Food Webs and Food Pyramids in Ecosystems

1. Food Webs and Food Pyramids in Ecosystems

2. General Definitions • Ecology: The study of the relationships between organisms in the environment • Ecosystem: a community of organisms and the physical space surrounding them • Food webs: A system of interlocking, interdependent food chains

3. Biomes • Ecosystems exist in five biomes • Deserts • Tundras • Forests • Marine/Aquatic • Grasslands

4. Ecosystems • Examples of ecosystems include: • Pond within a national forest • The “watering hole” in the savannah • Coral reef in Belize

5. Factors • Ecosystems are comprised of two types of factors • Biotic – living factors • Trees, animals, bacteria, fungi, plants • Abiotic – non living factors • Sunlight, Wind, Rain, Soil

6. Producers provide energy for other organisms in an ecosystem. • Producers get their energy from non-living resources. • Producers are also called autotrophs because they make their own food.

7. Consumers • Consumers are organisms that get their energy by eating other living or once-living resources. • Consumers are also called heterotrophs because they feed off of different things.

8. loss of energy loss of energy Energy Flows Through Ecosystems secondary consumers (carnivores- eat animals) sun primary consumers (herbivores-eat plants) producers (plants)

9. KEY CONCEPT Food webs model the flow of energy in an ecosystem.

10. Trophic levels are the nourishment levels in a food chain.

11. Correct Names of Trophic Levels

12. carnivore decomposer • Herbivores eat only plants. • Carnivores eat only animals. • Omnivores eat both plants and animals. • Decomposers break down dead organic matter into simpler compounds. • Consumers are not all alike.

13. GRAMA GRASS DESERT COTTONTAIL HARRIS’S HAWK A food chain is a model that shows a sequence of feeding relationships. • A food chain follows the connection between one producer and a single chain of consumers within an ecosystem.

14. A food web shows a complex network of feeding relationships. • An organism may have multiple feeding relationships in an ecosystem.

15. Example Food Web

18. KEY CONCEPT Pyramids model the distribution of energy and matter in an ecosystem.

19. Trophic Levels and Energy • Loss of energy between levels of food chain • can feed fewer animals in each level

20. energy lost energy transferred • Only 10 percent of the energy at each tier is transferred from one trophic level to the next.

21. tertiary consumers 75 g/m2 150g/m2 secondary consumers primary consumers 675g/m2 2000g/m2 2000g/m2 producers producers Other pyramid models illustrate an ecosystem’s biomass and distribution of organisms. • Biomass is a measure of the total dry mass of organisms in a given area.

22. KEY CONCEPT Populations grow in predictable patterns.

23. Changes in a population’s size are determined by four factors • The size of a population is always changing. • Four factors affect the size of a population. • immigration • births • emigration • deaths

24. Population growth is based on available resources. • Exponential growth is a rapid population increase due to an abundance of resources.

25. Carrying Capacity • The maximum number of individuals in a population that an ecosystem can support. • Think back to our “deer wolf” worksheet. The maximum number of deer that the ecosystem could support was 2500… What happened to the deer population when that number was reached?

26. Logistic growth is due to a population facing limited resources.