Regents Prep: Living Environment: Ecology:
Biotic vs. Abiotic

Abiotic Factors
Abiotic factors are those non-living physical and chemical factors which affect the ability of organisms to survive and reproduce.   

Some Abiotic Factors

  • light intensity
  • temperature range
  • type of soil or rock
  • pH level
    (acidity or alkalinity)
  • water availability
  • dissolved gases
  • level of pollutant

Abiotic factors vary in the environment and determining the types and numbers of organisms that exist in that environment.   Factors which determine the types and numbers of organisms of a species in an ecosystem are called limiting factors.   Many limiting factors restrict the growth of populations in nature.  An example of this would include low annual average temperature average common to the Arctic restricts the growth of trees, as the subsoil is permanently frozen.

Biotic Factors
Biotic factors
are all the living things or their materials that directly or indirectly affect an organism in its environment.   This would include organisms, their presence, parts, interaction, and wastes.  Factors such as parasitism, disease, and predation (one animal eating another) would also be classified as biotic factors.

Some Biotic Factors

  • parasitism
  • disease
  • predation

Carrying Capacity
Carrying capacity
is the maximum number of organisms the resources of an ecosystem can support.   The carrying capacity of the environment is limited by the available abiotic and biotic resources (limiting factors), as well as the ability of ecosystems to recycle the residue of dead organisms through the activities of bacteria and fungi.


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