BY TAL GALTON
On some mornings, the mountains across our valley radiate in the dawn light, but frequently they are coyly veiled by clouds. These are the highest peaks in the East — ancient mountains, among the oldest on the continent — and a tattered shawl of dark forest drapes over the ridge and its craggy shoulders. This high-elevation dark green forest is one of Western North Carolina’s unique natural features, the Southern Appalachian spruce-fir forest.
This plant community was once ranked as the second-most endangered ecosystems in America and is responsible for the names of iconic mountain ranges: the Blacks and the Balsams. For those who live in or visit the region, it is worth getting to know this bewitching habitat better. This forest’s story is compelling — the more you know, the more endearing these woods are. If you drive on the Blue Ridge Parkway, hike in Pisgah National Forest or on the Appalachian Trail, visit Mount Mitchell or the high elevations of the Smokies, you will find yourself in this forest, and you should know how singular it is.
I often hear people say that we live in a temperate rainforest. Most of our mountain forests, though temperate and humid, are not considered temperate rainforests by ecologists. However, the highest mountains in the region —ones that rise a mile or more above sea level — are considerably cooler and wetter than most of the lower hills and valleys where the towns are. Mount Mitchell averages 75 inches of rain per year, while Asheville — the epicenter of the driest valley in WNC — averages a mere 37 inches.
But even more important than the quantity of rain is how frequently the mountaintops are blanketed by clouds. When immersed, cloud vapor condenses on the trillions of coniferous needles and drips onto mossy beds below. This phenomenon, called fog drip, is most famous as the source of water for coastal forests of the Pacific Northwest. Similarly, fog drip is the mechanism that irrigates our high mountain forests — the headwaters of most of our mountain creeks and rivers. The spruce-fir really is a temperate rainforest, or more specifically, a cloud forest.
About 12,000 years ago, during the last ice age, evergreen forests blanketed much of the southern uplands. Glaciers covered the northern half of the continent: all of Canada, New England, New York and the Midwest down to the southern tip of Illinois. Those regions were scraped clean of plant life, and it took centuries for trees and herbs to recolonize the vast landscape. Meanwhile, the Southern U.S. was a refuge for a fantastic array of plant and animal species.
Nowhere was the diversity more prominent than in the mountains, where the various elevations provided numerous habitats, from alpine tundra to lush hardwoods of the foothills. Plants, unlike many animals, can only migrate so far in any given year, decade or even century. Here in the Southern mountains, they only had to move a few miles uphill to recolonize newly temperate territory. Due to this history and current variations in topography and climate, exceptional diversity remains a key feature of Southern mountain ecology.
As the climate warmed, these conifers retreated to the mountaintops, where it stays cool and moist year-round. Only about 70,000 acres of Southern Appalachian spruce-fir remain in the entire world, and every acre is within 100 miles of Asheville. The trees that give the forest its name are red spruce, a tree more at home in the boreal (northern) forests of New England and Canada, and Fraser fir, a Southern Appalachian endemic found nowhere else in the world.
Fraser firs, historically confused with the northerly balsam fir, prefer the very highest peaks, thriving at elevations above 6,000 feet. In an effort to simplify ecology for tourists, signs in the local parks often refer to these forests as “Canadian” or boreal. Though it is a close cousin to boreal and alpine (mountainous) forests throughout the hemisphere, Southern Appalachian spruce-fir is its own special variant. Some of its species are unique and exceptionally rare — Fraser fir, Carolina northern flying squirrel and spruce-fir moss spiders are the most oft-cited examples.
The trees give the forest its name and fame, but lowly moss is the magic sauce that engenders the forests’ enchanted feel. Mosses and liverworts are bryophytes, nonvascular plants that evolved before flowering plants and ferns. They lack roots and xylem, so they absorb water directly through their leaves. Though common the world-round, mosses are at their most abundant — and imposing — in temperate rainforests. Thick beds of mosses provide the feel of a cloud forest, but their individual natures are often overlooked. Due to high levels of ambient moisture, the species of mosses that grow here are ones more typically seen in boreal forests or in the rainforests of the Pacific Northwest.
Most bryophytes are tiny by nature (remember: no roots or vasculature to move water and nutrients), but in a cloud forest, where they benefit from fog drip, mosses can attain much greater stature. Growing in the shade of the Fraser firs, stairstep moss and big shaggy-moss are giants of the moss world. These mosses and others, like the conspicuous knight’s plume, make a plush bed, a striking contrast to the relatively modest mosses of lower-elevation hardwood forests.
Though mercilessly plundered for virgin timber 100 years ago — the Black Mountains were once crisscrossed with logging railroads — these forests, due to their high and remote locations, are now the backbone of the largest Appalachian wildlands. However, numerous bleached tree skeletons serve as a stark reminder of the fragility of this forest. From the 1970s through the 1990s, these forests were severely threatened by acid rain and balsam woolly adelgids, which attack mature Fraser firs. (The pests are an invasive cousin of hemlock woolly adelgids, which prey on hemlocks). Meanwhile, due to power plants and vehicular emissions, the cloud layer, the lifeblood of the forests, had become an acidic soup.
Thanks to regulations on coal plants and diesel engines, the acidity has moderated over the past two decades. The forests have recovered remarkably from both the logging and the more recent die-off, but the adelgid and other potential invasives are lingering threats, as are the unknown future effects of anthropogenic climate change. Scientists believe that the future health of these forests will largely depend on the continued flow of mountaintop moisture. Even in a warming world, if the atmosphere provides abundant water for the high mountains, our world-unique Carolina cloud forest may remain intact for many more generations.
Although the hold these forests have on our mountaintops is tenuous, take this moment in time to appreciate their lush beauty. When you are next caught in a dense cloud bank on the Blue Ridge Parkway, visualize how the cool mist infuses the evergreen forest with its life force.
Burnsville resident Tal Galton is a naturalist who loves introducing people to wild places. He runs Snakeroot Ecotours in Yancey County.