Chapter 8

1. Chapter 8 The Biosphere

2. The Biosphere The Biosphereis the layer of the Earth containing organisms and their habitats. Associated with the biosphere are the biogeochemical cycles of essential elements for life.

3. Biogeochemical Cycles

4. Biogeochemical Cycle • A set of processes by which an element passes from one environment to the next and eventually returns to its original environment. • Carbon Cycle • Nitrogen Cycle • Phosphorous Cycle

5. The Carbon Cycle • Carbon is often described as the building block of life, since it is the basic element of proteins, lipids and carbohydrates, and thus all living things. • Carbon is constantly being exchanged and recycled through different parts of the Earth.

7. Stages of the Carbon Cycle • Photosynthesis: plants and phytoplankton take in carbon dioxide (CO2) from the atmosphere and use it to make sugars. • Respiration: when living organisms breath they release carbon dioxide back into the atmosphere. CO2 CO2

8. Stages of the Carbon Cycle • Decomposition: organisms called ‘decomposers’ break down dead organisms and animal waste, releasing CO2 or methane in the process. CO2, methane

9. Stages of the Carbon Cycle • Ocean Sediment: Carbon dioxide from the atmosphere dissolves in oceans to form bicarbonate. This is used by marine organisms to create their shells and skeletons, which sink to the ocean floor when they die, and accumulate in the sediment, eventually forming carbonate rock. CO2

10. Stages of the Carbon Cycle • Fossil fuels: When dead plant and animal matter are buried under sediment, they are converted into oil, coal or natural gas after millions of years. The burning of these fossil fuels by humans releasescarbon dioxide into the atmosphere.

11. Stages of the Carbon Cycle • Volcanic eruptions and forest fires: Also release carbon into atmosphere. CO2 CO2

12. 1 1 2 Decomposers 4 3 4

13. Carbon passed around from organism to organism in food chains

14. 1 1 2 Decomposers 4 3 4

15. The Nitrogen Cycle • The nitrogen cycle is the biogeochemical cycle that describes all the exchanges of nitrogen on earth.

16. The Nitrogen Cycle • The vast majority of nitrogen is found in the atmosphere, as N2, which cannot be directly used by plants or animals.

17. The Nitrogen Cycle • Nitrogen is used by living organisms to produce a number of complex organic molecules like amino acids, proteins and DNA. Nitrogen is normally the most limiting nutrient for plant growth.

19. Stages of the Nitrogen Cycle • Nitrogen fixation: N2 Bacteria in soil (or associated with plant roots) convert N2 into ammonia, which reacts with water to ammonium. ammonium

20. Stages of the Nitrogen Cycle • Nitrification: bacteria convert ammonium into nitrites, then into nitrates.

21. Stages of the Nitrogen Cycle • Nitrogen absorption (Assimilation): plants absorb nitrates or ammonium from soil or water and use it to create proteins. Animals can then get their nitrogen by eating the plants.

22. Stages of the Nitrogen Cycle • Decomposition of waste: decomposers break down dead organisms and animal waste, producing ammonia which dissolves to form ammonium. ammonium

23. Stages of the Nitrogen Cycle • Denitrification: certain bacteria can convert nitrates into atmospheric nitrogen. N2

24. Stages of the Nitrogen Cycle Nitrogen recycling (Decomposers) Nitrogen absorption Nitrogen fixation Denitrification N2 N2 Nitrification

26. 5 4 3 1 1 2

27. The Phosphorous Cycle - EST • Phosphorous (like nitrogen) is a component of DNA and is therefore an essential element or all life. Bone consists predominantly of a mineral containing phosphate.

28. Stages of the Phosphorous Cycle • Weathering of rock: water dissolves phosphorous in the form of phosphate. Phosphate is transported by water.

29. Stages of the Phosphorous Cycle • Absorption by living organisms. • Plants absorb phosphates, • animals eat plants or other animals.

30. Stages of the Phosphorous Cycle • Decomposition of waste • Return of Phosphorous to the soil through animal waste • decomposers Phosphate Phosphate

31. Stages of the Phosphorous Cycle • Proliferation of plankton and sedimentation • Phosphate in water promotes the growth of plankton  eaten by animals • Phosphate minerals precipitate  sedimentary rock

32. 1 2 3 4

33. Terrestrial Biomes Biome: a distinct ecological community of plants and animals living together in a particular climate.

34. Factors contributing to climate Latitude Altitude

35. Climate- Temperature The main factors which influence temperature are: 1. Latitude: as you move away from the equator, sunlight is less intense  lower temperature. 2. Altitude: with increases in elevation at a given latitude, the temperature decreases.

36. Climate- Temperature • Temperature plays a vital role because most organisms are adapted to live within a very narrow temperature range. Increasing or decreasing the temperature by even a few degrees can cause some species to die.

37. Factors affecting Terrestrial Biomes • Latitude • Altitude • Solar energy • Temperature • Precipitation • Soil type • Winds • Proximity to bodies of water

38. Hadley Cells and climate zones • Hot moist air rises at the Equator (1) air cools and water condenses, it rains (2) • Dry air moves towards 30°, sinks and warms up (3). • Dry hot air moves back towards Equator, collecting all water from the land underneath (4) Latitude determines how much it rains  Desert

39. Also where Ferrel and Polar Cell meet warm moist air rises: water condenses  rain.

41. Influence of Altitude on precipitation Andes (mountain chain) West wind zone Desert in wind shadow

42. Climate- Precipitation • Plays a vital role because all living organisms require water

43. Climate- Precipitation • Precipitation tends to be generally higher where air is rising & cooling, releasing moisture: • near the equator, most significantly- produces tropical rainforests or tropical seasonal forests • at 60o N & S latitude, to lesser extent- produces temperate deciduous forests, temperate rainforests, coniferous forests.

44. Climate- Precipitation • Precipitation tends to be generally lower: • near 30 o N & S latitude- dry, descending air masses produce deserts (all great world deserts lie near 30 o N or S latitude) • in interiors of large continents- due to great distance from sea (ultimate source of most moisture)

45. Terrestrial Biomes: Can you name these? Desert Desert Boreal Forest Arctic Tundra Tropical Rainforest

46. Tropical Forests • Lie on either side of the equator (warm temperatures) • High precipitation • Contain over half of the world’s terrestrial biodiversity • Soil rather infertile due to leaching (excessive rain), and very fast decomposition of organic matter.

47. Seasonal tropical rain forest • Mainly in Africa • Dry season of varying length

48. Temperate Forests • Contain mix of deciduous and coniferous trees • Nutrient rich soils make an excellent habitat for plant growth and animals • Warm and cold season • Precipitation evenly throughout year

49. Boreal Forest/Taiga • Composed mostly of coniferous trees, which do not lose leaves/needles • Acidic, nutrient poor soils • Long, cold winters; short, cool summers

50. Taiga: trees become shorter and more scarce