Evergreen forest
An evergreen forest is a forest consisting entirely or mainly of evergreen trees that retain green foliage all year round. Such forests reign in the equatorial region, between the tropics primarily as broadleaf evergreens, and in temperate and boreal latitudes primarily as coniferous evergreens.
Moist forest, montane forest,mossy forests, laurel forest, cloud forest, fog forest, are generally tropical or subtropical or mild temperate evergreen forest, found in areas with high humidity and relatively stable and mild temperatures, characterized by a persistent, frequent or seasonal low-level cloud cover, usually at the canopy level. Cloud forests often exhibit an abundance of mosses covering the ground and vegetation.
The Tropical evergreen forests
Tropical evergreen forests or (tropical rainforests) are usually found in areas receiving more than 200 cm of rainfall and having a temperature of 15 °C to 30 °C and have annual humidity exceeding 77%. They occupy about seven per cent of the Earth's land surface and harbour more than half of the planet's terrestrial plants and animals. Tropical evergreen forests are dense, multi-layered, and harbour many types of plants and animals. The trees are evergreen as there is no period of drought or frost. The canopy tree species are mostly tall hardwoods with broad leaves that release large quantities of water through transpiration, in a cycle that is important in raising as much mineral nutrient material as possible from the soil.
In India, evergreen forests are found on the eastern and western slopes of the Western Ghats in such states as Tamil Nadu, Karnataka, Kerala and Maharashtra. And also found in Assam, Arunachal Pradesh, Meghalaya, Nagaland, Tripura, West Bengal and Andaman and Nicobar Islands. They are also found in the hills of Jaintia and Khasi. Some of the trees found in Indian tropical forests are rosewood, mahogany and ebony. Bamboo and reeds are also common. Because of dense foliage competing for light, little direct sunlight reaches the understory.
Temperate evergreen forests
Temperate evergreen forests, coniferous, broadleaf, and mixed, are found largely in the temperate mid-latitudes of Montane North America, Siberia, Canada, Australia, Africa and Scandinavia. Broadleaf evergreen forests occur in particular in eastern North America and in countries around the Mediterranean Basin, such as Lebanon and Morocco. Many subtropical broadleaved evergreen forests occur along the eastern margins of major land masses, e.g., in southeastern United States, southern China and in southeastern Brazil. Other examples include the wet temperate conifer forests of northwestern North America.
Temperate evergreen forests are the regional climax vegetation, commonly dominated by hardy trees that can deal with sandy, rocky, and various other soils of poor quality. Most such communities also are subject to intermittent fire, drought and cold. Coniferous temperate evergreen forests are most frequently dominated by species in the families Pinaceae and Cupressaceae. Broadleaf temperate evergreen forests include those in which Fagaceae such as oaks are common, those in which Nothofagaceae predominate, and the Eucalyptus forests of the Southern Hemisphere. There also are assorted temperate evergreen forests dominated by other families of trees, such as Lauraceae in laurel forest.
Evergreen forests around the world are under threat of logging, mining, oil and gas developments, pollution, hydroelectric projects and other human developments planned in these areas.
See also
- Deciduous forest
- Biomes
- Ecoregion
- Ecological land classification
- List of terrestrial ecoregions (WWF)