What is a biome?

Picture the Earth as a giant patchwork quilt. Each patch has its own colours, its own weather and its own plants and animals. These huge patches are biomes (Fig. 2.1).

The word helps: bio comes from the Greek bios, meaning life, and -ome means a group of a particular kind. So a biome is a large natural region of the world where certain kinds of plants and animals live under similar climate. Icy tundra, hot desert, green forest and wide grassland are all different biomes.

Biome or ecosystem? Think of a city and a neighbourhood. A biome is like the whole big region. An ecosystem is like one small neighbourhood of that region, where particular plants, animals and non-living things (soil, water, air) live closely together and affect one another.

Biomes come in two main kinds:

• Terrestrial biomes, on land: forests, grasslands, deserts and tundra.
• Aquatic biomes, in water: freshwater and marine.

What decides which plants and animals can live in a biome? Mainly the temperature, the pattern of rain or snow (precipitation), the main kinds of plants that grow there, and the shapes those plants grow in (tall trees, grass, low shrubs).

Two more biomes appear on the world map (Fig. 2.2): the temperate deciduous biome, with broad-leaved trees that drop their leaves each year and clear seasons; and the taiga, with forests of cone-bearing trees such as pines, spruces and larches. (Coniferous means cone-bearing: these trees carry their seeds in cones.)

Together, all the biomes make up the living world of our planet and help keep nature in balance.