Download The Piedmont – the in-between land

The Piedmont – the in-between land?
by Alan Weakley, UNC Herbarium Curator
One often hears a promoter of the Triangle area saying “it’s a great place to live, since
it’s only a few hours drive to the coast and only a few hours drive to the mountains.” The
not-so-subtle implication of this is that the Piedmont is a place of little distinction itself in
scenery or recreational resources, but that it provides good access to the more diversely
scenic areas to the east and west. In matters of natural diversity, there is a similar
perception – that the Southern Appalachians and the Southeastern Coastal Plain have the
special habitats and the special plants, and the Piedmont is a rather boring area of rolling
hills, once cloaked in a monotonous oak-hickory forest, and now mostly converted into
fields, clear-cuts, subdivisions, and malls. B.W. Wells, in his classic Natural Gardens of
North Carolina (published in 1932 and recently reissued in a new edition by the
University of North Carolina Press) devoted seven chapters to the Coastal Plain, two to
the Mountains, and only one chapter (about old field succession!) to the Piedmont. Even
the name “Piedmont” (“foot of the mountains”) defines the region by what it is next to,
not what it is. But is the Piedmont’s ecological impoverishment more apparent than real?
Richness, uniqueness, and rarity are all measures of the biological diversity of an area.
Richness is the number of species in an area. Uniqueness measures the degree to which
the biological resources of an area are not present elsewhere and are therefore
irreplaceable. Rarity measures the imperilment of the species and communities in an
area, whether that rarity is natural or caused by human activities.
Perhaps surprisingly, the North Carolina Piedmont has high richness – it has more plant
species than either the state’s Coastal Plain or Mountains. In part, this is because it is an
“in-between” land and has habitats enough like those of the Mountains and the Coastal
Plain to have many species that one might consider more typical of adjacent provinces.
For instance, longleaf pine (Pinus palustris) and many of its ecological associates extend
westwards into the eastern Piedmont: one can see open longleaf pine woodlands on steep,
rocky slopes of the Uwharrie National Forest, south of Asheboro. Similarly, mountain
plants like Carolina hemlock (Tsuga caroliniana) occur disjunctly on low mountain
monadnocks such as Hanging Rock State Park in Stokes County. But the Piedmont also
has a surprisingly large number of species that are not present in either the Mountains or
the Coastal Plain – many associated with unique Piedmont habitats.
What are some of these unique habitats? Over the last several decades, biodiversity
surveys have revealed many Piedmont habitats that are surprising to most North
Carolinians: prairies, oak savannas, shale barrens, bogs, granite flatrocks, mesic soil
bluffs, diabase flatrocks, wet meadows, riverside flood-scoured grasslands, and more.
These habitats support hundreds of plant species unique to the Piedmont, including the
plume goldenrod (Solidago plumosa), endemic to a quarter-mile stretch of flood-scoured
Yadkin River shore, Schweinitz’s sunflower (Helianthus schweinitzii), endemic to
remnant prairies and rocky oak barrens from Winston-Salem south through Charlotte into
South Carolina, and Piedmont Merlin’s-grass (Isoetes piedmontana), growing in seepage
on granite flatrocks near Raleigh and near Wadesboro. At least three new Piedmont
endemics will soon be described by botanists at the University of North Carolina
Herbarium, the result of taking a closer look at the Piedmont’s plant life.
So, are these unique Piedmont species and natural communities rare and imperiled?
Alas, yes. Many of these habitats were naturally rare, associated with unusual rock types
or other environmentally unique situations. But the extensive alteration of the Piedmont
landscape has added greatly to their imperilment. The rivers have been dammed, and
flood-scoured grasslands have dwindled. Fire has been suppressed, and fire-maintained
prairies and oak savannas have grown thick with shrubs that choke out sun-loving
rarities. Alien plants such as privet invade the edges of barrens and rock outcrops.
Fortunately, state and federal agencies, private conservation organizations, and private
individuals are working to conserve important remnants of the Piedmont’s flora. Local
land trusts and The Nature Conservancy have purchased and manage as natural areas
many Piedmont preserves. Uwharrie National Forest has many typical Piedmont
landscapes, as well as a number of highly unusual habitats. The North Carolina Botanical
Garden manages important Piedmont natural areas at the Mason Farm Biological Reserve
and at Penny’s Bend (north of Durham). Such areas provide a glimpse of the Piedmont’s
glory – not gone, and not forgotten.