1. Chapter 54 Ecosystem Ecology

2. From a small “closed system” to the biosphere Ecosystem – all the organisms living in a community, plus all the abiotic factors with which they interact

3. Microorganisms and other detritivores Detritus Primary producers Primary consumers Secondary consumers Tertiary consumers Heat Sun Key Chemical cycling Energy flow Two principal ecosystem processes: energy flow & chemical cycling Energy flows through an ecosystem (energy from the sun ultimately dissipates into space as heat) Fig. 54.2

4. Microorganisms and other detritivores Detritus Primary producers Primary consumers Secondary consumers Tertiary consumers Heat Sun Key Chemical cycling Energy flow Two principal ecosystem processes: energy flow & chemical cycling Chemical elements are continually recycled Fig. 54.2

5. Microorganisms and other detritivores Detritus Primary producers Primary consumers Secondary consumers Tertiary consumers Heat Sun Key Chemical cycling Energy flow Two principal ecosystem processes: energy flow & chemical cycling Physical laws govern these processes Fig. 54.2

6. Microorganisms and other detritivores Detritus Primary producers Primary consumers Secondary consumers Tertiary consumers Heat Sun Key Chemical cycling Energy flow Two principal ecosystem processes: energy flow & chemical cycling 1 st Law of Thermodynamics: Conservation of Energy Fig. 54.2

7. Microorganisms and other detritivores Detritus Primary producers Primary consumers Secondary consumers Tertiary consumers Heat Sun Key Chemical cycling Energy flow Two principal ecosystem processes: energy flow & chemical cycling Fig. 54.2 2 nd Law of Thermodynamics: Energy transformation is inefficient (between trophic levels)

8. Microorganisms and other detritivores Detritus Primary producers Primary consumers Secondary consumers Tertiary consumers Heat Sun Key Chemical cycling Energy flow Two principal ecosystem processes: energy flow & chemical cycling Fig. 54.2 Primary producers take elements in inorganic molecules and incorporate them into organic molecules

9. Microorganisms and other detritivores Detritus Primary producers Primary consumers Secondary consumers Tertiary consumers Heat Sun Key Chemical cycling Energy flow Two principal ecosystem processes: energy flow & chemical cycling Fig. 54.2 Additional organic molecules are produced at other trophic levels

10. Microorganisms and other detritivores Detritus Primary producers Primary consumers Secondary consumers Tertiary consumers Heat Sun Key Chemical cycling Energy flow Two principal ecosystem processes: energy flow & chemical cycling Fig. 54.2 Organic molecules are broken down into inorganic molecules by metabolism and decomposition of detritus

11. Energy budgets Gross primary production (GPP)  the amount of light energy converted to chemical energy per unit time (by primary producers through photosynthesis) Net primary production (NPP)  GPP minus energy used by primary producers for respiration NPP = GPP - R

12. Lake and stream Open ocean Continental shelf Estuary Algal beds and reefs Upwelling zones Extreme desert, rock, sand, ice Desert and semidesert scrub Tropical rain forest Savanna Cultivated land Boreal forest (taiga) Temperate grassland Tundra Tropical seasonal forest Temperate deciduous forest Temperate evergreen forest Swamp and marsh Woodland and shrubland 010203040506005001,0001,5002,0002,500 0510152025 (c) Percentage of Earth’s net primary production Key Marine Freshwater (on continents) Terrestrial 5.2 0.3 0.1 4.7 3.5 3.3 2.9 2.7 2.4 1.8 1.7 1.6 1.5 1.3 1.0 0.4 125 360 1,500 2,500 500 3.0 90 2,200 900 600 800 600 700 140 1,600 1,200 1,300 2,000 250 5.6 1.2 0.9 0.1 0.04 0.9 22 7.9 9.1 9.6 5.4 3.5 0.6 7.1 4.9 3.8 2.3 0.3 65.0 24.4 Figure 54.4 (a) Percentage of Earth’s surface area (b) Average net primary production (g/m 2 /yr) Energy budgets Different ecosystems vary in overall size (Fig. a), NPP (Fig. b), and their contributions to total NPP on Earth (Fig. c)

13. Lake and stream Open ocean Continental shelf Estuary Algal beds and reefs Upwelling zones Extreme desert, rock, sand, ice Desert and semidesert scrub Tropical rain forest Savanna Cultivated land Boreal forest (taiga) Temperate grassland Tundra Tropical seasonal forest Temperate deciduous forest Temperate evergreen forest Swamp and marsh Woodland and shrubland 010203040506005001,0001,5002,0002,500 0510152025 (c) Percentage of Earth’s net primary production Key Marine Freshwater (on continents) Terrestrial 5.2 0.3 0.1 4.7 3.5 3.3 2.9 2.7 2.4 1.8 1.7 1.6 1.5 1.3 1.0 0.4 125 360 1,500 2,500 500 3.0 90 2,200 900 600 800 600 700 140 1,600 1,200 1,300 2,000 250 5.6 1.2 0.9 0.1 0.04 0.9 22 7.9 9.1 9.6 5.4 3.5 0.6 7.1 4.9 3.8 2.3 0.3 65.0 24.4 Figure 54.4 (a) Percentage of Earth’s surface area (b) Average net primary production (g/m 2 /yr) Energy budgets Terrestrial ecosystems contribute about 2/3 and marine ecosystems about 1/3 of global NPP

14. Energy budgets Resources limit primary production (just as they limit population growth) Resources = light, water, nutrients Figure 54.7 For example, large-scale manipulations often demonstrate N or P limitation of NPP

15. Actual evapotranspiration (mm H 2 O/yr) Tropical forest Temperate forest Mountain coniferous forest Temperate grassland Arctic tundra Desert shrubland Net primary production (g/m 2 /yr) 1,000 2,000 3,000 0 5001,0001,500 0 Energy budgets Figure 54.8 For example, actual evapotranspiration correlates well with NPP across biomes

16. Actual evapotranspiration (mm H 2 O/yr) Tropical forest Temperate forest Mountain coniferous forest Temperate grassland Arctic tundra Desert shrubland Net primary production (g/m 2 /yr) 1,000 2,000 3,000 0 5001,0001,500 0 Energy budgets Figure 54.8 Actual evapotranspiration is the amount of water transpired plus evaporated (a function of water availability and solar energy)

17. Plant material eaten by caterpillar Cellular respiration Growth (new biomass) Feces 100 J 33 J 200 J 67 J Figure 54.10 Energy budgets Secondary production is the amount of chemical energy in consumers’ food converted to consumer biomass Some energy at each trophic level remains unassimilated (uneaten; not shown in the fig.)

18. Plant material eaten by caterpillar Cellular respiration Growth (new biomass) Feces 100 J 33 J 200 J 67 J Figure 54.10 Energy budgets Secondary production is the amount of chemical energy in consumers’ food converted to consumer biomass Some assimilated energy is passed in waste, some is used in respiration, and the rest is net secondary production In this example, <17% is used for secondary production

19. Energy budgets Trophic efficiency is the percentage of production transferred from one trophic level to another Tertiary consumers Secondary consumers Primary consumers Primary producers 1,000,000 J of sunlight 10 J 100 J 1,000 J 10,000 J Figure 54.11 Primary producers only convert ~1% of sunlight Other trophic levels ~10% (5% to 20%)

20. Energy budgets Pyramid of net production Tertiary consumers Secondary consumers Primary consumers Primary producers 1,000,000 J of sunlight 10 J 100 J 1,000 J 10,000 J Figure 54.11 Primary producers only convert ~1% of sunlight Other trophic levels ~10% (5% to 20%)

21. Energy budgets Pyramid of biomass Figure 54.12 Trophic level Dry weight (g/m 2 ) Primary producers Tertiary consumers Secondary consumers Primary consumers 1.5 11 37 809 The standing crop at each trophic level Usually narrows from the base upwards

22. Energy budgets Pyramid of biomass Figure 54.12 The standing crop at each trophic level But sometimes increases upwards if primary producers turn over rapidly Trophic level Primary producers (phytoplankton) Primary consumers (zooplankton) Dry weight (g/m 2 ) 21 4

23. Energy budgets Pyramid of numbers Figure 54.13 Predators tend to be larger than prey, so pyramids of numbers nearly always narrow upwards Trophic level Number of individual organisms Primary producers Tertiary consumers Secondary consumers Primary consumers 3 354,904 708,624 5,842,424 E.g., field in Michigan

24. Energy budgets Pyramid of numbers Figure 54.13 For a given amount of grain, carnivorous humans fair worse than vegetarians! Trophic level Secondary consumers Primary consumers Primary producers

25. Biogeochemical cycles Organic materials available as nutrients Living organisms, detritus Organic materials unavailable as nutrients Coal, oil, peat Inorganic materials available as nutrients Inorganic materials unavailable as nutrients Atmosphere, soil, water Minerals in rocks Formation of sedimentary rock Weathering, erosion Respiration, decomposition, excretion Burning of fossil fuels Fossilization Reservoir a Reservoir b Reservoir c Reservoir d Assimilation, photosynthesis Figure 54.16 Earth is nearly a closed system with respect to amounts of elements (with the exception of minor additions and losses, e.g., meteorites)

26. Biogeochemical cycles Organic materials available as nutrients Living organisms, detritus Organic materials unavailable as nutrients Coal, oil, peat Inorganic materials available as nutrients Inorganic materials unavailable as nutrients Atmosphere, soil, water Minerals in rocks Formation of sedimentary rock Weathering, erosion Respiration, decomposition, excretion Burning of fossil fuels Fossilization Reservoir a Reservoir b Reservoir c Reservoir d Assimilation, photosynthesis Figure 54.16 The general biogeochemical cycle of an element (see fig.) Elements cycle among pools that vary in whether they are: (1) incorporated in organic vs. inorganic molecules, or (2) available vs. unavailable to organisms

27. Transport over land Solar energy Net movement of water vapor by wind Precipitation over ocean Evaporation from ocean Evapotranspiration from land Precipitation over land Percolation through soil Runoff and groundwater THE WATER CYCLE Key processes include evaporation, transpiration, condensation in clouds, and precipitation Major reservoir is the ocean (which contains about 97% of Earth’s water) Figure 54.17

28. THE CARBON CYCLE The largest pool is sedimentary rock, but turnover is very slow Major reservoirs with “fast” turnover include fossil fuels, soils, dissolved carbon compounds in the oceans, biomass, CO 2 Figure 54.17 CO 2 in atmosphere Photosynthesis Cellular respiration Burning of fossil fuels and wood Higher-level consumers Primary consumers Detritus Carbon compounds in water Decomposition

29. CO 2 in atmosphere Photosynthesis Cellular respiration Burning of fossil fuels and wood Higher-level consumers Primary consumers Detritus Carbon compounds in water Decomposition THE CARBON CYCLE Key processes are photosynthesis, respiration, burning of fossil fuels, volcanoes Figure 54.17

30. Rain Consumption Decomposition Geologic uplift Weathering of rocks Runoff Sedimentation Plant uptake of PO 4 3  Soil Leaching THE PHOSPHORUS CYCLE Key processes include weathering of rocks and decomposition; little cycling in the atmosphere Major reservoirs are sedimentary rocks, soils, oceans, and biomass Figure 54.17

31. N 2 in atmosphere Denitrifying bacteria Nitrifying bacteria Nitrifying bacteria Nitrification Nitrogen-fixing soil bacteria Nitrogen-fixing bacteria in root nodules of legumes Decomposers Ammonification Assimilation NH 3 NH 4 + NO 3  NO 2  THE NITROGEN CYCLE Key process for N to enter an ecosystem is fixation, the conversion of N 2 by bacteria (or lightning) to forms usable by plants Major reservoir is the atmosphere (which is about 80% N 2 ) Figure 54.17

32. Humans have dramatically altered biogeochemical cycles and ecosystems Figure 54.19 The Hubbard Brook, NH experiment demonstrates the importance of forests for nutrient cycling Whole watersheds were experimentally deforested or not

33. Humans have dramatically altered biogeochemical cycles and ecosystems Weirs measured nutrient loss from watersheds Figure 54.19 The Hubbard Brook, NH experiment demonstrates the importance of forests for nutrient cycling

34. Humans have dramatically altered biogeochemical cycles and ecosystems The Hubbard Brook, NH experiment demonstrates the importance of forests for nutrient cycling Figure 54.19 Nitrate concentration in runoff (mg/L) Deforested Control Completion of tree cutting 19651966 1967 1968 80.0 60.0 40.0 20.0 4.0 3.0 2.0 1.0 0 Deforested watersheds lost nutrients at prodigious rates

35. Humans have dramatically altered biogeochemical cycles and ecosystems Oxides of sulfur and nitrogen from burning of fossil fuels have formed sulfuric and nitric acid, which have acidified soils Figure 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

36. Humans have dramatically altered biogeochemical cycles and ecosystems Anthropogenic CO 2 is the direct cause of global warming and various other manifestations of climate change Figure 54.24 CO 2 concentration (ppm) 390 380 370 360 350 340 330 320 310 300 196019651970 1975198019851990199520002005 1.05 0.90 0.75 0.60 0.45 0.30 0.15 0  0.15  0.30  0.45 Temperature variation (  C) Temperature CO 2 Year