Chapter 48: The Biosphere

1. Chapter 48: The Biosphere

2. Factors that Affect Distribution • Geologic history • Topography • Climate • Species interactions

3. Biosphere • Sum total of the places in which organisms live • Includes portions of the hydrosphere, lithosphere, and atmosphere

4. Climate • Average weather condition in a region • Affected by: • amount of incoming solar radiation • prevailing winds • elevation

5. The Atmosphere • Three layers • Outer mesosphere • Middle stratosphere (includes ozone layer) • Inner troposphere (where air is warmed by the greenhouse effect)

6. Fig. 48-2, p.868

7. Ozone Layer • Region 17 to 27 kilometers above sea level in the stratosphere • Molecules of ozone absorb most layers of ultraviolet light • Protects living organisms from excess exposure to UV light

8. Warming the Atmosphere • Solar energy warms the atmosphere and sets global air circulation patterns in motion Figure 48.3 Page 868

9. Rotation and Wind Direction • Earth rotates faster under the air at the equator than it does at the poles • Deflection east and west Figure 48.2 Page 868

10. Seasonal Variation • Northern end of Earth’s axis tilts toward sun in June and away in December • Difference in tilt causes differences in sunlight intensity and day length • The greater the distance from the equator, the more pronounced the seasonal changes

11. cold cool temperature warm temperature tropical (equator) tropical warm temperature cool temperature cold March 231/2º June December September Fig. 48-4, p.869

12. Fig. 48-5a, p.869

13. Fig. 48-5b, p.869

14. Pollutants • Substances with which an ecosystem has had no prior evolutionary experience • No adaptive mechanisms are in place to deal with them

15. Air Pollutants • Carbon oxides • Sulfur oxides • Nitrogen oxides • Volatile organic compounds • Photochemical oxidants • Suspended particles

16. Industrial Smog • Gray-air smog • Forms over cities that burn large amounts of coal and heavy fuel oils; mainly in developing countries • Main components are sulfur oxides and suspended particles

17. Photochemical smog • Brown-air smog • Forms when sunlight interacts with components from automobile exhaust • Nitrogen oxides are the main culprits • Hot days contribute to formation

18. Thermal Inversion • Weather pattern in which a layer of cool, dense air is trapped beneath a layer of warm air cool air warm inversion air cool air Figure 48-7  Page 870

19. Acid Deposition • Affects much of eastern North America • Caused by the release of sulfur and nitrogen oxides • Coal-burning power plants and motor vehicles are major sources

20. Fig. 48-8, p.871

21. South America Antarctica Ozone Thinning • In early spring and summer ozone layer over Antarctica thins • Seasonal loss of ozone is at highest level ever recorded Figure 48-6  Page 870

22. Effect of Ozone Thinning • Increased amount of UV radiation reaches Earth’s surface • UV damages DNA and negatively affects human health • UV also affects plants, lowers primary productivity

23. Protecting the Ozone Layer • CFC production has been halted in developed countries, will be phased out in developing countries • Methyl bromide will be phased out • Even with bans it will take more than 50 years for ozone levels to recover

24. Fig. 48-9, p.871

25. Ocean Currents • Upper waters move in currents that distribute nutrients and affect regional climates Figure 48-10 Page 872

26. Rain Shadow • Air rises on the windward side, loses moisture before passing over the mountain Figure 48.11 Page 873

27. Monsoons • A pattern of wind circulation that changes seasonally • Affect continents north and south of warm-water oceans • Can cause seasonal variation in rains

28. Coastal Breezes • Breeze blows in direction of warmer region • Direction varies with time of day Night Afternoon

29. Biogeographic Realms • Six areas in which plants and animals are somewhat similar • Maintain their identity because of climate and physical barriers that tend to maintain isolation between species

30. Biomes • Regions of land characterized by habitat conditions and community structure • Distinctive biomes prevail at certain latitudes and elevations

31. Soil Characteristics • Amount of humus • pH • Degree of aeration • Ability to hold or drain water • Mineral content

32. Soil Profiles • Layer structure of soil • Soil characteristics determine what plants will grow and how well Rainforest Desert Grassland Figure 48.13 Page 876

33. Fig. 48-14a, p.877

34. Fig. 48-14b, p.877

35. Fig. 48-15, p.877

36. Deserts • Less than 10 centimeters annual rainfall, high level of evaporation • Tend to occur at 30 degrees north and south and in rain shadows • One-third of land surface is arid or semiarid

37. Fig. 48-16, p.878

38. Dry Shrublands and Woodlands • Semiarid regions with cooler, wet winters and hot, dry summers • Tend to occur in western or southern coastal regions between latitudes of 30 and 40 degrees

39. Fig. 48-17a, p.879

40. Fig. 48-17b, p.879

41. Fig. 48-18a, p.879

42. Forest Biomes Tall trees form a continuous canopy • Evergreen broadleaves in tropical latitudes • Deciduous broadleaves in most temperate latitudes • Evergreen conifers at high temperate elevations and at high latitudes

43. Fig. 48-19a, p.880

44. Fig. 48-19b, p.880

45. Fig. 48-19c, p.880

46. Fig. 48-19d, p.880

47. Fig. 48-19e, p.880

48. Deforestation • Removal of all trees from large tracts of land • 38 million acres logged each year • Wood is used for fuel, lumber • Land is cleared for grazing or crops

49. Effects of Deforestation • Increased leaching and soil erosion • Increased flooding and sedimentation of downstream rivers • Regional precipitation declines • Possible amplification of the greenhouse effect

50. Regions of Deforestation • Rates of forest loss are greatest in Brazil, Indonesia, Mexico, and Columbia • Highly mechanized logging is proceeding in temperate forests of the United States and Canada