1. Chapter 57 -- Dynamics of Ecosystems 1 Chapter 57 – Dynamics of Ecosystems Trophic levels Nutrient flow Energy Flow Biodiversity Productivity Question

2. Chapter 57 -- Dynamics of Ecosystems 2 Ecologists categorize species based upon their nutrients and energy sources What are sources of energy? heterotrophs autotrophs What are sources of nutrients? producers consumers decomposers What is the final fate of energy? What happens to nutrients?

3. Chapter 57 -- Dynamics of Ecosystems 3 Knowledge of food chains helps us to understand ecosystem dynamics In 1997, ~500,000 short-tailed shearwater birds were found dead in the Bering Sea off Alaska. What happened? Climate shift favored Ehux Question

4. Chapter 57 -- Dynamics of Ecosystems 4 How do energy and nutrients move through an ecosystem? Food chains Trophic levels (feeding levels)

5. Chapter 57 -- Dynamics of Ecosystems 5 What happens to the energy as it passes through an ecosystem? Question

6. Chapter 57 -- Dynamics of Ecosystems 6 Why are food chains relatively short?

7. Chapter 57 -- Dynamics of Ecosystems 7 FoodChain 1 Foodchain 2 Food Chain What do ‘ecological pyramids’ show? energy numbers biomass Inverted pyramids?

8. Chapter 57 -- Dynamics of Ecosystems 8 Food webs How much disruption can a food web withstand? What is a “Keystone species”? e.g., CA sea otter Importance to Kelp Forests Conflicts with shellfish industry -- crabs, abalone Surge of sea urchins

9. Chapter 57 -- Dynamics of Ecosystems 9 Carbon cycle How do nutrients flow through ecosystems? -- Biogeochemical Cycles Carbon cycle

10. Chapter 57 -- Dynamics of Ecosystems 10 Do all essential nutirents flow through biogeochemcal cycles? Limiting nutrients Key steps of The N cycle Roles of Microorganisms Plants Animals Environmental issues Note: you are not responsible for the individual steps of the phosphorus cycle, but should have a general understanding of the role of P-related issues.

11. Chapter 57 -- Dynamics of Ecosystems 11 So why did DDT cause ecological harm? DDT and Bioaccumulation Which types of pollutants will tend to bioaccumulate? See page 1227 Question

12. Chapter 57 -- Dynamics of Ecosystems 12 How do disruptions to specific trophic levels affect ecosystems? Top down effects Restoring aspen growth in Yellowstone with wolves Bottom-up effects Disruption of producers Human impacts Adadpted from Ripple WJ and Bescht RL (2007) Restoring Yellowstone’s aspen with wolves. Biological Conseravation 138: 514-519 http://www.cof.orst.edu/leopold/paper s/Restoring%20Yellowstone%20aspen %20with%20wolves.pdf

13. Chapter 57 -- Dynamics of Ecosystems 13 How many organisms exist within an ecosystem? “Biodiversity” Global diversity: 100 million??? What factors influence diversity? -- productivity -- climate -- habitat heterogeneity -- other species Diversity ‘hot spots’ Question

14. Chapter 57 -- Dynamics of Ecosystems 14 Ecosystems are diverse in their scale and dynamics Biomes to microscopic Simple to complex Of great longevity to the ephemeral Familiar to bizarre Redwood canopy Vernal pool