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Title: Chapter 20 Terrestrial Biomes


1
Chapter 20Terrestrial Biomes
  • Geosystems 5e
  • An Introduction to Physical Geography

Robert W. Christopherson Charlie Thomsen
2
Final Exam
  • On April 11 at the Alumni Hall (AH) STAGE.
  • Will cover chapters 7,15,16,17,18,19,20, and 21.
  • Will cover all information on the PowerPoint
    slides.
  • It will contain 100 multiple choice and T/F
    questions.
  • MUST BRING 2 Pencils !!!
  • Exam will start at 2pm until 4pm. Once you are
    finished please leave class quietly.
  • Know the boldface terms at each chapter.
  • Review summary questions at the end of each
    chapter most of them I specifically answered in
    the PowerPoint presentations.

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Key Learning Concepts
  • Define the concept of biogeographical realms of
    plants and animals and define ecotone,
    terrestrial ecosystem, and biome.
  • Define six formation classes and the life-form
    designations and explain their relationship to
    plant communities.
  • Describe ten major terrestrial biomes and locate
    them on a world map.
  • Relate human impacts, real and potential, to
    several of the biomes.

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2. What is a biogeographical realm? How is the
world subdivided according to plant and animal
types?
  • Biogeographical realms of plants and animals are
    geographic regions where groups of species
    evolved. From these centers, species migrate
    worldwide according to their niche requirements,
    reproductive success, competition, and climatic
    and topographic barriers. Recognition that such
    distinct regions of flora and fauna exist was an
    early beginning of biogeography as a discipline.
    The next two slides (maps) illustrate the
    botanical (plant) and zoological (animal) regions
    forming these biogeographical realms. Each realm
    contains many distinct ecosystems that
    distinguish it from other realms.

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2. Describe a transition zone between two
ecosystems. How wide is an ecotone?
  • The transition zone between two ecosystems is
    called an ecotone. Boundaries between natural
    systems are zones of shared traits, therefore
    they are zones of mixed identity and composition,
    rather than rigidly defined boundaries. A
    tropical savanna is a good example of an ecotone.
    Situated between tropical forests and tropical
    steppes or deserts, tropical savanna is a mixture
    of trees and grasses. The savanna biome includes
    treeless tracts of grasslands, and in very dry
    savannas, grasses grow discontinuously in clumps,
    with bare ground between them.

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3. Define biome. What is the basis of the
designation?
  • A large, stable terrestrial ecosystem is known as
    a biome. Specific plant and animal communities
    and their interrelationship with the physical
    environment characterize a biome. Each biome is
    usually named for its dominant vegetation. We
    further define these general biomes into more
    specific vegetation units called formation
    classes. These units refer to the structure and
    appearance of dominant plants in a terrestrial
    ecosystem, for example, equatorial rain forest,
    northern needleleaf forest, Mediterranean
    shrubland, arctic tundra.

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4. Distinguish between formation classes and
life-form designations as a basis for spatial
classification.
  • Interacting populations of plants and animals in
    an area form a community, or association of
    related species. Large vegetation units, the
    floristic component of a terrestrial ecosystem
    characterized by a dominant plant community, are
    called plant formation classes. Each formation
    includes numerous plant communities, and each
    community includes innumerable plant habitats.
    Within those habitats, Earth's diversity is
    expressed in approximately 250,000 plant species.
  • More specific systems are used for the structural
    classification of plants. Such life-form
    designations are based on the outward physical
    properties of individual plants or the general
    form and structure of a vegetation cover. These
    physical life-forms, (see next slide), include
    trees (larger woody main trunk, perennial,
    usually exceeding 3 m) lianas (woody climbers
    and vines) shrubs (smaller woody plants
    branching stems at ground) herbs (small plants
    without woody stems above ground) bryophytes
    (mosses, liverworts) epiphytes (plants growing
    above the ground on other plants, using them for
    support) and thallophytes, which lack true
    leaves, stems, or roots (bacteria, fungi, algae,
    lichens).

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5. Describe the equatorial and tropical rain
forests. Why is the rain forest floor somewhat
clear of plant growth? Why are logging activities
for specific species so difficult there?
  • Biomass in a rain forest is concentrated high up
    in the canopy, that dense mass of overhead leaves
    with a vertical distribution of life that is
    dependent on a competitive struggle for sunlight.
    The canopy is composed of a rich variety of
    plants and animals. Lianas (vines) branch from
    tree to tree, binding them together with cords
    that can reach 20 cm in diameter. Epiphytes (a
    plant that derives its moisture and nutrients
    from the air and rain and grows usually on
    another plant) flourish there as well. The floor
    of the rain forest and the floor of the ocean are
    roughly parallel in that both are dark or dimly
    lit, relatively barren, and a place of fewer
    life-formsalthough the rainforest floor is much
    livelier than the sea floor. Logging is
    difficult because individual species are widely
    scattered a species may occur only once or twice
    per square kilometer.

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6. What issues surround deforestation of the rain
forest? What is the impact of these losses on the
rest of the biosphere?
  • Burning is more common than logging in
    deforestation because of the scattered
    distribution of specific types of trees mentioned
    earlier. Fires are used to clear land for
    agriculture, which is intended to feed the
    domestic population as well as to produce cash
    exports of beef, rubber, coffee, and other
    commodities. Every year, approximately 15.25
    million acres are thus destroyed, and more than
    10 million acres are selectively logged. The
    United Nations Food and Agricultural Organization
    (FAO) estimates that if this destruction to rain
    forests continues unabated, these forests will be
    completely removed by the year 2050!
  • Another threat to the rain forest biome emerged
    in the 1990s exploration for and development of
    oil reserves.

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7. What do caatinga, chaco, brigalow, and
dornveld refer to? Explain.
  • Local names are applied to the tropical seasonal
    forest and scrub on the margins of the rain
    forest the caatinga of northeast Brazil, chaco
    area of Paraguay and northern Argentina, the
    brigalow scrub of Australia, and the dornveld of
    southern Africa.

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8. Why does the northern needleleaf forest biome
not exist in the Southern Hemisphere? What is its
relationship to climate type?
  • Stretching from the East coast of Canada and the
    Maritimes westward to Alaska and continuing from
    Siberia across the entire extent of the Russia to
    the European Plain is the northern needleleaf
    forest, also called the taiga (a Russian word) or
    boreal forest. The Southern Hemisphere, lacking D
    climates except in mountainous locales, has no
    biome designated as such. However, forests of
    needleleaf trees exist worldwide at high
    elevation.

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9. In which biome do we find Earth's tallest
trees? Which biome is dominated by small, stunted
plants, lichens, and mosses?
  • The temperate rain forest biome is recognized by
    its lush forests at middle and high latitudes,
    occurring only along narrow margins of the
    Pacific Northwest in North America, with some
    similar types in southern China, small portions
    of southern Japan, New Zealand, and a few areas
    of Chile. The tallest trees in the world, the
    coastal redwoods (Sequoia), are found in this
    biome (their distribution is shown on the map in
    the next slide). These trees can exceed 1,500
    years of age and typically range in height from
    60 to 90 m ,with some exceeding 100 m. Other
    representative treesDouglas fir, spruce, cedar,
    and hemlockhave been reduced to a few remaining
    valleys in Oregon and Washington.
  • Tundra vegetation is characterized by low,
    ground-level plants and some woody plants.
    Representative plant species are sedges, mosses,
    arctic meadow grass, snow lichen, and dwarf
    willow. They are found in the arctic tundra -the
    extreme northern area of North America and
    Russia, bordering on the Arctic Ocean.

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10. What type of vegetation predominates in the
Mediterranean dry summer climates?
  • The dominant shrub formations that occupy these
    regions are short, stunted, and tough in their
    ability to withstand hot-summer drought. The
    vegetation is called sclerophyllous (from sclero
    for hard and phyllos for leaf) it averages a
    meter or two in height and has deep,
    well-developed roots, leathery leaves, and uneven
    low branches. Plant ecologists think that this
    biome is well adapted to frequent fires, for many
    of its characteristically deep-rooted plants have
    the ability to resprout from their roots after a
    fire.

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11. Describe some of the unique adaptations found
in a desert biome.
  • Much as a group of humans in the desert might
    behave with short supplies, plant communities
    also compete for water and site advantage. Some
    desert plants, called ephemerals, wait years for
    a rainfall event, at which time their seeds
    germinate quickly, develop, flower, and produce
    new seeds, which then rest again until the next
    rainfall event. The seeds of some xerophytic
    species open only when fractured by the tumbling,
    churning action of flash floods cascading down a
    desert arroyo, and of course such an event
    produces the moisture that a germinating seed
    needs.
  • Desert plants employ other strategies such as
    long, deep tap roots succulence (that is, thick,
    fleshy, water-holding tissue such as that of
    cacti) spreading root systems to maximize water
    availability, waxy coatings and fine hairs on
    leaves to retard water loss leafless conditions
    during dry periods reflective surfaces to reduce
    leaf temperatures and, tissue that tastes bad to
    discourage herbivores.

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12. What is the relationship between island
biogeography and biosphere reserves? Describe a
biosphere reserve.
  • Setting up formal natural reserves called
    biosphere reserves at continental sites involves
    principles of island biogeography. Island
    communities are special places for study because
    of their spatial isolation and the relatively
    small number of species present. They resemble
    natural experiments because the impact of
    individual factors, such as civilization, can be
    more easily assessed on islands than they can
    over larger continental areas. It is now known
    that the number of species should increase with
    the size of the island, decrease with increasing
    distance from the nearest continent, and remain
    about the same over time, even though composition
    may vary. These considerations are important to
    establishing the optimum dimensions for biosphere
    reserves. The race is on between setting aside
    tracts of land in reserves and the permanent loss
    of remaining natural biomes.
  • The goal of biosphere reserves is to preserve
    species diversity.

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End of Chapter 20
  • Geosystems 5e
  • An Introduction to Physical Geography

Robert W. Christopherson Charlie Thomsen
21
Chapter 21Earth and the Human Denominator
  • Geosystems 5e
  • An Introduction to Physical Geography

Robert W. Christopherson Charlie Thomsen
22
Key Learning Concepts
  • Determine an answer for Carl Sagan's question,
    Who speaks for Earth?
  • Describe the growth in human population and
    speculate on possible future trends.
  • List the subjects of recent environmental
    agreements, conventions, and protocols and relate
    them to physical geography and Earth systems
    science (geosystems).
  • Appraise your place in the biosphere and realize
    your physical identity as an Earthling.
  • Analyze the An Oily Bird and relate your
    analysis to energy consumption patterns in the
    United States and Canada.

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1. Who speaks for Earth?
  • Carl Sagan answered his question who speaks for
    Earth with this perspective
  • We have begun to contemplate our origins
    starstuff pondering the stars organized
    assemblages of ten billion billion billion atoms
    considering the evolution of atoms tracing the
    long journey by which, here at least,
    consciousness arose. Our loyalties are to the
    species and the planet. We speak for Earth. Our
    obligation to survive is owed not just to
    ourselves but also to that Cosmos, ancient and
    vast, from which we spring.
  • (Carl Sagan, Cosmos, New York Random House,
    1980, p. 345.)

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2. What is meant by the Gaia hypothesis?
  • Just as the abiotic spheres affect the biosphere,
    so do living processes affect abiotic functions.
    All of these interactive effects in concert
    influence Earth's overall ecosystem. In essence,
    the planetary ecosystem sets the physical limits
    for life, which in turn evolves and helps to
    shape the planet. Thus, Earth can be viewed as
    one vast, self-regulating organism. The
    hypothesis contends that life processes control
    and shape inorganic physical and chemical
    processes. The biosphere is so interactive that a
    very small mass can affect a very large mass.
    Thus, Lovelock and Margulis think that the
    material environment and the evolution of species
    are tightly joined as the species evolve through
    natural selection, they in turn affect their
    environment.

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3.What factors led to the Exxon Valdez accident?
  • On 24 March 1989, in Prince William Sound off the
    southern coast of Alaska, in clear weather and
    calm seas, a single-hulled supertanker operated
    by Exxon Corporation, an international energy
    corporation, struck a reef that was outside the
    normal shipping lane. The tanker spilled 41.64
    million liters of oil. It took only 12 hours for
    the Exxon Valdez to spill its contents, yet a
    reasonable cleanup will take years and billions
    of dollars. Because contingency emergency plans
    were not in place, and promised equipment was
    unavailable, response by the oil industry took 10
    to 12 hours to activate, about the same time that
    it took the ship to empty.
  • The immediate effect on wildlife was
    contamination and death, but the issues involved
    are bigger than these damaged ecosystems. Many
    factors influence our demand for oil. Well over
    half of our imported oil goes for transportation.
  • The death toll for animals was massive at least
    3000 sea otters killed (or about 20 of the
    resident otters), 300,000 birds, and uncounted
    fish, shellfish, plants, and aquatic
    microorganisms. Sublethal effects, namely
    mutations, now are appearing in fish. This latter
    side effect of the spill is serious because
    salmon fishing is the main economy in Prince
    William Sound, not oil.
  • Many factors influence our demand for oil.
    Improvement in automobile efficiency began in
    1975 due to federal regulations. During the
    1980's, there was a rollback of auto efficiency
    standards, a reduction in gasoline prices, large
    reductions in funding for rapid transit
    development, and the continuing slow demise of
    America's railroad network. The demand for
    fossil fuels was also affected by the slowing of
    domestic conservation programs, elimination of
    research for energy alternatives, such as solar
    and wind power, and even the political delay of a
    law requiring small appliances to be more
    energy-efficient. Conservation plans again were
    politically blocked in the Department of Energy
    in 1990 and early 1991.

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3a.What factors led to the Exxon Valdez accident?
  • In 2001, comparatively inefficient sports utility
    vehicles represented more than half of new car
    sales. These SUVs are classified as light trucks
    and are thus exempt from auto-efficiency and some
    pollution standardsthey burn more gas to go
    fewer miles and pollute more per mile driven and
    they are involved in a disproportionate share of
    accidents. A combination of waste, low prices,
    and a lack of alternatives has spurred the demand
    for petroleum. In addition in 2002 the U.S.
    Administration formally abandoned funding for
    efforts to make vehicles more efficient and
    instead announced an effort to develop fuel cells
    for future times. Alternatives such as
    conservation, efficiency strategies, solar, wind,
    and photovoltaic cells also took budgetary hits.

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Worldwide Oil Spills
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Movie AMERICA'S BIGGEST OIL SPILL.
  • In 1989, the Exxon Valdez ran ashore on a
    well-known nautical hazard in Prince William
    Sound. Within 48 hours, over 48 million gallons
    of crude oil had spewed out into the environment.
    Can this happen again? Why did it happen this
    time? Are we ready? Actual footage.

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End of Chapter 21
  • Geosystems 5e
  • An Introduction to Physical Geography

Robert W. Christopherson Charlie Thomsen
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