Ecosystems and Human Interferences

1. Ecosystems and Human Interferences Chapter 48

2. Outline • Biotic Components • Autotrophs • Heterotrophs • Energy Flow • Laws of Thermodynamics • Ecological Pyramids • Biogeochemical Cycles • Hydrologic Cycle • Carbon Cycle • Nitrogen Cycle • Phosphorus Cycle

4. Biotic Components • Autotrophs • Require only inorganic nutrients (EX?) and an outside energy source (EX?) to produce organic nutrients. • Examples of autotrophs?

5. Heterotrophs • Heterotrophs need a preformed source of organic nutrients. • Consumers • Herbivores EX? • Carnivores EX? • Omnivores EX? • Decomposers EX?

6. Biotic Components

7. Abiotic Components: Energy And Matter • Energy---Flows through an ecosystem • WHY? • Matter—Cycles within an ecosystem • EXAMPLES?

8. Definitions • Energy • Potential • Kinetic • Chemical • Matter and energy are interconvertible. • Work • Spontaneous change vs non-spontaneous change • Do characteristics of life require work?

9. Types of Energy in Biological Systems • Kinetic energy - energy of motion, work done • Potential energy - stored energy, can be released to do work • Archer draws bowstring back - used kinetic energy • Tension now in bowstring represents potential energy • Release of bowstring converts potential energy to kinetic energy

10. Energy (cont’d)

11. Thermodynamics • a system: Some portion of the universe that you wish to study • The surroundings: The adjacent part of the universe outside the system, i.e. everything but the system NOTE: Changes in a system are associated with the transfer of energy Natural systems tend toward states of minimum energy

13. 1st Law of Thermodynamics • Total Energy in Universe is Constant • energy cannot be created or destroyed • Energy can be converted from one form to another • The pathway of conversion is irrelevant, the energy change between identical initial and final states is equal • When it comes to energy-You can’t get ahead!

14. 2nd Law of Thermodynamics-You can’t break even, either! • No conversion is 100% efficient. • Total useful energy in a closed system decreases as conversions occur. • Closed systems go from complex to simple. • Entropy • Measure of Disorder •  Closed systems tend to their highest state of disorder • Entropy of the universe increases with every conversion

15. 2nd Law of Thermodynamics Randomness is spontaneous in a closed system

16. Examples of Entropy • Beaker on left has different colored marbles separated from each other • Highly ordered system • Low entropy highentropy low entropy • Beaker on right has different colored marbles scattered amongst each other • Highly disordered system • High entropy Other examples?

17. SUMMARY-THERMODYNAMICS • First Law: Energy cannot be created or destroyed, but it can be changed from one form to another. • Second Law: Energy cannot be changed from one form to another without loss of usable energy

18. Thermodynamics • The System • Open • Closed • System+Surroundings=Universe • First Law—You Can’t Win • Ways to State? • Second Law—You Can’t Break Even Either • Ways to State? Examples?

19. Energy Balances and Thermoodynamics

20. Energy Flow • Food Web - Interconnecting paths of energy flow describing trophic relationships.

21. Ecological Pyramids • A trophic level is composed of all the organisms that feed at a particular link in a food chain. • Pyramid of Biomass • Pyramid of Numbers • Pyramid of Energy • 10% Rule

22. Ecological Pyramid

23. Chemical Cycling • Chemicals cycle as organic nutrients are returned to the producers. • Excretion • Death • Cellular Respiration

25. Global Biogeochemical Cycles • Chemical cycling may involve: • Reservoir • Exchange Pool • Biotic Community • When exploring chemical cycles, evaluate the human impact on that cycle

27. Hydrologic Cycle • Fresh water evaporates from bodies of water. • Precipitation on land enters the ground, surface waters, or aquifers. • Water eventually returns to the oceans.

28. Hydrologic Cycle

29. Carbon Cycle • Exchange pool? • Reservoir? • Biotic community: How does carbon enter the biotic community?

30. Circle of Life Energy Respiration Carbon compounds, O2 CO2, H2O Photosynthesis Energy

31. Carbon Cycle

32. Greenhouse Effect • Greenhouse gases allow solar radiation to pass through atmosphere but trap heat (infrared radiation) from escaping. • Carbon dioxide, nitrous oxide, methane, H2O • If Earth’s temperature rises, more water will evaporate, forming more clouds and setting up a potential positive feedback loop.

33. Earth’s Radiation Balances

34. Nitrogen Cycle • Atmospheric nitrogen is fixed by bacteria in order to make it available to plants. • Nodules on legume roots (Rhizobium/legume symbiosis). • Nitrification - Production of nitrates. • Denitrification - Conversion of nitrate to nitrous oxide and nitrogen gas. • Balances nitrogen fixation.

35. The Nitrogen Cycle

36. Nitrogen and Air Pollution • Acid Deposition • Nitrogen oxides and sulfur dioxide are converted to acids when they combine with water vapor.

37. Thermal Inversion

38. Phosphorus Cycle • Phosphorus does not enter the atmosphere. • Sedimentary cycle. • Phosphate taken up by producers incorporated into a variety of organic molecules. • Can lead to water eutrophication. • Biomagnification

39. Phosphorus Cycle

40. Sources of Water Pollution

41. Review • Biotic Components • Autotrophs • Heterotrophs • Energy Flow • Ecological Pyramids • Biogeochemical Cycles • Hydrologic Cycle • Carbon Cycle • Nitrogen Cycle • Phosphorus Cycle

42. Energy Balances