Appalachian temperate rainforest
|Appalachian temperate rainforest|
The Appalachian Trail traverses the dense, moss-covered spruce-fir understory near the summit of Old Black in the Great Smoky Mountains of Tennessee
The Appalachian temperate rainforest is located in the southern Appalachian Mountains of the eastern U.S. About 351,500 square kilometers (135,000 square miles) of forest land is spread across southwestern Virginia, western North Carolina, northern Georgia, and eastern Tennessee. The annual precipitation is more than 60 inches (over 1500mm). The Southern Appalachian spruce–fir forest is a temperate rainforest located in the higher elevations in southwestern Virginia and western North Carolina. Fir is dominant at higher elevation, spruce at middle elevation, and mixed forests at low elevation.
The Appalachian temperate rainforest has a cool and mild climate. The mean annual low temperature is 4.4 °C (39.9 °F) and high is 15.5 °C (59.9 °F). High altitudes of the rainforest receive less than 2,000 millimetres (79 in) of precipitation. This temperate rainforest is classified as a perhumid temperate rainforest. It is one of four subtypes of temperate rainforest identified by Alabak, and it has a cool summer, typical transient snow in winter, mean annual temperature of 7 °C (45 °F), and summer rainfall is above 10% of precipitation means. Precipitation in this area is more than evapotranspiration; as a result, the condition is wet whole year. Moist air comes from the Gulf of Mexico and western Atlantic Ocean, and when they hit the Appalachian ranges then rain falls by the orographic effect.  The high elevation is likely to cover clouds, which make the rate of evapotranspiration low and clouds are one of the water sources. They are an important water source in this area; Interception by clouds supplies 20% to 50% of the annual water supply, which is a relatively high rate. In the eastern Canada Temperate Rainforest, fog has a role of increasing precipitation about 5 to 8%.
The Appalachian Mountains started to form in the middle Ordovician period by the collision of plates. The collision which caused the uplift of the mountains began around 440 to 480 million years ago and ended around 230 million years ago. This range has an important role of forming the temperate rainforest in this area, because of the orographic effect. In the Last Ice Age, ice did not cover the south Appalachian Mountains. Uncovered area was a refuge for animals and plants which lived in northern area. After the ice receded, some species spread back to north, while some of them stayed in this area. This is one of the reasons why there is a high biodiversity in the temperate rainforest.
High mountains make northern species able to survive. At the present, many plants form the temperate rainforest and the forests have a high rate of biodiversity. About 10,000 species, including endemic salamanders and turtles live in this area.
Red spruce and Fraser fir are dominant canopy trees in high mountain areas. In higher elevation (over 1,980 meters or 6,500 feet), Fraser fir is dominant, in middle elevation (1,675 to 1,890 meters or 5,495 to 6,201 feet) red spruce and Fraser fir grow together, and in lower elevation (1,370 to 1,650 meters or 4,490 to 5,410 feet) red spruce is dominant. Yellow birch, mountain ash, and mountain maple grow in the understory. Younger spruce and fir and shrubs like raspberry, blackberry, hobblebush, southern mountain cranberries, red elderberry, minniebush, southern bush honeysuckle are understory vegetation. Below the spruce-fir forest, at around 1,200 metres (3,900 ft), are forests of American beech, yellow birch, maple, birch, and oak. Skunk cabbage and ground juniper are northern species that remained in this region after the glacier retreated.
More than 30 species of salamanders are found in the rainforest and some of them are endemic, such as Black Mountain salamander, southern dusky salamander, Jordan’s salamander, and Cheat Mountain salamander. Rotten trees and moist leaves on ground provide a good, wet environment for amphibians, including salamanders. Many species of salamanders in this area do not have lungs, so they breathe through their skin and the wet environment is conducive for their survival.
Two species of turtles are endemic as well: flatted muck turtle and Alabama map turtle.
As mammals, the most familiar is likely the American black bear. Other common mammals are white-tailed deer and groundhog. Northern species like northern flying squirrel and red squirrel survive in the area because of the cool climate.
Native Americans have lived in this area for about 10,000 years. After contact with European settlers, the Cherokee Nation was forced to move in 1838 to 1839 from their traditional homeland to Oklahoma. Cherokees were relatively late comers to this region, and prior to their removal they were notorious for warring with rival tribes including the Muscogee and the Creeks. 
The Appalachian Trail, which is a 2,000 miles (3,200 km) or more trail from Georgia to Maine provides one of the main recreational uses. The trail passes through the Appalachian mountain range, including the Appalachian temperate rainforest. The trail plan was published in 1921, and the trail was completed in 1937. According to the Appalachian Trail Conservancy website, 2500 hikers started at the Appalachian Trail southern trailhead in Georgia. Non-profit organizations and the National Park Service maintain the trail.
Part of the Appalachian temperate rainforest is in the Nantahala National Forest (established in 1920), the Cherokee National Forest (established in 1920 as well), and the Great Smoky Mountains National Park (established in 1934). The rainforest, protected federal-owned land, is host to recreational visitors. The Cherokee National Forest reported that millions of people visit the national forest each year.
Air pollution is caused by anthropogenic factors, such as power plants, factories, and automobiles. It is related to acid rain and water pollution. Vegetation in high elevation is easy to collect pollutants. Acid rain damages the plants and makes streams more acidic. Acidic water affects aquatic species, such as fish, salamanders, and also vegetation. Air pollution affects ground ozone, which experience a biochemical change with sun light. The ground ozone damages plants. In the National Park Service, 30 plants species were damaged by the ground ozone and plants in higher elevation are prone damage.
Wild fire is created by lightning on average twice per year, usually in May or June. Although fire created by lightning is a natural disturbance and can be a threat, it is an important factor for ensuring biodiversity; Some native species, such as table mountain pines and woodpeckers, benefit from the environmental changes after fire.
In the Great Smoky Mountains National Park, the National Park Service performs controlled burns: "to invigorate a species or ecosystem that benefits from fire" and "to reduce heavy accumulations of dead wood and brush which under drought conditions could produce catastrophic wildfires that threaten human life and valuable property." Some rare plants thrive after a controlled fire.
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