A temperate rainforest is a forest that is located in a temperate region, but receives a large amount of rainfall. Temperate rainforests are considered one of the rarest ecosystems in the world. Most are located in the Pacific Northwest region of North America, though these forests can also be found in South America, Australia, New Zealand, South Africa, Asia, and Europe. Temperate rainforests are generally situated near a seacoast and usually have a very high biomass. Most of the plants in a typical temperate rainforest are epiphytes, or rootless plants, that draw moisture from the air rather than from the soil.
The Pacific Northwest region of North America may contain the world's largest concentration of temperate rainforest lands. About two-thirds of the world's temperate rainforests can be found in this region. Other such rainforests exist off the coasts of Chile, Australia, New Zealand, and South Africa. Some tracts of temperate rainforest may continue to thrive in Western Europe, Asia, and other regions of North America. Altogether, there are currently about 75 million acres of temperate rainforest in the world, and they are generally found between 23 and 66 degrees of latitude in both the northern and southern hemispheres.
The typical temperate rainforest receives between 55 and 200 inches (1.39 to 5.08 meters) of rain yearly. Most temperate rainforests enjoy a long rainy season and a short dry season. During this dry season, 7 to 12 inches (17.8 to 30.5 cm) of rain may fall as fog. Temperate rainforests are usually located in coastal regions, and may draw most of their rainfall from the sea.
Due to their generally high levels of biomass, temperate rainforests are widely considered among the world's most biologically diverse regions. The temperate rainforest is typically marked by its many epiphytes. Epiphytes are rootless plants that typically grow from other plants, especially maple trees. Epiphytes don't generally depend on the soil at all, but draw their moisture from the humid air of the temperate rainforest.
Though temperate rainforests receive much of their precipitation in the form of rainfall during the wet season, precipitation in the form of fog can be crucial to these ecosystems during the dry season. Heavy fog helps keep the air humid and moist to help the many fungi and ferns of the temperate rainforest thrive during the brief period of low precipitation.