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Chapter 57 – Dynamics of Ecosystems Trophic levels Nutrient flow Energy Flow Biodiversity Productivity. Question. Ecologists categorize species based upon their nutrients and energy sources What are sources of energy? heterotrophs autotrophs - PowerPoint PPT Presentation
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Chapter 57 -- Dynamics of Ecosystems
1
Chapter 57 – Dynamics of Ecosystems
Trophic levels
Nutrient flow
Energy Flow
Biodiversity
Productivity
Question
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?
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
Chapter 57 -- Dynamics of Ecosystems
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How do energy and nutrients move through an ecosystem?
Food chains
Trophic levels (feeding levels)
Chapter 57 -- Dynamics of Ecosystems
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What happens to the energy as it passes through an ecosystem?
Question
Chapter 57 -- Dynamics of Ecosystems
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Why are food chains relatively short?
Chapter 57 -- Dynamics of Ecosystems
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FoodChain 1Foodchain 2
Food Chain
What do ‘ecological pyramids’ show?
energy
numbers
biomass
Inverted pyramids?
Chapter 57 -- Dynamics of Ecosystems
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Food webs
How much disruption can a food web withstand?
What is a “Keystone species”?
e.g., CA sea otterImportance to Kelp ForestsConflicts with shellfish industry
-- crabs, abaloneSurge of sea urchins
Chapter 57 -- Dynamics of Ecosystems
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Carbon cycle
How do nutrients flow throughecosystems?-- Biogeochemical Cycles
Carbon cycle
Chapter 57 -- Dynamics of Ecosystems
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Do all essential nutirents flow through biogeochemcal cycles?
Limiting nutrients
Key steps ofThe N cycle
Roles of
Microorganisms
Plants
Animals
Environmentalissues
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.
Chapter 57 -- Dynamics of Ecosystems
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So why did DDT cause ecological harm?
DDT and Bioaccumulation
Which types of pollutants will tend to bioaccumulate?
See page 1227
Question
Chapter 57 -- Dynamics of Ecosystems
12
How do disruptions to specific trophic levels affect ecosystems?
Top down effects
Restoring aspen growthin Yellowstone with wolves
Bottom-up effects
Disruption of producers
Human impacts
Adadpted fromRipple WJ and Bescht RL (2007) Restoring Yellowstone’s aspen with wolves. Biological Conseravation 138: 514-519http://www.cof.orst.edu/leopold/papers/Restoring%20Yellowstone%20aspen%20with%20wolves.pdf
Chapter 57 -- Dynamics of Ecosystems
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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
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