Lecture 14: Community Assembly, Ecological Succession

What is ecological succession? What are the stages in ecological succession?

ecological succession: the predictable series of changes in a community after a severe disturbance.

Stages:

Pioneer species - the first species to arrive in a primary succession area

• lichens: fungi+algae

• do not need much nutrients

Climax community - remains in place with few changes (until another disturbance restarts succession)

Intermediate Stage -Increased biodiversity as shrubs, grasses, and other species invade.

What are the main features of primary succession? What type of species are responsible for primary succession? What is their role?

primary succession: occurs after a disturbance removes all vegetation and soil like.

• glaciers, drying of lakes, volcanic eruption, strip mining

species are responsible for primary succession:

Pioneer species: the first species to arrive in a primary succession area.

lichens: fungi+algae

• Lichens (fungi + algae) are the quintessential pioneer species that colonize barren substrates.

• Fungi enhance decomposition, soil formation, and nutrient cycling.

• Algae contribute to energy production, oxygen release, and organic matter buildup.

What are the main features of secondary succession? What type of species are responsible for secondary succession what is their role?

secondary succession: occurs after a disturbance has removed much, but not all, of the biotic community. (fires, hurricanes, logging, farming)

Soil still contains most of its nutrients and organic matter.

seed still exist in the soil

revegetated by trees and some bushes

Climax community - remains in place with few changes (until another disturbance restarts succession)

Intermediate Species - Increased biodiversity as shrubs, grasses, and other species invade. Start to grow

Pioneer species: the first species to arrive in a primary succession area.

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