12 ecosystems


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12 ecosystems

  1. 1. Announcements March 7, 2011 <ul><li>Exam 1 results are in! </li></ul><ul><ul><li>Please see your TA if you want to go over your exam </li></ul></ul><ul><li>In discussion this week: </li></ul><ul><ul><li>Global Climate Change </li></ul></ul><ul><ul><li>Water Use vs. Distribution </li></ul></ul>
  2. 2. Exam 1 distribution Mean = 87
  3. 3. Types of Ecosystems I & II Lecture Objectives: <ul><li>Understand Succession </li></ul><ul><li>Learn the characteristics of the major ecosystems </li></ul>
  4. 4. Recurring Themes… <ul><li>Terrestrial vs. Aquatic </li></ul><ul><li>Type of ecosystem influenced by: </li></ul><ul><ul><li>rock/soil type </li></ul></ul><ul><ul><li>temperature </li></ul></ul><ul><ul><li>precipitation </li></ul></ul><ul><ul><li>producers/consumers </li></ul></ul><ul><ul><li>surrounding ecosystems </li></ul></ul><ul><ul><li>time </li></ul></ul>
  5. 5. Community Properties <ul><li>Abundance -Total number of organisms in a community. </li></ul><ul><li>Diversity - Number of different species, ecological niches, or genetic variation. </li></ul><ul><ul><li>As a general rule, diversity decreases when moving from the equator to the poles </li></ul></ul><ul><ul><li>Don ’t forget, its not only about the number of species but also the number of interactions… </li></ul></ul>
  6. 6. <ul><li>Succession - communities proceeding through predictable changes through time </li></ul>
  7. 7. Succession <ul><li>Outcome is a climax community </li></ul><ul><ul><li>- stable, long-lasting community </li></ul></ul>
  8. 8. Two types of succession <ul><ul><li>Primary - begins with total lack of organisms, bare mineral surface </li></ul></ul>bssv01.lancs.ac.uk/bs/research/ soilecol/linkgrd.htm Succession following melting of the Muir Glacier
  9. 9. Primary succession <ul><ul><li>Starts with bare rock, sand, clay, etc. </li></ul></ul><ul><ul><li>Colonized by pioneer community </li></ul></ul><ul><ul><ul><li>First to colonize bare rock </li></ul></ul></ul><ul><ul><ul><li>Mainly lichens = mutualistic association of algae or bacteria and fungi </li></ul></ul></ul>
  10. 10. Primary succession <ul><ul><li>Acids produced by lichens, physical, chemical weathering break down rock </li></ul></ul><ul><ul><li>Dead organic matter and weathered rock create soil </li></ul></ul>
  11. 11. Primary succession <ul><ul><li>Lichens eventually replaced by small, annual plants </li></ul></ul><ul><ul><li>Replaced by smaller perennial plants: herbs and grasses </li></ul></ul><ul><ul><li>Replaced by grasses, shrubs, shade intolerant trees </li></ul></ul><ul><ul><li>Climax forest composed of shade tolerant trees </li></ul></ul>
  12. 12. <ul><ul><li>“ Climax” community is not a preordained set of species </li></ul></ul><ul><ul><li>Rate of succession and kind of climax community determined by: </li></ul></ul><ul><ul><ul><li>Type of initial substrate </li></ul></ul></ul><ul><ul><ul><li>Climate </li></ul></ul></ul><ul><ul><ul><ul><li>Rate of soil accumulation </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Water availability </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Temperature </li></ul></ul></ul></ul>
  13. 13. <ul><ul><li>Secondary - begins with destruction or disturbance of existing ecosystem </li></ul></ul>Primary takes longer than secondary http://content.lib.washington.edu/mtsthelens/ © Roger del Moral Mount St. Helens 1980 1996 Two types of succession
  14. 14. Secondary succession <ul><li>Main difference from primary succession: </li></ul><ul><ul><li>Results from disturbance to “climax” community </li></ul></ul><ul><ul><ul><li>- Soil already formed </li></ul></ul></ul><ul><ul><ul><li>- Pool of species in soil or nearby that can quickly colonize </li></ul></ul></ul>
  15. 17. Biomes - climax communities with wide geographical distributions <ul><li>Terrestrial biomes primarily influenced by: </li></ul><ul><ul><li>Precipitation : </li></ul></ul><ul><ul><ul><li>total amount per year </li></ul></ul></ul><ul><ul><ul><li>seasonal distribution </li></ul></ul></ul><ul><ul><ul><li>form (rain, snow) </li></ul></ul></ul><ul><ul><li>Temperature : </li></ul></ul><ul><ul><ul><li>range of temperatures </li></ul></ul></ul><ul><ul><ul><li>seasonal patterns </li></ul></ul></ul><ul><ul><li>Other factors: soil type, wind, fire, etc. </li></ul></ul>
  16. 18. <ul><ul><ul><li>Precipitation and temperature influenced by latitude, longitude, and altitude </li></ul></ul></ul>
  17. 19. % IB 105 students who have visited: Tropical Forest: 26% Prairie or other grassland: 69% Desert: 39%
  18. 20. Major Terrestrial Biomes
  19. 21. Tundra <ul><li>Occurs at extreme northern latitudes, </li></ul><ul><li>or high elevations (mountain tundra) </li></ul>
  20. 22. Tundra <ul><li>Key characteristics </li></ul><ul><ul><li>low precipitation (<35cm) </li></ul></ul><ul><ul><li>Permanently frozen soil layer = permafrost </li></ul></ul><ul><ul><li>Waterlogged soils common in summer </li></ul></ul><ul><ul><ul><li>Low evaporation, permafrost </li></ul></ul></ul><ul><ul><li>Short plants dominate </li></ul></ul><ul><ul><ul><li>Grasses, dwarf birch, dwarf willow, lichens </li></ul></ul></ul>
  21. 23. Desert <ul><li>Key characteristics </li></ul><ul><ul><li>Very little water (<25 cm/year) </li></ul></ul><ul><ul><li>High evaporation </li></ul></ul><ul><ul><li>Large daily temperature fluctuations </li></ul></ul><ul><ul><li>Species not very dense </li></ul></ul><ul><ul><li>Species have adaptations to hot, dry environment </li></ul></ul><ul><ul><ul><li>Plants – small leaves, store water, dormancy </li></ul></ul></ul><ul><ul><ul><li>Animals – Night activity, conserve water </li></ul></ul></ul>
  22. 24. Common myths about deserts: <ul><li>They are nothing but sand </li></ul>Joshua Tree National Park, CA Gobi Desert, Asia Mohawk Dunes, AZ
  23. 25. Common myths about deserts: <ul><li>Not much lives there </li></ul><ul><li>Burrowing animals, rodents, lizards, snakes </li></ul>
  24. 26. Common misperceptions about deserts: <ul><li>They are always unbearably hot </li></ul>
  25. 27. results from over grazing, intense agricultural use, erosion, water runoff, and over heating of soil. Desertification : change from fertile land to desert.
  26. 28. Boreal Forest <ul><li>Also called taiga, northern coniferous forest </li></ul><ul><li>Occurs in southern Canada, northern Europe, much of Russia </li></ul>
  27. 29. Boreal Forest <ul><li>Key characteristics </li></ul><ul><ul><li>Moderate to low precipitation (25-100 cm) </li></ul></ul><ul><ul><li>Short, cool summer; Long harsh winters </li></ul></ul><ul><ul><li>Spruce and fir, dominant vegetation </li></ul></ul><ul><ul><li>Humid due to precipitation and low evaporation, but winter dry because precipitation is snow </li></ul></ul>
  28. 30. Temperate Deciduous Forest <ul><li>Occur in eastern half of U.S., south central and eastern Canada, southern Africa, Europe, Asia </li></ul>
  29. 31. Temperate Deciduous Forest <ul><li>Key characteristics </li></ul><ul><ul><li>Moderate rainfall (75-100 cm), relatively evenly distributed </li></ul></ul><ul><ul><li>Warm summers and relatively mild winters </li></ul></ul><ul><ul><li>Trees dominant vegetation, type of tree varies geographically </li></ul></ul><ul><ul><ul><li>In North America, dominant trees are maples, aspen, oaks, hickories, etc. </li></ul></ul></ul>
  30. 32. Grasslands <ul><li>Occur in temperate areas </li></ul><ul><li>Also called prairies or steppes </li></ul>
  31. 33. Grasslands <ul><li>Key characteristics </li></ul><ul><ul><li>Medium precipitation (25-75 cm) </li></ul></ul><ul><ul><li>Hot summers, cold to mild winters </li></ul></ul><ul><ul><li>Grasses dominant vegetation </li></ul></ul><ul><ul><ul><li>Need fire to prevent invasion of trees, release nutrients </li></ul></ul></ul>
  32. 34. Grasslands <ul><li>Key characteristics </li></ul><ul><ul><li>Lots of grazing animals </li></ul></ul><ul><ul><ul><li>Wastes fertilize prairies, grazing helps keep out trees </li></ul></ul></ul><ul><ul><li>Most grassland has been converted to agriculture </li></ul></ul>
  33. 35. Savanna <ul><li>Occurs in Africa, South America, Australia </li></ul><ul><li>Key characteristics </li></ul><ul><ul><li>High rainfall (50-150 cm), but unevenly distributed </li></ul></ul><ul><ul><ul><li>Periods of high rainfall, followed by droughts </li></ul></ul></ul><ul><ul><li>Temperature warm, relatively constant </li></ul></ul>
  34. 36. Savanna <ul><li>Key characteristics </li></ul><ul><ul><li>Plants dominated by grasses and drought resistant trees </li></ul></ul><ul><ul><li>Dominant animals are grazers </li></ul></ul><ul><ul><li>Plant and animal reproduction timed around rainy season, when resources least limiting </li></ul></ul>
  35. 37. Mediterranean Shrublands <ul><li>Also known as Chaparral . </li></ul><ul><li>Receives 40-100 cm annual precipitation. </li></ul><ul><ul><li>Wet, cool winters and hot, dry summers. </li></ul></ul><ul><ul><ul><li>Typical of Mediterranean coast and coastal southern California. </li></ul></ul></ul>
  36. 38. Mediterranean Shrublands <ul><li>Vegetation dominated by woody shrubs adapted to hot, dry summers. </li></ul><ul><li>Fire is a common feature. </li></ul>
  37. 39. Tropical Dry Forest <ul><li>Annual precipitation ranges 50-200 cm. </li></ul><ul><li>Many exhibit monsoon climate. </li></ul><ul><ul><li>Rainfall highly seasonal. </li></ul></ul><ul><ul><ul><li>Drought resistant plants. </li></ul></ul></ul>
  38. 40. Tropical Rainforest <ul><li>Occur along equator in Central and South America, Africa, Southeast Asia, Caribbean and Pacific Islands </li></ul>
  39. 41. Tropical Rainforest <ul><li>Key characteristics </li></ul><ul><ul><li>Temperature warm and relatively constant </li></ul></ul><ul><ul><li>Very high rainfall (>200 cm/year) </li></ul></ul><ul><ul><li>Rapid growth, but nutrient poor soils </li></ul></ul><ul><ul><li>Multi-layered forests of emergent trees, canopy trees, understory trees, shade-tolerant plants, and epiphytes </li></ul></ul><ul><ul><li>Most diverse biome on earth </li></ul></ul>