Bellringer You are trying to stop world hunger. On your quest to do so, you choose to provide food for a third world country. Which would be ideal to provide: grains or meat? Why?

Energy Transformation

What is an ecosystem? An ecosystem consists of –all the organisms in a community and –the abiotic environment with which the organisms interact. In an ecosystem, energy flow moves through the components of an ecosystem and chemical cycling is the transfer of materials within the ecosystem.

A Terrarium A terrarium represents the components of an ecosystem and illustrates the fundamentals of energy flow. Light energy Chemical energy Energy flow Chemical elements Heat energy Bacteria, protists, and fungi

In real time…

Primary production sets the energy budget for ecosystems Primary production –carried out by producers –is the amount of solar energy converted to chemical energy by an ecosystem’s producers for a given area and during a given time period –produces biomass, the amount of living organic material in an ecosystem Different ecosystems vary in their –primary production and –contribution to the total production of the biosphere. © 2012 Pearson Education, Inc.

Figure Open ocean Estuary Algal beds and coral reefs Desert and semidesert scrub Tundra Temperate grassland Cultivated land Boreal forest (taiga) Savanna Temperate deciduous forest Tropical rain forest 05001,0001,5002,0002,500 Average net primary productivity (g/m 2 /yr)

Figure 37.16A Plant material eaten by caterpillar 100 kilocalories (kcal) 50 kcal 35 kcal 15 kcal Feces Cellular respiration Growth 50% is eliminated in feces, 35% is used in cellular respiration 15% is used for growth.

Why do food chains and webs typically have only three to five levels?

Energy supply limits the length of food chains A pyramid of production shows the flow of energy –from producers to primary consumers and to higher trophic levels © 2012 Pearson Education, Inc. Only about 10% of the energy stored at each trophic level is available to the next level.

Figure 37.16B Tertiary consumers Secondary consumers Primary consumers Producers 10 kcal 100 kcal 1,000 kcal 10,000 kcal 1,000,000 kcal of sunlight Energy comes in the form of CALORIES here.

CONNECTION: A pyramid of production explains the ecological cost of meat When humans eat… –grain or fruit  primary consumers –beef or other meat from herbivores  secondary consumers –fish like trout or salmon  tertiary or quaternary consumers © 2012 Pearson Education, Inc.

Figure 37.8_s5 Trophic level Plant A terrestrial food chainAn aquatic food chain Producers Phytoplankton Grasshopper Primary consumers Zooplankton Mouse Secondary consumers Herring Tuna Snake Tertiary consumers Killer whaleHawk Quaternary consumers

Only about 10% of the chemical energy available in a trophic level is passed to the next higher trophic level. Therefore, the human population has about ten times more energy available to it when people eat plants instead of the meat of herbivores. Eating meat of any kind is expensive both economically and environmentally © 2012 Pearson Education, Inc.

Figure 37.17_1 Trophic level Vegetarians Corn Primary consumers Secondary consumers Producers

Figure 37.17_2 Corn Cattle Meat-eaters Trophic level Primary consumers Secondary consumers Producers

Chemicals are cycled between organic matter and abiotic reservoirs Ecosystems are supplied with a continual influx of energy from the sun and Earth’s interior. Except for meteorites, there are no extraterrestrial sources of chemical elements. Thus, life also depends on the recycling of chemicals. © 2012 Pearson Education, Inc.

Biogeochemical cycles include –biotic components –abiotic components (non-living factors i.e. water) –abiotic reservoirs, where a chemical accumulates or is stockpiled outside of living organisms Biogeochemical cycles can be –local or –global. Biogeochemical Cycles © 2012 Pearson Education, Inc.

Exit Slip Thinking back on our primary production graph, what explains why tropical rain forests were among the highest contributors?

End of Class/Homework In your textbook, read pages 752 (starting with section 37.18) to 756. Be sure to add any “new” words to your vocabulary list.