Appalachian Temperate Rainforests

The Appalachian temperate rainforest or Appalachian cloud forest is located in the southern Appalachian Mountains of the eastern United States and is among the most biodiverse temperate regions in the world. Centered primarily around Southern Appalachian spruce–fir forests between southwestern Virginia and southwestern North Carolina, it has a cool, mild climate with highly variable temperature and precipitation patterns linked to elevation. The temperate rainforest as a whole has a mean annual temperature near 7 °C (45 °F) and annual precipitation exceeding 140 centimeters (55 in), though the highest peaks can reach more than 200 centimeters (79 in) and are frequently shrouded in fog. Due to variable microclimates across different elevations, the rainforest is able to support both southern and northern species, including some which were forced south during the Last Ice Age. Dominated by evergreen spruce and fir forests at higher elevations and deciduous cove forests at lower elevations, the ecosystem contains thousands of plant species, including epiphytes, orchids, and numerous mosses and ferns. 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. Humans have shaped the rainforest environment for the last 12,000 years through activities such as hunting and agriculture. 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. By the 1880s, industrialization left the forest devastated by mining, logging and the introduction of destructive invasive species, examples being chestnut blight and the balsam woolly adelgid. Conservation efforts, such as the establishment of national forests and parks, have helped preserve the ecosystem, though it continues to face ongoing threats such as wildfire and climate change.

In order to be defined as a rainforest, the forest must average at least 140 cm (55 in) of precipitation annually and a temperate rainforest as opposed to a tropical rainforest is defined by a mean annual temperature between 4 and 12 degrees Celsius (39 and 54 degrees Fahrenheit). Some sources however say even at least 50 inches of precipitation annually qualifies an area as being a rainforest. On the other hand, the book Temperate and Boreal Rainforests of the World states that a temperate rainforest is defined by least 1,200 mm (47.24 inches) of average annual precipitation. Alaback also adds some additional criteria to the definition of a temperate rainforest as having at least 10% of its average annual precipitation during the summer months, cool and frequently overcast summers with average July temperature less than 16 degrees Celsius (60.8 degrees Fahrenheit), and forest fires or wildfires are rare and do not play an important role in the forest ecosystem. It must also be dense and lush with a rich understory and epiphytes.

The Appalachian temperate rainforest has a cool and mild climate and meets the criteria of temperate rainforests identified by forest ecologist Paul Alaback. Temperature and precipitation are extremely variable with elevation, with rainforest conditions usually but not always concentrated around spruce–fir forests at higher elevations. These spruce–fir forests have an annual mean temperature of 6.5 °C (43.7 °F) and a growing season mean (May–September) of 13.5 °C (56.3 °F), though this is likely somewhat cooler than the average across the entire rainforest ecosystem. It has annual precipitation above 140 centimetres (55 in), a cool summer, typical transient snow in winter, mean annual temperature near 7 °C (45 °F), and sum

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