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Terrestrial Ecosystems

Terrestrial Ecosystems. Terrestrial ecosystems are limited by four major abiotic factors:. 1 . Soil : nutrients for plants. . Litter – partly decomposed leaves and grasses Topsoil – small particles of rock and decaying plant / animal matter

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Terrestrial Ecosystems

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  1. Terrestrial Ecosystems

  2. Terrestrial ecosystems are limited by four major abiotic factors: 1. Soil: nutrients for plants.

  3. Litter – partly decomposed leaves and grasses Topsoil – small particles of rock and decaying plant / animal matter Subsoil – more rock with slight amounts of organic matter Soil pH – acidity of the soil will be affected by acid deposition, leaching and by percolation. Different plants grow better under specific pH conditions.

  4. Available Water • Temperature: strategies such as hibernation, shedding leaves, a winter coat and dormancy help survival 4. Sunlight: varies with the geographical location and with the canopy plants that are growing in a specific area.

  5. Grassland Biome

  6. Deciduous Forest Biome

  7. Taiga Biome

  8. Tundra Biome

  9. Changes to terrestrial ecosystems: • Forestry – deforestation by slash and burn, clear cutting or by selective cutting

  10. Forest Fires –natural ecological process to clean up dead plant material and stimulate re-growth of young healthy plants.

  11. Ecological succession • gradual change of a community as it is either developed from bare land or replaced by another community.

  12. Pioneer Community – is the first species to appear during succession. • Climax Community – is the final stable community that results at the end of succession.

  13. Primary Succession – the gradual colonization of an area that has not supported an ecosystem before. (from bare rock)

  14. Secondary Succession – the colonization of an area that once supported an ecosystem that was destroyed by fire, flood, etc.

  15. Limnology Limnology Freshwater Ecology Freshwater Ecology

  16. Freshwater Aquatic Communities • lakes and ponds • rivers and streams • Estuaries – are where freshwater in river meets salt ocean water (brackish)

  17. Standing Water – Lakes and Ponds • Ponds are shallow enough so that light penetrates to bottom • Lakes are too deep for light to reach bottom (in middle)

  18. Structure of Lakes and Ponds

  19. Structure of Lakes and Ponds Zones: - Littoral Zone – shallow enough for rooted aquatic plants (emergent vegetation)

  20. Littoral zone contains a great variety of living creatures

  21. Structure - Limnetic Zone – from edge of emergent plant zone to the center of the lake, but only to depth of effective light penetration

  22. In limnetic zone, plankton are major life forms • Plankton are creatures too small to swim against currents • Phytoplankton – include algae, duckweed • Zooplankton – include protists and single-celled creatures

  23. Phytoplankton Zooplankton

  24. Profundal Zone – deep, dark area beneath the limnetic zone • Feed on ‘organic rain’ of detritus • Bacteria, worms and other decomposers

  25. Benthic Zone – the area at the bottom of the lake or pond

  26. Benthic Organisms

  27. Lake and Pond Succession • Eutrophication: “aging” to become bogs, meadows and then forest • Matter is added to water through erosion, runoff, etc.

  28. Eutrophication • shallow regions first

  29. Eutrophication • Excess nutrients can speed eutrophication • Especially nitrates and phosphates can speed algal growth and deposition of sediment • increases the cloudiness (turbidity) of the water

  30. Eutrophication • Eutrophic lakes: shallow, warm, turbid and low oxygen levels

  31. Oligotrophic Lakes • have few nutrients, so eutrophication is very slow • Deep, cold, higher oxygen

  32. Mesotrophic Lakes • Are between eutrophic and oligotrophic

  33. Lake Temperature • water is most dense at 4oC and sinks

  34. A) Spring Overturn • warming causes the top layer to become more dense as it reaches 4 oC • Top layer sinks to bottom, bottom layer is pushed to top

  35. brings nutrients from the bottom to the surface • brings oxygen to the bottom

  36. B) Summer • In deeper lakes, stratification

  37. The layer in which the temperature rapidly drops is the thermocline

  38. C) Fall • cooling causes the top layer to become more dense as it reaches 4 oC • Top layer sinks to bottom, bottom layer is pushed to top

  39. brings nutrients to surface, often causing late summer algal blooms • brings oxygen to depths

  40. D) Winter • Lake reaches equilibrium • Snow/ice on surface insulates water beneath

  41. Thermal Pollution • Heat added to lakes when water is used for cooling equipment • Decreases dissolved oxygen • More algal growth, thus faster eutrophication of the water body

  42. Coliform Bacteria • A typical test of raw sewage levels in water bodies

  43. Chlorophyll • Another test used to determine how much microscopic algae is in water

  44. Summary • Often nutrient status of lakes/ponds is determined by tests like: • Secchi disc • Dissolved oxygen • Temperature profile • Coliform test • Chlorophyll test • Nutrient tests (nitrate, phosphate) • pH

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