Characteristics of Terrestrial Biomes

Learning Outcomes

  • Identify the two major abiotic factors that determine terrestrial biomes

Terrestrial ecosystems are known for their diversity; they are grouped into large categories called biomes. Grouping these ecosystems into just a few biome categories obscures the great diversity of the individual ecosystems within them. For example, there is great variation in desert vegetation: the saguaro cacti and other plant life in the Sonoran Desert, in the United States, are relatively abundant compared to the desolate rocky desert of Boa Vista, an island off the coast of Western Africa (Figure 1).

Photo (a) shows saguaro cacti that look like telephone poles with arms extended from them. Photo (b) shows a barren plain of red soil littered with rocks.

Figure 1. Desert ecosystems, like all ecosystems, can vary greatly. The desert in (a) Saguaro National Park, Arizona, has abundant plant life, while the rocky desert of (b) Boa Vista island, Cape Verde, Africa, is devoid of plant life. (credit a: modification of work by Jay Galvin; credit b: modification of work by Ingo Wölbern)

There are eight major terrestrial biomes: tropical wet forests, savannas, subtropical deserts, chaparral, temperate grasslands, temperate forests, boreal forests, and Arctic tundra. Temperature and precipitation, and variations in both, are key abiotic factors that shape the composition of animal and plant communities in terrestrial biomes. Comparing the annual totals of precipitation and fluctuations in precipitation from one biome to another provides clues as to the importance of abiotic factors in the distribution of biomes. Temperature variation on a daily and seasonal basis is also important for predicting the geographic distribution of the biome and the vegetation type in the biome. The distribution of these biomes shows that the same biome can occur in geographically distinct areas with similar climates (Figure 2).

Some biomes, such as temperate grasslands and temperate forests, have distinct seasons, with cold weather and hot weather alternating throughout the year. In warm, moist biomes, such as the tropical wet forest, net primary productivity is high, as warm temperatures, abundant water, and a year-round growing season fuel plant growth. Other biomes, such as deserts and tundra, have low primary productivity due to extreme temperatures and a shortage of available water. Terrestrial biomes on Earth are each distinguished by characteristic temperatures and amount of precipitation.

This world map shows the eight major biomes, polar ice, and mountains. Tropical forests, deserts and savannas are found primarily in South America, Africa, and Australia. Tropical forests also dominate Southeast Asia. Deserts dominate the Middle East and are found in the southwestern United States. Temperate forests dominate the eastern United States, Europe, and Eastern Asia. Temperate grasslands dominate the midwestern United States and parts of Asia, and are also found in South America. The boreal forest is found in northern Canada, Europe, and Asia, and tundra exists to the north of the boreal forest. Mountainous regions run the length of North and South America, and are found in northern India, Africa, and parts of Europe. Polar ice covers Greenland and Antarctica, which the latter is not shown on the map.

Figure 2. Each of the world’s major biomes is distinguished by characteristic temperatures and amounts of precipitation. Polar ice and mountains are also shown.

 

Watch this Assignment Discovery: Biomes video for an overview of biomes. To explore further, select one of the biomes on the extended playlist: desert, savanna, temperate forest, temperate grassland, tropic, tundra.

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