Biome Definition and Examples in Biology


Biome Definition and Examples

A biome is a geographical region characterized by specific climate conditions, vegetation, and animal life. Each biome consists of multiple ecosystems and habitats. The main factors that define a biome include temperature, precipitation, humidity, altitude, and soil type, all shaping the environment and determining the organisms that thrive there.

Biome vs Ecosystem

While the terms biome and ecosystem are sometimes used interchangeably, they refer to different levels of ecological organization. An ecosystem is a community of organisms interacting with their physical environment within a specific area. In contrast, a biome is a broader classification that encompasses multiple ecosystems with similar climatic and biological characteristics.

Biome vs Microbiome

The key difference between a biome and microbiome is scale. While biomes are a large-scale geographical regions, microbiomes are much smaller and focus on the microscopic inhabitants. A microbiome is the collective community of microorganisms—bacteria, fungi, and viruses—inhabiting a particular environment, such as the human body or a soil sample.

Factors That Determine a Biome

There are several criteria that determine a biome, including:

  • Climate: Temperature, precipitation, and sunshine
  • Altitude: Elevation or latitude affect temperature and precipitation, impacting the types of organisms found in an area.
  • Soil Type: Soil composition and fertility influence plant growth and, consequently, the types of animals that live there.
  • Geography: Proximity to oceans, mountains, and other geographical features also influences local climate and vegetation.
  • Pressure: Extreme altitude affects the amount of oxygen and carbon dioxide. Meanwhile, water pressure affects aquatic ecosystems.
  • Salinity/Minerals: The availability of minerals or the salinity (osmotic pressure) of aquatic ecosystems helps determine the biome.

Biome Classification – How Many Are There?

Biome classification is according to similar climate patterns, vegetation types, and animal communities. However, scientists do not universally agree on a single classification system. At a minimum, there are five main biomes (aquatic, forest, grassland, desert, tundra). But, some scientists greatly expand the list to 30 or more biomes, including ones like caves, coral reefs, bog, and managed biomes like field crop and tree crop.

Here is one common classification scheme:

  • Terrestrial Biomes: Terrestrial biomes are land-based biomes, including forests, grasslands, deserts, and tundra.
  • Aquatic Biomes: Aquatic biomes include freshwater and marine (saltwater) biomes.

List of Biomes

List of Biomes of the World
(Ville Koistinen, Creative Commons Attribution-Share Alike 3.0 Unported)

The five fundamental biomes are:

Forest Biome

The Amazon Basin is a classic example of a forest biome. The climate is tropical, with high temperatures and high humidity and lots of rainfall. The Amazon houses a range of tree species, including mahogany, rubber trees, and Brazil nut trees. Many trees have buttress roots for stability, large leaves to maximize sunlight absorption, and smooth bark to prevent parasitic plants. The wildlife is diverse, including jaguars, sloths, and poison dart frogs. Many animals live in the dense forest canopy, such as arboreal monkeys and birds.

  • Latitude: Generally between 0° to 60° latitude.
  • Climate: Ranges from tropical (hot and wet) to temperate (moderate) to boreal (cold).
  • Sun: Varies, with dense canopies affecting sunlight.
  • Soil: Rich in organic material but varies.
  • Flora: Trees dominate, such as broadleaf and coniferous species.
  • Fauna: Diverse, including mammals, birds, insects.
  • Subcategories: Tropical rainforests, temperate forests, boreal forests (taiga).

Grassland Biome

The Serengeti ecosystem in northern Tanzania and southwestern Kenya is an example of a grassland biome. The climate is tropical, with distinct wet and dry seasons. Grasses dominated the landscape, with scattered acacia trees. Deep root systems help plants survive dry periods. There are large herbivores like zebras, wildebeests, and gazelles, and predators like lions and cheetahs. Herbivores migrate according to rainfall patterns, while predators use camouflage and speed for effective hunting.

  • Latitude: Generally between 23.5° to 55° latitude.
  • Climate: Moderate temperatures, moderate to low rainfall.
  • Sun: Abundant sunlight.
  • Soil: Fertile, often used for agriculture.
  • Flora: Dominated by grasses.
  • Fauna: Large herbivores, small mammals, birds.
  • Subcategories: Savannas, temperate grasslands.

Aquatic Biome

Australia’s Great Barrier Reef is an example of an aquatic biome. The marine climate features warm water temperatures and high salinity. The reef primarily consists of coral polyps, which have a symbiotic relationship with algae. There are symbiotic relationships between other organisms, too, like clownfish and anemones. The reef hosts a plethora of marine life, including clownfish, sea turtles, and sharks. Creatures use camouflage both for stealthy hunting and to escape predator detection.

  • Latitude: Found worldwide.
  • Climate: Varies; influenced by water temperature.
  • Sun: Varies with depth.
  • Soil: Sediments, sand, or coral.
  • Flora: Aquatic plants, algae, phytoplankton.
  • Fauna: Fish, amphibians, invertebrates.
  • Subcategories: Freshwater (lakes, rivers), marine (oceans, coral reefs).

Desert

The Sahara of Africa is a huge example of a desert. The Sahara is hot and arid. On average, it gets less than 25 cm or 10 in of precipitation annually. Vegetation includes drought-resistant plants like date palms and cacti. Plants survive long periods of drought with waxy leaves, long roots, or by storing water. Animal life includes the fennec fox, desert lizards, and camels. Many animals are nocturnal to avoid the daytime heat.

  • Latitude: Generally between 15° to 30° latitude. However, some scientists consider the extreme polar regions as deserts.
  • Climate: Hot or cold, very low rainfall.
  • Sun: Intense sunlight.
  • Soil: Sandy, rocky, low in nutrients.
  • Flora: Cacti, succulents, drought-resistant shrubs.
  • Fauna: Reptiles, insects, small mammals.
  • Subcategories: Hot deserts, cold deserts.

Tundra

The Arctic has large regions of tundra spanning across northern Alaska, Canada, and Siberia. The climate is cold and dry. Vegetation includes low-growing plants like mosses, lichens, and dwarf shrubs. Low-growing plants minimize exposure to cold winds, while dark-colored vegetation absorbs heat. The tundra is home to polar bears, Arctic foxes, and migratory birds. Bears and foxes have thick fur for insulation against the cold. Birds exploit seasonal resources using migration.

  • Latitude: Typically above 60° latitude.
  • Climate: Cold, low precipitation.
  • Sun: Low sunlight, long winter nights.
  • Soil: Permafrost, nutrient-poor.
  • Flora: Mosses, lichens, low shrubs.
  • Fauna: Arctic foxes, caribou, migratory birds.
  • Subcategories: Arctic tundra, alpine tundra.

Dynamics

Biomes are dynamic and change over time due to various factors:

  • Climate Change: Alterations in global or regional climate shift temperature and precipitation patterns, impacting biome distribution.
  • Human Activity: Deforestation, agriculture, and urbanization transform biomes.
  • Natural Events: Events like wildfires, storms, volcanic eruptions, earthquakes, floods, and meteor impacts temporarily or permanently alter biomes.

One example of biome alteration is desertification. This is where grasslands turn into deserts due to overgrazing, deforestation, or climate change. For example, the Sahara Desert was once a green landscape, with rivers and completely different plants and animals.

Coral bleaching is another example of biome transformation. Increasing ocean temperatures change the chemistry of seawater. Coral reefs lose their symbiotic algae and fall into a decline.

Forest regeneration is another form of biome change. For example, abandoned agricultural lands return to forest through natural succession. The reforestation of the area surrounding Chernobyl is one example.

References

  • Bowman, William D.; Hacker, Sally D. (2021). Ecology (5th ed.). Oxford University Press. ISBN 978-1605359212.
  • Marcolla, Barbara; Migliavacca, Mirco; et al. (2020). “Patterns and trends of the dominant environmental controls of net biome productivity”. Biogeosciences. 17 (8): 2365–2379. doi:10.5194/bg-17-2365-2020
  • Olson, D. M., Dinerstein, E., et al. (2001). “Terrestrial Ecoregions of the World: A New Map of Life on Earth.” Bioscience. 51(11): 933–938.
  • Whittaker, Robert H. (1962). “Classification of Natural Communities”. Botanical Review. 28 (1): 1–239. doi:10.1007/BF02860872
  • Williams, John W.; Jackson, Stephen T.; Kutzbach, John E. (2007). “Projected distributions of novel and disappearing climates by 2100 AD”. Proceedings of the National Academy of Sciences. 104 (14): 5738–5742. doi:10.1073/pnas.0606292104