KEY CONCEPT Every ecosystem includes both living and nonliving factors.

1. KEY CONCEPT Every ecosystem includes both living and nonliving factors.

2. plants An ecosystem includes both biotic and abiotic factors. • Biotic factors are living things. • plants • animals • fungi • bacteria

3. sunlight moisture • moisture • temperature • wind • sunlight • soil • Abiotic factors are nonliving things.

4. Changing one factor in an ecosystem can affect many other factors. • Biodiversity is the assortment, or variety, of living things in an ecosystem. • Rain forests have more biodiversity than other locations in the world, but are threatened by human activities.

5. keystone • A keystone species is a species that has an unusually large effect on its ecosystem.

6. creation of wetland ecosystem increased waterfowl Population keystone species increased fish population nesting sites for birds • Keystone species form and maintain a complex web of life.

7. Which of the following is an example of a biotic factor in an ecosystem? • Sunlight • Stream • Tree • Rock

8. Wind is considered to be an abiotic factor because it • Is not related to biodiversity • Is a nonliving thing • Is in equilibrium • Is not in any ecosystem

9. A rainforest has a high level of biodiversity because it has • Many abiotic factors • Some endangered species • Few connections between living things • A wide variety of living things

10. A keystone species is a species that • Goes unnoticed if its numbers decrease • Alters an area by building bridges and dams • Leads to a decrease in an area’s biodiversity • Has an unusually large impact on its ecosystem.

11. Beavers are sometimes trapped for their fur. What could be one effect of increased trapping of beavers in an area? • Biodiversity among the area’s fish would increase • The number of herons and kingfishers would decrease • There would be more nesting areas for waterfowl • More trees would be cut down