✕
☰

Water World

Temperate rainforests of the Southern Appalachians

by

Don McGowan photo

What is a temperate rainforest? The short answer is that it’s a forest that’s wet with mild temperatures. The not-so-short-answer is that in the Southern Appalachians it’s complicated.

“We had lots of long, lively scientific discussions regarding the Southern Appalachians,” said Dr. Paul Alaback, professor emeritus of forest ecology at the University of Montana and one of the co-authors of Temperate and Boreal Rainforests of the World. In the book they note, “Although the Appalachian mixed-mesophytic forests of the southeastern United States has been recognized as temperate rainforests by some it was not predicted by the rainforest distribution model, presumably because the region has relatively high year-round temperatures and dry summers. However because there was evidence of rainforest conditions at high elevations (moist pockets of spruce-fir within the larger ecoregion), we briefly mentioned them as a southerly extension of Appalachian boreal rainforests from Eastern Canada that require further study.” 

And it is pretty clear from other research that some forests in the Smokies fit nicely within (and some marginally within) Alaback’s definition for a temperate rainforest, which calls for annual precipitation over 55 inches and a mean annual temperature between 39 and 54 degrees Fahrenheit. In a 2005 study regarding productivity of different types of forests in the Smokies, R.T. Busing noted that the area around Alum Caves Bluff parking area in the Great Smoky Mountains National Park (GSMNP) had a mean annual precipitation of around 79 inches and the mean annual temperature was about 50 degrees Fahrenheit. Data from Jim Renfro, air quality program manager for the GSMNP, also shows that Mt. Leconte is a good fit as a temperate rainforest. Twenty-five years of data show that Mt. LeConte averages more than 70 inches of rain a year and an average high temperature of 51 degrees Fahrenheit, and an average low temperature of 32 degrees Fahrenheit.

The GSMNP is not the only place across the Blue Ridge that falls into the temperate rainforest range. Grandfather Mountain, along the Blue Ridge Parkway, in Linville, N.C., has an average rainfall of 63 inches per year with an average high temperature of 53 degrees Fahrenheit and an average low temperature of 39 degrees Fahrenheit. And according to Dr. Alan Weakley, plant community ecologist, curator of the UNC Herbarium, adjunct assistant professor at UNC-Chapel Hill and author of the Flora of the Southern & Mid-Atlantic States, the Jocassee Gorges receives the highest rainfall in eastern North America. Rainfall in some places in the Jocassee Gorges reaches nearly 100 inches a year and the average annual temperature in the area ranges from about 55 degrees Fahrenheit in Brevard, N.C., to 51 degrees Fahrenheit in Highlands, N.C. The Jocassee Gorges extend from Lake Jocassee, near where North Carolina, South Carolina and Georgia all meet, northward and eastward to around Caesar’s Head State Park on the North Carolina-South Carolina border. They include the gorges created by the Whitewater, Horsepasture and Estatoe rivers plus other mountain streams.

 “It is somewhat controversial to call any of these Southern Appalachian forests  temperate rainforest because, while they meet the most basic definition, they are not strongly differentiated in species composition or physiognomy (structure) from other forests in the Southern Appalachians,” Weakley writes. “Unlike, say, the Olympic Peninsula forests in western Washington.” 

While these Southern Appalachian temperate rainforests may not be strongly differentiated regarding species composition, there are definitely some plants and/or plant types either endemic to or strongly associated with them.

Shortia galacifolia, Oconee bells, is one plant endemic to the Jocassee Gorges area. Oconee bells is a biogeographic relic meaning that it is part of a once widespread taxa, now restricted to a small geographic area. Oconee bells’ closest relatives are in Asia. Shortia loves the deep shade, abundant rainfall, stream banks and steep slopes of the Gorges. According to Weakley, another rare plant from the Jocassee Gorges is Turnbridge filmy-fern, which grows on rock outcrops in the Gorges. This disjunct species’ closest relatives are in the West Indies.

Michael Schafale, plant community ecologist at the North Carolina Natural Heritage Program, said that the Gorges were “… home to a remarkable number of rare bryophytes [bryophytes are plants of the order Bryophyta that includes mosses and liverworts], including some that are disjunct from the tropics.” The Jocassee Gorges are home to more than 60 species of rare and/or endemic plants. Butternut or white walnut, Appalachian mock orange, rock fir-clubmoss and grotto alumroot are a few of the rare plants associated with the Jocassee Gorges.

Epiphytes and lichens are not unique to rainforests, but Alaback calls them characteristic and says they are good indicators. Epiphytes can be plants, fungi or microbes that grow upon other plants. The key is they are nourished by nutrients and water gathered non-parasitically from the forest canopy where they live. Abundant moisture is conducive for epiphytes as they gather their nutrients from the air and/or the damp surface of their host. Lichens are unique in that they are actually a combination of two organisms—a fungus and an alga—that live in a symbiotic relationship. The moist forests of the Southern Appalachians are home to a host of epiphytic mosses, lichens and ferns. One of the most common is Old Man’s Beard, a gray-green lichen seen hanging from tree limbs like Spanish moss. A two-day lichen “foray” in GSMNP sponsored by Discover Life in America recorded 88 species of lichens.

Scott Ranger is a naturalist who splits his time between Marietta, Ga., and Juneau, Alaska. Ranger spends his time in Alaska as a guide for Gastineau Guiding Company. And he has spent much time in the Lower 48 botanizing and leading trips in the GSMNP. Ranger noted a couple of Mt. Leconte specialties that revel in the dampness. Narrowleaf gentian, Gentiana linearis, occurs primarily in the northeastern United States and eastern Canada but makes its way down the Southern Appalachians to high-elevation sites in the Smokies. According to Ranger, narrowleaf gentian “needs its roots in moist soil at all times.”

Rugel’s ragwort, Rugelia nudicaulis, is endemic to the Smokies of Western North Carolina and East Tennessee, all known populations are within the GSMNP. Ranger said that Rugel’s ragwort requires the rainforest conditions found on Mt. Leconte.

Water water everywhere

These temperate rainforests are awash in water. High annual rainfall, snow in the high elevations like Mt. Leconte, and blankets of dense fog that clings to vegetation and adds to precipitation totals in the form of fog drip assure an abundance of water. 

The topography of the Southern Appalachians coupled with prevailing winds from the south-southwest join in a process known as orographic lift to create this bounty of precipitation. When these prevailing winds carrying moisture from the Gulf of Mexico and the Atlantic Ocean hit the mountains they are abruptly lifted up. This orographic lifting quickly cools the air mass, raising the humidity  and often resulting in precipitation. 

Copious precipitation coupled with steep rocky terrain is the perfect recipe for waterfalls, and the Southern Appalachians are renowned for their waterfalls. Ramsey Cascades with a 100-foot drop is the tallest falls in the GSMNP. Rainbow Falls and Grotto Falls are two that grace Mt. Leconte. Some other notable waterfalls in the GSMNP include Juney Whank, Abrams, Hen Wallow and Mingo.

The Jocassee Gorges are home to the highest waterfall east of the Rockies. Whitewater Falls has a total drop of 411 feet. Other falls in Jocassee include several on the Horsepasture River—Drift, Turtleback, Stairway, Sidepocket and Windy. Thompson or Big Falls, Twin Falls, White Owl, High Falls and Slippery Witch are just a few more falls that dot the Gorges.

Besides being beautiful to look at, these waterfalls create unique habitats called “spray communities.” Algae, mosses and ferns are common in spray communities. Rare ferns, found in spray communities in Jocassee Gorges include the gorge filmy fern, which is endemic to the Gorges, Appalachian filmy fern and dwarf filmy fern. Carolina star-moss and Pringle’s aquatic moss are two rare mosses found in spray communities in Jocassee Gorges. Some herbaceous plants associated with spray communities across the Southern Appalachians include Appalachian bluet, grass-of-Parnassus, round-leaf sundew, branch-lettuce, grotto alumroot and jewelweed.

One faunal community comes to mind immediately when you think of spray communities—salamanders. Salamanders are certainly common in spray communities but they are also at home throughout the rich moist confines of Southern Appalachian temperate rainforests. There are more species of salamanders in the Southern Appalachians than anywhere else in the world. There are more than 30 species of salamanders in the GSMNP with many more spread across Western North Carolina and East Tennessee.

“The very rich salamander flora is relictual [dating back to an earlier time] and definitely related to the rainfall and long stability of the area,” according to Weakley. The fact they’ve been here so long may explain the fact that they reach their highest diversity in the Southern Appalachians.

The feel of a rainforest

Scott Ranger has lots of experience as a naturalist in the Smokies and in the Southeast Temperate Rainforest of Alaska. “I see a lot of the same plants, like lady fern and goat’s beard, in both places,” Ranger said. Sometimes the species may change but plants of the same type (often the same genus) are found in similar habitats. Ranger said that Canada mayflower, Maianthemum canadense, is a common spring wildflower in high moist woodlands in the Smokies. In high moist woodlands in Alaska, Ranger said it is replaced by Maianthemum stellatum. 

But according to Ranger, there is more than simply a similarity in vegetation. “When I walk into the spruce-fir forest on Mt. Leconte there is an immediate coolness, and smell—I might as well be in Juneau,” Ranger said. “Or leaving LeConte lodge on Bullhead Trail, passing head-high stands of Turk’s-cap lilies, then stepping onto that carpet of needles—there’s just such a refreshing feel and fragrance.”

The floor of a temperate rainforest is like a green lumpy incubator. The cool wet environment means that logs and woody debris are broken down and recycled slowly creating a fecund bacterial stew where other living organisms can get a toehold. One decaying log on the forest floor can create its own ecosystem of bacteria, microbes, moss, fungi, worms, larvae and salamanders. Researchers have documented more biomass in temperate rainforests than any other habitat on the planet.

Thick carpets of moss often cover logs and even boulders in the Southern Appalachians providing the perfect nursery for the seeds of other plants. It’s not uncommon in the Smokies to see rhododendron and other plants sprouting from these “nurse logs.” Yellow birch seems particularly adapted to this process and one can often see birches perched atop boulders, roots snaking over the rock to the ground below like a tree on stilts.

Biodiversity

The Southern Appalachians are a bastion of biodiversity. Antiquity, diverse topography, abundant precipitation and temperate climate all combine to create levels of diversity and endemism unsurpassed in the temperate regions of the world. The GSMNP is a United Nations’ International Biosphere Preserve.

There are more than 100 species of trees in the GSMNP alone and more than 2,000 species of vascular plants across the Southern Appalachians. Water and/or moisture plays a critical role in this biodiversity. Nearly 10 percent of the total global diversity of freshwater mussels and salamanders can be found in the Southern Appalachians.

Schafale notes that areas of high rainfall contribute to this biodiversity, “Because there are so many rare species, including some endemic ones, the high rainfall area is very important to the biodiversity of the Southern Appalachians. There are species that occur nowhere else, even in other parts of the Southern Appalachians.”

Discover Life in America (DLIA) is a non-profit organization that sponsors the All Taxa Biodiversity Inventory (ATBI), an ambitious effort to identify and record every living species in the GSMNP. The ATBI started in 2003 and since that time researchers have recorded nearly 18,000 species in the park. Of those, 7,391 are new park records and 922 are species new to science.

Climate change

Probably the one thing as complicated (or more so) as trying to delineate boundaries, scopes and extents of temperate rainforests in the Southern Appalachians is trying to predict the effects of climate change on them. According to Jim Renfro of the GSMNP, “Some models [of climate change] predict warmer and wetter and some models predict warmer and drier. The only thing they seem to agree on is that it is getting warmer.” But a few degrees increase in temperature may not be as important as precipitation.

According to Schafale, “We don’t know that well what the impacts will be from climate change. The high rainfall is created by the interaction of topography with weather patterns [orographic lift]. If climate change shifted the moist southerly winds away, things could dry up quickly. But if it doesn’t, the warmer ocean temperatures may just mean more moisture in the air and higher rainfall. Since these areas are already pretty warm, a few degrees of warmer air may not matter so much. Most of the species there span a pretty broad range of elevation.” 

Weakley believes areas like the Blue Ridge escarpment where the Jocassee Gorges are and south-facing slopes of the Southern Appalachians will remain among the wettest places in Eastern North America. “Presumably the landforms of these areas (south-facing escarpment that catches moist air from the Gulf of Mexico, causing orographic precipitation) means that under a wide range of climate scenarios they are likely to be among the wettest places in Eastern North America.” As for temperature change, Weakley notes, “Moisture buffers temperature, so they will change less than other areas.”

The Southern Appalachians have served as refugia for northern and southern species of plants and animals since the last ice age and Weakley feels they could serve that purpose again in the face of climate change. “They [Southern Appalachians] have relictual species that have survived for many millions of years there because that [orographic precipitation] is the case. Therefore they are also likely to serve as refuges in the future as well. Moisture also helps maintain conditions for many plant species. Many trillium species that are now common and also some that are rare appear to have survived the Pleistocene glaciation at the Southern End of the Southern Appalachians (in the mountains south of Asheville, especially.)”

Many climate change models predict the loss of spruce-fir forests in the high elevations of the Southern Appalachians but rainfall could play a part in this scenario as well. According to Schafale, “The warmer temperatures may make a difference to the spruce-fir forest. But the more crucial question is whether they stay foggy and rainy. If they do, they may not warm up as much as the lowlands.”

One thing for sure

It’s a worn but true caveat—the only thing constant in nature is change. Our forests across the Southern Appalachians are facing a slew of unprecedented challenges from climate change to pollution, to attacks by invasive exotic insects, to encroachment from invasive exotic plants, to fragmentation, to development and questionable land management practices. But one thing is for sure. If you live in the High Country or Western North Carolina or East Tennessee, these magnificent and diverse forests are in your backyard. That means residents—and visitors—have a unique opportunity to see these marvelous ecosystems up close and personal.

Mt. Leconte wildflowers

Mt. Leconte is a good fit as a temperate rainforest. Twenty-five years of data show that Mt. LeConte averages more than 70 inches of rain a year and an average high temperature of 51 degrees Fahrenheit, and an average low temperature of 32 degrees Fahrenheit. Spring through autumn hikes on Mt. Leconte provide great opportunities for viewing wildflowers in this moist, fecund habitat.

There are five trails that lead to the summit of Mt. Leconte. All offer some similar and some unique opportunities. We will look at Trillium Gap Trail and Bullhead trail for wildflower viewing (though others may be just as good).

A couple of reminders: All trails to the summit of LeConte are moderate/strenuous to strenuous hikes. We would suggest hiking up Trillium Gap and back down Bullhead for a loop. But you don’t have to hike all the way to the summit to see great wildflowers. Trillium Gap to Brushy Mountain is a great up and back wildflower excursion.

Trillium Gap is aptly named an observant hikers may see 4 to 7 different species (depending on season) as they ascend the trail.

The lower elevations are good places to find a couple of the “sessile” trilliums. Sessile means the flowers have short or no stalk, basically sitting right atop the leaves.

Two of the sessile trilliums that may be found along Trillium Gap Trail are:

Stalked trilliums that might be encountered include:

Other wildflowers that could be encountered (depending on season) along Trillium Gap Trail, Bullhead Trail and around the summit at Mt. Leconte include:

This short list is intended to give just a taste for the variety of types of wildflowers found on Mt. Leconte some are spring ephemerals and some last till autumn’s killing frost.

Mt. Leconte is also known for a few endemic and/or rare plants:

Back to topbutton