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39 Lecture Ppt

  1. 1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 39 Major Ecosystems of the Biosphere
  2. 2. On Land, the Biosphere Is Organized into Terrestrial Ecosystems 39-
  3. 3. 39.1 Major terrestrial ecosystems are characterized by particular climates <ul><li>Each major terrestrial ecosystem has a particular mix of plants and animals that are adapted to living under certain conditions, particularly climate </li></ul><ul><ul><li>Climate - average yearly temperature and precipitation of a region </li></ul></ul><ul><li>When terrestrial ecosystems are plotted according to their climate, a particular distribution pattern results </li></ul>39-
  4. 4. Figure 39.1 Pattern of ecosystem distribution on land 39-
  5. 5. 39-
  6. 6. 39.2 The tundra is cold and dark much of the year <ul><li>Arctic tundra encircles the Earth just south of the ice-covered polar seas in the Northern Hemisphere </li></ul><ul><ul><li>Covers about 20% of the Earth’s land surface </li></ul></ul><ul><li>Arctic tundra is cold and dark much of the year </li></ul><ul><ul><li>Its winters are extremely long, cold, and harsh, and its summers are short (6–8 weeks) </li></ul></ul><ul><li>Because rainfall amounts to only about 20 cm a year, the tundra could possibly be considered a desert </li></ul><ul><ul><li>Only the topmost layer of soil thaws, permafrost beneath this layer is always frozen </li></ul></ul><ul><li>Trees are not found in the tundra </li></ul><ul><ul><li>Growing season too short and roots cannot penetrate permafrost </li></ul></ul>39-
  7. 7. Figure 39.2 Tundra, the northern-most ecosystem 39-
  8. 8. 39.3 Coniferous forests are dominated by gymnosperms <ul><li>Coniferous forests are found in three locations </li></ul><ul><ul><li>Taiga - which extends around the world in the northern part of North America and Eurasia </li></ul></ul><ul><ul><li>Near mountaintops (called montane coniferous forest) </li></ul></ul><ul><ul><li>Along the Pacific coast of North America, as far south as northern California </li></ul></ul><ul><li>Taiga (called boreal or northern) forest, exists south of the tundra and covers approximately 11% of the Earth’s landmasses </li></ul><ul><ul><li>Needlelike leaves of its cone-bearing trees can withstand the weight of heavy snow </li></ul></ul><ul><li>Temperate rain forest - coniferous forest that runs along the west coasts of Canada and the United States </li></ul><ul><ul><li>Plentiful rainfall and rich soil produce some of tallest trees ever </li></ul></ul><ul><ul><li>Also called old-growth because some trees are >1,000 years old </li></ul></ul>39-
  9. 9. Figure 39.3 Taiga, a northern coniferous forest 39-
  10. 10. 39.4 Temperate deciduous forests have abundant life <ul><li>Temperate deciduous forests </li></ul><ul><ul><li>Found south of the taiga in eastern North America, eastern Asia, and much of Europe </li></ul></ul><ul><ul><li>Seasons are well defined, and growing season ranges between 140 and 300 days </li></ul></ul><ul><ul><li>Trees (oak, beech, sycamore, and maple) have broad leaves and are deciduous - lose their leaves in fall and grow them in spring </li></ul></ul><ul><ul><li>Tallest trees form a canopy, but enough sunlight penetrates to provide energy for understory trees </li></ul></ul><ul><ul><ul><li>Stratification provides habitats for insects and birds </li></ul></ul></ul><ul><ul><li>Autumn fruits, nuts, and berries provide food for the winter </li></ul></ul><ul><ul><li>Leaves, after turning brilliant colors and falling to the ground, contribute to a rich layer of humus </li></ul></ul>39-
  11. 11. Figure 39.4 Temperate deciduous forest in the fall 39-
  12. 12. 39.5 Temperate grasslands have extreme seasons <ul><li>Temperate grasslands </li></ul><ul><ul><li>Include Russian steppes, South American pampas, and North American prairies </li></ul></ul><ul><ul><li>Bitterly cold winters and hot and dry summers </li></ul></ul><ul><ul><li>Across the United States from east to west </li></ul></ul><ul><ul><ul><li>Temperate deciduous forest transitions into tall-grass prairie roughly along the border between Illinois and Indiana </li></ul></ul></ul><ul><ul><ul><li>Tall-grass prairie requires more rainfall than does the short-grass prairie , which occurs near desert </li></ul></ul></ul><ul><ul><li>Large herds of bison (hundreds of thousands) once roamed the prairies, and pronghorn antelope </li></ul></ul><ul><ul><li>Small mammals, (mice, prairie dogs, and rabbits) live below ground, but usually feed aboveground </li></ul></ul>39-
  13. 13. Figure 39.5 Temperate grassland in the summer 39-
  14. 14. 39.6 Savannas have wet-dry seasons <ul><li>Savannas - in regions where a cool dry season is followed by hot rainy season </li></ul><ul><ul><li>Largest savannas are in central and southern Africa </li></ul></ul><ul><ul><ul><li>Other savannas in Australia, Southeast Asia, and South America </li></ul></ul></ul><ul><ul><li>Characterized by large expanses of grasses with sparse populations of trees </li></ul></ul><ul><ul><ul><li>Plants have extensive and deep root systems that enable them to survive drought and fire </li></ul></ul></ul><ul><ul><li>African savanna supports the greatest variety and number of large herbivores of all the biomes </li></ul></ul><ul><ul><ul><li>Elephants and giraffes are browsers that feed on tree vegetation </li></ul></ul></ul><ul><ul><ul><li>Antelopes, zebras, wildebeests, water buffalo, and some rhinoceroses are grazers that feed on grasses </li></ul></ul></ul>39-
  15. 15. Figure 39.6 The African savanna 39-
  16. 16. 39.7 Deserts have very low annual rainfall <ul><li>Deserts usually found at latitudes of about 30° in both the Northern and Southern Hemispheres </li></ul><ul><ul><li>Winds that descend in these regions lack moisture, and the annual rainfall is less than 25 cm </li></ul></ul><ul><ul><li>Days are hot because a lack of cloud cover allows the sun’s rays to penetrate easily </li></ul></ul><ul><ul><ul><li>Nights are cold because heat escapes easily into atmosphere </li></ul></ul></ul><ul><ul><li>Most have plants highly adapted to survive long droughts, extreme heat, and extreme cold </li></ul></ul><ul><ul><ul><li>Thick epidermal layers, water-storing stems and leaves, and the ability to set seeds quickly in the spring </li></ul></ul></ul><ul><ul><ul><li>Sahara Desert and a few others have little vegetation </li></ul></ul></ul><ul><ul><li>Some animals are adapted to the desert environment </li></ul></ul><ul><ul><ul><li>To conserve water, many desert animals are nocturnal or burrowing and have a protective outer body covering </li></ul></ul></ul><ul><ul><ul><li>A desert has numerous insects, which pass through the stages of development when there is rain </li></ul></ul></ul>39-
  17. 17. Figure 39.7 Desert with some vegetation 39-
  18. 18. 39.8 Tropical rain forests are warm with abundant rainfall <ul><li>Tropical rain forests of South America, Africa, and the Indo-Malayan </li></ul><ul><ul><li>Temperature is always warm (20° to 25°C) </li></ul></ul><ul><ul><li>Rainfall is plentiful (minimum of 190 cm/year) </li></ul></ul><ul><li>May be the richest ecosystem </li></ul><ul><ul><li>Diversity of species is enormous </li></ul></ul><ul><ul><ul><li>10 km 2 area of tropical rain forest may contain 1,500 species of flowering plants </li></ul></ul></ul><ul><li>Complex structure, with many levels of life, including the forest floor, the understory, and the canopy </li></ul><ul><ul><li>Sunlight is filtered out by canopy, and plants of the forest floor, such as ferns, are tolerant of minimal light </li></ul></ul><ul><ul><li>Understory consists of shorter trees that receive some light and bear epiphytes </li></ul></ul><ul><ul><ul><li>Epiphytes are plants that grow on other plants but usually have roots of their own that absorb moisture and minerals leached from their hosts </li></ul></ul></ul><ul><li>Some animals live on the forest floor, but most live in the trees </li></ul><ul><ul><li>Insects are so abundant that majority of species have not been identified </li></ul></ul>39-
  19. 19. Figure 39.8A Levels of life in a tropical rain forest 39-
  20. 20. Figure 39.8B Representative animals of the tropical rain forests of the world 39-
  21. 21. 39.9 Solar radiation and winds influence climate <ul><li>Sun’s rays are more direct at the equator and more spread out at the polar regions </li></ul><ul><ul><li>Tropics are warmer than temperate regions </li></ul></ul><ul><li>Overall flows of warm and cold air are modified into three large circulation cells in each hemisphere </li></ul><ul><ul><li>Rising air flows toward the poles, but at about 30° north and south latitude, it sinks toward the Earth’s surface and reheats </li></ul></ul><ul><ul><li>Deserts of Africa, Australia, and the Americas occur at these latitudes </li></ul></ul><ul><ul><ul><li>At Earth’s surface, air flows both poleward and equatorward </li></ul></ul></ul><ul><ul><ul><li>At about 60° north and south latitude, the air rises and cools, producing additional zones of high rainfall </li></ul></ul></ul><ul><li>Besides affecting precipitation, the spinning of the Earth also affects the direction of the winds </li></ul><ul><ul><li>Periods of calm, called the doldrums, occur at the equator </li></ul></ul>39-
  22. 22. Figure 39.9A Left : Distribution of sun’s rays as the Earth orbits the sun. Right : Distribution of solar energy as the Earth orbits the sun 39-
  23. 23. Figure 39.9B Wind circulation as air moves from the equator to the poles and back again 39-
  24. 24. 39.10 Topography and other effects also influence climate <ul><li>Topography - surface features of land </li></ul><ul><ul><li>Mountains are topographic features that affect climate, and distribution of ecosystems </li></ul></ul><ul><ul><ul><li>Difference between the windward side and the leeward side can be quite dramatic </li></ul></ul></ul><ul><ul><ul><li>Example: Hawaiian Islands </li></ul></ul></ul><ul><ul><ul><ul><li>Windward receives more than 750 cm of rain a year </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Leeward side, which is in a rain shadow, gets on the average only 50 cm of rain and is generally sunny </li></ul></ul></ul></ul><ul><li>Nearby Bodies of Water </li></ul><ul><ul><li>Ocean temperature is more stable than landmasses </li></ul></ul><ul><ul><li>Ocean water gains or loses heat more slowly than terrestrial environments </li></ul></ul><ul><ul><li>Monsoon climate - wet ocean winds blow onshore for almost half the year </li></ul></ul>39-
  25. 25. Figure 39.10A Elevation affects the distribution of terrestrial ecosystems 39-
  26. 26. Figure 39.10B Formation of a rain shadow 39-
  27. 27. Fresh Water and Salt Water Are Organized into Aquatic Ecosystems 39-
  28. 28. 39.11 Fresh water flows into salt water <ul><li>Fresh water flows within streams and rivers and is contained, at least temporarily, in lakes and ponds </li></ul><ul><ul><li>Mountain streams have cold, clear water with waterfalls and rapids </li></ul></ul><ul><ul><li>Streams join to form a river that flows gently </li></ul></ul><ul><ul><li>River meanders across broad valleys, and empties into ocean </li></ul></ul><ul><ul><li>At its mouth, river divides into many muddy channels of a delta </li></ul></ul><ul><ul><li>Salt marshes are extremely productive ecosystems </li></ul></ul><ul><li>Wetlands (wet some part of year) directly absorb storm waters and also absorb overflows from lakes and rivers </li></ul><ul><ul><li>In this way, they protect farms, cities, and towns from the devastating effects of floods </li></ul></ul><ul><li>Lakes are often classified by nutrient status </li></ul><ul><ul><li>Oligotrophic lakes are nutrient-poor, having a small amount of organic matter and low productivity </li></ul></ul><ul><ul><li>Eutrophic lakes are nutrient-rich, having plentiful organic matter and high productivity </li></ul></ul>39-
  29. 29. Figure 39.11A A freshwater and saltwater ecosystem 39-
  30. 30. Figure 39.11B Types of lakes 39-
  31. 31. 39.12 Marine ecosystems include those of the coast and the ocean <ul><li>Coastal Ecosystems Border the Oceans </li></ul><ul><ul><li>Salt marshes, discussed previously, and also mudflats and mangrove swamps are ecosystems that occur at a delta </li></ul></ul><ul><ul><ul><li>Mangrove swamps develop in subtropical and tropical zones, while marshes and mudflats occur in temperate zones </li></ul></ul></ul><ul><li>Estuary - partially enclosed body of water where fresh water and sea water meet and mix as a river enters the ocean </li></ul><ul><ul><li>Organisms living in an estuary must be able to withstand constant mixing of waters and rapid changes in salinity </li></ul></ul><ul><ul><li>Nearly two-thirds of marine fishes and shellfish spawn and develop in the protective and rich environment of estuaries </li></ul></ul><ul><li>Intertidal zone - lies between the high and low tide marks </li></ul><ul><ul><li>Rocky shores and sandy shores are constantly bombarded by the sea as the tides roll in and out </li></ul></ul>39-
  32. 32. Figure 39.12A Coastal ecosystems 39-
  33. 33. Figure 39.12B Ocean ecosystems 39-
  34. 34. Oceans <ul><li>Shallow ocean waters ( euphotic zone ) contain a greater concentration of organisms than the rest of the sea </li></ul><ul><ul><li>Phytoplankton (algae) is food not only for zooplankton (protozoans and microscopic animals) but also for small fishes </li></ul></ul><ul><li>Coral reefs - areas of biological abundance just below the surface in shallow, warm, tropical waters </li></ul><ul><ul><li>Chief constituents are stony corals, animals that have a calcium carbonate (limestone) exoskeleton, and calcareous red and green algae </li></ul></ul><ul><li>Most of the ocean lies within the pelagic zone </li></ul><ul><ul><li>Epipelagic zone lacks the inorganic nutrients of shallow waters, and therefore it does not have as high a concentration of phytoplankton </li></ul></ul><ul><ul><li>Animals in the deeper waters of the mesopelagic zone are carnivores, which are adapted to the absence of light, </li></ul></ul><ul><ul><li>Waters of the bathypelagic zone are in complete darkness except for an occasional flash of bioluminescent light </li></ul></ul><ul><ul><li>Abyssal plain - many invertebrates survive there by feeding on debris floating down from the mesopelagic zone </li></ul></ul><ul><ul><li>At hydrothermal vents , sea water percolates through cracks and is heated to about 350°C, causing sulfate to react with water and form hydrogen sulfide </li></ul></ul>39-
  35. 35. Figure 39.12C Ocean inhabitants in divisions of pelagic zone 39-
  36. 36. 39.13 Ocean currents affect climates <ul><li>Climate is driven by the sun, but the oceans play a major role in redistributing heat in the biosphere </li></ul><ul><ul><li>Air takes on the temperature of the water below, and warm air moves from the equator to the poles </li></ul></ul><ul><ul><ul><li>The oceans make the winds blow </li></ul></ul></ul><ul><li>Because the ocean currents eventually strike land, they move in a circular path </li></ul><ul><ul><li>Clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere </li></ul></ul><ul><li>As the currents flow, they take warm water from the equator to the poles </li></ul><ul><ul><li>One such current, called the Gulf Stream, brings tropical Caribbean water to the east coast of North America and the higher latitudes of western Europe </li></ul></ul>39-
  37. 37. Figure 39.13 Ocean currents 39-
  38. 38. Connecting the Concepts: Chapter 39 <ul><li>Earth’s diverse ecosystems have resulted from interactions between the biotic communities and the abiotic environment </li></ul><ul><ul><li>Organisms create chemical and physical conditions of streams, lakes, and oceans </li></ul></ul><ul><li>Over geologic time, the biosphere has been changing constantly </li></ul><ul><ul><li>Changes in the sun’s radiation output and in the tilt of the Earth’s axis have altered the pattern of solar energy reaching the Earth’s surface </li></ul></ul><ul><ul><li>Geologic processes have modified conditions for life </li></ul></ul><ul><li>Modern humans have transformed vast areas of many of the terrestrial biomes into farmland, cities, highways, and other developments </li></ul><ul><ul><li>Through our use of resources and release of pollutants, we have now become an agent of global importance </li></ul></ul><ul><ul><li>We still depend on the biodiversity that exists in the Earth’s biomes, and on the interactions of other organisms within the biosphere </li></ul></ul><ul><ul><li>These interactions influence climate, patterns of nutrient cycling and waste processing, and basic biological productivity </li></ul></ul><ul><ul><li>The Earth’s biotic diversity also provides enjoyment and inspiration to millions of people, who spend billions of dollars to visit coral reefs, deserts, rain forests, and even the Arctic tundra </li></ul></ul>39-