The southern spruce-fir forest is the highest and coldest forest ecosystem in the Appalachian range, thriving in elevations above 5,500 feet where the climate is too harsh to support the broad-leaved hardwood forest that dominates the region's lower elevations. A relic of the last Ice Age, this forest type covers just over 100 square miles, and is considered the second-most endangered ecosystem in the United States. Southern spruce-fir stands consist primarily of two needle-leaved evergreen species— the red spruce and the Fraser fir.
Over the past two centuries, the southern spruce-fir stands have been decimated by logging, pollution, and a European aphid infestation. The southern spruce-fir forest is home to one endangered species, the spruce-fir moss spider, and several threatened species. While red spruce is common throughout North America, the Fraser fir— a relative of the balsam fir— is found only in the spruce-fir stands of Southern Appalachia.[4] In the second half of the 20th century, nearly all of the mature Fraser firs of Southern Appalachia were killed off by the balsam woolly adelgid— a parasite introduced from Europe around 1900.

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