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Biotic and Abiotic Factors (PowerPoint download)

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					Biotic and Abiotic Factors
 Different Approaches to the Study of Ecology

• Ecology is the study of an
  organism or organisms and
  their relationship to the
  environment.
• An organism’s environment
  consists of the physical,
  chemical and biological
  factors with which it interacts.
• The mollusks seen at the right
  must deal with changes in
  temperature, tides, wave
  action, predators and
  competition for food. Each
  plays its own role or niche.
How can we study Environmental Interactions?

• At the most basic level, an ecologist may be interested
  in the interactions of a single organism and its
  environment.
• Population ecologists focus on factors that affect
  populations of organisms that are found in a specific
  area. (i.e. What determines the reproductive success
  of wood storks in South Florida.)
• At the community level of study one is interested in
  understanding the interactions between populations of
  different species living in an area. For example, what
  determines composition and distribution of trees in a
  hardwood hammock?
            An Ecosystem Approach

• At a fourth level, studies may examine an ecosystem.
• The ecosystem includes all the organisms in an area
  and all of the abiotic factors that affect them.
• In South Florida there are many ongoing studies of the
  Everglades ecosystem, as biologists, geologists,
  hydrologists and atmospheric scientists work together in
  efforts to understand how all the parts of it relate to each
  other. Without this knowledge we cannot hope to
  preserve, protect or manage the unique natural
  environment that is South Florida .
Abiotic factors are the non-living Components
              of the Environment

• Abiotic factors include:
   –   Sunlight
   –   Water
   –   Temperature
   –   Wind
   –   Soil/substrate
   –   Special events such as:
        •   Fires
        •   Hurricanes
        •   Floods
        •   Volcanic eruptions
        •   Tsunamis
The atmosphere has a tremendous effect on the distribution of plants
  and animals. Global patterns of circulations affect rainfall patterns
and the prevailing wind directions. Changes in air circulation over the
Pacific Ocean can lead to events, such as El Nino, which have global
repercussions (i.e. torrential rains in the Andes and severe drought in
                                 Australia)
    Regional climate affects biological communities
•   The unequal heating of the earth’s surface leads to the global patterns of
    rainfall and winds. At the equator there is maximum heating of the earth’s
    surface. This causes hot air to rise, and as it rises it cools, forming clouds
    and increasing precipitation. At high altitudes the air cools and moves away
    from the equator. At the mid-latitudes this cool air sinks back to the surface.
    This results in both the trade winds and relatively dry conditions.
Prevailing wind patterns, set ocean currents in
                    motion.

•   The patterns of wind flow can be
    seen in the figure at the right.
    Land masses can interrupt these
    patterns at a local or regional level.

•   Ocean currents are created by the
    flow of winds, and cause great
    patterns of circular flow in the
    oceans. The Gulf Stream is one
    such current. Without the heat in
    this mass of water, the climate of
    northern Europe would be much
    cooler. This would alter the
    biological communities found
    there.
    Rain shadows greatly affect the availability of
                    moisture!
•    As previously stated, land masses affect atmospheric movements. Rain
     shadow effects are seen when moist oceanic air masses encounter
     mountains. The moist air is forced up, cools, and releases its moisture in the
     form of rain. On the back side of the mountains, the cooled air decends
     towards the surface, but is no quite dry. This may create arid or semi-arid
     conditions.
                   Other Abiotic Factors
• Temperature also affects the distribution of plants and animals.
• As a rule, temperature are lower as you move towards the poles or
  as you climb in elevations. For this reason arctic or sub-arctic
  plant communities can be found at high elevations in the tropics.
• In the temperate latitudes living organisms must be able to tolerate
  the temperature extremes of summer and winter. This could range
  from 90’s in the summer to well below freezing in the winter.
• In the tropics there is very little seasonal change and many
  organisms have a narrow range of temperature tolerance. Years
  ago an important paper was publish titled ‘ Why mountain passes
  are higher in the tropics’. What does that mean??
• It means that in the tropics differences in elevation can be barriers
  to the distribution of species. The temperature at which you can
  live may prevent your population from moving from one suitable
  habitat to another, because of the temperature zones through
  which you would need to pass in a vertical migration.
                   Other Abiotic Factors
• Here are some abiotic factors that you may not have
  thought about.

   – Calcium: The lack of availability of calcium will restrict the distribution of
     land snails. If there is no calcium a shell can’t be secreted.

   – Sand: the size of the sand grains in the soil can impact animal that are
     burrowers.

   – Nitrogen: Not just nitrogen, but nitrate (NO 3). This is the form of
     nitrogen used by plants. When nitrate is not readily available in the soil,
     some plants supplement it with a meat diet. (insectivorous plants).
                        Biotic Factors


• A living organism is also affected by the living components of its
  environment.
• Competition exists for available food resources.
• Predators feed on members of the population.
• Microbes can bring diseases. (If time travel were possible, and you
  could be transported to the Cretaceous Era to look at dinosaurs,
  don’t be afraid of fear Tyrannosaurus, fear the microbes. You
  would have no immunity to them!!)
• There may be competition for nesting space.
• Plants may compete for the light needed to carryout
  photosynthesis.
• These are many other biological factors determine the success of
  an individual or species.

				
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posted:12/26/2011
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