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APES 10/4

Explore the dynamics of food webs in ecosystems, from energy flow to trophic levels and the significance of keystone species. Learn about producers, consumers, and decomposers, as well as energy pyramids and biomass distribution. Enhance your understanding with hands-on activities and worksheets.

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APES 10/4

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  1. APES 10/4 Please take out your Wetlands FRQ Get a laptop for note-taking

  2. FRQ Scoring • With a partner, carefully score each section of your FRQ • Give yourself a total score out of 11 • Be ready to ask questions about FRQs, in general

  3. Today: • Measuring energy within food webs • Major players in food webs • Some are more important than others! (producers, keystone species)

  4. Players in the Food Web • Plants are called producers, and also autotrophs • Autotroph = makes own food using sunlight • First level consumers eat producers • Second level consumers eat first level consumers, and so on • Consumers are also called heterotrophs (get food/energy from outside source)

  5. Other Players Detritivores (mites, snails, and worms) feed on dead matter Decomposers (bacteria and fungi) break down dead matter

  6. Trophic Levels • Each step along a food chain or web is called a trophic level • Producers are the first trophic level • Consumers make up the second, third, and higher trophic levels • Also called primary, secondary, tertiary consumers

  7. Energy Pyramids • The energy that producers and consumers can possibly make and pass on can be represented in an energy pyramid • Because producers photosynthesize and are numerous, they are on the bottom of the pyramid

  8. Pyramid of Energy Example

  9. Measures of Energy in Ecosystems • Gross Primary Productivity (GPP) = total solar energy captured by plants (ONLY ABOUT 1%) • Net Primary Productivity (NPP) = total energy captured minus the energy used by producers for their own respiration (what’s left over for consumers!) NPP = GPP – Respiration by Producers

  10. Practice Problem • A forest has an NPP of 1.4 kg C/m2/year and the rate of cellular respiration is 2.4 kg C/m2/year. What is the GPP? NPP = GPP – Respiration 1.4 = GPP – 2.4 GPP = 1.4 + 2.4 = 3.8 kilograms of Carbon per square meter per year

  11. Biomes Differ in NPP

  12. Ecological Efficiency • Proportion of energy that is passed between trophic levels, after cellular respiration • 10% on average!

  13. 10% 90% lost as heat 10% rule...

  14. ? Cal ? Cal ? Cal 1000 Cal How much energy is at each level?

  15. 1 Cal 10 Cal 100 Cal 1000 Cal How much energy is at each level? 9 Cal as heat 90 Cal as heat 900 Cal as heat

  16. Pyramid of Biomass Biomass= total mass of living matter in an area At which level is the most biomass located?

  17. 100 grams 200 grams 600 grams 1000 grams Pyramid of Biomass • Same as pyramid of energy • More mass in bottom trophic levels

  18. Keystone Species • Not all species in a food web have equal importance! • Some species are KEYSTONE SPECIES. • Be prepared to define and give examples after the video. http://www.hhmi.org/biointeractive/some-animals-are-more-equal-others-keystone-species-and-trophic-cascades

  19. Due Next Time • First two worksheets, front and back • Either get started, or finish making the top (terrestrial part of your eco-column) • All groups need to do one rinse.

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