For some, a hike in the Great Smoky Mountains may have been as early as last week; others may have never gone at all. But nearly everyone, not matter how often they frequent the mountains, can appreciate the natural beauty that is a part of the region.
However, in the next few years, the mountains that are known so well may no longer look so glorious.
In 1925, a small bug called the woolly adelgid made its way from Asia to the U.S. and now threatens one of the most important tree species in the Smokies, the Eastern Hemlock.
According to Emily Delanzo, a 2013 UT graduate in environmental studies, the adelgid was likely brought in by hikers on their firewood, resulting in the current firewood ban in the forest.
Currently, it can take up to a decade for a tree to die from the adelgid. More than 95 percent of hemlocks have already been infected, and there is little one can do to save the tree after that happens. While there are methods such as removing branches, or spraying and injecting the tree with chemicals, the sheer scope of this project remains daunting.
For comparison on how destructive this species can be, the Shenandoah National Park discovered to have the aphid-like creature in the 1980s, and three decades later, four out of five hemlocks in that forest have already died.
The Eastern Hemlock, native to Eastern North America and the state tree of Pennsylvania, provides vital services to the forest that any other species would have a hard time trying to replicate. It mainly helps to keep streams cool, assisting trout and other temperature-sensitive species in maintaining a stable home.
According to Matthew Reed, a graduate research assistant in the Department of Forestry, Wildlife and Fisheries, a decrease in the number of hemlock in the forest would have a direct impact on the ecosystem.
"There are a lot of things that they do for forested environments that are invaluable that we really don't even know the extent of at this point," Reed said.
In addition to their importance on habitat and soil stabilization, the hemlock also prevents the native rhododendron from spreading out of control, giving other wildflowers a chance to grow. However, the loss of these trees to the woolly adelgid could change all that.
"It's all connected, that's what everyone has to remember," Reed said. "One little thing like that can lead to a myriad of terrible things that are impossible to see all of. The woolly adelgid is intolerant to cold weather, so as minimum temperatures rise... they're fine."
The hemlock species is unique to the region, as it was mainly left alone by early settlers as wood was not useful for lumber. As a result, the Smokies contain some trees up to 500 years old. The hemlock provides excellent tree cover, and its low branches also provide a way for smaller animals to climb to the top of the canopy.
Michael McKinney, professor of geology and researcher of conservation biology, said the woolly adelgid kills the hemlock by burrowing into the phloem layer of the tree, the area that transports the nutrients, weakening the tree.
"It stresses the tree out," McKinney said. "It reduces the immune system, and makes it a lot more liable to other diseases, drought, things like that."
The aphid-like creature feeds on the sap, essentially starving the tree. The aphid covers itself in a white, filmy structure, giving it the appearance of cotton balls and can be easily seen on the needles of infected hemlocks.
The solution to the problem, sadly, is rather mixed. McKinney said the best chance for survival is creating a hybrid version of the tree with its Asian relative. The adelgid co-evolved with the Asian hemlock, giving the latter more of an evolutionary defense against the bug.
"You can't really contain it at this point," Delanzo said. "They have certain treatments like a topical spray that kills the insect on impact and a fluid injected into the tree to make it resistant.
"These are unfortunately temporary solutions to a permanent problem."
Other methods such as cutting off infected limbs and introducing a predator, a beetle from Asia, show promise, but the long-term outlook remains somber for other reasons.
"I hate to say this, but I think the hemlock is going to disappear anyway from the heat stress," McKinney said.
Excessive heat due to climate change has hurt several aspects of the forest, and the rising temperatures suggest that eventually the region will likely have a climate more similar to southern Georgia in about 200 years.
"At this point, all we can do is educate others on the importance of never introducing firewood. You never know what's on it," Delanzo said.