Brian Stansberry/Creative Commons
Grassy Ridge Bald at Roan Mountain
Grassy Ridge Bald at Roan Mountain.
The Southern Appalachians are a paragon of biological diversity. The Appalachians are the country’s most significant biodiversity hotspot east of the Rockies, and the Central and Southern Appalachians are unrivaled in the U.S. for aquatic diversity, comparable only to China in terms of forest diversity, according to the Appalachian Landscape Conservation Cooperative.
The Appalachians were formed 200-300 billion years ago and plant communities have been evolving ever since. Disjunct populations, organisms found from two or more disparate regions, are common in the Southern Appalachian. Take for example Liriodendron, our tulip poplar — there are two known species in the world, one common across the Smokies and one common in China. Other disjunct populations found in the Southern Appalachians and Asia include witch hazel, ginseng, trumpet creeper, trillium, pipevine and doghobble. These plants are evolutionary remains of similar growing conditions and habitats changed through climatic and geological upheaval.
It takes a host of contributing factors to create the amazingly diverse ecosystems of the Southern Appalachians. Topography and elevation combined with various soil types play a large part. Plant communities at the lower elevations resemble those across the Southeast, and higher elevations give way to more northern forest types. Hiking 12 miles roundtrip from Kephart Prong to Charlie’s Bunion along the Appalachian Trail and back illustrates the forest landscape’s diversity with cove hardwood, northern hardwood, grassy bald and spruce-fir forests.
“It’s like hiking from Tennessee to Maine,” said author and instructor at the Great Smoky Mountains Institute at Tremont, Jeremy Lloyd.
The Great Smoky Mountains Institute at Tremont (GSMIT) is a non-profit that partners with the U.S. Park Service to provide hands-on learning experiences for students, teachers, naturalists and the public through programs that celebrate ecological and cultural diversity, foster stewardship, and nurture appreciation of Great Smoky Mountains National Park.
Jennie McGuigan, school programs director at GSMIT, often takes kids on a short jaunt along Spruce Flat Falls Trail that begins right at Tremont and is only a 2-mile roundtrip.
“We begin walking through a cool shaded forest and I ask the kids to ‘let me know when you feel different.’ In less than a half-mile we reach a ridge on the southern side and it’s suddenly dry and warm,” McGuigan said. “We often see snakes and lizards and rhododendron, mountain laurel and pine trees line the trail. That short walk will take us from old growth cove hardwood, through northern hardwood to xeric oak-pine forest.”
These three specific forest types are among the region’s five to be found across the mountain landscape.
“That said, there are more than 100 classical plant communities just in the Smokies, but these are generally included in the larger forest types,” Lloyd said.
The high-elevation spruce-fir forest is found on mountain peaks above 5,000 feet and originated around 10,000 to 20,000 years ago with the last ice age.
“Northern species were chased south in front of the glaciers, and when the glaciers retreated southern species advanced up the mountains,” Lloyd said.
This geological movement left isolated islands of spruce-fir on the highest peaks of the Southern Appalachians.
Spruce-fir forests once stood tall and lush on the peaks of the Southern Appalachians. Fraser fir dominated the higher elevations from around 6,000 feet sometimes creating pure stands. Red spruce was the major species between 5,000 and 5,500 feet with yellow birch, beech and mountain ash beginning below 5,000 feet. There was little shrubby understory in these mature spruce-fir forests, and the forest floor was a carpet-like covering of conifer needles and nearly 300 species of mosses with wildflowers such as bead lily, Canada mayflower and mountain wood sorrel found in appropriate habitats.
These pristine forests danced atop the peaks of the Appalachians for millennia, then in the late 1950s rangers on Mt. Mitchell discovered a white powdery fluff on the needles of some Fraser firs — the exotic adelgids, small, aphid-like insects that feed on the fluids trees use for food. Nymphs settle at hemlock needles’ base, where they spend winter feeding on trees’ starches until reaching maturity. Infestation can cause needles to drop and branches to die. Tree death may take as long as a decade, but it’s a virtual certainty. The one-two punch of acid precipitation and adelgid infestation has dealt what could be a knockout punch to the spruce-fir ecosystem.
Today’s Southern Appalachian spruce-fir forests are small isolated remnants of those cold glacial times. At the Richland Balsam Overlook—the highest point on the Blue Ridge Parkway—steel-grey snags of dead trees mar the landscape, a memorial to a forest that was. Animal species depend on the cool, dense forests that evergreens create.
“What’s going to happen is trout streams are going to warm up, and that could impact our native trout as well as the bugs that live in the stream,” said Bill Yarborough, special assistant for the North Carolina Department of Agriculture and Consumer Services.
The forest remnants still are home to a number of rare, threatened and/or endangered species, many of which are endemic to the region. The Fraser fir (Abies fraseri) of the Southern Appalachian spruce-fir forest is found nowhere else in the world. The endangered spruce-fir moss spider, the tiniest tarantula in the world, also is endemic to this habitat. Other rare plants include Rugel’s ragwort, Appalachian oak fern, Mt. Leconte moss and Clingman’s hedgenettle.
“Just below the spruce-fir at around 4,500 feet you get northern hardwoods, similar to the forests of New England,” Lloyd said.
Northern hardwood canopy species include sugar maple, American beech, yellow buckeye, eastern hemlock, white pine, red oak and sweet birch with an understory dotted with rosebay rhododendron, which are known for their white flowers. Continuing upwards, the cove hardwood forest meets with the oak-pine forest where the rich purplish-pink Catawba rhododendrons and mountain laurel grow, leading to the spruce-fir forest where wildflowers include umbrella leaf, flowering raspberry, fly-poison, bee balm, bluet, trillium, obedient plant and monkshood.
Tiptoe between forest types and experience “transitional zones” at the Heintooga Picnic Area and Flat Creek Trail in the Great Smoky Mountains National Park, at the end of Heintooga Road, which leaves the Blue Ridge Parkway at milepost 458.2 and runs for about nine miles before ending at the Heintooga Picnic Area. This picnic area (with running-water restrooms and concrete picnic tables on plush moss carpets) sits beneath a spruce-fir canopy alive with golden-crowned kinglets, red-breasted nuthatches and other high-elevation species like black-capped chickadees.
Flat Creek Trail skirts the Heintooga picnic area and runs 2.6 miles to Heintooga Ridge Road. There’s little by way of transition here from the spruce-fir to the northern hardwood — it’s almost like exiting one room and entering another. As soon as one passes the last picnic table one begins to pick up birch and yellow buckeye. Turning back one sees the tall, cylindrical conifers and the carpet of moss below, and facing the trail one sees the round-crowned hardwoods and understory dotted with wildflowers.
Hemlock forests and beech gaps are found within the northern hardwood forests. There are nearly 100,000 acres of eastern hemlock in the Great Smoky Mountains National Park, including 800 acres of old growth. Hemlocks can form dense stands but hemlock forests are often interspersed with yellow birch, tulip poplar, red maple, red oak, black cherry and other northern hardwood species, following rivers, streams and creeks with an understory of rhododendron and mountain laurel. The exotic hemlock woolly adelgid has heavily infested most of the hemlock forests of the East and threatens their existence. A 2013 U.S. Forest Service study indicated that losing the hemlock could permanently change the region’s water cycle, as well, because the large trees photosynthesize year-round, helping to regulate water flow.
“The loss of this tree is the most significant loss since the American chestnut,” Yarborough said. “It will change Western North Carolina as well as the other parts of its habitat.”
Beech gaps, generally found on exposed slopes near mountain passes above 4,500 feet, are unique to the Southern Appalachians. The beech trees here, which account for 75 percent or more of the canopy, usually are gnarled and stunted from the winds and harsh elements. Other canopy species that occur in beech gaps include Carolina silverbell, yellow birch and yellow buckeye.
Two types of balds – heath balds and grassy balds - occur in the Southern Appalachians and they are both mysteries. They are unique because, unlike Alpine balds, they occur below the tree line. Naturalists, scientists and/or botanists seem much more comfortable contemplating the creation of heath balds rather than grassy balds. Heath balds are named after the assemblage of bushes and shrubs that grow there. Blueberries, huckleberries, azaleas and rhododendrons belong to the heath or Ericaceae family of plants — invaders that quickly move in after disturbances such as fire. They establish quickly, can handle poor soil conditions and grow densely successfully blocking the propagation of woody species, creating a self-perpetuating ecosystem.
Early settlers clearing land and then introducing free ranging stock created many of the region’s grassy balds, but others contain relic species like mountain oat grass that predates European settlement. Some theorize these balds could have evolved during the last Ice Age when it was too cold for even spruce and fir to get established. Grazing beasts like mammoths, followed by bison, elk and deer nibbled down vegetation, which continued as Native American and European settlers used the balds for hunting game and keeping livestock.
Roan Mountain State Park, located near the Tenneesee-North Carolina border, offers up prime examples of heath and grassy balds. The rhododendrens atop Roan Mountain’s 6,327-foot peak cover an area of 600 acres, the largest display of blooming rhododendron to be found anywhere in the world today.
The Forest Service also maintains grassy balds at Max Patch, a major landmark on the Appalachian Trail with 360 degree views of the Bald Mountains, the Unakas to the north, the Great Smokies to the south, and the Great Balsams and Black Mountains to the southeast.
In the Great Smoky Mountains National Park, Gregory Bald includes about 10 acres of grassy meadow, maintained by the Park Service, surrounded by azaleas, blueberries and other ericaceous plants. Late June and early July are spectacular on Gregory Bald as the azaleas that have crossbred create spectacular firey hues.
Below the northern hardwoods and balds come the oak-pine and cove hardwood forests, which establish based on the ground’s moisture content. The xeric (dry) oak-pine forests include chestnut oak, scarlet oak, southern red oak, black oak, pitch pine, Virginia pine, white pine, shortleaf pine, black gum and sourwood among others.
Cove hardwoods are dominant in wetter areas. Lloyd calls the cove hardwood forest the “rock-star of plant communities.” This forest type may contain 40 to 60 different species of trees and shrubs including basswood, magnolia, tulip popular, dogwood, sugar maple, yellow buckeye and northern red oak within a quarter of an acre.
Dr. Alan Weakley, assistant adjunct professor and director of the UNC Herbarium at the University of North Carolina Chapel Hill, notes two cove forest subdivisions — rich and acidic. Rich coves have few shrubs in the understory but lots of wildflowers like trillium, bloodroot, fringed phacelia, anemones and others that flower before the trees leaf-out. Acidic coves often have hemlock and sweet birch in the canopy and rhododendron and dog hobble in the understory.
Weakley said that while we can protect or preserve an area by creating a park, or a wilderness or a conservation easement, that doesn’t necessarily protect the flora and fauna of the area. Invasive species such as the adelgids and emerald ash borers and non-natives plants like princess tree and kudzu don’t recognize boundaries; nor does air pollution, acid rain and/or climate change. The Southern Applachians’ diversity is complex, awe-inspiring and terribly threatened. These forests hold treasures and secrets from millions of years of evolution and our actions at this point in history will determine what these forests will look and be like in the future. To learn about a landscape is to learn to love it — not just for how it looks but for what it means to our overall environment and its role in creating a sense of place.
“We only love the things we know, and we only protect the things we love,” Weakley said.