Ecosystem Productivity

1. Ecosystem Productivity • Gross primary productivity (GPP) – the total amount of solar energy that the producers in an ecosystem capture via photosynthesis over a given amount of time • Net primary productivity (NPP) – the energy captured (GPP) minus the energy respired by producers • NPP = GPP – energy used by producers • Measured in kg C/m2/year

3. Where in the world is NPP the highest?

5. Biogeochemical Cycles • “life-earth-chemical” cycles • Water cycle • Carbon cycle • Nitrogen cycle • Phosphorus cycle • Sulfur cycle

6. Atoms “[Atoms] are also fantastically durable. Because they are so long lived, atoms really get around. Every atom you possess has almost certainly passed through several stars and been part of millions of organisms on its way to becoming you. We are each so atomically numerous and so vigorously recycled at death that a significant number of our atoms - up to a billion for each of us, it has been suggested - probably once belonged to Shakespeare. A billion more each came from Buddha and Genghis Khan and Beethoven and any other historical figure you care to name.” ~ Bill Bryson

7. Water Cycle

8. How are humans affecting the water cycle?

9. How are humans affecting the water cycle? • Using large quantities of freshwater from rivers, lakes, and underground aquifers • Clearing vegetation and replacing it with impermeable materials (like concrete), which increases runoff • Adding pollutants and excess nutrients to the water

10. Water Cycle

11. What can people do to improve the water cycle? • Water conservation • Use more permeable materials on the ground • Reduce the amount of runoff and the chemicals it contains

12. Green Roofs

13. Green Roofs

14. Green Roofs

15. Permeable Pavement

17. Carbon Cycle

18. Where is carbon stored?

19. Where is carbon stored? • Air – 0.037% is CO2 • Vegetation – during photosynthesis, plants convert CO2 into C6H12O6 (glucose) • Fossil fuels – plant matter that’s been subjected to heat and pressure • Ocean – dissolves CO2 • Marine organisms – used to make shells • Rocks – limestone is primarily CaCO3

20. Fossil Fuels

21. White Cliffs of Dover

22. How are humans affecting the carbon cycle?

23. How are humans affecting the carbon cycle? • By cutting down trees and clearing vegetation that naturally absorbs CO2 • Burning fossil fuels (especially coal) releases their stored carbon into the atmosphere

24. Effects of disrupting the carbon cycle • Global Warming – more CO2 in the atmosphere will lead to a stronger greenhouse effect • Acidification of the oceans – more dissolved CO2 in the water creates more carbonic acid

25. Nitrogen

26. Nitrogen • 78% of the air is nitrogen (N2) • Nitrogen is essential for organisms to make DNA, protein, amino acids, etc. • Yet, N2 is useless to plants and animals

27. How do organisms get nitrogen? • Two natural processes convert nitrogen gas into usable nitrogen: • Lightning • Nitrogen cycle

28. Nitrogen Cycle • 5 main processes cycle nitrogen through the atmosphere, biosphere, and lithosphere: • Nitrogen fixation • Nitrification • Assimilation • Ammonification • Denitrification

29. Nitrogen Cycle

30. Nitrogen Cycle • Nitrogen fixation • Bacteria (such as Rhizobium) convert gaseous nitrogen into ammonia, which is taken up by plants • N2 + 3H2 2NH3 Rhizobium nodules

31. Nitrogen Cycle

32. Nitrogen Cycle • Nitrification • Ammonia in soil converted by bacteria into nitrite ions (NO2-) and nitrate ions (NO3-)

33. Nitrogen Cycle

34. Nitrogen Cycle • Assimilation • Plants use ammonia (NH3), ammonium ions (NH4+), and nitrate ions (NO3-) • Make DNA, amino acids, and protein • Animals get their nitrogen from eating plants

35. Nitrogen Cycle

36. Nitrogen Cycle • Ammonification • Animals excrete excess nitrogen in their urine and feces • Additional nitrogen is added to the soil when organisms die • Decomposing bacteria and fungi convert the nitrogen in their waste into usable ammonia (NH3) and ammonium ions (NH4+)

37. Nitrogen Cycle

38. Nitrogen Cycle • Denitrification • Bacteria in the soil convert usable ammonia (NH3) and ammonium ions (NH4+) back into nitrogen gas (N2) and nitrous oxide gas (N2O)

39. Nitrogen Cycle

40. How are humans affecting the nitrogen cycle? • Burning fuels release nitric oxide (NO) into the atmosphere • Creates acid rain • Harms vegetation • Harms aquatic ecosystems • Damages materials (metal, stone, etc.)

41. How are humans affecting the nitrogen cycle? • Excess livestock waste and fertilizer adds nitrous oxide (N2O) to the atmosphere • N2O is a greenhouse gas • May lead to global warming

42. How are humans affecting the nitrogen cycle? • Runoff from agricultural lands and sewage facilities adds nitrogen to aquatic ecosystems • Results in algal blooms • Leads to “dead zones”

43. Nitrogen Summary • What allows nitrogen to be used by plants? • How do animals get their nitrogen? • What makes the nitrogen cycle a cycle? • How are humans affecting the nitrogen cycle?

44. Phosphorus

45. Phosphorus • Phosphorus is an essential nutrient for plant growth • It does not exist as a gas, but is mainly found in water, soil, and sediment

46. Phosphorus Cycle • Phosphorus is found naturally in rocks • Erosion by rainfall, weathering, and runoff allows phosphorus to be available to plants

47. Phosphorus Cycle • Phosphorus is absorbed by roots in plants • Animals eat the plants and it is passed up the food chain • Phosphorus is returned to the soil by animal excretion and decomposition

48. How are humans affecting the phosphorus cycle? • Humans mine phosphate rocks to make fertilizers and detergents • Increasing erosion by removing vegetation • Adding excess phosphorus to water from runoff from fertilizers and livestock waste

49. Sulfur Cycle • Most sulfur is buried in rocks and minerals underground • Hydrogen sulfide (H2S) and sulfur dioxide (SO2) are released by volcanoes

50. Rotorua, New Zealand (aka – “Sulfur City”)