An Introduction to Ecology and the Biosphere

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Chapter 50

• An Introduction to Ecology and the Biosphere
• (contd)

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RECALL

• Concept 50.1 Ecology is the study of
  interactions between organisms and the
  environment
• Concept 50.2 Interactions between organisms and
  the environment limit the distribution of species
• Concept 50.3 Abiotic and biotic factors
  influence the structure and dynamics of aquatic
  biomes

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TODAY

• Aquatic Biomes
• Lakes
• Wetlands
• Streams
• Rivers
• Estuaries
• Intertidal biomes
• Oceanic pelagic biomes
• Coral reefs
• Marine benthic biomes

• Terrestrial Biomes
• Tropical Forests
• Deserts
• Savanna
• Chaparrals
• Temperate Grasslands
• Coniferous Forest
• Temperate Broadleaf Forests
• Tundra

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• Concept 50.3 Abiotic and biotic factors
  influence the structure and dynamics of aquatic
  biomes
• Varying combinations of both biotic and abiotic
  factors
• determine the nature of Earths many biomes
• Biomes
• are the major types of ecological associations
  that occupy broad geographic regions of land or
  water

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Aquatic zones

• Many aquatic biomes
• are stratified into zones or layers defined by
  light penetration, temperature, and depth

Figure 50.16a, b
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Lakes

• physical environment standing body of water can
  be stratified seasonal thermocline
• chemical environment oligotrophic deep,
  nutrient-poor, oxygen rich eutrophic lakes
  shallower, increased nutrients, oxygen depleted
  in winter mesotrophic moderate amount of
  nutrients, phytoplankton productivity
• geologic features oligotrophic lakes have less
  surface area compared to depth oligotrophic lake
  can become eutrophic over time
• photosynthetic organisms ps. rates higher in
  eutrophic lakes plants in littoral zone
  phytoplankton cyanobacteria in limnetic zone
• animals zooplankton in limnetic zone
  invertebrates in benthic zone fish present
  throughout if O2 present
• human impact runoff from fertilizers, dumping of
  municipal waste nutrient enrichment algal
  blooms, O2 depletion

Figure 50.17
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Wetlands

• physical environment area covered with water for
  long enough period to support aquatic life
• chemical environment high organic production,
  decompositionlow dissolved O2
• geologic features basin wl. shallow basin
  riverine wl. shallow, flooded banks of rivers,
  streams fringe wl. along coasts of lakes, seas
  depending on tides
• photosynthetic organisms plants with adaptations
  to grow in water with low O2
• animals invetebrates birds herbivores,
  carnivores
• human impact draining filling destroyed up to
  90 of wl. in some regions

WETLANDS
Okefenokee National Wetland Reserve in Georgia
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Streams and Rivers

• physical environment current headwater streams
  cold, clear, turbulent downstream warmer,
  more turbid stratified
• chemical environment salt, nutrient content
  increases from headwater to mouth headwater O2
  rich
• geologic features headwater narrow, rocky
  bottom downstream wider, bottom silty
• photosynthetic organisms streams through
  grassland or dessert are rich in algae or rooted
  plants in forests leaves etc. from terrestrial
  plants primary food source for consumers
• animals fishes, invertebrates
• human impact municipal, agricultural, industrial
  pollution, damming

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Estuaries

• physical environment transition area between
  river sea complex flow patterns higher
  density sea water bottom of estuary channel
• chemical composition salinity variable nutrient
  from river make estuaries very productive
• geologic features tidal channels, islands,
  levees, mudflats
• photosynthetic organisms grasses, algae
  including phytoplankton
• animals invertebrates, fishes important
  breeding grounds for marine species feeding area
  for waterfowl
• human impact pollution from upstream, filling,
  dredging

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Intertidal Zones

• physical environment periodically submerged
  exposed by tides upper zones greater exposure to
  air, more variation in environment (temp.,
  salinity, wave action)
• chemical environment O2, nutrient levels high
• geologic features rocky or sandy substrate
  variable influence of tides depending on
  coastline
• photosynthetic organisms attached marine algae
• animals invertebrates with special adaptations
  to attach to substrate
• human impact oil pollution, recreational use

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Ocean pelagic biome

• physical environment open water, mixed by ocean
  currents higher clarity that coastal zones,
  photic zone is deeper
• chemical environment O2 high nutrient levels
  low temperate regions there is surface turn over
• geologic features vast, deep waters 70 of
  Earths surface
• photosynthetic organisms phytoplankton
• animals zooplankton, free swimming
  invertebrates, vertebrates
• human impact overfishing, pollution (oil spills,
  waste dumping)

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Coral reefs

• physical environment limited to photic zones of
  stable tropical environments with high water
  clarity
• chemical environment high O2, stable salinity,
  stable nutrient levels
• geologic features coral reef formed from calcium
  carbonate of corals needs solid substrate
• photosynthetic organisms dinoflagellate algae
  within tissues of corals red, green marine algae
• animals cnidarians predominant animals fish,
  invertebrates
• human impact poisons, explosives for aquarium
  trade, global warming, pollution

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Marine benthic

• physical environment seafloor below neritic zone
  (WATER THAT IS ABOVE THE CONTINETIAL SHELF
  pelagic zone no sunlight in benthos beneath
  pelagic deep benthic abyssal zone (cold 3ºC,
  high pressure)
• chemical environment O2 sufficient for diversity
  of animals
• geologic features soft sediments some rocky
  substrate submarine mountains volcanoes
• food producing organisms ps organisms only in
  shallow benthos some organisms associated with
  deep-sea hydrothermal vents- chemoautotrophic
  prokaryotes
• animals neritic benthic invertebrates, fishes
  deep water tube worms arthropods, echinoderms
• human impact overfishing, dumping

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• Concept 50.4 Climate largely determines the
  distribution and structure of terrestrial biomes
• Climate
• is particularly important in determining why
  particular terrestrial biomes are found in
  certain areas

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Climate and Terrestrial Biomes

• Climate has a great impact on the distribution of
  organisms, as seen on a climograph

Figure 50.18
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The distribution of major terrestrial biomes
Figure 50.19
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General Features of Terrestrial Biomes

• Terrestrial biomes
• are often named for major physical or climatic
  factors and for their predominant vegetation
• Stratification
• is an important feature of terrestrial biomes

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Tropical forest

• distribution equatorial, subequatorial
• precipitation tropical rain forests -relatively
  constant, 200-400 cm annually tropical dry
  forests 150-200 cm annually (6-7 month dry
  season)
• temperature 25-29ºC
• plants stratified canopy, subcanopy trees
  rain forest -broadleaf evergreen dominant
  deciduous broadleaf in tropical dry forest
• animals most animal diversity than any other
  terrestrial biome
• human impact destruction for agriculture,
  development

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Desert

• distribution in band near 30º N S latitude or
  interior of continents
• precipitation low, highly variable less than 30
  cm per year
• temperature variable can exceed 50ºC some cold
  deserts -30ºC
• plants low, scattered vegetation high
  proportion of bare ground succulents, shrubs
• animals reptiles, rodents, insects many species
  nocturnal adaptations to deal with scarce water
• human impact conversion to irrigated land,
  urbanization

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Savanna

• distribution equatorial, subequatorial
• precipitation 30-50 cm per year dry season 8-9
  months
• temperature 24-29ºC
• plants scattered trees adapted for seasonal
  drought grasses forbs dominant
• animals large herbivores insects
• human impact cattle ranching, overhunting

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Chaparral

• distribution midlatitude coastal regions
• precipitation rainy winters, dry summers 30-50
  cm annual
• temperature fall, winter, spring 10-12ºC summer
  30-40ºC
• plants shrubs, small trees high plant
  diversity adaptations to drought
• animals browsing herbivores, high diversity of
  small animals (amphibians, birds, reptiles)
• human impact agriculture,urbanization

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Temperate grasslands

• distribution throughout various regions
• precipitation dry winters, wet summers 30-100
  cm
• temperature cold winters -10ºC hot summers 30ºC
• plants grasses forbs adapted to drought, fire
• animals large grazers, burrowing animals
• human impact agriculture

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Coniferous forest

• distribution broad band across northern N
  America Erasia to edge of arctic tundra
• precipitation 30-70 cm, periodic droughts
  coastal coniferous forests 300 cm
• temperature winters cold, long summers may be
  hot
• plants cone-bearing trees
• animals large herbivores, carnivores
• human impact logging

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Temperate broadleaf forest

• distribution midlatitude in northern hemisphere
• precipitation 70-200 cm annually
• temperature winter 0ºC summers 30ºC
• plants high diversity deciduous trees dominant
• animals mammals, birds, insects
• human impacts logging, agriculture, urban
  developement

Figure 50.20
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Tundra

• distribution arctic (20 of surface)
• precipitation 20-60 cm some areas 100 cm
• temperature winters long, cold -30ºC summers
  short cool 10ºC
• plants herbaceous (lichens, mosses, grasses,
  forbs, dwarf trees) permafrost prevents water
  infiltration into soil
• animals large grazing herbivores, large
  carnivores, migratory birds
• human impact mineral, oil extraction

Denali National Park, Alaska, in autumn
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Take home questions

• Which of the following statements best describes
  the effect of climate on biome distribution?
• Knowledge of annual temperature and precipitation
  is sufficient to predict which biome will be
  found in an area.
• Fluctuation of environmental variables is not
  important if areas have the same annual
  temperature and precipitation means.
• It is not only the average climate that is
  important in determining biome distribution, but
  also the pattern of climatic variation. On final
  Test.
• Temperate forests, coniferous forests, and
  grasslands all have the same mean annual
  temperatures and precipitation.
• Correlation of climate with biome distribution is
  sufficient to determine the cause of biome
  patterns.

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• Imagine some cosmic catastrophe that jolts Earth
  so that it is no longer tilted. Instead, its axis
  is perpendicular to the line between the Sun and
  Earth. The most predictable effect of this change
  would be
• No more night and day.
• A big change in the length of the year.
• A cooling of the equator.
• A loss of seasonal variations at northern and
  southern latitudes. In the textbook.
• The elimination of ocean currents.

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• Which of the following events might you predict
  to occur if the tilt of Earth's axis relative to
  its plane of orbit was increased beyond 23.5
  degrees?
• Summers in the United States might become warmer.
• Winters in Australia might become more severe.
• Seasonal variation at the equator might decrease.
• Both A and B are correct.
• A, B, and C are all correct.

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• If a meteor impact or volcanic eruption injected
  a lot of dust into the atmosphere and reduced
  sunlight reaching Earth's surface by 70 for one
  year, all of the following marine communities
  would be greatly affected except a
• deep-sea vent community.
• coral reef community.
• benthic community.
• pelagic community.
• estuary community.