Biomes
A biome is a unit resulting from the interaction of a regional climate, animal and plant life, and substrate. The types of biomes are grasslands, deserts, coniferous forests, deciduous forests, tropical forests, tundra, fresh water and marine environment.
(i) Grasslands : Every continent has one or more areas called grasslands. The type of grassland biome depends mostly on tallness of grasspoint. In western North America, tall-grass grasslands are called prairie, short-grass types are found on plains. The grasslands are typified by rainfall of 100 to 150 cm per year. Rainfall is erratic, thus accounting for the absence of trees.
(ii) Deserts : These are present in every major continent.It is estimated that about 1/5th of the earth's dry land is desert land. The extreme fluctuations in temperature in desert severely limit the possibilities of life. Plants called xerophytes are found in deserts as they can store water. As regards temperature, the days are hot, the nights cold with a difference of 27°C between the two. Annual rainfall is less than 25 cm.
(iii) Coniferous Forests : (Boreal Forests or Taiga) These are characterised by a band of evergreen trees crossing Europe, Asia and North America. The winters are severe,limiting the growing season to 3-5 months. The fauna include moose, lynx, rodents and many birds.
(iv) Deciduous Forests : These are typified by deciduous trees that lose all their leaves in winter. This biome has a moderate climate well suited to animal life. The fauna includes mountain lions, rodents, white-tailed deer and large predatory birds.
(v) Tropical Forests : They are essentially rain forests receiving over 200 cm rainfall per year. They occur around the equator and, therefore, the temperature is usually high. The forests are very dense and house nocturnal and arboreal (tree-dwelling) animals.
(vi) Tundra : It borders the Arctic ocean and is treeless and always frozen. The growing season lasts only about 60 days. The fauna is restricted to waterfowl, rodents, lemmings, and insects.
