Biome is a large ecosystem occupying a part of the earth like tropical forests, grasslands, tundra, etc. Each biome has distinct vegetation.
Forests are classified into (a) Evergreen and (b) deciduous forests.
The Evergreen Forests
(i) Tropical Evergreen Forests
These are found in areas having high rainfall and high temperature that is in Equatorial regions, tropical coastal regions. Hot and humid climatic conditions favour luxuriant growth of a variety of trees. The trees have broad leaves to permit transpiration of surplus moisture throughout the year. As there is no dry season plants grow throughout the year and shedding of old leaves and growth of new leaves takes place throughout the year, e.g., ebony, mahogany, rosewood. Mangrove forests occur in deltas and coastal swamps.
(ii) Mid-latitude Evergreen Forests
These are found on the eastern margins of continents in the subtropical belt in South China, South Eastern USA, South Brazil, East coast of South Africa and South-Eastern Australia. The forests have hard wood, with broad leaves. Trees such as oak, eucalyptus and wattle are some trees of economic value.
(iii) Mediterranean Forest
These occur on the western margins of the continents in middle latitudes. These regions have moderate winter rainfall and the summers are long, hot and dry. The trees are adapted to the dry summers without shedding of leaves. Trees have deep roots, small, spiny or waxy leaves and thick barks to reduce loss of moisture, e.g., cork, oak, figs, olives and chestnuts.
(iv) Coniferous Forests:
These evergreen forests of the high latitude forms a continuous belt around the North Polar region and high mountains in Europe, Asia and North America. Trees are tall, soft wooded, conical in shape with thick needle like leaves to reduce transpiration. Due to low temperature, tree growth is restricted to the summer season. Trees have greater commercial value, e.g., spruce pine, fir and cedar.
The forests in which trees shed their leaves in a particular season in order to conserve moisture through transpiration. They include – (i) Tropical deciduous forests are found in regions having distinct dry seasons as in the monsoon regions of Asia, parts of Central America, Brazil and Northern Australia. Trees shed their leaves in the dry summer season. As compared to the tropical evergreen forest species of trees are lesser and the forests are less dense too. Teak is an important hardwood tree of the forest; (ii) Mid-latitude deciduous forests are found in coastal regions of cool climate in Western Europe, North-eastern China, Japan, North-eastern United State. Southern Chile and New Zealand. Trees shed their leaves in winter when temperature falls below 6 °C. New leaves sprout in spring.