Home » Biologists in the Field » Grasslands of Central Pennsylvania

Grasslands of Central Pennsylvania

On a day in late August, members of the Pennsylvania Native Plant Society visited what ecologist Roger Latham calls “wild-ungulate pastures” in Clearfield County’s Quehanna Wild Area. Latham, who has been working on a meadow and grass inventory of Pennsylvania, was searching for “meadows and grasslands that have persisted for a long while and for one reason or another seem likely to persist for some time to come.” He is also interested in relatively “new” meadows or grasslands that cover large areas such as those maintained by deer overbrowsing, hence our field trip to the Quehanna Wild Area.

As expected the ferns that spread easily from underground rhizomes–New York, hay-scented, and bracken–blanketed the area. A few old, twisted, black locust trees poked through the understory, but, for the most part, high deer densities had prevented tree regeneration for more than half a century. Some of the area was moist underfoot. The rest was dry and sandy.

When we took a closer look we found occasional wildflowers such as pearly and sweet everlasting, little St. Johnswort, grass-leaved goldenrod, arrow-leaved violet, and wood aster and shrubs that included black huckleberry, meadow-sweet, and Allegheny blackberry. We also identified five native grasses. Of those, an island of tawny cottongrass growing in the midst of swamp dewberry was especially striking. Five rushes and sedges completed our botanical inventory.

None of these plants were uncommon. Most were generalists that thrive on waste places, in sandy soils, or in moist meadows. We had not found hobblebush, fly honeysuckle, or American yew, all species whose recovery would indicate proper deer numbers, according to Latham.

Altogether Latham pronounced the area we explored low in species’ richness. He has looked at many such wild-ungulate pastures throughout Pennsylvania and discovered that they vary from site to site and patch to patch.

“Some areas,” he says, “are mostly dominated by lowbush blueberries, black huckleberry, meadow-sweet and other low shrubs, some by hay-scented fern and bracken, and some wetter areas by sedges, bulrushes, and rushes. A few areas are dominated by native grasses, usually mixtures of warm-season and cool-season species.”

Of course, what kinds of species grow in places depends, in part, on what species are within seed-dispersal distance and on the site’s fire history. Latham thinks that if wildfire has been common in an area, native grasses are more abundant because they respond more positively to repeated or severe burning than other plants. Still, that is only an hypothesis at this point.

However, compared to other remnant, native grassland and meadow types he has studied in Pennsylvania, including serpentine grasslands, xeric limestone prairies, mesic limestone meadows, diabase meadows, Great Lakes sandplains, coastal plain sandy meadows and riverine ice-scour meadows, wild-ungulate pastures are low in total species. They also are not refuges for populations of endangered and threatened species as all the native grassland and meadow types are. At least not so far.

“I wouldn’t rule it out, and I’m still looking for a rare species,” he says.

But it’s a lot easier to find rare species at places like the xeric (relatively dry), limestone Westfall Ridge Prairie in Juniata County, a calcareous rocky summit community that is itself globally rare and one of the best examples of its kind in Pennsylvania.

My son Dave and I first visited the area on a dismal, rainy day in mid-June back in 1996, shortly after The Nature Conservancy (TNC) had acquired a portion of the ridge.

“Are you sure anyone will be here?” Dave asked as we slithered our car uphill on a muddy farm road, following directions we had received from Karen Budd, who at that time was TNCs Science and Stewardship Assistant in charge of organizing volunteers.

But Budd, along with one local volunteer, also showed up, and, clad in rain parkas, we picked up several pairs of pruning shears Budd provided, and slogged steeply uphill on an even muddier track to our work area, our boots weighed down by thick, gummy, muck.

“Not only do TNC volunteers pay no attention to the weather,” she joked, “but they also volunteer, in part, to learn,” which explained her short lecture to us about the Westfall Ridge Prairie.

The Nature Conservancy, she told us, had acquired the core prairie property of 30 acres as a donation from its former owners–the Merril Benner family–in the fall of 1994. The surrounding 120-acre farm, also owned by the Benners, had been sold to a third party who had agreed to a conservation easement that limited development rights and restricted nutrient and biocide use.

The calcareous rocky summit has a southwest exposure that makes it hot and dry (when it’s not raining), and its limestone soil supports a wide variety of plants including two prairie grasses that are also native in the eastern United States–side oats gramma or tall gramma Bouteloua curtipendula and false gromwell or marble-seed Onosmodium molle var. hispidissimum.

Side oats gramma is indigenous to dry woods and is a clumping, warm-season grass that can adapt to a wide range of habitats and easily tolerate drought conditions. While it is abundant globally, it is a state-imperiled species in Pennsylvania.

False gromwell is indigenous to dry and calcareous rocky habitats, prairies, banks, and glades. In 1995 researchers had found 25 plants, less than similar counts in 1989 and 1992. Critically imperiled in Pennsylvania because of its extreme rarity, it too is apparently globally secure.

Both grass species only grow in the open and our job, that rainy day, was to cut out species threatening to overwhelm two small openings–smooth sumac, raspberry, Virginia pine, oaks, and the beautiful, small, purple-flowered tree redbud. But the caterpillars of a butterfly–Henry’s elfin (Incisalia henrici)–also a Pennsylvania rare species, feed on the flowers and young leaves of redbud. These pale to dark green caterpillars metamorphose into small, dark brown butterflies that nectar on redbud, fleabane, and phlox. Since their flight takes place in April and May, we had little chance of seeing any even when the rain slowed to a drizzle and below us we caught glimpses of the remote farming valley through swirling clouds.

Still, I wondered at the time why we should cut out redbud if it was the major host plant for Henry’s elfin in the Appalachians. A visit in May of 2005 to the Westfall Ridge Prairie with Latham and members of the Pennsylvania Native Plant Society cleared up this puzzle.

“Redbud is an invader of grasslands, and there’s plenty of it in the surrounding woods and along the edge of woods in Pennsylvania’s Ridge and Valley. Henry’s elfin probably occurs elsewhere in the Ridge and Valley where there is a good supply of redbuds and little or no pesticide use in the immediate vicinity,” Latham explained.

And why, if redbud is common and its other host plants, from southeastern Canada and the upper Midwest south to Florida and Texas, are similarly common, is Henry’s elfin uncommon, especially in the northern part of its range?

“I don’t think anyone knows why Henry’s elfin seems to be as rare in Pennsylvania and Indiana, for instance, as it is in Maine, Ontario and Wisconsin, even though Pennsylvania and Indiana are much closer to areas where it’s more common,” Latham answered. “My typical scientist’s response–more research is needed.”

On that sparkling, breezy, clear May day of our second visit to the Westfall Ridge Prairie, Latham also told us more about side oats gramma, which grows in shortgrass prairies in the West as well as in isolated patches in the Appalachians. Ten of the 15 known sites in Pennsylvania are on dry limestone prairies like the Westfall Ridge Prairie. Four more are on serpentine barrens. And how did it get to such isolated patches? Latham hypothesizes that perhaps its seeds had stuck to American bison and other extinct, grazing species such as giant horses, which spread the prairie grasses into the open areas of the eastern United States.

We re-found both grasses, but we also identified several other prairie flowers, specifically the showy orange-yellow hoary puccoon or Indian-paint Lithospermum canescens, the lance-leaved, tiny green-flowered wild licorice (Galium circaezans), the purplish-red-flowered wild-coffee or orange-fruited horse gentian (Triosteum aurantiacum), and the white-flowered false boneset (Brickellia eupatorioides), all of which like dry limestone prairies or barrens in Pennsylvania. So too does the shrub fragrant sumac or squawbush Rhus aromatica, which was covered with yellow flowers, a contrast to the white blossoms of black-haw Viburnum prunifolium that grows more commonly in woods, thickets, old fields, and along roads. Unfortunately, we also found the light purple flowers of spotted knapweed (Centaurea maculosa), a European invasive of native grasslands.

The patches of open grassland remain tiny, but at least the rare grasses are still there. In fact, the place remained much as I remembered it, an isolated prairie remnant surrounded by forest.

But that’s not good enough if we are serious about creating more native meadows and grasslands for wildlife habitat and biodiversity conservation. Altogether at least 150,000 acres of meadows and grasslands existed before the arrival of Europeans and only 350 acres remain today.

According to studies by Latham and others, the total limestone prairie area in Pennsylvania when Europeans arrived was probably about 25,000 acres. Today there are less than 10 acres left. The xeric limestone prairies, such as Westfall Ridge Prairie, are declining even faster than most of the other grassland types in Pennsylvania.

“Every time we lose another native grassland or meadow remnant that’s existed since pre-European settlement times, we’re losing an irretrievable part of our natural heritage and further degrading our options for effective restoration and research in the future,” Latham says.

And we are not only losing sites, we are losing species on sites that still exist because those sites are too small to maintain a healthy population during year-to-year fluctuations. If, for some reason, a rare species fails to reproduce one year, which regularly happens with even common species, that may be the end of it.

So, not only must we protect what little is left, we must increase their area by undertaking a vigorous restoration program that uses the native remnants as models for how such areas should look.

Most importantly, Latham says, these remnants “are the last and only sources left for the native, local genotypes of the plant species that have inhabited these ecosystems for many thousands of years. When a local population is extirpated due to loss of habitat, its unique genetic endowment is lost forever.”

But he is pleased that interest by both scientists and ordinary citizens in creating new native grasslands and meadows is growing. A recent workshop on grasslands co-sponsored by The Nature Conservancy and the Pennsylvania Game Commission was so popular that they had to turn people away.

Only 0.4% of pre-European-settlement acreage of native grasslands and meadows remains. With a commitment to restoration, we should be able to do much better. Maybe the next time we visit the Westfall Ridge Prairie, it will be spreading instead of contracting.

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