Glossary
Climax Community
The final, stable stage of ecological succession, where the ecosystem has reached a state of equilibrium with its environment and experiences minimal further change.
Example:
A mature oak-hickory forest in the eastern United States, stable for centuries, represents a climax community for that region's climate and soil conditions.
Ecological Succession
The process by which the structure of a biological community evolves over time, involving changes in species composition and community characteristics.
Example:
After a major wildfire, a forest undergoes ecological succession as new plant and animal species gradually colonize and replace previous ones.
Fauna
All the animal life present in a particular region or time.
Example:
The diverse fauna of the Amazon rainforest includes jaguars, monkeys, sloths, and countless insect species.
Indicator Species
A species whose presence, absence, or abundance reflects the health or specific environmental conditions of an ecosystem.
Example:
The presence of certain types of aquatic insects, like mayfly larvae, can indicate good water quality, making them valuable indicator species for stream health.
Keystone Species
A species that has a disproportionately large effect on its natural environment relative to its abundance, often playing a critical role in maintaining ecosystem structure.
Example:
Sea otters are considered a keystone species because their predation on sea urchins prevents the urchins from overgrazing kelp forests, which are vital habitats for many other marine organisms.
Pioneer Species
The first species to colonize barren environments or disturbed ecosystems, often hardy organisms capable of surviving harsh conditions and initiating soil formation.
Example:
In a newly exposed glacial till, hardy lichens and mosses act as pioneer species, breaking down rock and creating the first organic matter for future plant growth.
Primary Succession
Ecological succession that begins in an area where no soil exists, such as on bare rock exposed by a retreating glacier or after a volcanic eruption.
Example:
The slow colonization of newly formed volcanic rock on a Hawaiian island by lichens and mosses is an example of primary succession.
Secondary Succession
Ecological succession that occurs in an area where a community has been removed by a disturbance, but the soil or substrate remains intact.
Example:
Following a clear-cutting operation in a forest, the rapid regrowth of grasses, weeds, and then shrubs and trees demonstrates secondary succession.