Continental Habitat Islands

Bob Gruver held the small snake by the back of its head as we gathered around to look. The owner of the shale barren we were exploring, John Cantrell, was aghast.

“That’s a copperhead,” he said.

“No, no,” Gruver answered. “Look at the turned-up snout. This is a young hognose snake.”

The rest of us agreed and explained to Cantrell that the snakes he had been killing over the years were not copperheads but harmless, and increasingly scarce, hognose snakes. Denizens of dry soil, which they use their snouts to bury into, they are also known as “spreadheads,” “blowing vipers,” and “puff adders” because of their peculiar manner of defense. As my husband Bruce described it to Cantrell, when they are threatened, they inflate their bodies with air, flatten their heads and necks and hiss as they expel air or writhe and twist, rub their mouths against the ground and finally roll over and play dead, their mouths open and tongues hanging out.

Then we found a second, young hognose which obligingly flattened its head. As he watched, Cantrell made up his mind.

“I’ll never kill those snakes again,” he promised.

Were we participating in a herp count that overcast day in late August? Absolutely not! We were members of a Native Plant Society field trip to shale barrens in Huntingdon and Fulton counties. Led by retired Penn State botanist and authority on the mid-Applachian shale barrens, Dr. Carl Keener, our first stop, along a winding back country road near Three Springs in southern Huntingdon County, was to see one of the few remaining stands of the Pennsylvania-threatened plant, the shale-barren evening-primrose (Oenothera argillicola). Keener pointed out the reddish stems and larger, showier yellow blossoms that distinguish this species from common evening primrose (O. biennis).

“A plant to treasure,” Keener told us, “an old species and rare.” Cameras clicked as we admired many beautiful specimens in full bloom.

Since this shale barren is on private land, we were walking at the edge of the road and looking up at the barren, which stretched enticingly over the hill. That was when Cantrell appeared to find out why so many cars were parked along the little-traveled back road and so many people were peering intently at what, to him, was extremely infertile land so dry that it was covered with the Pennsylvania-rare plant, prickly-pear cactus (Opuntia humifusa).

He had recognized how unusual it was to have cacti on his property, but he had not known that the shale-barrens evening- primrose was also rare. His goats had been eating it, he told us. But once he learned about the rarity, not only of the plants but the shale barren habitat they grow on, he proudly showed us the full extent of it. We spent a happy hour on both sides of the road, up the hill and down to Aughwick Creek, admiring a host of interesting plants as well as the hognose snakes.

One of approximately 200 hot, dry, shale outcroppings that extend from Huntingdon, Mifflin, Franklin, Perry, Bedford and Fulton counties in south central Pennsylvania through the panhandle of western Maryland, all of eastern West Virginia, and into southwestern Virginia, it consists of hard Devonian shale that breaks off to form talus. Because shale barrens occur mostly on the south-facing slopes of hills, surface temperatures can reach as high as 150 degrees Fahrenheit. This heat effectively burns off most seeds that try to sprout, setting the stage for the few plants able to withstand the rigorous conditions, those plants that Keener calls “obligate heliophytes” which means “dependent on sunlight.” They also have extensive root systems to take advantage of whatever moisture penetrates the rocky soil.

Although botanists have identified 97 species and varieties of plants that grow on shale barrens, the endemic plants (those found only on shale barrens) are the most interesting and often the rarest species. According to Keener, shale barrens host 18 plants that are endemics. In Pennsylvania, these “continental habitat islands,” as Keener calls them, have eight of these plants–Kate’s mountain clover, Harris’ goldenrod, forked chickweed (the only annual shale barren endemic plant), mountain pimpernel, shale barren dwarf bindweed or low bindweed, cat’s-paw ragwort, shale barren pussy-toes, and shale-barren evening- primrose. Although each barren has its own suite of plants, only a few dozen barrens throughout the Appalachians are rich in flower species.

Cantrell’s barren specializes not only in shale-barren evening-primrose and prickly-pear cactus, but also forked chickweed or shale barrens whitlowwort (Paronychia montana), a wiry member of the Chickweed family. Keener pointed out still other plants there that adapt well to the hot, dry habitat–long-leaved houstonia or summer bluet (Houstonia longifolia), and bracted plantain (Plantago aristata), a native plant that lives on roadsides and waste places.

Many shale barren outcroppings, like Cantrell’s, are along roads or on hillside land with thin soils and are considered worthless land so they are often destroyed by road work. One example is the construction of U.S. Route 322 from State College to Harrisburg which obliterated a shale-barren evening-primrose site, Keener says. But we felt confident, when we said goodbye to Cantrell, that this was one site that would now be valued by its owner.

Other threats to shale barrens are shale quarrying, grazing and browsing by deer and livestock, and dam building. The most egregious of the latter is the Raystown Dam, built and owned by the Army Corps of Engineers in Huntingdon County, which drowned a substantial portion of the largest concentration of Pennsylvania shale barrens. Today, the surviving upper slopes still host a population of shale-barren evening-primrose which is best seen by boat.

At our other stop, along U.S. Route 30 near Harrisonville in Fulton County, the road workers had been there ahead of us. Keener ranged up and down the side of the busy highway, looking slightly bewildered as he tried to get his bearings. He had last been there 25 years ago and the site didn’t look the same to him. After some poking around, though, he was able to find remnants of what had once been a large population of the Pennsylvania endangered cat’s-paw ragwort (Senecio antennariifolius. Although its bright yellow flower heads had faded, its crowded rosette of leaves distinguished it from other plants. That rosette grows close to the ground to protect it from the drying wind and intense heat reflected from the shale. In addition, its upper leaf surfaces are whitened to reflect the heat and a covering of dense hairs on the lower leaf surfaces also serve to insulate the plant. Altogether, it is a wildflower elegantly designed to live in its specialized habitat.

As we were contemplating what were obviously fresh excavations in the area, a man in a pickup truck drove up. Like Cantrell, he wondered what we were looking at. When we told him, he said that he and his wife had tried to protect the area. But it was private property and a neighbor, who lives across the road from the shale barren, had wanted a better view before pulling off the highway, so part of the hill had been cut away to oblige him.

All the while we talked and looked for plants, cars and trucks whizzed past, and I thought with longing and gratitude for the remote Sideling Hill Creek Natural Area in southwestern Fulton County owned by the Western Pennsylvania Conservancy. It, too, is a refuge for cat’s-paw ragwort. The shale barren, itself, is a 50-acre tract that is part of the larger 136-acre natural area. The natural area itself is part of one of the most pristine and ecologically significant areas in central Appalachia–Sideling Hill Creek.

Much of the land bordering the creek in both Pennsylvania and Maryland is in private hands and contains numerous shale barrens that support several rare plants and moths. The creek, itself, shelters the state-endangered Tennessee pondweed (Potamogeton tennessesnis), two rare mussels, a rare fish (the Potomac sculpin), the rare wildflower golden club (Orontium aquaticum,) and an unusual freshwater sponge (Spongilla lacustros).

On the natural area barren, there are four species of rare moths, including the Packard’s lichen moth (Cisthene packardii) and five rare plants. In addition to cat’s-paw ragwort, there is an excellent population of the Pennsylvania-rare Allegheny stonecrop (Sedum telephoides), also known as “wild live-forever” and “American orpine.” Like its close relative, the garden plant European stonecrop, its leaves are succulent. Although the plant has flat-topped clusters of white-to-dark pink flowers in August and September, its pale, reddish-tinged, gray-green leaves make it easy to identify throughout the season.

Other rare plants include small-flowered crowfoot, Allegheny plum, dwarf spirea, and another shale barren endemic–the Pennsylvania endangered Harris’ or leather-leaved goldenrod (Solidago arguta var. harrisii), the earliest and longest-blooming of the goldenrods, which often opens in May. Other Sideling Hill Creek barrens shelter Pennsylvania rare shale-barren pussytoes (Antennaria virginica), Pennsylvania endangered mountain pimpernel (Taenidia montana), and Pennsylvania-endangered Kate’s mountain clover (Trifolium virginicum).

It was the discovery of Kate’s mountain clover back in 1892 by botanist John Kunkel Small that first focused attention on the shale barren habitat. He was exploring Kate’s Mountain in southeastern West Virginia when he emerged from a dry forest on to a steep slope covered with loose shale. Amid the few scraggly trees and sparse vegetation, he spotted a new plant with thin, clover-like leaflets and round, white, clover-like flowers which he named Kate’s mountain clover. Even today, Kate’s Mountain remains the type locality for most of the endemic species along with another shale barren in Bath County, Virginia.

Kate’s mountain clover or shale-barren clover is found in Bedford, Fulton and Franklin counties in Pennsylvania. Altogether it is distributed unevenly at 54 sites, most of which are in the northern half of the shale barren region. It is the least abundant of all the endemics, with often less than a dozen plants on a barren.

In 1911 botanist Edward Steele called the steep, rocky habitat a shale barren. Another botanist, Robert Platt of Emory University described shale barrens’ soil as “brownish-yellow” and “covered with a thin mantle of flattish and variously sized weather resistant rock fragments.” Further study of barrens’ soil by Platt revealed eight to 10 inches of normal soil sandwiched between the rocky surface and fractured rock beneath. Platt also found that of 35,000 seedlings on a shale barren in April, only nine had survived by June. Furthermore, the few trees growing on a barren were badly stunted, for instance, a 300 year-old juniper was 15 feet tall and a 108-year-old oak six feet tall.

Shale barrens continue to fascinate scientists, and both the Western Pennsylvania Conservancy and the Maryland Department of Natural Resources’ Natural Heritage Program are conducting ongoing inventories of the flora and fauna of Sideling Hill Creek’s aquatic and shale barrens’ habitats. Thankfully, the Sideling Hill Creek Natural Area’s barren should be safe from road building, dam building, and other indignities and remain a source of knowledge and inspiration for both scientists and interested laypersons.

As Keener so aptly expressed it in the conclusion to his definitive paper, “Distribution and Biohistory of the Endemic Flora of the Mid-Appalachian Shale Barrens,” “Hidden away on the Appalachian shale barrens are partial clues to unravelling the complicated history of the eastern Appalachian forest, and it would be tragic if members of Homo sapiens L., a destructive (and potentially self-destructive) species recently on the scene, wantonly destroyed remnants of far more ancient population systems.”


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