Ecological Succession (College Board AP® Environmental Science): Flashcards
0Still learning
Know0
Define primary succession.
Was this flashcard helpful?
Cards in this collection (22)
Define primary succession.
Primary succession is the process in which newly formed or newly exposed land with no species present is gradually colonized by an increasing number of species.
What are two ways that new bare land for primary succession can form?
New bare land can form when magma cools into new rock surfaces, when sea level drops, when a lake dries up, or when glaciers retreat.
Define secondary succession.
Secondary succession is succession on bare soil where there has been a pre-existing community, such as an abandoned agricultural field or a forest after an intense fire.
True or False?
Primary succession only occurs on bare rock.
False.
Primary succession occurs on any barren terrain being colonized, such as coastal sand dunes, where marram grasses are the pioneer species.
Why does secondary succession develop faster than primary succession?
Secondary succession is faster because soil is already present.
Define pioneer species.
Pioneer species are the first species to colonize new land, often mosses and lichens, and they modify the environment so it becomes suitable for other organisms.
As pioneer species die and decompose, their dead organic matter, called , forms basic soil.
As pioneer species die and decompose, their dead organic matter, called humus, forms basic soil.
Define seral community.
A seral community (or sere) is a temporary, intermediate stage in the ecological succession of an ecosystem.
How do the roots of small plants and shrubs help succession progress?
Their roots form a network that holds the soil in place and prevents it from being washed away.
Define climax community.
A climax community is the final, stable community formed at the end of succession.
How do biomass and species richness change as succession proceeds in a disturbed ecosystem?
As succession proceeds, biomass increases as plant and animal matter accumulates, and species richness increases as the ecosystem diversifies.
True or False?
Gross productivity is high in the early stages of succession.
False.
Gross productivity is low early on because of harsh conditions, low nutrient availability, and a low density of producers.
Define net productivity.
Net productivity is the energy that remains after respiration by producers, which is available for growth and consumption by other organisms.
Why does biomass accumulation slow in the mid-stages of succession?
Biomass accumulation slows because respiration increases as more organisms join the system and competition for light, water, and nutrients increases.
Why does net productivity approach zero in a climax community?
Net productivity approaches zero because most energy from photosynthesis is used up by the cellular respiration of producers and consumers.
Define keystone species.
A keystone species is an organism that has a disproportionately large impact on the structure and function of an ecosystem relative to its abundance.
How do African elephants increase habitat diversity in savanna grasslands?
Elephants feed on shrubs and trees, creating gaps in the vegetation that promote the growth of grasses.
True or False?
Removing a keystone species has little effect on an ecosystem because keystone species are often low in abundance.
False.
Removing a keystone species can have cascading effects that change community structure and function and increase the risk of ecosystem collapse.
Without purple sea stars, populations would expand rapidly and outcompete other intertidal species, reducing species diversity.
Without purple sea stars, mussel populations would expand rapidly and outcompete other intertidal species, reducing species diversity.
Define indicator species.
An indicator species is a plant or animal that signals the health or quality of an ecosystem through its presence, abundance, or absence.
What does the presence of bloodworms in a stream indicate?
Bloodworms indicate low dissolved oxygen levels and high organic pollution.
Stonefly and nymphs are highly sensitive to pollution, so their presence indicates clean, well-oxygenated water.
Stonefly and mayfly nymphs are highly sensitive to pollution, so their presence indicates clean, well-oxygenated water.
Sign up to unlock flashcards
or