A biome is an area of the planet that can be classified according to the plants and animals that live in it. Temperature, soil, and the amount of light and water help determine what life exists in a biome.

A biome is different from an ecosystem. An ecosystem is the interaction of living and nonliving things in an environment. A biome is a specific geographic area notable for the species living there. A biome can be made up of many ecosystems. For example, an aquatic biome can contain ecosystems such as coral reefs and kelp forests.

Not all scientists classify biomes in the same way. Some use broad classifications and count as few as six biomes. These are forest, grassland, freshwater, marine, desert, and tundra.

Other scientists use more precise classifications and list dozens of different biomes. For example, they consider different kinds of forests to be different biomes. Tropical rain forests that are warm and wet year-round are one biome. Temperate deciduous forests—those that have cold winters, warm summers, and are dominated by trees that lose their leaves—are a different biome. Taiga forests, which are in cold regions and are dominated by cone-bearing firs and spruces, are yet another biome.

Boundaries between biomes are not always sharply defined. For instance, there are sometimes transition zones between grassland and forest biomes. Coasts and wetlands are transition zones between terrestrial and aquatic biomes.

Biomes move as the climate changes. Ten thousand years ago, parts of North Africa were lush landscapes cut by flowing rivers. Hippopotamuses, giraffes, and crocodiles lived amid abundant trees. Gradually, the climate dried out. Today, this region is part of the Sahara Desert, the world's largest desert.

biome
This marine biome is dominated by kelp, a kind of seaweed.

Bountiful Biomes
There are more than a dozen ways to classify biomes. Climatologists, botanists, ecologists, biologists, and anthropologists have different criteria for deciding what constitutes a biome. One of the simplest classification systems has only two biomes: terrestrial (land) and aquatic (water). One of the most complex has more than a dozen.

abundant
Adjective

in large amounts.

amid
Preposition

in the middle of.

aquatic
Adjective

having to do with water.

Noun

area of the planet which can be classified according to the plant and animal life in it.

broad
Adjective

wide or expansive.

classify
Verb

to identify or arrange by specific type or characteristic.

Noun

all weather conditions for a given location over a period of time.

Noun

edge of land along the sea or other large body of water.

coral reef
Noun

rocky ocean features made up of millions of coral skeletons.

deciduous
Adjective

type of plant that sheds its leaves once a year.

Noun

area of land that receives no more than 25 centimeters (10 inches) of precipitation a year.

Noun

community and interactions of living and nonliving things in an area.

environment
Noun

conditions that surround and influence an organism or community.

fir
Noun

variety of pine tree.

forest
Noun

ecosystem filled with trees and underbrush.

freshwater
Noun

water that is not salty.

grassland
Noun

ecosystem with large, flat areas of grasses.

kelp forest
Noun

underwater habitat filled with tall seaweeds known as kelp.

lush
Adjective

abundant and rich.

marine
Adjective

having to do with the ocean.

network
Noun

series of links along which movement or communication can take place.

precise
Adjective

exact.

Noun

area of tall, mostly evergreen trees and a high amount of rainfall.

Sahara Desert
Noun

world's largest desert, in north Africa.

soil
Noun

top layer of the Earth's surface where plants can grow.

spruce
Noun

coniferous, or cone-bearing, tree.

Noun

evergreen forest in cool, northern latitudes. Also called boreal forest.

Noun

degree of hotness or coldness measured by a thermometer with a numerical scale.

terrestrial
Adjective

having to do with the Earth or dry land.

transition zone
Noun

area between two natural or artificial regions.

tropical
Adjective

existing in the tropics, the latitudes between the Tropic of Cancer in the north and the Tropic of Capricorn in the south.

tundra
Noun

cold, treeless region in Arctic and Antarctic climates.

Noun

area of land covered by shallow water or saturated by water.