2.7: Biotic and Abiotic Influences on the Ecosystem
pg. 52
Key Concepts:
4. Human activities influence biogeochemical cycles such as the water and carbon cycles.
5. Ecosystems are composed of biotic and abiotic components.
Evidence of Learning: Students can …
- list abiotic factors important to both terrestrial and aquatic ecosystems.
- give examples of predation, competition, mutualism, parasitism, and commensalism.
- define carrying capacity and tolerance range.
Influence of Abiotic Factors
Limiting Factor: is any factor that restricts the size of the population.
Tolerance Range: The abiotic conditions within which a species can survive.
Figure 1: species can be successful over a range of abiotic conditions. However, they
will become stressed and will die out if conditions exceed their tolerance level.
Figure 3: The distribution of black spruce
Table 1: Key Abiotic Factors of Terrestrial and Aquatic Ecosystems and the Effects
Human Activities Can Have on Them
Ecosystem
Terrestrial
Ecosystems
Aquatic
Ecosystems
Key Abiotic Factors
Light Availability
Water Availability
Nutrient Availability
Temperature
Light Availability
Nutrient Availability
Acidity
Temperature
Salinity
Human action and result
Influence of Biotic Factors
- The ability for a species to live in a given ecosystems can be determined by abiotic
factors.
- Biotic factors involve the interactions between individuals
- Competition for limiting resources between the same species (Intraspecific) and
different species (Interspecific) can impact survival of individuals.
- Other interactions, such as; predation, parasitism, mutualism, and commensalism also
influence species success rate.
Table 2: Key Types and Examples of Species Interaction
Relationships
Competition
Definitions
Two individuals vie for the same
resource
One individual feeds on another
Predation
Mutualism
Two individuals benefiting each
other
Parasitism
One individual lives on or in and
feeds on a host organism
One individual benefits and the
Commensalism other neither benefits nor is
harmed
Examples
Carrying Capacity
Carrying Capacity: the maximum population size of a particular species that a given
ecosystem can sustain.
- The upper sustainable limit of an ecosystem can support is called its Carrying Capacity.
- When populations increases, the demand for resource will increase. Organisms will
have to compete for these resources, which will limit their success rate, and are now
known as limiting resources.
- Carry Capacity is dynamic, always changing. Humans can be a factor in an ecosystems
carrying capacity, causing it to change.
Check Your Learning
Questions 1 – 8, page 55
Summary:
- Many factors place limits on the sizes of populations in an ecosystem.
- Tolerance ranges describe the physical conditions under which a species can survive.
- The type of ecosystem that occurs is a particular location is strongly influenced by
abiotic factors such as light, water, and temperature.
- Species interactions include competition, predation, mutualism, parasitism, and
commensalism.
- Carrying capacity is the maximum population size that an ecosystem can sustain.