BackCh 8.2 Succession in General Biology
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Terms in this set (28)
Succession is the change in communities following the creation of new substrate or a disturbance.
A disturbance is any process that destroys or removes biomass and causes marked change in a community or population.
Disturbance removes biomass, while stress decreases population growth rates without necessarily removing biomass.
Primary succession occurs on bare land with no living organisms present, typically after large-scale disturbances like volcanoes or glaciers.
Secondary succession is the regeneration of a community after a minor disturbance that does not remove all biomass, such as a fallen tree or small forest fire.
Low frequency and low intensity disturbances cause little successional change; increasing intensity leads to secondary or primary succession depending on biomass removed.
Pioneer communities are first to establish after disturbance, often r-selected species; climax communities are stable, late-successional communities dominated by K-selected species.
Pioneer species include Doug fir, aspen, black spruce; climax species include white hemlock, which tolerate shade and outcompete pioneers over time.
Succession involves changes in species composition, primary production, respiration, nutrient retention, and biodiversity.
He used dunes as a space-for-time substitution to study succession, observing older communities on leeward dunes and younger on windward dunes.
Clements viewed succession as a superorganism life cycle leading inevitably to a stable climax community.
Gleason believed communities are products of particular times and places, emphasizing abiotic environmental factors over deterministic climax stages.
Elton argued both biotic and abiotic factors shape succession, with community changes influenced by environment and species interactions.
Early species modify the environment to aid colonization of later species, e.g., nitrogen-fixing legumes improving soil for future plants.
Early species modify the environment to hinder colonization of later species by occupying space or resources.
Later species are unaffected by early species and outcompete them over time due to traits like longevity.
Different community development outcomes can occur under similar environmental conditions, leading to multiple stable community types.
Hysteresis is when a community cannot return to its original state even if environmental conditions are restored.
Coral reefs may shift to algal dominance due to disturbances like overfishing and nutrient pollution, and may not revert back to coral dominance.
No, some species and ecosystem services are unique to early successional stages, and climax communities can change over time.
Community diversity is highest at intermediate levels of disturbance, balancing competition and mortality.
Low disturbance allows competitive exclusion to dominate, reducing species diversity.
High disturbance causes high mortality, limiting species diversity.
They studied species diversity on intertidal boulders of different sizes and found highest diversity on medium-sized boulders with intermediate disturbance.
It describes how predation, competition, and physical stress vary in importance along a disturbance gradient.
Predation is most important at low disturbance, limiting dominant competitors.
Competition becomes more important as disturbance increases and predation decreases.
Physical stress dominates at high disturbance, favoring stress-tolerant species.