[12][13][14][15] It is also home to many animals and fungi, including endangered and endemic species, reaching the highest diversities of mushrooms, salamanders, land snails, and millipedes in the world.

[16] These impacts grew following European colonization, which brought about significant changes, including the decline of native populations, land use alterations, and the introduction of non-native species.

[16] By the 1880s, industrialization reached the region, leaving the forest devastated by mining, logging and the introduction of destructive invasive species, examples being chestnut blight and the balsam woolly adelgid.

[16][17][18][19] Conservation efforts such as the establishment of national forests and parks have helped preserve the ecosystem, however, it continues to face ongoing threats such as wildfire and climate change.

[29] Weak upslope air flow in summer brings more precipitation to the highest elevations, while autumn is typically driest with occasional intense rainfall from tropical systems.

The temperate rainforest also includes the mountains in Northern Georgia such as Chattahoochee–Oconee National Forest, Cohutta Wilderness, western Virginia, northwestern South Carolina, and southeastern Kentucky.

[5][7][11] The rainforest is more biodiverse than any temperate region of similar size in the world, with over 19,000 species identified in Great Smoky Mountains National Park alone.

[5] This has combined with a relatively stable year-round climate to enable northern and southern species to live in close proximity each other, lending the rainforest its high biodiversity.

[5][7] Around 12,000 years ago, Paleo-Indians first settled in the Southern Appalachians, crafting stone projectile points from local materials, indicating their long-term inhabitance.

[16] However, evidence for residential activities in the highlands are absent prior to about 7,500 BCE, though the archaeological record does indicate hunting, flintworking, butchering, hideworking, and woodworking in the region.

[16] Throughout the Archaic period, Paleo-Indians adopted more advanced technologies such as textiles, basketry, and the atlatl and transitioned from hunter-gatherer activities towards an increasing reliance on fishing and the emergence of agriculture in lowlands.

[16] Cultural developments accelerated with the adoption of agriculture in the highlands in the Middle Woodland period, delayed relative to the lowlands by rugged terrain, low population, limited fertile soil, and a shorter growing season.

[16] As intensive plant husbandry expanded through the introduction of corn, beans, pumpkin, squash, and tobacco by around 1000 CE, it fostered more complex societies centered around permanent villages in Appalachian river valleys.

[16][50] By the 1880s, Appalachia's natural resources had drawn the attention of industrialist Civil War veterans and vacationers from the North, buying up land and dramatically expanding the nascent railway system.

[16][19] While Appalachia is famous for its coal, mica mining was far more dominant in rainforested areas, and logging remained generally confined to the valleys along significant rail lines.

Wolves, beavers, and mountain lions vanished; bear, turkey, and deer populations plummeted; and exotic invasives like chestnut blight, wild boar, and rainbow trout were introduced.

[16][19][20] Encouraged by these factors and the Appalachian National Park Association (founded in 1899), Congress passed the Weeks Act in 1911 to enable the purchase of Federal lands in the Eastern United States.

[52] However, fire suppression instituted after European colonization has created two significant issues in the region: a higher risk of "catastrophic wildfires", and declines in the abundance of disturbance-dependent species like Table Mountain pine and woodpeckers.

[52][53] High peaks in the temperate rainforest have some of the highest air pollution of any region in the Eastern United States, with a 1999 study finding sulfate and nitrate deposition 6–20 times higher than lower elevation sites.

[8] Any change in cloud patterns or height could significantly disrupt the cloud-based deposition this forest type relies on for up to 50% of their water budget, forcing them upslope until extirpation.

[21] Similarly, climate change is predicted to increase the rate of wildfires and place more stress on existing forests, leading them more susceptible to current threats.

[18] Originally a fungal pathogen introduced from Asia, the blight quickly spread, wiping out vast populations of mature chestnuts and dramatically altering the composition of forests across the Eastern US.

[18] Though there are signs of recovery in recent years—such as Kuwohi having three times more adult trees in 2020 than in the 1980s[18]—these threats to the forest are not independent and scientists warn climate change may lead to another adelgid outbreak.

"If we were to have a period of warm winters and hot, dry summers, the trees will be stressed, I wouldn’t be surprised to see a resurgence of balsam woolly adelgid," says Kristine Johnson, supervisory forester at the Great Smoky Mountains National Park.