2.4-2.5 Tolerance and Limiting Factors/ Natural Disruptions to Ecosystems

2.4

^^Range of Tolerance:^^ Populations thrive within certain ranges of abiotic factors such as pH, temperature, light, amount of moisture, etc.

Different organisms have different ranges, such as with temperature
An organism’s tolerance may change over its lifetime, such as salmon with salinity

^^Limiting factors:^^ The environmental factor that is most often in short supply

Even if all the other factors are optimum, it’s the one most likely to regulate population growth
important limiting factors
- Soil: Often nitrogen, phosphorus, or potassium—this is why NPK testing kits are used and why those nutrients are components of fertilizers
- Open Ocean: Sometimes nitrogen, silica or iron; sometimes dissolved oxygen (DO)
- Freshwater Lakes and Rivers: Often phosphorus
- Bays and estuaries: Salinity

^^Resistance:^^ Ability to remain unchanged when being subjected to disturbance

^^Resilience:^^ Ability and rate of an ecosystem to recover from a disturbance and return to its pre-disturbed state

^^INTERMEDIATE DISTURBANCE HYPOTHESIS:^^

Ecosystems require a certain level of disturbance for maximum health and diversity