1. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings PowerPoint ® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Chapter 55 Ecosystems Energy flows through ecosystems while matter cycles within them. These are the 2 processes in ecosystems.

2. Fig. 55-1 1 st law of thermodynamics - energy cannot be created or destroyed, only transformed 2 nd law of thermodynamics - every exchange of energy increases the entropy of the universe Law of conservation of mass - matter cannot be created or destroyed Ecosystems are open systems, absorbing energy and mass and releasing heat and waste products

3. Fig. 55-4 Microorganisms and other detritivores Tertiary consumers Secondary consumers Primary consumers Primary producers Detritus Heat Sun Chemical cycling Key Energy flow

4. Fig. 55-3 Detritivores, or decomposers, are consumers that derive their energy from detritus, nonliving organic matter Decomposition connects all trophic levels Decomposition rate is controlled by temperature, moisture, and nutrient availability (low = rapid decomp)

5. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 55.2: Energy and other limiting factors control primary production in ecosystems Primary production - amount of light energy converted to chemical energy by autotrophs during a given time period Total primary = gross primary production (GPP) Net primary production (NPP) - GPP minus energy used by primary producers for respiration

6. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Nutrient Limitation Limiting nutrient - element that must be added for production to increase in an area – N2 and P most often limit marine production In terrestrial ecosystems, temperature and moisture affect primary production on a large scale Actual evapotranspiration - water annually transpired by plants and evaporated from a landscape

7. Net primary production (g/m 2 ·yr) Fig. 55-8 Tropical forest Actual evapotranspiration (mm H 2 O/yr) Temperate forest Mountain coniferous forest Temperate grassland Arctic tundra Desert shrubland 1,500 1,000 5000 0 1,000 2,000 3,000 ·

8. Fig. 55-9 Cellular respiration 100 J Growth (new biomass) Feces 200 J 33 J 67 J Plant material eaten by caterpillar Secondary production - amount of chemical energy in food converted to new biomass during a given period of time Production efficiency - fraction of energy stored in food that is not used for respiration

9. Fig. 55-10 Primary producers 100 J 1,000,000 J of sunlight 10 J 1,000 J 10,000 J Primary consumers Secondary consumers Tertiary consumers Trophic efficiency – % of production transferred from one trophic level to the next

10. Fig. 55-11 (a) Most ecosystems (data from a Florida bog) Primary producers (phytoplankton) (b) Some aquatic ecosystems (data from the English Channel) Trophic level Tertiary consumers Secondary consumers Primary consumers Primary producers Trophic level Primary consumers (zooplankton) Dry mass (g/m 2 ) Dry mass (g/m 2 ) 1.5 11 37 809 21 4 Turnover time - ratio of standing crop biomass to production

11. Most terrestrial ecosystems have large standing crops despite the large numbers of herbivores Green world hypothesis proposes several factors that keep herbivores in check: Plant defensesLimited availability of essential nutrients Abiotic factors Intraspecific competitionInterspecific interactions

12. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Biogeochemical Cycles Gaseous C, O2, S, and N2 occur in the atmosphere and cycle globally Less mobile elements such as P, K, and Ca cycle on a more local level Cycling of H2O, C, N, and K, we focus on 4 factors: – Each chemical’s biological importance – Forms in which each chemical is available or used by organisms – Major reservoirs for each chemical – Key processes driving movement of each chemical through its cycle

13. Fig. 55-13 Reservoir A Reservoir B Organic materials available as nutrients Fossilization Organic materials unavailable as nutrients Reservoir DReservoir C Coal, oil, peat Living organisms, detritus Burning of fossil fuels Respiration, decomposition, excretion Assimilation, photosynthesis Inorganic materials available as nutrients Inorganic materials unavailable as nutrients Atmosphere, soil, water Minerals in rocks Weathering, erosion Formation of sedimentary rock

14. Fig. 55-14a Precipitation over land Transport over land Solar energy Net movement of water vapor by wind Evaporation from ocean Percolation through soil Evapotranspiration from land Runoff and groundwater Precipitation over ocean 97% of the biosphere’s water is contained in the oceans, 2% is in glaciers and polar ice caps, and 1% is in lakes, rivers, and groundwater Water Cycle

15. Fig. 55-14b Higher-level consumers Primary consumers Detritus Burning of fossil fuels and wood Phyto- plankton Cellular respiration Photo- synthesis Photosynthesis Carbon compounds in water Decomposition CO 2 in atmosphere Carbon Cycle

16. Fig. 55-14c Decomposers N 2 in atmosphere Nitrification Nitrifying bacteria Nitrifying bacteria Denitrifying bacteria Assimilation NH 3 NH 4 NO 2 NO 3 + – – Ammonification Nitrogen-fixing soil bacteria Nitrogen-fixing bacteria Nitrogen Cycle

17. Leaching Consumption Precipitation Plant uptake of PO 4 3– Soil Sedimentation Uptake Plankton Decomposition Dissolved PO 4 3– Runoff Geologic uplift Weathering of rocks Phosphorus Cycle Major constituent of nucleic acids, phospholipids, and ATP Phosphate (PO 4 3– ) most important inorganic

18. Fig. 55-17 Why is this picture important?

19. WinterSummer Critical load for a nutrient is the amount that plants can absorb without damaging the ecosystem Remaining nutrients can contaminate groundwater as well as freshwater and marine ecosystems Sewage runoff causes cultural eutrophication, excessive algal growth that can greatly harm freshwater ecosystems

20. Copyright © 2008 Pearson Education, Inc., publishing as Pearson 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 Acid precipitation changes soil pH and causes leaching of calcium and other nutrients Environmental regulations and new technologies have allowed many developed countries to reduce sulfur dioxide emissions

21. Fig. 55-19 Year 20001995 1990 19851980 19751970 19651960 4.0 4.1 4.2 4.3 4.4 4.5 pH

22. Fig. 55-20 Lake trout 4.83 ppm Concentration of PCBs Herring gull eggs 124 ppm Smelt 1.04 ppm Phytoplankton 0.025 ppm Zooplankton 0.123 ppm Biological magnification - concentrates toxins at higher trophic levels, where biomass is lower

23. Fig. 55-21 CO 2 CO 2 concentration (ppm) Temperature 1960 300 Average global temperature (ºC) 1965197019751980 Year 19851990199520002005 13.6 13.7 13.8 13.9 14.0 14.1 14.2 14.3 14.4 14.5 14.6 14.7 14.8 14.9 310 320 330 340 350 360 370 380 390 Burning fossil fuels and other human activities have increased the conc. of atmospheric CO 2 CO 2, water vapor, and other greenhouse gases reflect infrared radiation back toward Earth; this is the greenhouse effect

24. Ozone layer thickness (Dobsons) Fig. 55-23 Year ’05 2000 ’95’90’85 ’80 ’75’70 ’65 ’60 1955 0 100 250 200 300 350 Life on Earth is protected from damaging effects of UV radiation by a protective layer of ozone molecules in the atmosphere Satellite studies suggest that the ozone layer has been gradually thinning since 1975

25. O2O2 Sunlight Cl 2 O 2 Chlorine Chlorine atom O3O3 O2O2 ClO Destruction of atmospheric ozone probably results from chlorine- releasing pollutants such as CFCs produced by human activity

26. Fig. 55-25 (a) September 1979(b) September 2006 Scientists first described an “ozone hole” over Antarctica in 1985; it has increased in size as ozone depletion has increased Ozone depletion causes DNA damage in plants and poorer phytoplankton growth