Ecosystem Restoration

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Ecosystem Restoration

• Repaying the Ecological Debt

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Conceptual issues

• After manipulation of a natural system, have
  three choices

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Ecosystem Restoration

• Restoration bring back to pre-disturbance
  condition
• Rehabilitation partial replacement of original
  ecosystem
• Enhancement alternative ecosystem
• Note to understand above scenarios of recovery
  have to consider two biological factors of
  colonization and succession

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Colonization and Succession

• - Both are ecosystem changes with time
• Colonization arrival of new species in an empty
  patch
• Colonization of bare areas based on MacArthur
  and Wilson theory of island biogeography ?
  CONSIDER DENUDED PATCHES AS ISLANDS
• Ex. Clear-cuts, strip mine are islands in a sea
  of mixed deciduous forest

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Seq
S Seq (1-e -Gt)
?S
G ____ colonization rate
Species (s)
?t
Time (t)

• Number of species depends on colonization rate
  (G)
• G starts out high, gets smaller and smaller
• Colonization rate based on two relationships

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inhospitable terrain
Species source (mainland, deciduous forest)
islands (clear-cut, toxic waste site, strip
mine)
? Longer distance from source (mainland) lower
of species
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inhospitable terrain
Larger patches higher probability of being
hit by propagules ? Increased size/area
increased of species on islands
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Seq
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Factors Affecting Colonization Rates
Immigration Extinction

• Proximity to source
• Kind of organism (vagility)
• Reproductive rate (r- vs K-selection)
• Air, water currents (rafting)

• Residual disturbance, toxics
• Competition
• Habitat diversity and quality
• Generalist/Specialist

Note once reach equilibrium ? dynamics become
interactive succession
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Non-interactive
Interactive succession
Seq
Species (s)
Time (t)
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Succession

• Orderly change in community composition over time
• Usually follows colonization ? especially studied
  in plant communities
• Two models
• relay floristics
• initial floristics

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Relay floristics
Abandonment
Crop Weeds Grassland
Shrubland Forest
Species
Years
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Initial floristics
Abandonment
Crop Weeds Grassland
Shrubland Forest
Species
Years
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Implications for Reserve Design
better worse
A
B
C
D
E
F
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Significance to restoration of altered ecosystems

• Relay floristics ongoing process based on
  external input
• Initial floristics happens all at once based on
  internal input
• ?Might have to manage system to help recovery
• - stock fish
• - soil stabilization with annual plants
• - etc.

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Tionesta Natural Area, Allegheny National Forest,
PA
Photo by R. Grippo