Chapter 17 section 1 Studying the Environment Key concepts: - Biomes are made up of many connected ecosystems. - Abiotic factors affect the organisms in an environment. - Similar biomes occur in similar climates.

How Biomes Differ from Ecosystems Biomes are large areas made up of many connected land and water ecosystems. An ecosystem is defined by all of its organisms and its abiotic factors. Biomes are defined by unique plant communities that support unique animal communities.

The kind of plant community in a biome is determined by the climate in the biome. Climate is made up of a combination of a few abiotic factors, such as the average yearly rainfall and average yearly temperature.

◄ Climate map Biome map ►

Abiotic Factors of an Environment Some abiotic factors, such as water, are resources that organisms use. Other abiotic factors, such as temperature, are conditions to which organisms are adapted. Organisms rely on the abiotic factors in their environment in different ways.

Sunlight Most producers convert the energy in sunlight to chemical energy, or food, through photosynthesis. On land, fewer plants survive during seasons of lower light. In the ocean, producers that need light must live closer to the ocean’s surface.

Temperature The cells of many organisms function best at warm temperatures. Therefore, a greater variety of organisms are found in warm environments than in environments that are extremely hot or extremely cold.

Rainfall Generally, areas with a high amount of rainfall have rich plant growth. In turn, these plants are able to support a larger number of other organisms. For example, more organisms live in a forest than in a desert.

Soil Plants rely on nutrients in the soil to grow. Many plants need soil that is high in nutrients. Fertilizer can be added to soil to increase the growth of plants.

Roles of Organisms in an Environment Each organism has one of three main functions, or ecological roles, in an environment. The roles are producer, consumer, or decomposer. All biomes and ecosystems have producers, consumers, and decomposers.

Producers Producers convert energy in the environment to food. Some producers, such as plants and algae, rely on the energy from sunlight to make food. Other producers, such as some bacteria, make food from chemicals.

Consumers All animals are consumers. Consumers feed on other organisms to get the energy they need. Three kinds of consumers are herbivores, omnivores, and carnivores.

Decomposers Some bacteria and fungi are decomposers. Decomposers break down dead organisms into simple chemicals that other organisms can use. Areas such as Antarctica are so cold that decomposition can take thousands of years.

Similar Climates, Similar Biomes Widely separated biomes with similar climates have similar kinds of plants and animals. Climate varies with latitude and altitude. Temperature and rainfall decrease as you move from low latitudes near the equator to high latitudes at the poles.

Temperature and rainfall also decrease from low altitudes near sea level to high altitudes in the mountains. These patterns help explain why similar biomes are found at similar latitudes and altitudes.