Biomes

Biomes Scientists group ecosystems into larger areas called biomes. Biome: a large region characterized by a specific type of climate and certain types of plants and animal communities.

The World’s Major Terrestrial Biomes

Major Biomes The major biomes are divided into Terrestrial (ground) and Aquatic (water) biomes. The aquatic biome can be divided into both Marine (saltwater) and Freshwater biomes. The Terrestrial Biomes are: Tropical Forest Temperate (Deciduous) Forest Taiga (Boreal or Coniferous Forest) Savannah Grasslands (also called Prairie, Steppe, or Pampas) Desert Tundra

Further Classification Some biologists define more than seven terrestrial biomes, adding Chaparral, Mountain, Island, or Tropical Dry Forest. Biomes are often known in English by local names. For example, a temperate grassland or shrubland biome is known commonly as steppe in central Asia, prairie in North America, and pampas in South America. Tropical grasslands are known as savanna in Australia, whereas in Southern Africa it is known as veldt (from Afrikaans).

Biomes and Vegetation Biomes are described by their vegetation because plants are the most noticeable characteristic of a region. The plants also determine the other organisms that can live in an area. Plants (& animals) in a particular biome have adaptations that enable them to live there.

Temperature and Precipitation

1)Tropical Rain Forests Located in a belt around the Earth near the equator. Regulate world climate. Play a vital role in the nitrogen, oxygen, and carbon cycles.

Tropical Rain Forests

Tropical Rain Forests Always humid and warm Get 200 to 450 cm of rain a year. Strong sunlight year round. Relatively constant temperature year round.

Layers of the Rain Forest

Threats to Rain Forests Once covered 20% of the Earth’s surface. Now cover only 7% of the Earth’s surface. Every minute of every day, 100 acres of tropical rain forest are destroyed.

2)Temperate Forests

Temperate Deciduous Forests Trees drop their broad, flat leaves each fall Range of temperatures can be extreme Growing season only lasts four to six months Winter temperatures often fall below freezing. This means little water available for plants.

Temperate Deciduous Forests Vegetation also changes with the seasons. Organic matter decomposes slowly in the winter. The soil contains more organic matter and nutrients than the soil in a tropical rain forest.

3) Taiga Northern coniferous forest (trees with cones & needles like pine trees) Just below the Arctic Circle Winters are long (6 to 10 months) Average temperatures just below freezing. Plant growth is most abundant during the summer because of constant daylight and more precipitation.

Taiga

Plants of the Taiga Conifer – tree with needle-like leaves and seeds that develop in cones The shape of the leaves and waxy coating prevent them from losing too much water. Cone-like shape prevents snow from building up on branches and causing breakage.

Plants of the Taiga Needles contain substances to make the soil acidic when the needles fall to the ground. Most plants cannot grow in acidic soil. Soil forms slowly because of the climate and acidity of the soil.

A Comparison

4) Savannas Parts of Africa, Western India, Northern Australia, South America Tropical Biome Dominated by grasses, shrubs, small trees Have a wet season and dry season

Savannas

5) Temperate Grasslands Large areas of the interior of continents Moderate rainfall but still too little for trees Prairies in North America, steppes in Asia, veldt in South Africa, pampas in South America

Temperate Grasslands

Prairie (North American Grasslands)

Steppe (Grasslands in Asia)

Veldt (Grasslands in South Africa)

Pampas (Grasslands in South America)

Plants of Temperate Grasslands Most fertile soil in the world Farmland

6) Deserts Widely scattered vegetation Very little rain In extreme cases, it never rains and there is no vegetation Temperature changes rapidly during a 24 hour period. Often located near mountains that block rain clouds.

Deserts

Deserts

7) Tundra Northern arctic regions Too cold and dry for trees Permafrost – deeper layers of soil are permanently frozen throughout the year. Thin topsoil When the topsoil thaws, the land becomes wet and spongy and is covered in bogs.

Tundra