Succession Defined:

• The sequential change in the relative abundances of the dominant species in a biological community following a disturbance.

• Primary succession: beginning from a abiotic environment following a cataclysmic disturbance.

• Secondary succession: beginning from a major disturbance, but all forms of life are not destroyed.

Primary Succession

After……..?

And……..

And……..

Example – Surtsey Island, Iceland

Diagram of bog succession.

Primary Succession

• No soil

• Pioneer species take hold, break down rock and contribute organic material = soil

• Grasses, shrubs, then trees after soils

• Climax community– May vary– Depends on environment

Secondary Succession

After…………..

Or…………

Stages of Succession• Early: plants typically small with short

lifecycles (annuals…), rapid seed dispersal, environmental stabilizers.

• Middle: plants typically longer lived, slower seed dispersal, and in woodland systems: larger.

• Late: plants and animal species are those associated with older, more mature ecosystem.

• “Climax”?

Marine Succession 1

• Whale dies and sinks to floor

• Scavengers/decomposers

Marine Succession 2

• Smaller # of organisms

• Sediment dwellers with enrichment of sediments from decomposition

Marine Succession 3

• Skeleton remains• Heterotrophic bacteria decompose oils in

bones• Release chemicals for chemosynthetic

bacteria• Bacteria support mussels, limpets, snails,

worms, crabs, clams, sediment dwellers around remaining bones

Fig 10.8 Graphs showing changes in biomass and diversity with succession.

Changes in soil nitrogen and phosphorus.

Aldo Leopold (1934):

• “The time has come for science to busy itself with the earth itself. The first step is to reconstruct a sample of what we had to begin with.”• “…a starting point in the long and laborious job of building a permanent and mutually beneficial relationship between civilized men and the landscape.”

Steve Packard (early 1990s),The Nature Conservancy

• “Chicagoans will feel patriotic about their native landscape.”• “Cab drivers will point out our savanna and prairie preserves to out-of-town visitors with the same pride they now feel when pointing out the Sears Tower.”