1 / 26

Chapter 55

Chapter 55. Ecosystems. Energy flows through ecosystems while matter cycles within them. These are the 2 processes in ecosystems. Fig. 55-1. 1 st law of thermodynamics - energy cannot be created or destroyed, only transformed

francesjlee
Download Presentation

Chapter 55

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 55 Ecosystems • Energy flows through ecosystems while matter cycles within them. These are the 2 processes in ecosystems.

  2. Fig. 55-1 • 1st law of thermodynamics - energy cannot be created or destroyed, only transformed • 2nd 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 Tertiary consumers Microorganisms and other detritivores Secondary consumers Primary consumers Detritus Primary producers Heat Key Chemical cycling Sun 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. 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. 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. Fig. 55-8 3,000 Tropical forest · 2,000 Net primary production (g/m2·yr) Temperate forest 1,000 Mountain coniferous forest Desert shrubland Temperate grassland Arctic tundra 0 0 500 1,500 1,000 Actual evapotranspiration (mm H2O/yr)

  8. Fig. 55-9 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 Plant material eaten by caterpillar 200 J 67 J Cellular respiration 100 J Feces 33 J Growth (new biomass)

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

  10. Fig. 55-11 Trophic level Dry mass (g/m2) Tertiary consumers 1.5 Secondary consumers 11 Primary consumers 37 Primary producers 809 (a) Most ecosystems (data from a Florida bog) Trophic level Dry mass (g/m2) Primary consumers (zooplankton) 21 Primary producers (phytoplankton) 4 (b) Some aquatic ecosystems (data from the English Channel) 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 defenses Limited availability of essential nutrients • Abiotic factors • Intraspecific competition Interspecific interactions

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

  14. Fig. 55-14a 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 Transport over land Solar energy Net movement of water vapor by wind Precipitation over land Precipitation over ocean Evaporation from ocean Evapotranspiration from land Percolation through soil Runoff and groundwater

  15. Fig. 55-14b Carbon Cycle CO2 in atmosphere Photosynthesis Cellular respiration Photo- synthesis Burning of fossil fuels and wood Phyto- plankton Higher-level consumers Primary consumers Carbon compounds in water Detritus Decomposition

  16. Fig. 55-14c Nitrogen Cycle N2 in atmosphere Assimilation Denitrifying bacteria NO3 – Nitrogen-fixing bacteria Decomposers Nitrifying bacteria Ammonification Nitrification NH3 NH4 NO2 – + Nitrogen-fixing soil bacteria Nitrifying bacteria

  17. Phosphorus Cycle Major constituent of nucleic acids, phospholipids, and ATP Phosphate (PO43–) most important inorganic Precipitation Geologic uplift Weathering of rocks Runoff Consumption Decomposition Plant uptake of PO43– Plankton Dissolved PO43– Soil Uptake Leaching Sedimentation

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

  19. 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 Winter Summer

  20. 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 4.5 4.4 4.3 pH 4.2 4.1 4.0 1970 1975 1990 1960 1965 1980 1985 1995 2000 Year

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

  23. Fig. 55-21 Burning fossil fuels and other human activities have increased the conc. of atmospheric CO2 14.9 390 14.8 380 14.7 14.6 370 Temperature 14.5 360 14.4 14.3 350 CO2 concentration (ppm) Average global temperature (ºC) 14.2 340 14.1 CO2 330 14.0 CO2, water vapor, and other greenhouse gases reflect infrared radiation back toward Earth; this is the greenhouse effect 13.9 320 13.8 310 13.7 13.6 300 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 Year

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

  25. Destruction of atmospheric ozone probably results from chlorine-releasing pollutants such as CFCs produced by human activity Chlorine atom O2 O3 Chlorine ClO O2 ClO Cl2O2 Sunlight

  26. 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 Fig. 55-25 (a) September 1979 (b) September 2006

More Related