Biomes
Some parts of the art have more or less the same kind of abiotic and biotic factors spread over a large are, creating a typical ecosystem over that area. Such major ecosystems are termed as biomes.
An ecologist recognises a number of large ecological units called biomes, which are based on the growth forms of the dominant vegetation. The distribution of terrestrial biomes is determined primarily by temperature and precipitation, but is also influenced by soil fertility and fire. Each biome is more or less isolated by oceans, mountain ranges or desert barriers. This geographical isolation tends to restrict gene flow between these biomes. As a result, each biome maintains a characteristic species of living organisms.
Terrestrial biomes Seven categories of the earth’s major biomes arranged by distance from equator are listed below.
1. Tropical rain /evergreen forest occur near equator, receive an enormous amount of rain year round, temperature ranges between 25° C - 29° C year round and are characterized by the growth of tall tress and lush vegetation. Animal diversity is highest in trophical forests.
2. Savanna ( hot deserts) alo lie near the equator but experience lesser rain than tropical rain forests and sometimes have prolonged dry spells. Savannas are characterised by open grasslands with scattered tress and shrubs.
3. Deserts (Cold Desert ) are extremely dry biomes; hot deserts are hot yearn round, whereas cold deserts are hot only in the summer. Deserts are great biological interest due to the extreme behavioral , morphological and physiological adaptations of plants and animals that live there.
4. Temperate grasslands receive less rainfall than savannas but more than deserts; the soil in temperate grassland is rich, so they are well suited to agriculture. Large grazers and burrowing mammals are native to temperate grasslands.
