Chapter 3 Ecosystem Ecology

1. Chapter 3 Ecosystem Ecology

2. Ecosystem Ecology Examines Interactions Between the Living and Non-Living World • Ecosystem – a particular location on Earth distinguished by its particular mix of interacting biotic and abiotic components

3. Ecosystem Boundaries • Some ecosystems, such as a caves and lakes have very distinctive boundaries • However, in most ecosystems it is difficult to determine where one ecosystems stops and the next begins

5. Ecosystem Processes • Even though it is helpful to distinguish between two different ecosystems, ecosystems interact with other ecosystems

6. Energy Flows through Ecosystems

7. Photosynthesis and Respiration • Producers (autotrophs) are able to use the sun’s energy to produce usable energy through the process called photosynthesis

9. Photosynthesis and Respiration • Cellular respiration is the process by which other organisms gain energy from eating the tissues of producers

10. Trophic Levels, Food Chains, and Food Webs • Consumers (heterotrophs) – obtain energy by consuming other organisms • Primary Consumers (herbivores) – consume producers • Secondary Consumers (carnivores) – obtain their energy by eating primary consumers • Tertiary Consumers (carnivores) – eat secondary consumers

11. Consumers (heterotrophs) • scavengers: feed on dead organisms

12. Consumers (heterotrophs) • detritivores: feed on detritus (partially decomposed organic matter, such as leaf litter & animal dung) and breakdown this organic material into smaller particles

13. Consumers (heterotrophs) • decomposers: consumers that complete the “circle of life” by digesting organic materials into smaller molecules

14. What is the difference between a food chain and a food web?

15. Food Chains • Food chain – the sequence of consumption from producers through tertiary consumers

16. Food Web • Food web – a more realistic type of food chain that takes into account the complexity of nature

17. Ecosystem Productivity • Gross primary productivity (GPP) – the total amount of solar energy that the producers in an ecosystem capture via photosynthesis over a given amount of time • Net primary productivity (NPP) – the energy captured (GPP) minus the energy respired by producers • NPP = GPP – energy used by producers • Measured in kg C/m2/year

19. Where in the world is NPP the highest?

20. Net Primary Productivity

21. Net Primary Productivity

22. What do you think? • Why do food chains rarely have more than 4 or 5 trophic levels?

23. Food Chains • Which are more numerous in an ecosystem: producers or consumers? • Producers are always more numerous than consumers, why?

24. Energy Loss • Of the energy that an organism consumes, only a small fraction (ecological efficiency of about 10%) is transferred to the next trophic level

25. Where does that energy go? • Most of the energy is lost as heat