Can the red spruce thrive in Appalachia again?

For those who haven’t spent time on an Appalachian sky island, the red spruce is a rare site.

Sky islands are not a domicile of George Jetson or something out of "Star Wars," they are high elevation mountaintops in the Appalachians cut off by topography from other areas of similar heights. The red spruce thrives in their naturally cool temperatures, but farther down the slopes, the trees no longer grow.

Brenn Kurtz, a master’s degree student in the Department of Forest Resource and Environmental Conservation, is studying the viability of spurring an adaptation to the warmer climate.

“The red spruce used to be more southern because conditions were cooler and wetter, but as the climate shifted, the trees moved northward and upward,” Kurtz said. “They once grew continuously from Georgia northward. Now they’re mainly in Canada — Ontario, New Brunswick, Nova Scotia — and New England.” 

They also have populations in West Virginia and four sky islands along the Central Appalachians: Clingman’s Dome in the Great Smoky Mountains; Roan Mountain, Tennessee; and two areas of Virginia, the Grayson Highlands and Mountain Lake. 

“The lowest you’ll find them is around 800 meters" in elevation, Kurtz said.

Under the direction of Professor John Seiler in the College of Natural Resources and Environement, Kurtz is now experimenting with red spruce seedlings.

“My project is on red spruce and how they may adapt to warmer growing conditions versus colder conditions,” she said. “We have two different growing environments, a cold chamber and a warm chamber. Both are in the greenhouse, but they’re only about 7 degrees [Celsius] different — not 20 degrees or anything extreme.”

The experiment looks at whether the seedlings can adapt to warmer growing condition.

“We plotted photosynthesis versus temperature to see if the optimum temperature differs between warm-grown and cool-grown seedlings,” Kurtz said.

She is examining if there are differences in the seedling populations from the various sky islands and if one seed source is better able to adjust to the warmer temperatures. 

“We want to know if some seed sources are taller, shorter, or show higher photosynthetic rates and whether warmer growth conditions alter their adaptability. For example, the Mountain Lake trees grow at the lowest elevations, so they may already tolerate warmer conditions. If so, they might be prioritized for restoration,” she said.

Seiler said the red spruce has interested foresters and conservationists for decades.

“My first research project ever was on the red spruce, and as it turns out, my last research project is on the red spruce,” said Seiler, who plans to retire in the near future.

“When you’re trying to restore a forest, one of the first things you want to find out is how much genetic diversity there is in the species,” Seiler said. “If they have high genetic diversity, you always want to try to plant local sources. If seed sources are really different, you really have to do it carefully. They’re almost like a different species.” 

In addition to the possibility that red spruce behave differently from the various sky islands, “The southern red spruce have been stuck down here, and they may not be like the big population up north, in Canada or in Maine. Here you have to be above 4,000 feet or so, but near Acadia National Park, they go right to the ocean, elevation zero,” he said.

The results of Kurtz’s work will determine if the red spruce can acclimatize to warmer temperatures and give restoration groups such as the Southern Appalachian Spruce Restoration Society and the Nature Conservancy an idea of the best way to source the seeds.

“If we find there’s no difference in the seed sources, we can say ‘Get your seeds from anywhere,’” Seiler said. “If we find they’re really different, we would say ‘If you want to start planting up in Mountain Lake, you probably want to use Mountain Lake seeds.’”

Kurtz said musicians, especially those of the Appalachians, used red spruce as material for making stringed instruments. A restoration of range also enlarges the habitat for species of squirrels as well as some spiders. 

“Historically, they were important lumber and pulp trees, used for musical instruments like mandolins, violins, and guitars,” Kurtz said. “Ecologically, they’re crucial for species like the Carolina northern flying squirrel, the Virginia northern flying squirrel, and the spruce-fir moss spider, which is the smallest tarantula in the world. Their dense canopies provide refuge and habitat.” 

While environmental change is a key factor causing red spruce populations to retreat to cooler climates, the warming that thinned the population in the Southern Appalachians goes back to the thawing of the ice age. The populations that covered the forests at lower elevations and latitudes were here hundreds, if not thousands of years ago, during and after a period of glaciation.