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