ENERGY

1. ENERGY PATTERNS OF ENERGY FLOW IN ECOSYSTEMS

2. WHAT IS AN ECOSYSTEM? Biological community plus all abiotic factors affecting the community http://eesc.columbia.edu/courses/ees/life/lectures/lect02.html

3. LAWS OF THERMODYNAMICS • 1st LAW: • 2nd LAW:

5. ENERGY SOURCES IN BIOSPHERE • Sunlight energy – driving force • Energy distribution and carbon dioxide in atmosphere shape ecosystems and biosphere • Biosphere energy and CO2 shape world climate and weather

6. CHARLES ELTON & FOOD WEBS • 1920s, Charles Elton and others proposed: • Organisms living in the same place not only have similar tolerances of physical factors, but • Feeding relationships link these organisms into a single functional entity • Food web http://www.history.vt.edu/Barrow/Hist3144/readings/ecology/index.html

7. http://www.nature.ca/ukaliq/images/a196_fwb_e.jpg

8. Feeding relationships of the snowshoe hare-dominated food web in the boreal forest of northwestern Canada Dominant species in yellow

9. OLD FIELD FOOD WEB

11. ALFRED J. LOTKA AND THE THERMODYNAMIC CONCEPT • Alfred J. Lotka

12. LINDEMAN’S SYNTHESIS 1942 – Raymond Lindeman brought Lotka’s ideas of the ecosystem as an energy-transforming machine to the attention of ecologists Incorporated: http://www.cedarcreek.umn.edu/people/photo/LindemanRaymond1942.jpg

13. LINDEMAN’S FOUNDATIONS OF ECOSYSTEM ECOLOGY • Ecosystem is fundamental unity of ecology • Within an ecosystem, energy passes through many steps or links in a food chain

14. Cedar Bog Lake in Minnesota…site of Raymond Lindemen’s classic research paper in 1942: "The Trophic-Dynamic Concept in Ecology“. Ecology 23:399-418

16. ODUM’S ENERGY FLUX MODEL Recognized the utility of energy and masses of elements as common “currencies” in comparative analysis of ecosystem structure and function Eugene Odum http://www.researchmagazine.uga.edu/summer2002/odum.htm

17. ODUM EXTENDED HIS MODELS TO INCORPORATE NUTRIENT CYCLING • Fluxes of energy and materials are closely linked in ecosystem function • But: • Energy enters ecosystems as light and is degraded into heat • Nutrients cycle indefinitely, converted from inorganic to organic forms and back again • Studies of nutrient cycling provides index of energy fluxes

20. Single trophic level Example food chain Odum’s “universal” model of energy flow, which can be applied to any organism

21. Energy dissipated as heat SUN Producers Consumers Detritus + Decomposers Inorganic nutrients Nutrient pool Import Export Energy Flow Nutrient Cycling

22. AUTOTROPHS - PRODUCERS Photoautotrophs - Chemoautotrophs – Primary producers – Transform sunlight energy to chemical energy Sugars, starch, ATP http://www.scienceclarified.com/images/uesc_01_img0028.jpg http://141.150.157.117:8080/prokPUB/figures/normal/p323-006.jpg

23. PRIMARY PRODUCTION • Producers capture energy of light • Transform sunlight energy into energy of chemical bonds in carbohydrates • 6CO2 + 6H2O → C6H12O6 + 6O2 • For each g of C assimilated, 39 kj energy stored • Gross primary production = total energy assimilated by primary producers • Net primary producion = energy accumulated (in stored form) by primary producers • GPP – NPP = Respiration • Energy consumed by producers for maintenance and biosynthesis

24. Energy lost and unavailable to consumers Partitioning gross primary productivity into respiration and net primary productivity GPP NPP

25. NUTRIENTS STIMULATE PRIMARY PRODUCTION • Terrestrial production may be nutrient limited • Aquatic systems often strongly nutrient-limited

26. Effects of fertilization with N & P on primary production in a salt marsh dominated Carex subspathecea in southern Hudson Bay, Canada.

28. AQUATIC ECOSYSTEMSRESPONSIVE TO PHOSPHORUS 1975 1994 http://www.umanitoba.ca/institutes/fisheries/eutro.html

29. Slow-moving coastal plain stream choked with algal bloom caused by nitrogen and phosphorus from upstream farmland. http://wps.prenhall.com/wps/media/objects/57/58641/51_8089ic.gif

30. GLOBAL PRIMARY PRODUCTION • Correlates with annual precipitation (when light not limiting) • Note relationship among tundra, deserts, and tropics • Oceans – nutrient poor • CO2 Source of carbon • Follows 1st Law of Energy

32. Grams carbon/m2/yr for globe, as calculated from satellite imagery. Oceans = 46%, land = 54%

33. PRIMARY PRODUCTION VARIES AMONG ECOSYSTEMS • Maximum under favorable conditions

34. NPP vs. Temperature + Precipitation

35. HETEROTROPHS - CONSUMERS • Get energy from external sources • “Animals” • Primary consumers • Secondary consumers • Tertiary consumers • Carnivores • Decomposers • Detritivores • Eat dead organic matter

36. Tertiary consumers Decomposers Secondary consumers Primary consumers Primary producers

37. Tertiary consumers Decomposers Secondary consumers Primary consumers Primary producers

38. ECOLOGICAL PYRAMIDS Trophic levels placed in order Reflects: Numbers of organisms at each level Biomass of each level Energy at each level

39. ECOLOGICAL PYRAMIDS Elton observed predators tended to be larger and less numerous than their prey - described as the ‘pyramid’ of numbers or biomass Elton hypothesized that this occurred because predators have to be larger than prey

40. PYRAMID OF NUMBERS # CONSUMERS=TOP CARNIVORES # DECOMPOSERS # CONSUMERS # HERBIVORES # PRIMARY PRODUCERS

41. PYRAMID OF BIOMASS kg CONSUMERS=TOP CARNIVORES kg CONSUMERS kG DECOMPOSERS kg HERBIVORES kg PRIMARY PRODUCERS

42. PYRAMID OF ENERGY kJ CONSUMERS=TOP CARNIVORES kJ CONSUMERS kJ DECOMPOSERS kJ HERBIVORES kJ PRIMARY PRODUCERS

43. NUMBERS PYRAMID

44. NUMBERS PYRAMID http://www.bbc.co.uk/schools/gcsebitesize/img/bi01010.gif

45. BIOMASS PYRAMID

46. BIOMASS PYRAMID

47. BIOMASS AND (NUMBERS) PYRAMID

48. ENERGY PYRAMID

49. Heat is lost as energy flows through food chain

50. Energy pyramids can never be inverted, but biomass pyramids can be inverted when lower trophic levels are dominated by palatable and small organisms that turnover rapidly