ECOLOGY: SUCCESSION

IMPORTANT TERMS

• Ecological Succession – A series of predicable changes that occur in a community over time.• Primary Succession – Begins in an area with no

remnants of the old community.• Secondary Succession – Occurs in areas where

the original community has not been completely destroyed.• Pioneer Species – The first species to colonize a

barren area.

BRAINSTORMING

• Does succession involve changes to the whole ecosystem? • Can you think of any examples of primary

succession?• Can you think of any examples of secondary

succession?

KRAKATAU

• Explosive eruption in 1883• Seismically active for

several years before eruption• Completely wiped out

the island

KRAKATAU

PRIMARY SUCCESSION

• Succession that begins in an area that does not have any biotic factors left.• Primary succession occurs after:• Volcanic eruptions• Retreating glaciers• Any event that results in the complete destruction of a

community

PRIMARY SUCCESSION

PRIMARY SUCCESSION

• A very slow process• Environment changes over time in response to

new factors that emerge• New organisms interact with abiotic factors to influence

the ecosystem• Subsequent species emerge in response to changes in

the ecosystem

PIONEER SPECIES

• The first species to colonize an area that previously had no biotic factors.• Pioneer species change the environment to make

it habitable for more species• Lichen• A combined lifeform composed of a fungus and an alga

(or cyanobacteria)• Nitrogen-fixing organism; adds nutrients to soil (begins

nitrogen cycle again)

SECONDARY SUCCESSION

• Succession that occurs in ecosystems that have been altered but that still maintain some elements from the original community.• Process occurs much faster than primary

succession.• Commonly occurs after natural disturbances:• Hurricanes• Wildfires• Human activity

SECONDARY SUCCESSION

WHY DOES SUCCESSION OCCUR?

• All organism influence their environment• Competition between species

CLIMAX COMMUNITIES

• The final stage of succession that represents the most stable community.• Succession does not always occur uniformly• Areas with frequent disturbances may never

reach stability• Secondary succession frequently reproduces the

original community.