Ecological Succession Flashcards

Flashcards covering key concepts of ecological succession, keystone and indicator species, ecosystem engineers, and examples from the lecture notes.

What are the two main types of ecological succession?

Primary succession and secondary succession.

Define a keystone species.

A species whose role in an ecosystem is far more important than its relative abundance; a few individuals can have a big impact on many other organisms.

Why is the sea otter considered a keystone species in kelp forest ecosystems?

It top-predates sea urchins, preventing overgrazing of kelp and maintaining healthy kelp forests.

What is the role of dung beetles in ecosystems?

Keystone species that rapidly remove, bury, and recycle animal wastes and aerate the soil.

What is an ecosystem engineer? Provide an example.

A keystone species that creates or maintains habitat for other species; example: the North American beaver builds dams that create ponds and new habitat.

What is an indicator species?

An organism whose presence, abundance, or chemical composition indicates a distinctive aspect of ecosystem quality or degradation; used as an early warning.

Why are amphibians good indicator species?

Because their thin skin makes them highly susceptible to environmental contaminants; substances like atrazine can affect them at low levels.

What initiates primary succession and who are the pioneer species?

Primary succession begins on lifeless ground; pioneer species such as lichens and mosses colonize bare rock and begin soil formation.

How does secondary succession differ from primary succession, and what are typical early colonizers?

Secondary succession begins after disturbance with some soil remaining and proceeds more rapidly; early colonizers are grasses and wildflowers with wind-dispersed seeds.

What characterizes late-successional or old-growth forests?

High biodiversity, stability, and self-sustaining processes; dominance of shade-tolerant species; complex habitats and presence of species such as grizzly bear, wolf, condor, owl.