Biomes

We explain what biomes are and how they are classified. In addition, we describe their characteristics and climate, and discuss their plant and animal life.

What is a biome?

A biome is a vast area of Earth characterized by specific climate, flora, and fauna. Each biome is defined by particular climatic conditions and soils which support the growth of the organisms composing its various ecosystems.

Biomes provide essential environmental services for the world’s climate and ecological balance. They are not only home to the planet’s plant and animal life, but they also contribute to temperature regulation, soil formation, and the hydrologic cycle.

Biomes can be classified as terrestrial, aquatic, and mixed. Some of the most widespread biomes on Earth's surface are forests, jungles, and deserts.

• See also: Oceanic climate

Terrestrial biomes

The general characteristics of terrestrial biomes are shaped by the climate, soil, and vegetation of each location. For this reason, highly diverse terrestrial biomes can be found in different regions of the Earth.

Tundra

The tundra is the characteristic biome of the coldest regions of Earth, where winter temperatures can reach as low as -58 °F (-50 °C). Its distinguishing feature is permafrost. This means that the soil remains frozen all year round, with only the surface layers thawing during warmer months.

Vegetation in the tundra is sparse, primarily consisting of mosses, lichens, and frost-resistant small plants. Animal life is adapted to the scarce resources and extreme temperatures, examples including mammals such as reindeer, polar bears, and arctic foxes. Migratory birds use the tundra as a breeding ground during the summer.

The tundra biome is found in the Arctic region, Antarctica, and the highest mountainous areas on Earth.

Desert

A desert is a type of terrestrial biome widely spread across Earth's surface. It is characterized by extremely low precipitation levels and sparse plant and animal life. Though the typical image of a sandy desert is associated with hot, equatorial climates, desert areas are also found in temperate and cold regions.

Broadly speaking, deserts are the result of lack of rainfall. This may result from the desert’s location far from sources of moisture, the presence of dry air preventing cloud formation and precipitation or mountains hindering the passage of moist air, or even climate change, which contributes to the desertification of certain environments.

Existing vegetation develops adaptations to survive these conditions, including small, spiny leaves or long roots to better utilize the limited water available.

Animals are also adapted to the arid conditions: reptiles have scales to prevent water loss, certain mammals—like camels—can go long periods without drinking water, and insects often develop hard exoskeletons that allow them to retain water within their bodies.

Grassland

The main characteristic of grasslands is the predominance of herbaceous vegetation, such as grasses and herbs, with very few trees and shrubs. This biome is commonly found in regions with moderate precipitation and well-defined seasons, featuring cold winters and warm summers.

The terrain in grasslands is generally flat or slightly undulating, which supports the spread of herbaceous vegetation. Fauna in grasslands is highly diverse: herbivorous animals such as deer and sheep, foxes and weasels, rodents, and birds are commonly found in these biomes.

Forest

Forests are characterized by hosting a large number of trees. They are also home to a wide variety of biodiversity. Forests play a crucial role in maintaining the balance of nature, absorbing carbon dioxide from the atmosphere and producing oxygen.

Forests are found in regions with highly diverse climates. Tropical forests are located in hot climate regions; temperate forests are situated in mid-latitude areas with cold winters and hot summers; and cold forests, boreal forests, or taiga are found in high-latitude regions near the tundra.

Rainforest

A rainforest is a biome with a hot and humid climate, characterized by abundant vegetation. It is typically found in latitudes near the equator. Rainfall is frequent, receiving over 98 inches (2,500 mm) per year.

Rainforest vegetation can vary in height, and is distributed across multiple layers. Among its remarkably diverse species are orchids, bromeliads, lianas, shrubs, ceiba trees, fig trees, and palms.

Tropical rainforest wildlife includes an enormous variety of insects (ants, butterflies, flies, stick insects), reptiles (anacondas, turtles, caimans, boas), and mammals (monkeys, jaguars, panthers, otters, bats). Birds inhabit both the treetops (with species including toucans) and areas near water surfaces (examples including ducks).

Chaparral

The chaparral, also known as Mediterranean shrubland, has a climate defined by very hot and dry summers, with precipitation occurring only in winter and autumn. Plant and animal life is adapted to the arid soil and the near-total lack of rainfall during the hot summer months.

Vegetation is low (hence the biome's name), with resilient leaves adapted to endure water scarcity. Examples of animals include foxes, goats, squirrels, and a wide variety of reptiles and rodents.

This biome is found mainly around the Mediterranean Sea, as well as in similar climates on the west coast of the Americas, and the southern coasts of Africa and Australia.

Steppe

A steppe is a biome characterized by sparse vegetation. Precipitation levels are slightly higher than in the desert biome, reaching 20 inches (500 mm) annually.

Wildlife includes mammals such as sheep, guanacos, pumas, and foxes, as well as birds like rheas and falcons. Steppe vegetation is adapted to survive long periods without water, featuring thick leaves and deep roots. Unlike deserts, steppes can support grasslands and a greater variety of shrubs.

Savanna

A savanna is a biome defined by a marked dry season and sparse vegetation. It is similar to the grassland, but has a tropical climate and scattered trees.

The wildlife of the savanna features large predatory mammals such as lions and tigers, as well as herbivores like giraffes and elephants. Vegetation is adapted to prolonged periods of drought, appearing and growing during the rainy months.

Aquatic biomes

A distinctive feature of aquatic biomes is the constant presence of water, which serves as an essential habitat for a variety of life-forms. These types of biomes provide food and resources for a large number of animal and human communities, and have been vital for social development throughout history.

Water temperature, salinity, and the amount of light that penetrates the depths of aquatic biomes are key factors in the composition and growth of species in aquatic biomes.

Freshwater biomes

Freshwater biomes are found in environments whose main component is water with a low salt concentration. In addition to providing habitats for a wide variety of species, they offer numerous environmental services by supplying drinking water, preventing and regulating floods, reducing the effects of erosion, retaining nutrients, and removing toxic substances.

They also produce oxygen, support food production, and often serve as attractive tourist destinations.

Freshwater aquatic biomes encompass:

• Rivers and streams. They are water flows varying in size from small streams to large rivers. Vegetation and wildlife in these biomes depend on factors such as water flow speed, temperature, and available nutrients.
• Lakes and ponds. They are bodies of water ranging in size from small ponds to large lakes. Life in these biomes includes various species of fish, aquatic plants, and microorganisms.
• Aquifers. They are underground water systems. Life in aquifers is typically microscopic, including bacteria and other unicellular organisms.

Marine biomes

Marine aquatic biomes are found in seas and oceans, accounting for 70% of the Earth's surface. They host a wide variety of plant and animal life, from tiny microorganisms to large predators.

These types of biomes are subdivided into three zones: the intertidal zone, where the sea meets the land, the open ocean, and the ocean floor.

Freshwater and marine aquatic biomes

Estuaries and deltas, located where rivers meet the sea, form aquatic ecosystems in which saltwater and freshwater mix. These areas are home to plant and animal life that must adapt to fluctuations in water salinity.

Life in these ecosystems is highly dynamic, not only in the water but also out it, hosting bird species that have a varied source of food to feed on.

Mixed biomes

Mixed biomes are characterized by the presence of ecosystems that develop in areas where land and water meet. The natural dynamics of these regions, between wet and dry environments, is unique, being home to plant and animal species adapted to both types of environments.

Mangrove

A mangroves ecosystem is defined by high levels of salinity and fluctuating water levels. These environments, found in tropical and subtropical regions, feature waterlogged and muddy soils, typically present in coastal areas.

Predominant vegetation in mangroves includes species adapted to saline environments, such as rhizophores and avicennia. Examples of wildlife include a number of aquatic species like fish, crabs, and mollusks.

Wetland

Wetlands are biomes characterized by their extraordinary biodiversity and the presence of species adapted to waterlogged soils. They are commonly found in humid and rainy regions, featuring diverse and abundant vegetation. The permanent or temporary presence of water in the soil shapes vegetation, which presents ecological adaptations to thrive in these types of environments.

Most animals found in wetlands can live both in the water and on land. The fauna associated with this biome includes waterfowl, amphibians, reptiles, and a variety of invertebrates adapted to aquatic environments.

Explore next: