Chapter eleven


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Chapter eleven

  1. 1. Title Page Photo “ In short, the animal and vegetable lines, diverging widely above, join below in a loop.” —Asa Gray (
  2. 2. Ecosystems and Biomes <ul><li>Two organizing principles are ecosystem and biome. </li></ul><ul><li>Ecosystem: A Concept for All Scales </li></ul><ul><ul><li>Ecosystem —the totality of interactions among organisms and the environment in the area of consideration. </li></ul></ul><ul><ul><ul><li>Encompasses both the living and nonliving portion and how energy flows among them. </li></ul></ul></ul><ul><ul><ul><li>Weakness—there is an almost infinite variety in the magnitude of ecosystems that can be studied: </li></ul></ul></ul><ul><ul><li>Range includes whole Earth itself to drop of water. </li></ul></ul>
  3. 3. Ecosystems and Biomes <ul><li>Biome: A Scale for All Biogeographers </li></ul><ul><ul><li>Biome—a large, recognizable assemblage of plants and animals in functional interaction with its environment. </li></ul></ul><ul><ul><li>Most appropriate scale for understanding world distribution patterns. </li></ul></ul>
  4. 4. Ecosystems and Biomes <ul><li>Eleven major types </li></ul><ul><ul><li>Often significant and even predictable relationships exist between the biota (particularly the flora) of a biome and the associated climate and soil types. </li></ul></ul><ul><li>Ecotone—the transition zone between biotic communities in which the typical species of one community intermingle or interdigitate with those of another. </li></ul>Marsh/mangrove ecotone with fire, freeze, and hurricane damage. Taken September 20, 2001
  5. 5. Terrestrial Flora <ul><li>Geographers interested in natural vegetation of landscape for three reasons: </li></ul><ul><ul><li>Plants are likely to dominate a landscape (except where terrain is rugged, climate is harsh, or humans have intervened); </li></ul></ul><ul><ul><li>Vegetation is a sensitive indicator of other environmental attributes; </li></ul></ul><ul><ul><li>Vegetation is often instrumental to human settlement and activities. </li></ul></ul>
  6. 6. Characteristics of Plants <ul><li>Most very hardy. </li></ul><ul><li>High survival potential dependent on: </li></ul><ul><ul><li>Subsurface root system </li></ul></ul><ul><ul><li>Reproductive mechanism </li></ul></ul><ul><ul><ul><li>Perennial—plant that can live more than a single year despite seasonal climatic variations. </li></ul></ul></ul><ul><ul><ul><li>Annual—plant that perishes during times of climatic stress but leaves behind a reservoir of seeds to germinate during the next favorable period. </li></ul></ul></ul>
  7. 7. Characteristics of Plants <ul><li>Common characteristics: </li></ul><ul><ul><li>Roots (to gather nutrients and moisture and to anchor plant); </li></ul></ul><ul><ul><li>Stems and branches (to support and transport nutrients); </li></ul></ul><ul><ul><li>Leaves (to collect solar energy, exchange gases, and transpire water); </li></ul></ul><ul><ul><li>Reproductive organs. </li></ul></ul>
  8. 8. Floristic Terminology <ul><li>Categorizing by reproduction: </li></ul><ul><ul><li>Through spores </li></ul></ul><ul><ul><ul><li>Those that reproduce by spores are in two major groups: </li></ul></ul></ul><ul><ul><ul><ul><li>Bryophytes—spore-bearing plants such as mosses and liverworts; never dominated in history, but can be very important in some localized situations. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Pteridophytes—spore-bearing plants such as ferns, horsetails, and clubmosses; used to dominate continental vegetation, but no more. </li></ul></ul></ul></ul>Spores Bryophytes Pteridophytes
  9. 9. Floristic Terminology <ul><ul><li>Through seeds </li></ul></ul><ul><ul><ul><li>Those that reproduce by seeds are in two major groups: </li></ul></ul></ul><ul><ul><ul><ul><li>Gymnosperms—seed-reproducing plants that carry their seeds in cones; also known as conifers. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Used to be more important, in geologic past. </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><li>Angiosperms—plants that have seeds encased in some sort of protective body, such as a fruit, a nut, or a seedpod. </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Have dominated planet vegetation for last 50 million to 60 million years. </li></ul></ul></ul></ul></ul>Seeds Gymnosperms Angiosperms
  10. 10. <ul><ul><li>Other terms </li></ul></ul><ul><ul><ul><ul><li>Fig. 11-3 </li></ul></ul></ul></ul>Trees Gymnosperms Angiosperms Softwood Coniferous Needleleaf Hardwood Deciduous Broadleaf
  11. 11. Floristic Terminology <ul><li>Categorizing by stem or trunk composition: </li></ul><ul><ul><li>Woody plant—plant that has stem composed of hard fibrous material; refers mostly to trees and shrubs. </li></ul></ul><ul><ul><li>Herbaceous—refers to plants that have soft stems; mostly grasses, forbs, and lichens. </li></ul></ul><ul><li>Categorizing by leaf retention: </li></ul><ul><ul><li>Deciduous—refers to trees that experience an annual period in which all leaves die and usually fall from the tree, due either to a cold or dry season. </li></ul></ul><ul><ul><li>Evergreen—a tree or shrub that sheds its leaves on a sporadic or successive basis, but at any given time appears to be fully leaved. </li></ul></ul>
  12. 12. Floristic Terminology <ul><li>Categorizing by leaf shape: </li></ul><ul><ul><li>Broadleaf—tree that has flat and expansive leaves. </li></ul></ul><ul><ul><ul><li>Majority are deciduous. </li></ul></ul></ul><ul><ul><ul><li>In rainy tropics, everything is evergreen. </li></ul></ul></ul><ul><ul><li>Needleleaf—refers to trees adorned with thin slivers of tough, leathery, waxy needles rather than typical leaves. </li></ul></ul><ul><ul><ul><li>Almost all are evergreen. </li></ul></ul></ul>
  13. 13. Floristic Terminology <ul><li>Categorizing by supposed structure—but this is unsatisfactory. </li></ul><ul><ul><li>Hardwood—angiosperm tree that is usually broad-leaved and deciduous. Wood has a relatively complicated structure, but is not always hard. </li></ul></ul><ul><ul><li>Softwood —gymnosperm tree; nearly all such trees are needle-leaved evergreens with wood of simple cellular structure but not always soft. </li></ul></ul>
  14. 14. Environmental Adaptations <ul><li>Two prominent adaptation strategies of plants to protect against environmental stress are </li></ul><ul><ul><li>Xerophytic adaptations </li></ul></ul><ul><ul><li>Hygrophytic adaptations </li></ul></ul>
  15. 15. Environmental Adaptations <ul><li>Xerophytic—refers to plants structurally adapting to withstand protracted dry conditions. </li></ul><ul><ul><li>Roots, stems, leaves, reproductive cycle can all adapt in various ways. </li></ul></ul><ul><li>Succulent—plant that has fleshy stem that stores water. </li></ul>
  16. 16. Environmental Adaptations <ul><li>Hygrophytic—refers to plants structurally adapting to withstand protracted wet conditions. </li></ul><ul><li>Hygrophytic Adapatation </li></ul><ul><ul><li>Hygrophyte—plant that requires a saturated or semi-saturated environment (frequent soakings with water). </li></ul></ul>
  17. 17. Environmental Adaptations <ul><li>Likely to have extensive root system for anchoring in soft ground. </li></ul><ul><li>Usually relies on buoyancy of water for support rather than stem. </li></ul><ul><li>Many have weak, pliable stems so can withstand currents. </li></ul><ul><li>Hydrophytes are often grouped in with this category. </li></ul><ul><ul><li>Hydrophyte—a “water-loving” plant that is adapted to live in more or less permanently immersed in water. </li></ul></ul>
  18. 18. Environmental Adaptations <ul><li>Hygrophytic Adapatation </li></ul><ul><ul><li>Hygrophyte—plant that requires a saturated or semi-saturated environment (frequent soakings with water). </li></ul></ul><ul><ul><li>Likely to have extensive root system for anchoring in soft ground. </li></ul></ul><ul><ul><li>Usually relies on buoyancy of water for support rather than stem. </li></ul></ul><ul><ul><li>Many have weak, pliable stems so can withstand currents. </li></ul></ul><ul><li>Hydrophytes are often grouped in with this category. </li></ul><ul><ul><li>Hydrophyte—a “water-loving” plant that is adapted to live in more or less permanently immersed in water. </li></ul></ul>
  19. 19. The Critical Role of Competition <ul><li>Competition is key in which plants grow where. </li></ul><ul><ul><li>Even though all conditions (climatic, edaphic, etc.) are favorable, a plant may not take hold in one area because of competition. </li></ul></ul>Kudzu Vine
  20. 20. Spatial Groupings of Plants <ul><li>Geographers usually more concerned with spatial groupings than individual plants. </li></ul><ul><ul><li>Groups based on dominant members, dominant appearance, or both. </li></ul></ul>
  21. 21. Spatial Groupings of Plants <ul><li>Floristic pattern of Earth is impermanent. </li></ul><ul><li>Change can be slow and orderly, as in lake infilling. </li></ul><ul><li>Change can be abrupt and chaotic, as in wildfire. </li></ul><ul><ul><li>Climax vegetation—a stable plant association of relatively constant composition that develops at the end of a long succession of changes. </li></ul></ul>
  22. 22. Spatial Groupings of Plants <ul><li>Is an association in equilibrium with prevailing environmental conditions. </li></ul><ul><li>Should persist until environmental disturbance/change occurs. </li></ul><ul><li>Seral association—various stages leading up to climax vegetation. </li></ul>
  23. 23. Spatial Groupings of Plants <ul><li>Geographers can face significant difficulties in recognizing spatial groupings. </li></ul><ul><li>As one tries to identify patterns and recognize relationships, must make generalizations. </li></ul><ul><ul><li>When associations are portrayed on maps, boundaries usually represent approximations. </li></ul></ul><ul><ul><li>Human interference plays a major role. </li></ul></ul><ul><ul><li>Because of human impact, climax vegetation is now the exception rather than rule. </li></ul></ul><ul><li>Maps often ignore human interference, so are actually maps of theoretical natural vegetation. </li></ul>
  24. 24. Spatial Groupings of Plants <ul><li>Many ways to classify plant associations. </li></ul><ul><ul><li>Geographers usually place emphasis on structure and appearance of dominant plants. </li></ul></ul><ul><ul><li>Major associations include forests, woodlands, shrublands, grasslands, deserts, tundra, and wetlands. </li></ul></ul>
  25. 25. <ul><ul><ul><ul><li>Fig. 11-7 </li></ul></ul></ul></ul>
  26. 26. Spatial Groupings of Plants <ul><li>Forest—an assemblage of trees growing closely together so that their individual leaf canopies generally overlap. </li></ul><ul><ul><li>Likely to become climax association in any area where moisture is adequate and growing season isn’t very short. </li></ul></ul><ul><li>Woodland—tree-dominated association in which the trees are spaced more widely apart than those of forests and do not have interlacing canopies. </li></ul><ul><li>Shrubland —plant association dominated by relatively short woody plants. </li></ul><ul><ul><li>Wide latitudinal range but usually restricted to semiarid or arid areas. </li></ul></ul>
  27. 27. Spatial Groupings of Plants <ul><li>Grassland—plant association dominated by grasses and forbs. </li></ul><ul><ul><li>Prominent types are savanna, prairie, and steppe. </li></ul></ul><ul><ul><li>Associated with semiarid and subhumid climates. </li></ul></ul><ul><li>Desert—actually a climate, not an association per se, but is typified by plants widely scattered on bare ground. </li></ul><ul><li>Tundra—a complex mix of very low-growing plants, including grasses, forbs, dwarf shrubs, mosses, and lichens, but no trees. </li></ul><ul><ul><li>Only in the perennially cold climates of high latitudes or high altitudes. </li></ul></ul>
  28. 28. Spatial Groupings of Plants <ul><li>Wetland—landscape characterized by shallow, standing water all or most of the year, with vegetation rising above the water level. </li></ul><ul><ul><li>Have much more limited geographic extent than any other above associations. </li></ul></ul>Carson River, NV
  29. 29. Spatial Groupings of Plants <ul><li>Various plant associations will exist in relatively narrow zones when mountain slopes have significant elevational changes in short horizontal distances. </li></ul><ul><ul><li>Vertical zonation—the horizontal layering of different plant associations on a mountainside or hillside. </li></ul></ul><ul><ul><ul><li>Elevation changes are counterpart of latitude changes. </li></ul></ul></ul><ul><ul><ul><li>Treeline elevation varies with latitude. </li></ul></ul></ul><ul><ul><ul><li>Southern and Northern hemispheres experience different elevation–latitude relationship, with Southern Hemisphere having lower treelines. </li></ul></ul></ul><ul><ul><ul><li>Reason for discrepancy is not understood yet. </li></ul></ul></ul><ul><li>Can have significant local variations caused by a variety of local environmental conditions. </li></ul>
  30. 30. <ul><ul><ul><ul><li>Fig. 11-10 </li></ul></ul></ul></ul><ul><ul><li>Vertical Zonation </li></ul></ul><ul><ul><ul><li>Most apparent in mountains due to changes in elevations over short distances </li></ul></ul></ul>
  31. 31. Spatial Groupings of Plants <ul><li>Exposure to sunlight is often a critical determinant of vegetation composition. </li></ul><ul><ul><li>Adret slope—Sun slope; slope where Sun’s rays arrive at a relatively direct angle. </li></ul></ul><ul><ul><ul><li>Relatively hot and dry, and its vegetation is sparser and smaller than that on adjacent slopes with different exposures. </li></ul></ul></ul><ul><ul><ul><li>Likely to have species composition different from adjacent slopes. </li></ul></ul></ul><ul><ul><li>Ubac slope—a slope where sunlight strikes at a low angle and hence is much less effective in heating and evaporating than on the adret slope, thus producing more luxuriant vegetation of a richer diversity. </li></ul></ul><ul><ul><ul><li>Difference between adret and ubac decreases with increasing latitude. </li></ul></ul></ul><ul><ul><ul><li>Valley-bottom locations can have vegetation composition significantly different from slopes running to it. </li></ul></ul></ul>
  32. 32. <ul><ul><li>Local Variations </li></ul></ul><ul><ul><ul><li>Exposure to sunlight </li></ul></ul></ul><ul><ul><ul><ul><li>Mountainous landscapes </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Fig. 11-13 </li></ul></ul></ul></ul>
  33. 33. <ul><ul><li>Local Variation (continued) </li></ul></ul><ul><ul><ul><li>Valley-bottom location </li></ul></ul></ul><ul><ul><ul><ul><li>Fig. 11-14 </li></ul></ul></ul></ul>
  34. 34. Spatial Groupings of Plants <ul><li>Riparian vegetation—streamside growth, particularly prominent in relatively dry regions, where stream courses may be lined with trees, although no other trees are to be found in the landscape. </li></ul>
  35. 35. Terrestrial Fauna <ul><li>Animals occur in much greater variety than plants over Earth. </li></ul><ul><li>Animals, however, tend to be much less prominent than plants in the landscape. </li></ul><ul><li>They tend to be secretive and inconspicuous. </li></ul><ul><li>Also, environmental relationships are much less clearly evidenced by animals than plants. </li></ul><ul><li>Their inconspicuousness makes it more difficult to study them, and their mobility had lead to greater environmental adaptability among them. </li></ul>
  36. 36. Characteristics of Animals <ul><li>Variety of animal life is so great that it is difficult to find many unifying characteristics. </li></ul><ul><ul><li>Two universal traits (though these aren’t always immediately recognizable): </li></ul></ul><ul><ul><ul><li>Mobility </li></ul></ul></ul><ul><ul><ul><li>Need to eat plants and/or other animals </li></ul></ul></ul>The tree of life at Animal Kingdom 
  37. 37. <ul><li>Characteristics of Animals </li></ul><ul><ul><li>Great diversity </li></ul></ul><ul><ul><li>Two universal features </li></ul></ul><ul><ul><ul><li>Motile </li></ul></ul></ul><ul><ul><ul><li>Heterotrophs </li></ul></ul></ul><ul><ul><ul><ul><li>Consumers (incapable of manufacturing food from air, water and sunlight like plants do) </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Fig. 11-15, 16, 19a, 21, & 27 </li></ul></ul></ul></ul>
  38. 38. Kinds of Animals <ul><li>Size and habits are not valid indicators of animal’s significance to geographic study. </li></ul><ul><li>Minute and seemingly inconsequential organisms can play important roles. </li></ul><ul><li>Examples are carriers of disease, providers of scarce nutrients. </li></ul><ul><li>More than 90% of all animal species are invertebrates (without backbones). </li></ul><ul><li>Arthropods most prominent (insects, spiders, centipedes, millipedes, crustaceans). </li></ul><ul><li>Five groups of vertebrates, those with backbone: </li></ul><ul><ul><li>Fish, amphibians, reptiles, birds, and mammals. </li></ul></ul>
  39. 39. <ul><li>Kinds of Animals </li></ul><ul><ul><li>Invertebrates </li></ul></ul><ul><ul><li>Vertebrates </li></ul></ul><ul><ul><ul><li>Fishes </li></ul></ul></ul><ul><ul><ul><li>Amphibians </li></ul></ul></ul><ul><ul><ul><li>Reptiles </li></ul></ul></ul><ul><ul><ul><li>Birds </li></ul></ul></ul><ul><ul><ul><li>Mammals </li></ul></ul></ul><ul><ul><ul><ul><li>Fig. 11-15, 16, 19a, 21, 27 & 11-17 </li></ul></ul></ul></ul>
  40. 40. Kinds of Animals <ul><li>Most mammals are placentals, having young grow and develop in mother’s body. </li></ul><ul><ul><li>About 135 species are marsupials, in which mothers carry young, not fully developed at birth, in pouches. </li></ul></ul><ul><ul><li>Two species are monotremes—lay eggs. </li></ul></ul><ul><ul><ul><li>Echidna and duckbill platypus. </li></ul></ul></ul>
  41. 41. Environmental Adaptations <ul><li>Three different kinds of evolutionary adaptation by animals: </li></ul><ul><ul><li>Physiological </li></ul></ul><ul><ul><li>Behavioral </li></ul></ul><ul><ul><li>Reproductive </li></ul></ul>
  42. 42. Example of Animal Adaptations to Desert Life <ul><li>Faunal diversity can be astounding in desert areas where water is permanent or prolonged. </li></ul><ul><li>Even in areas where open water is not available, there are pockets of localized favorable habitat that permit remnant populations to survive. </li></ul><ul><li>Most animals are completely nocturnal. </li></ul><ul><li>Animals are more conspicuous when cooler, such as at night and winter. </li></ul><ul><li>Some animals follow rains in nomadic fashion. </li></ul><ul><li>Most prominently displayed by birds. </li></ul>
  43. 43. Example of Animal Adaptations to Desert Life <ul><li>Some spend significant time underground. </li></ul><ul><li>Some bury selves to survive long dry spells, such as freshwater crayfish and crabs. </li></ul><ul><li>Text provides detailed discussion of anatomical and physiological adaptations. </li></ul><ul><li>A few species of rodents can exist from birth to death without ever taking a drink. </li></ul><ul><li>Get moisture from food. </li></ul><ul><li>Some species display ability to delay reproductive processes over long dry periods until more favorable conditions occur. </li></ul><ul><li>Australian desert kangaroos can delay implantation of fertilized blastocyst, so it remains in inactive state in uterus until better weather conditions occur. </li></ul>
  44. 44. Competition Among Animals <ul><li>Competition can be both direct and indirect. </li></ul><ul><li>Indirect—rivalry for space and resources. </li></ul><ul><li>Direct—antagonism of predation. </li></ul><ul><li>Many create social groups among own species. </li></ul>
  45. 45. Competition Among Animals <ul><li>Some across species, such as communal relationship among zebras, wildebeest and impalas in East African savannas. </li></ul><ul><li>Individual animals are concerned either largely or entirely with own survival. </li></ul><ul><li>Some animal species concerned with survival of mates. </li></ul><ul><li>Some concerned with survival of young (more common as maternal instinct, though some paternal too). </li></ul><ul><li>Still fewer concerned with survival for group. </li></ul>
  46. 46. Cooperation among Animals <ul><li>Symbiosis—association of two dissimilar organisms, in which they live together in some fashion. </li></ul><ul><li>Mutualism—symbiotic relationship in which the association is mutually beneficial to both organisms. </li></ul><ul><li>Commensalism—symbiotic relationship in which the association is neither beneficial nor injurious to either. </li></ul><ul><li>Parasitism—symbiotic relationship, in which the association benefits one, but harms the other; that is, one lives on or in the other, to detriment of the host. </li></ul>Symbiosis Mutualism Commensalism Parasitism
  47. 47. Zoogeographic Regions <ul><li>Animals’ distribution patterns more complex and irregular because of their mobility. </li></ul><ul><li>The broad distributions of animals nevertheless do reflect a general distribution of energy and food diversity. </li></ul>
  48. 48. Zoogeographic Regions <ul><li>Nine zoogeographic regions are generally recognized. </li></ul><ul><li>Represent average conditions and cannot portray some common pattern in which different groups of animals fit precisely. </li></ul><ul><li>Map on page 329. </li></ul>
  49. 49. <ul><li>Zoogeographic Regions </li></ul><ul><li>Reflective of the general distribution of energy and richness of food chemistry </li></ul><ul><ul><ul><ul><li>Fig. 11-23 </li></ul></ul></ul></ul>
  50. 50. Zoogeographic Regions <ul><li>Ethiopian Region </li></ul><ul><ul><li>Has most diverse vertebrate fauna and greatest number of mammalian families. </li></ul></ul><ul><li>Oriental Region </li></ul><ul><ul><li>Similar to Ethiopian but with less diversity (save for birds and reptiles; large number of venomous snakes). </li></ul></ul><ul><li>Palearctic Region </li></ul><ul><ul><li>Poorer fauna than previous two; </li></ul></ul><ul><ul><li>Probably function of higher latitudes and more rigorous climate. </li></ul></ul>
  51. 51. <ul><li>Palearctic Region </li></ul><ul><ul><li>Separated from rest of Eurasia by mountains </li></ul></ul><ul><ul><li>Few endemic species, fewer species than in tropics </li></ul></ul><ul><ul><ul><ul><li>Fig. 11-23 </li></ul></ul></ul></ul>
  52. 52. <ul><li>Nearctic Region </li></ul><ul><ul><li>Non-tropical portions of North America </li></ul></ul><ul><ul><li>Similar to Palearctic due to Bering land bridge </li></ul></ul><ul><ul><ul><ul><li>Fig. 11-23 </li></ul></ul></ul></ul>
  53. 53. Zoogeographic Regions <ul><li>Nearctic Region </li></ul><ul><ul><li>Faunal assemblage relatively poor (save for being well-represented with reptiles). </li></ul></ul><ul><ul><li>Largely a transitional zone between Palearctic and Neotropical groups. </li></ul></ul><ul><ul><li>Great similarity to Palearctic, so that some group together into superregion, Holoarctic. </li></ul></ul><ul><ul><li>Reflects how faunal dispersal occurred via Bering land bridge in geologic past. </li></ul></ul><ul><li>Neotropical Region </li></ul><ul><ul><li>Has rich and distinctive faunal assemblage: </li></ul></ul><ul><ul><li>Variety of habitats and isolation from other regions; </li></ul></ul><ul><ul><li>Has a larger number of endemic mammal families than any other region; </li></ul></ul><ul><ul><li>Bird fauna is exceedingly diverse and conspicuous. </li></ul></ul>
  54. 54. Zoogeographic Regions <ul><li>Madagascar Region </li></ul><ul><ul><li>Dominated by relic assemblage of unusual forms. </li></ul></ul><ul><ul><li>Primitive primates (lemurs). </li></ul></ul><ul><li>New Zealand region </li></ul><ul><ul><li>Fauna dominated by birds (mostly flightless). </li></ul></ul><ul><ul><li>Almost no terrestrial vertebrates. </li></ul></ul><ul><ul><li>No mammals and only a few reptiles and amphibians. </li></ul></ul>
  55. 55. Zoogeographic Regions <ul><li>Pacific Islands Region </li></ul><ul><ul><li>Limited faunal assemblage. </li></ul></ul><ul><li>Australian Region </li></ul><ul><ul><li>Has most distinctive fauna of any region. </li></ul></ul><ul><ul><li>Lack of variety is made up by animals’ uniqueness. </li></ul></ul><ul><ul><li>The Unique Biota of Australia </li></ul></ul><ul><ul><li>More than 90% of the native tree species in Australia are of the single genus, Eucalyptus. </li></ul></ul><ul><ul><ul><li>Above should either be “a single genus, Euc” or “the single genus Euc” (no comma) </li></ul></ul></ul><ul><ul><li>These trees, which there are greater than 400 species of, are native only to Australia. </li></ul></ul><ul><ul><li>The shrubs and bushes of Australia are dominated by a single genus, Acacia. </li></ul></ul><ul><ul><li>The dominance of this genus is attributed to isolation. </li></ul></ul>
  56. 56. <ul><ul><li>Australia Region </li></ul></ul><ul><ul><ul><li>Australia and adjacent islands </li></ul></ul></ul><ul><ul><ul><li>Most distinctive fauna of any region due to the region’s lengthy isolation </li></ul></ul></ul><ul><ul><ul><ul><li>Few placental mammals </li></ul></ul></ul></ul><ul><ul><ul><li>Its unique biota are also primarily a result of isolation </li></ul></ul></ul><ul><ul><ul><ul><li>Fig. 11-17: Kangaroo. Fig. 11-18: Monotremes (egg-laying mammals) Echidna and duckbill platypus. </li></ul></ul></ul></ul>
  57. 57. Zoogeographic Regions <ul><li>Australian fauna is also unique because of isolation. </li></ul><ul><ul><li>Australian fauna is dominated by a single primitive mammalian order, marsupials. </li></ul></ul><ul><ul><li>The continent is also the only home to the primitive monotremes. </li></ul></ul><ul><ul><li>Marsupials and monotremes were able to flourish in relative isolation from competitive and predatory pressures that influenced animal evolution in other parts of the world. </li></ul></ul><ul><ul><li>As such, indigenous placental mammals are lacking on the continent. </li></ul></ul>
  58. 58. The Major Biomes <ul><li>Named for dominant vegetation, but encompasses fauna as well as interrelationships with soil, climate, and topography. </li></ul>
  59. 59. <ul><li>Major Biomes </li></ul><ul><li>Summary of each biome follows… </li></ul><ul><ul><li>Distribution (map) </li></ul></ul><ul><ul><li>Climate types </li></ul></ul><ul><ul><li>Main vegetation types </li></ul></ul><ul><ul><li>Limiting factors to flora and fauna </li></ul></ul><ul><ul><ul><ul><li>Fig. 11-25 </li></ul></ul></ul></ul><ul><ul><ul><ul><li>(left panel, p. 330) </li></ul></ul></ul></ul>
  60. 60. <ul><ul><ul><ul><li>Fig. 11-25 (right panel, p. 331) </li></ul></ul></ul></ul>
  61. 61. The Major Biomes <ul><li>Tropical Rainforest </li></ul><ul><ul><li>Selva — tropical rainforest; a distinctive assemblage of tropical vegetation that is dominated by a great variety of tall, high-crowned trees. </li></ul></ul><ul><ul><ul><li>Probably most complex of all terrestrial ecosystems. </li></ul></ul></ul><ul><ul><li>Distribution closely related to climate. </li></ul></ul><ul><ul><li>Consistent rainfall and relatively high temperatures. </li></ul></ul><ul><ul><li>Layered structure, with second layer being a branch canopy formed by the high trees that crest above the canopy. </li></ul></ul><ul><ul><li>Undergrowth relatively sparse because of lack of light. </li></ul></ul><ul><ul><li>Interior is region of heavy shade, high humidity, windless air, continuous warmth, aroma of mold and decomposition. </li></ul></ul><ul><ul><li>Fauna is largely arboreal—tree dwelling. </li></ul></ul><ul><ul><li>Canopy serves as principal food source. </li></ul></ul>
  62. 62. The Major Biomes <ul><li>Tropical Deciduous Forest </li></ul><ul><ul><li>Not closely correlated with specific climatic types; distribution more irregular and fragmented. </li></ul></ul><ul><ul><li>Compared to rainforest, canopy is less dense, trees are shorter, and there is less diversity of tree species (but greater variety of shrubs and other lesser plants). </li></ul></ul><ul><ul><li>Response to either less total precipitation or less periodic precipitation. </li></ul></ul><ul><ul><li>Many trees shed leaves at same time, so more sunlight can penetrate. </li></ul></ul><ul><ul><li>Produces classic jungle conditions. </li></ul></ul>
  63. 63. The Major Biomes <ul><li>Tropical Scrub </li></ul><ul><ul><li>Widespread in drier portions of A climatic realm (covers extensive areas in tropics and subtropics). </li></ul></ul><ul><ul><li>Dominated by low-growing scraggly trees and tall bushes, usually with extensive understory of grasses. </li></ul></ul><ul><ul><li>Plant species diversity less than that in tropical rainforest and tropical deciduous. </li></ul></ul><ul><ul><li>Faunal diversity very different from tropical rainforest and tropical deciduous. </li></ul></ul><ul><ul><li>Moderately rich assemblage of ground-dwelling mammals and reptiles, and of birds and insects. </li></ul></ul>
  64. 64. The Major Biomes <ul><li>Tropical Savanna </li></ul><ul><ul><li>Distribution of biome doesn’t exactly correlate with distribution of tropical savanna climate. </li></ul></ul><ul><ul><li>Incomplete correlation most noticeable where seasonal rainfall contrasts are greatest (which is associated with annual shifting of the intertropical convergence zone [ITCZ]). </li></ul></ul><ul><ul><li>Dominated by tall grasses. </li></ul></ul><ul><ul><li>Some regions actually former tropical deciduous forest and even tropical rainforest, but humans converted it through fires and by grazing domestic animals. </li></ul></ul><ul><ul><li>Has a very pronounced seasonal rhythm: wet season, dry season, and wildfire season. </li></ul></ul><ul><ul><li>Savanna fauna varies according to continent. </li></ul></ul><ul><ul><li>Africa has most remarkable, diverse large wildlife. </li></ul></ul><ul><ul><li>Latin America has only sparse population of large wildlife. </li></ul></ul>
  65. 65. The Major Biomes <ul><li>Desert </li></ul><ul><ul><li>Occurs extensively in midlatitude locations in Asia, North America, and South America with a fairly close correlation to Bwh and Bwk climates. </li></ul></ul><ul><ul><li>Vegetation surprisingly variable. </li></ul></ul><ul><ul><li>Shrubs are typical, with succulents common in drier parts. </li></ul></ul><ul><ul><li>Trees can be found, particularly in Australia. </li></ul></ul><ul><ul><li>Most deserts have moderately diverse faunal assemblage. </li></ul></ul><ul><ul><li>Variety of large mammals is limited. </li></ul></ul>
  66. 66. The Major Biomes <ul><li>Mediterranean Woodland and Shrub </li></ul><ul><ul><li>Six widely scattered and relatively small areas in midlatitudes. </li></ul></ul><ul><ul><li>Have pronounced dry-summer wet-winter precipitation. </li></ul></ul><ul><ul><li>Dominant vegetation associations are physically similar, but taxonomically quite varied. </li></ul></ul><ul><ul><li>Dominated by dense growth of woody shrubs, but also have open grassy woodlands. </li></ul></ul><ul><ul><li>Plant species vary from region to region, but in all, the trees and shrubs are primarily broadleaf evergreens. </li></ul></ul><ul><ul><li>Many plants are adapted to rapid recovery after wildfire. </li></ul></ul><ul><ul><li>Fauna not particularly distinctive. </li></ul></ul><ul><ul><li>Seed-eating, burrowing rodents common. </li></ul></ul><ul><ul><li>General overlap of animals between this biome and adjacent ones. </li></ul></ul>
  67. 67. The Major Biomes <ul><li>Midlatitude Grassland </li></ul><ul><ul><li>Locational coincidence between this biome and steppe climatic type is very pronounced in Northern Hemisphere. </li></ul></ul><ul><ul><li>Less distinct climatic correlations in Southern Hemisphere. </li></ul></ul><ul><ul><li>Occurs widely in midlatitudes of North America and Eurasia. </li></ul></ul><ul><ul><li>Low precipitation and/or frequency of fire prevent growth of tree or shrub seedlings. </li></ul></ul><ul><ul><li>Characteristics of grasses depends on moisture: taller in wetter area (prairie), shorter in dryer (steppe), and sometimes not continuous, but grow in discrete tufts. </li></ul></ul><ul><ul><li>Before human encroachment, fauna comprised of large numbers of relatively few species, with migratory larger herbivores. </li></ul></ul>
  68. 68. The Major Biomes <ul><li>Midlatitude Deciduous Forest </li></ul><ul><ul><li>Used to be far more extensive in all Northern Hemisphere continents and to some extent in tracts in Southern Hemisphere. </li></ul></ul><ul><ul><li>Humans have cleared away large portions for agriculture. </li></ul></ul><ul><ul><li>Fairly dense growth of tall broadleaf trees with complete canopy in summer. </li></ul></ul><ul><ul><li>Winter very different, with seasonal fall of leaves. </li></ul></ul><ul><ul><li>Tree species vary greatly from region to region. </li></ul></ul><ul><ul><li>Generally has the richest assemblage of fauna in midlatitudes. </li></ul></ul><ul><ul><li>Seasonal variation to fauna (hibernation and migration). </li></ul></ul>
  69. 69. The Major Biomes <ul><li>Boreal Forest </li></ul><ul><ul><li>An extensive needleleaf forest in subarctic regions of North America and Eurasia; also called taiga. </li></ul></ul><ul><ul><li>One of most extensive biomes, occupying vast expanse of northern North America and Eurasia. </li></ul></ul><ul><ul><li>Close correlation with subarctic climatic type. </li></ul></ul><ul><ul><li>Has perhaps simplest assemblage of plants. </li></ul></ul><ul><ul><li>Most trees are conifers, though in some places deciduous trees interrupt the coniferous cover. </li></ul></ul><ul><ul><li>Trees become spindlier, short, and openly spaced in north. </li></ul></ul><ul><ul><li>Bogs and swamps numerous because of permanently frozen subsoil and derangement of normal surface drainage from past glaciers. </li></ul></ul><ul><ul><li>Faunal diversity limited because of limited food supply. </li></ul></ul><ul><ul><li>Populations of some species can fluctuate enormously in space of year or so. </li></ul></ul><ul><ul><li>Insects absent in winter but superabundant in brief summer. </li></ul></ul>
  70. 70. The Major Biomes <ul><li>Tundra </li></ul><ul><ul><li>Distribution along northern edge of Northern Hemisphere continents. </li></ul></ul><ul><ul><li>Essentially a cold desert or grassland. </li></ul></ul><ul><ul><li>No trees, but considerable mixture of species (grasses, mosses, lichens, flowering herbs, and a scattering of low shrubs). </li></ul></ul><ul><ul><li>Dominant animal life consists of bird and insects during summer. </li></ul></ul><ul><ul><li>Few species of mammals and freshwater fishes and almost no reptiles or amphibians. </li></ul></ul>
  71. 71. The Major Biomes <ul><li>Alpine Tundra </li></ul><ul><ul><li>Found in many high-elevation regions. </li></ul></ul><ul><ul><li>Above timberline there is sparse vegetation cover, consisting mostly of herbaceous plants, grasses, and low shrubs. </li></ul></ul>
  72. 72. Human Modification of Natural Distribution Patterns <ul><li>Human activities severely alter natural distribution patterns of biota. </li></ul><ul><li>Humans directly influence biotic distributions in three ways: </li></ul><ul><ul><li>Physical removal of organisms </li></ul></ul><ul><ul><li>Habitat modification </li></ul></ul><ul><ul><li>Artificial translocation of organisms </li></ul></ul>
  73. 73. Physical Removal of Organisms <ul><li>Humans severely modify landscape, affecting both plants and animal inhabitants. </li></ul><ul><li>Cut down, plow up, pave over, burn out, poison, shoot, trap, otherwise eradicate. </li></ul><ul><ul><ul><ul><li>Fig. 11-41. Central America – one of highest rates of deforestation (due mainly to expansion of cattle ranching) </li></ul></ul></ul></ul>
  74. 74. Habitat Modification <ul><li>Humans affect native plants and animals by changing their habitat. </li></ul><ul><li>Humans change soil environment through farming, grazing, engineering, and construction. </li></ul><ul><li>Humans degrade atmospheric environment through pollution. </li></ul><ul><li>Humans impound, divert, and pollute waters. </li></ul><ul><ul><ul><li>Removal for agriculture often </li></ul></ul></ul><ul><ul><ul><li>results in soil erosion and </li></ul></ul></ul><ul><ul><ul><li>low crop yields as well as </li></ul></ul></ul><ul><ul><ul><li>wildlife habitat destruction. </li></ul></ul></ul>
  75. 75. Tropical Rainforest Removal <ul><li>One of Earth’s most serious environmental problems, as of last decade or so. </li></ul><ul><li>Rate of deforestation = 51 acres (21 hectares) per minute. </li></ul><ul><li>More than half of original African rainforest is now gone, about 45% of Asia’s and close to 40% of Latin America’s. </li></ul><ul><li>Current situation varies in five major rainforest regions. </li></ul><ul><li>In mid-1980s, extinction rates = about 1 species per day. </li></ul><ul><li>In mid 1990s, extinction rates = about 2 species per hour. </li></ul>
  76. 76. Tropical Rainforest Removal <ul><li>Loss of forest also contributes to: </li></ul><ul><ul><li>Accelerated soil erosion </li></ul></ul><ul><ul><li>Drought </li></ul></ul><ul><ul><li>Flooding </li></ul></ul><ul><ul><li>Water-quality degradation </li></ul></ul><ul><ul><li>Declining agricultural productivity </li></ul></ul><ul><ul><li>Greater poverty for rural inhabitants </li></ul></ul><ul><ul><li>Increasing atmospheric carbon dioxide (greenhouse effect). </li></ul></ul><ul><ul><li>Anticipated economic benefits are usually illusory. </li></ul></ul>
  77. 77. Tropical Rainforest Removal <ul><li>Continuous heavy (and expensive) fertilization necessary for sustainable agriculture. </li></ul><ul><li>Losing potential valuable resources—pharmaceutical products, new food crops, natural insecticides, industrial material, and crop hybridizations (for resisting disease, insects, parasites, and other environmental stresses). </li></ul><ul><li>Development of agroforestry (the planting of crops with trees) to counteract some of the destruction. </li></ul><ul><li>UNESCO project to set aside reserves to protect biodiversity. </li></ul><ul><li>At present about 300 preserves have been established in more than 75 countries, encompassing 12 million hectares. </li></ul><ul><li>Artificial Translocation of Organisms </li></ul>
  78. 78. Tropical Rainforest Removal <ul><li>Humans have introduced many wild plants and animals into “new” habitats. </li></ul><ul><li>Exotic species—organism that is introduced into “new” habitats in which it did not naturally occur. </li></ul><ul><li>Sometimes deliberate, sometimes accidental. </li></ul><ul><li>Exotics have had great impacts (cats on flightless bird populations in New Zealand, European flea in all parts of world). </li></ul>Walking Catfish, Florida
  79. 79. Biotic Rearrangement: The Sad Case of Florida <ul><li>Human actions in introducing exotic (nonnative) species result in usually one of two extremes: </li></ul><ul><li>Either exotic dies out in a short time; or </li></ul><ul><li>It flourishes extraordinarily. </li></ul><ul><li>When flourishes, can occasionally have a salutary effect, but many cases either unsatisfactory or absolutely disastrous. </li></ul>
  80. 80. Biotic Rearrangement: The Sad Case of Florida <ul><li>Florida presents perhaps the most frightening case study. </li></ul><ul><li>In last decade or so, state has experienced one of highest in-migration of people anywhere. </li></ul><ul><li>Has created massive disruptions in ecosystems, and exotics are most likely to prosper when ecosystem is unstable. </li></ul><ul><li>Artificial drainage provides routes for easy dispersal of aquatic organisms. </li></ul><ul><li>Has become the major world center for animal-import industry. </li></ul><ul><li>Has become almost as important in plant import industry. </li></ul><ul><li>Inevitable that many escape (some are turned loose). </li></ul>
  81. 81. Biotic Rearrangement: The Sad Case of Florida <ul><li>Dozens of species of exotic plants have become widespread, and most are expanding their ranges. </li></ul><ul><li>Spread of melaleuca tree has changed swamps to forests. </li></ul><ul><li>Aquatic weeds infest more than half a million acres of waters. </li></ul><ul><li>Many exotic animal species well established and some spreading rapidly. </li></ul><ul><li>Exotic fish more numerous and pose even more serious problems, competing with native species. </li></ul><ul><li>Greatest present and potential threat is so-called walking catfish from Southeast Asia. </li></ul>Salt Cedars
  82. 82. Focus: Desert Adaptations of the Amazing Camel <ul><li>Dromedary (one-humped) camel has developed the most remarkable series of adjustments to desert environment. </li></ul><ul><li>Anatomical adaptations include </li></ul><ul><li>Light-colored and shiny summer coat reflects hot sunlight. </li></ul><ul><li>Deeply cleft upper lip allows moisture loss from nose to be recycled back into mouth. </li></ul><ul><li>Nostrils are horizontal slits that keep sand and dust out. </li></ul>
  83. 83. Focus: Desert Adaptations of the Amazing Camel <ul><li>Eyes set beneath shaggy brows for shade, and double eyelids to protect eyes from sand. </li></ul><ul><li>Broad and elastic feet for good traction and protection against the hot sand. </li></ul><ul><li>Physiological adaptations include </li></ul><ul><li>Highly fluctuating body temperatures that allow them to conserve moisture through minimal perspiration. </li></ul><ul><li>Little production of urine and little moisture voided in their feces. </li></ul><ul><li>Can stand long periods without water and can rapidly rehydrate when drinking. </li></ul><ul><li>They cannot, however, store moisture in their hump. </li></ul>
  84. 84. People and the Environment: Rainforest Loss in Brazil <ul><li>Brazil contains about one-third of the planet’s tropical rainforest. </li></ul><ul><li>Settlement over the last 50 years in the forest has led to large tracts of it being cleared for settlement and logging. </li></ul><ul><li>This clearing has been facilitated by the construction of the Cuiabá-Port Velho highway. </li></ul><ul><li>By the late 1980s deforestation had increased substantially, and by 2001 the amount removed was extraordinary. </li></ul><ul><li>In 2004, more than 26,000 square kilometers of rainforest were lost. </li></ul><ul><li>Much of the land is cleared for grazing land, which is then abandoned after a couple of years due to the poor fertility of tropical soils. </li></ul><ul><li>This is leading to habitat and species loss in the region. </li></ul>