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Ecosystem Energy and Nutrient Flow

Ecosystem Energy and Nutrient Flow. Ecosystems. 1. Biotic community and the abiotic environment. 2. Functional system which transfers and circulates energy and matter. Function, not Species -- Stuff, not Things. Ecosystem:

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Ecosystem Energy and Nutrient Flow

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  1. Ecosystem Energy and Nutrient Flow

  2. Ecosystems • 1. Biotic community and the abiotic environment. • 2. Functional system which transfers and circulates energy and matter.

  3. Function, not Species -- Stuff, not Things

  4. Ecosystem: “a spatially explicit unit of the Earth that includes all of the organisms, along with all the components of the abiotic environment within its boundaries.” Gene Likens

  5. ECOSYSTEM ECOLOGY ENERGY

  6. Ecosystems Are Energy Transformers • J.M. Teal (1962)

  7. Trophic Structure Reminder • Express trophic structure as energy transfer • Energy pyramids can never be inverted • Is there room for anyone else • at the top of this food chain?

  8. 21.1 Production • Energy flow in an ecosystem: primarily plants • GPP: Gross Primary Production • Energy fixed in photosynthesis • NPP: Net Primary Production • Biomass accrued by plants: wt. living plant material • Energy loss: respiration, tissue turnover, herbivory

  9. Characteristics of Top Carnivores not dense (few per unit area) because of ecological efficiency large territory (widely ranging) large body long life fast moving charismatic hunt-able Extirpation Indirect Effects – Trophic Cascade

  10. R=2 I=10 R=50 I1=100 Transfer Efficiencies Kcal m-2 y-1 P=1 AE=80% Carnivores A=8 E=7 P=10 AE=50% Herbivores A=50 E=40 NPP=1000 R+E=1000 Plants A (GPP)=2000 AE= % Solar Energy= 1,000,000

  11. R=2 I=10 Transfer Efficiencies Kcal m-2 y-1 P=1 AE=80% Carnivores A=8 E=7 P=10 R=50 AE=50% Herbivores A=50 E=40 I1=100 NPP=1000 R+E=1000 Plants A (GPP)=2000 AE= % Solar Energy= 1,000,000

  12. Transfer Efficiencies Kcal m-2 y-1 P=1 R=2 AE=80% Carnivores A=8 E=7 I=10 P=10 R=50 AE=50% Herbivores A=50 E=40 I1=100 NPP=1000 R+E=1000 Plants A (GPP)=2000 AE= % Solar Energy= 1,000,000

  13. R=2 I=10 R=50 I1=100 Transfer Efficiencies Kcal m-2 y-1 P=1 AE=80% Carnivores A=8 E=7 P=10 AE=50% Herbivores A=50 E=40 NPP=1000 R+E=1000 Plants A (GPP)=2000 AE= % Solar Energy= 1,000,000

  14. R=2 I=10 R=50 I1=100 Transfer Efficiencies Kcal m-2 y-1 P=1 AE=80% Carnivores A=8 E=7 P=10 AE=50% Herbivores A=50 E=40 NPP=1000 R+E=1000 Plants A (GPP)=2000 AE=2% Solar Energy= 1,000,000

  15. R=2 I=10 R=50 I=100 Transfer Efficiencies Kcal m-2 y-1 P=1 AE=80% Carnivores A=8 E=7 P=10 AE= % Herbivores A=50 E=40 NPP=1000 R+E=1000 Plants A (GPP)=2000 AE=2% Solar Energy= 1,000,000

  16. R=2 I=10 Transfer Efficiencies Kcal m-2 y-1 P=1 AE=80% Carnivores A=8 E=7 P=10 R=50 AE=50% Herbivores A=50 E=40 I1=100 NPP=1000 R+E=1000 Plants A (GPP)=2000 AE=2% Solar Energy= 1,000,000

  17. R=2 I=10 Transfer Efficiencies Kcal m-2 y-1 P=1 AE=80% Carnivores A=8 E=7 P=10 R=50 AE=50% Herbivores A=50 E=40 I=100 NPP=1000 R+E=1000 Plants A (GPP)=2000 AE=2% Solar Energy= 1,000,000

  18. R=2 I=10 Transfer Efficiencies Kcal m-2 y-1 P=1 AE= % Carnivores A=8 E=7 P=10 R=50 AE=50% Herbivores A=50 E=40 I1=100 NPP=1000 R+E=1000 Plants A (GPP)=2000 AE=2% Solar Energy= 1,000,000

  19. Transfer Efficiencies Kcal m-2 y-1 P=1 R=2 AE=80% Carnivores A=8 E=7 I=10 P=10 R=50 AE=50% Herbivores A=50 E=40 I1=100 NPP=1000 R+E=1000 Plants A (GPP)=2000 AE=2% Solar Energy= 1,000,000

  20. R=2 I=10 Transfer Efficiencies Kcal m-2 y-1 P=1 AE=80% Carnivores A=8 E=7 P=10 R=50 AE=50% Herbivores A=50 E=40 I1=100 NPP=1000 R+E=1000 Plants A (GPP)=2000 AE=2% Solar Energy= 1,000,000

  21. Transfer Efficiencies Kcal m-2 y-1 P=1 R=2 AE=80% Carnivores A=8 E=7 I=10 P=10 R=50 AE=50% Herbivores A=50 E=40 I1=100 NPP=1000 R+E=1000 Plants A (GPP)=2000 AE=2% Solar Energy= 1,000,000

  22. Take home: Ecosystems are Energy Transformers • Approximate 10% energy transfer between each trophic level • More efficient energy use as you increase trophic levels • Is there room for anyone else at the top of the pyramid? • Which level is most important to pyramid stability?

  23. Ray Lindeman 1942 First Ecosystem model

  24. Eugene Odum 1953. Silver Springs, Florida.

  25. Carbon cycle http://www.grida.no/climate/vital/13.htm, 1980-1989

  26. Steady State (Equilibrium) Trillions of moles (per year) Turnover Time = 38,000,000/8400 = 4524 years Turnover rate is about 0.022% per year

  27. ECOLOGICAL STOICHIOMETRY Elemental Ratios REDFIELD RATIO C:N:P 106:16:1 C:N – decaying wood, DOC. N:P -- cyanobacteria advantage. C:P – phosphate limitation for Daphnia.

  28. ECOSYSTEM ECOLOGY ENERGY FLOW CHEMICAL CYCLES

  29. Trophic Structure Principles • Eltonian pyramids • Number of individuals per species • Is this pyramid stable?

  30. Trophic Structure Principles • What if we transformed each species into biomass instead of absolute numbers?

  31. Trophic Structure Reminder • Do biomass or counts include generation time/reproduction, how much energy is available for growth, or decomposers?

  32. Measuring the Energy Content of Plants • Calorimetry • Heat generation • Harvesting • Linear growth • Clip plots: why measure dry weight? • CO2 uptake method • Li-Cor photosynthesis system • O2 output • Lt. and dk. bottles • Chlorophyll concentration

  33. ECOSYSTEM SCALES

  34. Ecosystem: (trophic-dynamic) the system composed of physical-chemical-biological processes active within a space-time unit of any magnitude… Ray Lindeman 1941 Cedar Ck. Bog, MN

  35. Lake Wingra – ECOSYSTEM BOUNDARIES

  36. ECOSYSTEM Compartments include leaves, wood, soil, rhizosphere. Small size scale. Compartments contain living & non-living

  37. TROPHIC STRUCTURE Defined by energy flow. primary producer primary consumer (herbivore) secondary consumer (carnivore) …, top carnivore.

  38. BOUNDARIES

  39. Average Annual Net Primary Productivity, by Habitat Ricklefs Fig. 6.8

  40. Fig. 6.2 Ricklefs -- E.P Odum’s universal model of ecological energy flow

  41. TROPHIC STRUCTURE Defined by energy flow. primary producer primary consumer (herbivore) secondary consumer (carnivore) …, top carnivore.

  42. Measuring Primary Productivity Oxygen method c14method – a radioactive tracer technique  annual production

  43. CALORIMETRY Measuring Energy Flow calorie = 1 degree C increase at 15 degrees C, for 1 ml water 1000 calories = 1 Calorie carbohydrate and protein about 5 Cal per gram fat about 9 Cal per gram teaspoonsugar = 4 grams or 20 Calories (kilocalories)

  44. TROPHIC CONCEPTS Productivity Biomass Turnover Time = Pool/Input = Biomass/Productivity Turnover Rate = Inverse of Turnover Time At equilibrium, Input = Output

  45. ECOLOGICAL EFFICIENCY Ratio of the productivity for two adjacent trophic levels. EXAMPLE primary productivity = 2 grams per m2 per day herbivore productivity = 0.2 grams per m2 per day, then the ecological efficiency is: ???

  46. Rule of Thumb The ecological efficiency is ~ 10% per trophic level.

  47. TROPHIC CASCADES (CARPENTER) DIRECT & INDIRECT EFFECTS OF TOP PREDATORS ON BIOMASS PRODUCTIVITY

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