Transcript Document

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.”