What factors primarily determine a biome?

Climate is the primary factor that determines a biome, but latitude, elevation, soil, terrain, natural disturbances, and human activity also shape its characteristics. The interaction of these factors determines the temperature, moisture, vegetation, and animal communities that can survive in a region.

A biome is a large ecological region characterized by a particular climate and dominant types of vegetation and wildlife. Tropical rainforests, deserts, grasslands, temperate forests, and tundra are examples of different biomes.

5 Factors That Determine a Particular Biome

Several environmental factors work together to determine what type of biome develops in a region.

1. Climate

Climate is the strongest environmental factor determining a biome. It includes long-term patterns of temperature, precipitation, and seasonal conditions.

Warm, wet conditions can support dense vegetation such as tropical rainforests, while very cold conditions support vegetation adapted to short growing seasons, such as the plants found in tundra.

Climate also influences how much water is available to plants and how long the growing season lasts.

2. Latitude and Elevation

Latitude and elevation influence the temperature and moisture conditions that shape biomes.

Latitude affects the amount and angle of solar energy a region receives. This contributes to broad differences in climate from the equator toward the poles.

Elevation also affects temperature and precipitation. Temperatures generally decrease as elevation increases, which is why different vegetation communities can occur at different elevations on the same mountain.

Together, latitude and elevation help explain why different biomes occur in different parts of the world.

3. Soil and Terrain

Soil composition and terrain influence which plants can grow and how a biome develops.

Soils differ in nutrients, water-holding capacity, texture, depth, and organic matter. Fertile soils can support dense plant communities, while shallow, dry, or rocky soils may limit vegetation.

Terrain also affects sunlight exposure, drainage, temperature, and moisture. Mountains, valleys, slopes, and other landforms can create local differences in environmental conditions.

4. Natural Disturbances

Natural disturbances can change the structure and species composition of a biome over time.

Wildfires, floods, storms, droughts, volcanic activity, and grazing can alter vegetation and create opportunities for different species to establish.

For example, periodic fire and grazing can help maintain many grassland ecosystems by preventing woody plants from becoming dominant.

Natural disturbances do not always destroy a biome. In some ecosystems, they are part of the processes that maintain its characteristic vegetation.

5. Human Activity

Human activities can substantially alter biomes by changing vegetation, land use, water availability, and species composition.

Major examples include:

• Deforestation for agriculture, logging, and development
• Agriculture that replaces native vegetation with crops
• Overgrazing that reduces plant cover and changes soil conditions
• Urban development that converts natural habitats
• Pollution that alters air, soil, and water conditions
• Introduction of invasive species that can displace native species
• Water diversion that changes moisture availability
• Climate change that alters temperature and precipitation patterns

These changes can damage or displace native plant and animal communities and can gradually change the characteristics of a biome.

How Do Humans Alter Biomes?

Humans alter biomes mainly by changing land cover, removing native species, modifying water availability, and changing environmental conditions.

Deforestation can convert forests into agricultural or developed land. Intensive agriculture can replace diverse native plant communities with a small number of crop species. Overgrazing can reduce vegetation cover and contribute to soil degradation.

Urbanization also changes natural habitats by replacing vegetation with buildings, roads, and other infrastructure.

Human activities can therefore alter both the physical conditions of a region and the organisms that live there.

How Do Biomes Change Over Time?

Biomes are not fixed; they change when climate, natural disturbances, geography, species, or human activities change. Some changes occur quickly after events such as wildfires or floods, while others develop over thousands or millions of years.

The main factors include:

• Climate shifts: Changes in temperature and precipitation can expand, shrink, or shift biome boundaries. For example, long-term warming can make conditions more suitable for warmer vegetation and less suitable for some cold-adapted communities.
• Natural disturbances: Wildfires, floods, volcanic eruptions, droughts, and severe storms can remove vegetation and alter soil and habitat conditions, allowing new species to establish.
• Evolution and migration: Species can evolve or move into new areas as environmental conditions change, altering the composition and ecological relationships within a biome.
• Sea-level changes: Rising or falling sea levels can expand, shrink, or relocate coastal biomes. Sea levels have changed naturally with glacial cycles and can also rise because of current warming.
• Plate tectonics: Over geological time, moving continents can shift land into different climate zones. Mountain formation can also change rainfall patterns and create new environmental conditions.
• Human activities: Deforestation, agriculture, urbanization, overgrazing, pollution, overhunting, and invasive species can alter native biomes much more rapidly than many natural geological processes.
• Ecological succession: After a major disturbance, different species gradually establish and replace earlier communities, changing the structure of the ecosystem over time.

As these factors interact, the location and characteristics of a biome can shift. A region may gradually become wetter, drier, warmer, colder, more forested, or more open, leading to changes in its dominant vegetation and associated animal communities.

How Do Biomes Change After a Major Disturbance?

A major disturbance can trigger a sequence of ecological changes rather than producing a permanent end state.

For example, after a wildfire, surviving organisms and newly arriving species may recolonize the area. Early colonizers can change soil conditions and create conditions that allow other species to establish.

As vegetation develops, the availability of food, shelter, light, and nutrients changes. Different organisms may then become more common, gradually changing the community.

This process is known as ecological succession.

How Can Location of a Biome Shift?

A biome’s location can shift when environmental conditions change enough to favor different types of vegetation.

For example, if a region becomes warmer over a long period, plants adapted to warmer conditions may expand into areas that were previously too cold for them. If precipitation decreases, vegetation adapted to dry conditions may become more common.

Biome boundaries are therefore not permanently fixed. They can move as climate, geography, sea level, and other environmental conditions change.

What Causes Biomes and Vegetation to Change?

Biome and vegetation changes can result from both natural and human-driven factors.

Natural causes include:

• Changes in temperature and precipitation
• Droughts and floods
• Wildfires and severe storms
• Volcanic activity
• Tectonic and geographical changes
• Sea-level fluctuations
• Evolution and species migration
• Ecological succession
• Human causes include:
• Deforestation
• Agriculture
• Urbanization
• Overgrazing
• Pollution
• Introduction of invasive species
• Water management
• Human-caused climate change

The effects can occur at very different rates. A wildfire may transform vegetation within a short period, while changes associated with continental movement occur over geological timescales.

Why Are There Different Biomes?

Different biomes exist because environmental conditions vary across Earth. Temperature, precipitation, latitude, elevation, soil, terrain, and disturbance patterns differ from one region to another.

For example, warm and wet regions can support dense forests, while regions with very little precipitation tend to support drought-adapted vegetation. Cold regions with short growing seasons support a different set of plants and animals.

These environmental differences produce distinct biome types and influence the organisms that can survive in each one.