An Introduction to Ecology and the Biosphere

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Chapter 52

• An Introduction to Ecology and the Biosphere

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Ecology-the study of the interactions between
organisms and their environment

• Populationgroup of individuals of the same
  species in a particular geographical area
• Communityassemblage of populations of different
  species
• Ecosystemall abiotic factors and the community
  of species in an area
• Biospherethe sum of all the planets ecosystems

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Ecology provides a scientific context for
evaluating environmental issues

• Rachel Carson, 1962, Silent Spring
• Precautionary principle-should guide decisions in
  which not all answers are known.

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Components of the environment

• abioticnonliving chemical physical
  factors temperature, water, sunlight, wind, rocks
  and soil, periodic disturbances
• bioticliving factors predation, disease,
  famine, competition

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Factors affecting distribution of organisms

• Behavior and habitat selection- ovipositing
  insects often choose only certain host plants-may
  limit their distribution.
• Environmental conditions may change too rapidly
  due to human interventions.
• Biotic factors
• Abiotic factors-temperature and moisture are
  major climatic factors

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Global climate patterns

• Seasons

Precipitation Winds
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Biomes-the major types of ecosystems

• Aquatic -occupy the largest part of the
  biosphere.
• Terrestrial

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Lake stratification turnover

• Thermal stratification vertical temperature
  layering
• Biannual mixing spring and autumn
• Seasonal Turnover changing water temperature
  profiles brings oxygenated water from the
  surface to the bottom and nutrient rich water
  form the bottom to the surface

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Aquatic biomes

• Vertical stratification
• photic zone photosynthetic light
• aphotic zone little light
  thermocline narrow stratum of rapid temperature
  change
• benthic zone bottom substrate
• Benthos community of organisms at the bottom
  substrate
• Detritus dead organic matter food for benthic
  organisms

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Freshwater biomes

• Lake classification oligotrophic deep,
  nutrient poor
• eutrophic shallow, high nutrient
  content mesotrophic moderate productivity
• Wetland area covered with water
• Estuary area where freshwater merges with ocean

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Freshwater biomes

• Littoral zone shallow, well-lit waters close to
  shore may contain rooted and floating aquatic
  plants.
• Limnetic zone well-lit, open water farther from
  shore contains phytoplankton
• Profundal zone deep, aphotic waters microbes
  decompose detritus

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Marine biomes

• Intertidal zone area where land meets water
• Neritic zone shallow regions over continental
  shelves
• Oceanic zone very deep water past the
  continental shelves
• Pelagic zone open water of any depth
• Benthic zone seafloor bottom
• Abyssal zone benthic region in deep oceans

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Terrestrial biomes

• Tropical forests equator most complex constant
  temperature and rainfall canopy
• Savanna tropical grassland with scattered trees
  occasional fire and drought large herbivores
• Desert sparse rainfall (lt30cm/yr)
• Chaparral spiny evergreens at midlatitudes along
  coasts
• Temperate grassland all grasses seasonal
  drought, occasional fires large mammals
• Temperate deciduous forest midlatitude regions
  broad-leaf deciduous trees
• Coniferous forest cone-bearing trees
• Tundra permafrost very little precipitation