Ecosystem: Stability and Change
Stability
Is the ability to withstand or recover from externally imposed changes or stress
• resistance, persistence, or inertia• Resilience• Constancy-maintain certain size
– Applies to organisms, populations, communities ecosystems, and the ecosphere
– Provided that these external stresses are not too severe
Factors Contributing to Ecosystem Stability
• Food Web Complexity• Homeostatis- internal systems counteracting
external stress.• Continuous Dynamic Change
Movement of Matter and EnergyReplacement of OrganismsEcological Succession- the natural replacement of one
community in particular area with a different, and usually more complex community, over a period of time
Primary Succession
Secondary Succession
Secondary Succession
Tolerance Range/Limits
Minimum and maximum limits for physical conditions (such as temperature) and concentration of chemical substances beyond which no members of a particular species can survive.
Limiting Factor Principles
Too much or too little and any abiotic factor can limit or prevent growth of a population of a species in an ecosystem, even if all the other factors are at or near the optimal range of tolerance for the species
Law of Tolerance
The existence, abundance, and distribution of a species in an ecosystem are determined by whether the levels of one or more physical and chemical factors fall with the range tolerate by the species.