Ecosystems and Energy Transfer
Ecosystem Ecology Basics
We know Earth is a system, in which energy flows and matter cycles in Ecosystems and Ecosystems are composed of biotic and abiotic factors and form the Biosphere.
•What are ecosystems?•What are biotic and abiotic factors?•How can we model ecosystem interactions and the flow of energy and nutrients?
Energy Flow in Ecosystems can be Energy Flow in Ecosystems can be modeled in Food Chains & Food Websmodeled in Food Chains & Food Webs
Food ChainsShow 1 feeding relationship from producer consumers
Food WebsInterconnected food chainsThey show all of the feeding relationships in an ecosystem
Ultimate source of energy Sun
Producers• Organisms that produce their own energy are producers. Most producers utilize photosynthesis, but not all….• Autotrophs: self-feeding• Producers also use cellular respiration to convert chemical
energy of food into a different form of chemical energy, ATP
• Any energy unused by the producer or released as heat/waste is available to other organisms
C6H12O6 + 6O2 6H2O + 6CO2 + ATP
Consumers• Heterotrophs- “other feeders”• Primary (1st order) consumers eat producers;
Herbivores; Trophic Level 2• Secondary (2nd order) consumers eat primary
consumers; Omnivores or carnivores; Trophic Level 3• Tertiary (3rd order) consumers eat secondary
consumers; Typically carnivores; Trophic level 4
• Decomposers- Breakdown (no mouth parts) organic matter and return the nutrients to the soilEx. Fungi and Bacteria
• Detritivores- Eat (mouth parts) organic matter and help return nutrients to the soil Ex. earthworms
• Scavengers- Eat carcasses- they like a “free lunch”; Keep disease at bay in ecosystems
Ex. Turkey Vultures, Hyena
Other Heterotrophs…
• Black bear• Rabbit• Grass• Hawk• Blueberries• Squirrel• Acorns (Oak Tree)
Construct a food web using the following organisms:
Example Food Web
Blueberries Grass Acorns (oak)
Rabbit Squirrel
Black Bear Hawk
Can you identify…
• Autotrophs & Heterotrophs?• Which organism(s) are producers?• Which organism(s) is an omnivore?• Which organism(s) is a carnivore?• Do any organisms occupy more than one
trophic level?• What heterotrophs are missing?
Example Food Web
Blueberries Grass Acorns (oak)
Rabbit Squirrel
Black Bear Hawk
TL 1Producers
TL 21° ConsumersOmnivores
TL 32° ConsumersOmnivores or Carnivores
TL 2/31° /2 ° ConsumersOmnivore
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The transfer of energy from producer to primary consumer then to higher order consumers. One linear feeding relationship.
Food Chains- One line of Energy Transfer in an Ecosystem
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More Food Chain Examples
Food Webs- Interconnected food chains
They show all of the feeding relationships in an ecosystem
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How Many Chains are in this web?
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Identify the Producers, Consumers, & Decomposers:
Count the Count the Food Chains!Food Chains!
Energy in an Ecosystem
Energy FLOWS through ecosystems•Only 10% of the energy is available to organisms in the next trophic level; 10% rule.•90% of the energy is unavailable due to maintaining life functions, respiration, and heat energy transferred to the atmosphere.•So, more energy is stored in producers than available to top-level consumers.
10% rule in action• What trophic level should the bulk of the
biomass be in an ecosystem? Producers• Example- The Savanna of Africa
– 100 km2 of grasses (10 km x 10 km)– Herd of 450 wildebeests– Pride of 20 lions
• The higher up the food chain, the less available energy less top-level consumers
• 4th or 5th level consumers are rare in nature
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Energy Pyramids ShowEnergy Pyramids Show
•Amount of available energy Amount of available energy decreases for higher consumersdecreases for higher consumers•Amount of available energy Amount of available energy decreases down the food chaindecreases down the food chain•It takes a large number of It takes a large number of producers to support a small producers to support a small number of primary consumersnumber of primary consumers•It takes a large number of primary It takes a large number of primary consumers to support a small consumers to support a small number of secondary consumersnumber of secondary consumers
100%
10%
1%
0.1%
Trophic Levels indicate feeding
position in ecosystems
TL 4
TL 3
TL 2
TL 1
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Identify 1st, 2nd, 3rd and 4th level consumers in this food web.
Vultures TED Talks
The significance of scavengers:
http://www.ted.com/talks/munir_virani_why_i_love_vultures.html