Energy Flow in Ecosystems and Biogeochemical Cycles

1. Energy Flow in Ecosystems and Biogeochemical Cycles

3. What’s an Ecosystem? An ecosystem consists of all the organisms (biotic) in a community and the environment (abiotic) with which they interact. Ecosystems can be as small as the microorganisms living on your skin or as large as the entire biosphere.

5. Energy Flow in Ecosystems Almost all energy used in ecosystems comes from the sun From there it flows through a food chain or web and exits the ecosystem in the form of heat, light, kenetic or chemical energy

6. Energy pyramids show the efficiency of energy transfer between trophic levels Generally 10% of energy is transferred Food chains never get beyond 4-5 trophic levels

7. Biogeochemical Cycling of Nutrients We have a finite supply of chemical elements Abiotic reservoir – atmosphere, rocks Biotic reservoir – within organisms Biological processing – nitrogen fixation by bacteria, carbon fixation by photosynthesis

8. Atoms and Electron Shells

9. Biogeochemical Cycling of Nutrients We have a finite supply of chemical elements Abiotic reservoir – atmosphere, rocks Biotic reservoir – within organisms Biological processing – nitrogen fixation by bacteria, carbon fixation by photosynthesis Water cycle Carbon cycle Nitrogen cycle Phosphorous cycle

10. LE 37-15

11. Biogeochemical Cycling of Nutrients We have a finite supply of chemical elements Abiotic reservoir – atmosphere, rocks Biotic reservoir – within organisms Biological processing – nitrogen fixation by bacteria, carbon fixation by photosynthesis Water cycle Carbon cycle Nitrogen cycle Phosphorous cycle

12. What’s so great about water? Polar molecule High heat capacity – doesn’t change temperature rapidly Evaporative cooling Cohesion and adhesion “Universal” solvent Lower density when solid – ice floats Organisms are made of water

13. Water Cycle Solar energy drives the global water cycle Precipitation Evaporation Transpiration Water cycles between the land, oceans, and atmosphere Forest destruction and irrigation affect the water cycle

17. Runoff and Watershed Health

18. WATER A combination of factors threaten freshwater ecosystems Acid precipitation Climate warming Changes in land use

19. Biogeochemical Cycling of Nutrients We have a finite supply of chemical elements Abiotic reservoir – atmosphere, rocks Biotic reservoir – within organisms Biological processing – nitrogen fixation by bacteria, carbon fixation by photosynthesis Water cycle Carbon cycle Nitrogen cycle Phosphorous cycle

20. Carbon Cycle Abiotic reservoirs = atmosphere, sedimentary rocks, dissolved carbon in oceans, and fossil fuels Taken from the atmosphere by photosynthesis Used to make organic molecules Decomposed by detritivores Returned to the atmosphere by cellular respiration

21. What’s so great about carbon?

23. CONNECTION – Global Warming Burning of fossil fuels and wood is increasing the amount of CO2 and other greenhouse gases in the air Correlation with increased global temperature The greenhouse effect Natural phenomenon is essential for life on Earth Rapidly increasing CO2 is making global warming a danger

26. Biogeochemical Cycling of Nutrients We have a finite supply of chemical elements Abiotic reservoir – atmosphere, rocks Biotic reservoir – within organisms Biological processing – nitrogen fixation by bacteria, carbon fixation by photosynthesis Water cycle Carbon cycle Nitrogen cycle Phosphorous cycle

27. Ingredient of proteins and nucleic acids Essential to the functioning and structure of all organisms Crucial for plants, but limited in quantity What’s so great about nitrogen?

28. Nitrogen Cycle The nitrogen cycle relies heavily on bacteria Atmospheric N2 is not available to plants Soil bacteria convert gaseous N2 to usable ammonium (NH4+) and nitrate (NO3-) Some NH4+ and NO3- are made by chemical reactions in the atmosphere

30. Biogeochemical Cycling of Nutrients We have a finite supply of chemical elements Abiotic reservoir – atmosphere, rocks Biotic reservoir – within organisms Biological processing – nitrogen fixation by bacteria, carbon fixation by photosynthesis Water cycle Carbon cycle Nitrogen cycle Phosphorous cycle

31. Phosphorus is a component of nucleic acids, phospholipids, ATP, and as a mineral for bones and teeth. What’s so great about phosphorus?

32. Phosphorus Cycle Depends on the weathering of rock Phosphorus and other soil minerals are recycled locally Weathering of rock adds PO43- to soil Slow process makes amount of phosphorus available to plants low

34. Connections Nutrient runoff from agricultural lands and large livestock operations may cause excessive algal growth This cultural eutrophication reduces species diversity and harms water quality

36. 1. Plants store starch, where is the energy in this polymer? In the Carbon molecules In the Hydrogen bonds In the covalent bonds which hold glucose molecules together In its nutrient make-up

37. 3. A Covalent bond is formed when atoms SHARE electrons. TRUE FALSE

38. 5. Fill in the blanks: Energy flows__________ ecosystems, while nutrients cycle ___________ ecosystems. Within, Through Through, Within

39. 6. Approximately what percentage of energy is passed from one trophic level to the next in a food pyramid? 1% 5% 10% 100%

40. 7. How is Carbon released back to the Atmosphere? Through respiration Through photosynthesis By burning fossil fuels All of the above Both A and C