Chapter 4 - Ecosystem Dynamics Flashcards
What is ecological succession?
The gradual replacement of one assemblage of species by another as conditions change over time.
It involves a series of steps by which life comes back to an area.
What are the two basic types of ecological succession?
- Primary succession (bare rock - no soil)
- Secondary succession (due to disturbance but soil still remains)
Secondary succession is generally faster since the soil remains intact.
What are primary colonizers?
The first species to occupy an area during primary succession, able to withstand harsh conditions.
Examples include lichens and mosses.
What is a climax community?
A relatively stable, long-lasting, complex, and interrelated community of organisms, influenced by climate and soil factors.
It represents the final stage of ecological succession.
What is the difference between inertia and resilience in ecosystems?
- Inertia: Ability of an ecosystem to withstand change
- Resilience: Ability of an ecosystem to return to normal after a disturbance.
Fill in the blank: Secondary succession is the sequential development of biotic communities on previously _______ surfaces.
vegetated
What is the Intermediate Diversity Hypothesis?
Suggests that ecosystems subject to moderate disturbance maintain higher levels of diversity compared to those with low or high disturbances.
What are some natural causes of ecological changes?
- Fire
- Floods
- Volcanic eruptions
- Tsunamis
- Glacial retreat
What human activities can cause ecological changes?
- Logging
- Dam building
- Agriculture
What is an invasive species?
Organisms found in an area outside their normal range that can out-compete native species and alter habitats.
Examples include Purple Loosestrife and Zebra Mussels.
True or False: Climax communities are always stable and never change.
False
What are the stages of primary succession?
- Lichens
- Mosses
- Grasses
- Small plants
- Small trees
- Spruce and hemlock forest
What factors influence recovery patterns after ecological disturbances?
Recovery patterns depend on many factors including the type of disturbance and the resilience of the ecosystem.
What is the role of soil in ecological succession?
Soil can be more important than climate in determining community composition, especially in edaphic climaxes.
What is cyclic succession?
Occurs when a community progresses through several seral stages but is returned to an earlier stage by disturbance.
This can lead to high species diversity in blended areas known as ecotones.
What are the characteristics of immature ecosystems?
- Lower biodiversity
- Higher NPP (Net Primary Productivity)
- More susceptible to disturbances
What are some examples of invasive alien species in Canada?
- Purple Loosestrife
- Eurasian Water Milfoil
- Zebra Mussels
Explain the significance of the concept of ‘seral stages’ in ecological succession.
Each stage in the process of succession is known as a seral stage, representing a distinct community of organisms at that point in time.
What are ecotones?
Blended areas between communities that have high species diversity.
They occur where two different ecosystems meet.
What is the main mode of transport for invasive species between different countries?
Ballast water of ships
What are the two invasive species mentioned?
Zebra mussel, Rusty Crayfish
How do invasive zebra mussels affect native tiger mussels?
They get attached to the hard substrates of native mussels, preventing them from filter feeding, leading to their eventual death.
How does rusty crayfish affect the ecosystem?
It is a threat to the aquatic plant bed and native species in the environment they invade.
What is hyperabundance?
Native species populations increase to undesirable numbers where natural habitats have been disturbed or when predatory species are removed.
