⏳ Estimated Reading Time: 5 - 7 minutes

Describe the global distribution and principal environmental aspects of terrestrial biomes.

Ecological Organization

Humans like to sort and name things. Ecology studies how ecosystems work, from small to large.

There are seldom distinct boundaries between ecosystems. The transitional area between ecosystems is often called an ecotone. Like ecosystems, biomes do not usually have sharp boundaries between them, but tend to gradually shift from one to another. This lesson will focus on the major terrestrial biomes on Earth.

Explore the image below to learn more about Earth's spheres.

Terrestrial Biomes

Biomes tend to be named after the dominant type of vegetation in that biome. For example, a grassland is dominated by grasses. You can expect to see a predictable set of organisms living in each biome. The amount of rain that a biome receives, and the temperature of that biome are the most important factors determining who lives where.

Annual precipitation can range from virtually zero in deserts to over 250 cm. The wetter an area, the more likely large trees will be found in a biome. Temperatures on the planet can also fluctuate widely. The closer to the poles, the longer and colder the winters become, and the higher the altitude the colder the temperatures.

The graph maps biomes to climate, plotting ‘Average annual temperature (°C)’ from -10 to 30 on the x-axis and ‘Annual precipitation (cm)’ from 0 to 400 on the y-axis. Biomes are color-coded and range from tundra in cold, dry conditions to tropical rainforests in warm, wet climates, demonstrating the correlation between climate factors and biome locations. — ***The combination of temperature and rainfall in an area determines what kind of biome you are likely to find in that area.***

In AP Environmental Science, we will focus on 9 terrestrial biomes - taiga, temperate rainforest, temperate seasonal forests tropical rainforests, shrubland, temperate grassland, savanna, desert, and tundra. There are several other terrestrial biomes you might read about, but for our course, we will focus on these 9 biomes.

Explore the 9 biomes necessary for AP environmental science by clicking through the presentation below. Which biome would you most like to visit? Why?

Essential Knowledge

A biome contains characteristic communities of plants and animals that result from, and are adapted to, its climate.

The global distribution of nonmineral terrestrial natural resources, such as water and trees for lumber, varies because of climate, geography, latitude and altitude, nutrient availability, and soil.

The worldwide distribution of biomes is dynamic; the distribution has changed in the past and may again shift as a result of global climate change.

AP Exam Tip

In AP environmental science, we will focus on the following biomes: taiga, temperate rainforest, temperate seasonal forests, tropical rainforests, shrubland, temperate grassland, savanna, desert, and tundra.

You will not need to know everything about a biome, but you will need to know major characteristics of each biome and how humans have had an effect on these biomes.

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