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.