areas, but usually far, far away.”

One of those out-of-place species is the thick, hardy wild-land grasses common in the Dakotas and Montana. The grasslands once thrived in Pennsylvania too, but have now mostly gone the way of the wagon wheel.

“People don’t need to go to the Great Plains to see a prairie,” Latham said. “They can do it here in Pennsylvania.”

The barrens’ grasslands are a holdover from when American Indians would burn the land to promote regrowth. For the grasses to live, Latham said, they need to be burned about every three to five years. After European settlers took over the area, that practice died.

But in the serpentine soil, the grasses need to be burned only once every 30 years or so, said Latham, a former Swarthmore College biology professor who does contract work for environmental groups.

The burnings, historically, haven’t been a problem in the Nottingham Barrens, where fire has been as common as lighting in a summertime thunderstorm. While officials would race to extinguish the flames when Breeding was a child, DeCarme -- with the help of the Nature Conservancy, an environmental group -- now executes controlled burns throughout the park.

Smilax, a slender climbing vine filled with woody thorns, is thick, making off-trail hikes a bloody endeavor. “I’ve been in jungles in the tropics that are not nearly as hard to get through as the smilax at Nottingham,” Latham said.

The greenbriar’s fat roots help it survive fire, and its leaves are loaded with oils that catch fire even when green, he said.

Although biologists and geologists love the barrens for their rare ecologies, an untrained eye could easily pass by the serpentine aster -- a daisy-like flower that grows in only about 20 places worldwide -- or the prairie warblers, birds uncommon elsewhere in Pennsylvania.

Tim Quinn, a self-professed “city boy,” was recently hiking the park’s trails with his 6-year-old son, Matthew, and a 7-year-old friend, Bobby Parker. While hiking on the uncommon rock, with rare prairie warblers flying nearby, what were the boys looking for?

“Snakes,” they answered in unison.

Quinn brings the boys to the park for its good hiking trails, not the rare ecology.

The trio is typical of most of the park’s estimated 115,000 yearly guests.