Chapter 20 Terrestrial Biomes

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Chapter 20Terrestrial Biomes

• Geosystems 5e
• An Introduction to Physical Geography

Robert W. Christopherson Charlie Thomsen
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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
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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