Integrating ecological and physical processes for successful conservation and restoration of salt ma

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Integrating ecological and physical processes for
successful conservation and restoration of salt
marshes

• Bregje K. van Wesenbeeck,
• Johan van de Koppel, Daphne van der Wal, Jan P.
  Bakker, Mark D. Bertness, Peter M.J. Herman
  Tjeerd J. Bouma

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A non-biological view on the world
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A biological view on the world
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Ecosystem engineers building biogenic habitats

• Biogenic habitats habitats that are produced by
  life-processes
• (Wikipedia)
• Ecosystem engineering modification of the
  abiotic environment by biological activity
• (Jones et al. 1994, Jones et al. 1997)

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Salt Marshes
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Irregular patchiness
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1. Positive feedbacks
Interactions between species and the environment
can result in
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1. Positive feedbackSpartina and sedimentation
reduction in current velocities
increased altitude ? lower inundation stress
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1. Positive feedbackSediment fixation by
Spartina anglica
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2. Scale-Dependent Feedbacks
Interactions between species and the environment
can result in
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2. Scale-Dependent FeedbacksA Model
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2. Scale-Dependent FeedbacksTransplanting
Experiment
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2. Scale-Dependent FeedbacksConclusions

• Clonal expansion of Spartina tussocks can be
  delayed by scale-dependent feedbacks

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3. Negative Interactions
Interactions between species and the environment
can result in
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3. Negative InteractionsBioturbation by Lugworms
Arenicola marina
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3. Negative Interactions
Interactions between species and the environment
can result in
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3. Negative InteractionsMutual Exclusion
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3. Negative InteractionsAbiotic parameters
Bulk density (g/cm)
Silt fraction ( lt63)
Erosion threshold (Pa)
Total
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3. Negative InteractionsInvasion Experiments
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3. Negative InteractionsInvasion Experiments

• Is Arenicola able to invade Spartina tussocks?

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3. Negative InteractionsConclusions

• Modification of the environment by lugworms can
  hinder invasion of Spartina seedlings

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4. Thresholds
Interactions between species and the environment
can result in
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4. ThresholdsConceptual Model
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4. Thresholds Transplanting Experiment
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4. Thresholds Conclusions

• Dynamics of Spartina vegetation in salt-marsh
  pioneer zones are characterized by biomass
  thresholds for settlement

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Overall conclusions

• Small-scale habitat modification can result in
• Scale-dependent feedbacks,
• Negative species interactions via the
  environment,
• Thresholds resulting in unpredictable/non-linear
  ecosystem behavior

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Linking research and restoration
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Linking research and restoration

• No stability on longer time-scales but
• ?thresholds may induce sudden shifts

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Linking research and restoration

• Feedbacks between organisms and the environment
  that result in the presence of thresholds can
  obstruct restoration efforts
• Temporarily restoring favorable abiotic
  conditions can allow ecosystem engineers to
  establish and initiate habitat formation

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Many thanks to
Bas Koutstaal Jos van Soelen
Bert Sinke Ko Verschuure Gert Westraete Ko van
Sprundel Sander Bouwens Remment ter Hofstede
Stichting het Zeeuws Landschap, all the people
participating in the Coastal Ecology Excursion
2003 and the Schure-Beijerinck-Popping Fund
B.vanwesenbeeck_at_nioo.knaw.nl