1. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Chapter 54 Ecosystems

2. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Overview: Ecosystems, Energy, and Matter An ecosystem consists of all the organisms living in a community, as well as the abiotic factors with which they interact Ecosystems range from a microcosm, such as an aquarium, to a large area such as a lake or forest

3. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Regardless of an ecosystem’s size, its dynamics involve two main processes: energy flow and chemical cycling Energy flows through ecosystems while matter cycles within them Energy flows through an ecosystem, entering as light and exiting as heat

4. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Energy is conserved but degraded to heat during ecosystem processes Microorganisms and other detritivores Tertiary consumers Secondary consumers Detritus Primary consumers Sun Primary producers Heat Key Chemical cycling Energy flow

5. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Decomposition Decomposition connects all trophic levels Detritivores, mainly bacteria and fungi, recycle essential chemical elements by decomposing organic material and returning elements to inorganic reservoirs

6. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 54.2: Physical and chemical factors limit primary production in ecosystems Primary production in an ecosystem is the amount of light energy converted to chemical energy by autotrophs during a given time period

7. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Gross and Net Primary Production Total primary production is known as the ecosystem’s gross primary production (GPP) Net primary production (NPP) is GPP minus energy used by primary producers for respiration Only NPP is available to consumers Ecosystems vary greatly in net primary production and contribution to the total NPP on Earth

8. LE 54-4 Open ocean Continental shelf Upwelling zones Extreme desert, rock, sand, ice Swamp and marsh Lake and stream Desert and semidesert scrub Tropical rain forest Temperate deciduous forest Temperate evergreen forest Tropical seasonal forest Savanna Cultivated land Estuary Algal beds and reefs Boreal forest (taiga) Temperate grassland Woodland and shrubland Tundra 0.4 1.0 1.3 1.5 1.6 1.7 1.8 2.4 2.7 2.9 3.3 3.5 4.7 0.3 0.1 5.2 65.0 Freshwater (on continents) Terrestrial Marine Key Percentage of Earth’s surface area Average net primary production (g/m 2 /yr) 60 50 40 30 20 10 0 2,500 2,0001,500 1,000 500 0 Percentage of Earth’s net primary production 25 20 15 10 5 0 125 2,500 360 1,500 500 3.0 90 900 600 800 2,200 600 250 1,600 1,200 1,300 2,000 700 140 0.3 7.9 9.1 9.6 5.4 3.5 0.6 7.1 4.9 3.8 2.3 24.4 5.6 1.2 0.9 0.1 0.04 0.9 22

9. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Overall, terrestrial ecosystems contribute about two-thirds of global NPP Marine ecosystems contribute about one-third North Pole 60°N 30°N South Pole Equator 60°S 30°S 60°W 60°E 120°E 120°W 180° 0° 180°

10. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Primary Production in Marine and Freshwater Ecosystems In marine and freshwater ecosystems, both light and nutrients control primary production

11. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Light Limitation Depth of light penetration affects primary production in the photic zone of an ocean or lake

12. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A limiting nutrient is the element that must be added for production to increase in an area Nitrogen and phosphorous are typically the nutrients that most often limit marine production

13. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The addition of large amounts of nutrients to lakes has a wide range of ecological impacts In some areas, sewage runoff has caused eutrophication of lakes, which can lead to loss of most fish species Video: Cyanobacteria (Oscillatoria) Video: Cyanobacteria (Oscillatoria)

14. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Primary Production in Terrestrial and Wetland Ecosystems Climatic factors such as temperature and moisture affect primary production Actual evapotranspiration is the water annually transpired by plants and evaporated from a landscape It is related to net primary production

15. LE 54-8 Mountain coniferous forest Temperate forest Tropical forest Temperate grassland Arctic tundra Desert shrubland 1,500 1,000 5000 0 1,000 2,000 3,000 Actual evapotranspiration (mm/yr) Net primary production (g/m 2 /yr)

16. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Growth (new biomass) Cellular respiration Feces 100 J 33 J 67 J 200 J Plant material eaten by caterpillar Concept 54.3: Energy transfer between trophic levels is usually less than 20% efficient Secondary production of an ecosystem is the amount of chemical energy in food converted to new biomass during a given period of time

17. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Trophic Efficiency and Ecological Pyramids Trophic efficiency is the percentage of production transferred from one trophic level to the next It usually ranges from 5% to 20%

18. LE 54-11 1,000,000 J of sunlight 10,000 J 1,000 J 100 J 10 J Tertiary consumers Secondary consumers Primary consumers Primary producers

19. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Pyramids of Biomass In a biomass pyramid, each tier represents the dry weight of all organisms in one trophic level Trophic level Dry weight (g/m 2 ) Tertiary consumers Secondary consumers Primary consumers Primary producers 1.5 11 37 809 Most biomass pyramids show a sharp decrease in biomass at successively higher trophic levels, as illustrated by data from a bog at Silver Springs, Florida.

20. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Certain aquatic ecosystems have inverted biomass pyramids: Primary consumers outweigh the producers

21. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Pyramids of Numbers A pyramid of numbers represents the number of individual organisms in each trophic level Trophic level Number of individual organisms Tertiary consumers Secondary consumers Primary consumers Primary producers 3 354,904 708,624 5,842,424

22. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Dynamics of energy flow in ecosystems have important implications for the human population Eating meat is a relatively inefficient way of tapping photosynthetic production Trophic level Secondary consumers Primary consumers Primary producers

23. LE 54-16 Fossilization Reservoir a Reservoir b Reservoir c Reservoir d Organic materials available as nutrients Organic materials unavailable as nutrients Inorganic materials available as nutrients Inorganic materials unavailable as nutrients Living orgusanisms, detrit Coal, oil, peat Atmosphere, soil, water Minerals in rocks Assimilation, photosynthesis Burning of fossil fuels Weathering, erosion Formation of sedimentary rock Respiration, decomposition, excretion All elements cycle between organic and inorganic reservoirs

24. LE 54-17a Transport over land Precipitation over land Evaporation from ocean Precipitation over ocean Net movement of water vapor by wind Solar energy Evapotranspiration from land Runoff and groundwater Percolation through soil

25. LE 54-17b Cellular respiration Burning of fossil fuels and wood Carbon compounds in water Photosynthesis Primary consumers Higher-level consumers Detritus Decomposition CO 2 in atmosphere

26. LE 54-17c Assimilation N 2 in atmosphere Decomposers Nitrifying bacteria Nitrifying bacteria Nitrogen-fixing soil bacteria Denitrifying bacteria Nitrification Ammonification Nitrogen-fixing bacteria in root nodules of legumes NO 3 – NO 2 – NH 4 + NH 3

27. LE 54-17d Sedimentation Plants Rain Runoff Weathering of rocks Geologic uplift Soil Leaching Decomposition Plant uptake of PO 4 3– Consumption

28. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Decomposition and Nutrient Cycling Rates Decomposers (detritivores) play a key role in the general pattern of chemical cycling Rates at which nutrients cycle in different ecosystems vary greatly, mostly as a result of differing rates of decomposition

29. LE 54-18 Nutrients available to producers Decomposers Geologic processes Abiotic reservoir Consumers Producers

30. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Acid Precipitation Combustion of fossil fuels is the main cause of acid precipitation North American and European ecosystems downwind from industrial regions have been damaged by rain and snow containing nitric and sulfuric acid

31. LE 54-21 North America Europe 4.3 4.6 4.1 4.3 4.6 4.3 4.6

32. LE 54-22 Field pH  5.3 5.2–5.3 5.1–5.2 5.0–5.1 4.9–5.0 4.8–4.9 4.7–4.8 4.6–4.7 4.5–4.6 4.4–4.5 4.3–4.4 <4.3 5.3 5.2 5.3 5.6 5.9 5.4 5.2 5.4 5.5 6.0 5.0 5.4 6.3 5.3 6.1 5.5 5.4 5.6 5.5 5.6 5.2 5.1 5.7 4.9 5.7 5.0 4.9 4.1 4.3 4.4 4.5 4.6 4.7 4.8 5.0 5.3 5.2 5.1 5.2 5.3 5.4 5.5 4.7 4.9 4.8 4.6 4.7 4.8 4.9 5.0 5.1 5.0 5.1 5.2 5.3 5.4 5.7

33. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Toxins in the Environment One reason toxins are harmful is that they become more concentrated in successive trophic levels In biological magnification, toxins concentrate at higher trophic levels, where biomass is lower Zooplankton 0.123 ppm Phytoplankton 0.025 ppm Lake trout 4.83 ppm Smelt 1.04 ppm Herring gull eggs 124 ppm Concentration of PCBs