Restoration: The Ultimate Test

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Restoration The Ultimate Test

• By Nicole Kroutter
• Rob Harvey
• Nikki Thurgate

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Restoration A Win - Win Situation

• In his article, John Ewel proposes that
  ecosystem restoration is an activity at which
  everyone wins
• When successful, a disrupted fragment of the
  Earths surface is returned to its undisturbed
  state.
• When plagued with failure, the information
  learned about the environment becomes a powerful
  tool for future success.

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Ewels Five Point Criteria

• Sustainability
• Invasibility
• Productivity
• Nutrient Retention
• Biotic interactions

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Sustainability

• Sustainability is the ability of the newly
  reconstructed environment to perpetuate itself
  without constant management.
• Proper planning can increase the chances of a
  new system becoming independent.
• Sustainable development has become an important
  issue for restoration ecologists

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Sustainability Models

• Dr. Sylvia Earl, in conjunction with National
  Geographic has proposed a model for a Sustainable
  Seas program.
• Her program, like others, devotes itself to the
  human -side of sustainable development

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Invasibility

• To fulfill this criteria, a reconstructed
  community must be capable of resisting invasion
  by new species.
• Intact communities are more resistant to invaders
  than those that have suffered from disruption
• Invasion by non-indigenous species are now
  recognized as one of the leading threats to
  biodiversity and ecosystem function.

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Tracking the Enemy

• Invasive plants alter ecological processes,
  displace desirable species, and reduce wildlife
  habitat quality.
• Invasive species usually entered disturbed areas
  and fill in newly formed niches.
• Ecologists are devoting a great deal of study
  into what makes a species an invader and why some
  communities are resistant to invasion.

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Predicting Invaders

• Invasive species have a variety of
  characteristics that increase their fitness.
• In plants these includea history of invasion,
  an uneven phylogenetic distribution, and
  vegetative reproduction.

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Establishment as an Invader

• Species entrained in transport path
• Species survives transport and introduction
• Species becomes established in the new geographic
  area
• Species spreads from the point of introduction
• Species becomes abundant, and begins to fill in
  niches while adversely effecting the native
  population.

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Productivity

• Productivity depends upon the efficient use of
  resources by the restored community.
• Ideally, the newly restored community will become
  as productive as the original.
• Productivity can be measured on several levels

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Measurements of Productivity

• Primary production
• Secondary production
• Gross productivity
• Net productivity
• Net productivity is especially useful because it
  incorporates critical live processes such as
  respiration and photosynthesis.

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Productivity

• Improving productivity of the soil can have a
  powerful impact on the overall health of a
  restored or damaged community
• Tropical shifting cultivation systems that employ
  fallow periods have shown an increase in overall
  soil productivity.
• The increase in productivity increases the system
  resistance to invasive species especially weeds

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Nutrient Retention

• A reconstructed community must be able to
  maintain a steady level of critical nutrients.
• If the community can not control the rate of
  nutrient loss or gain of certain nutrients, the
  restored community will suffer.
• Either extreme of nutrient balance will result
  in a decrease in productivity, sustainability,
  and lead to invasion by other species

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Nutrient Retention in Action

• Two of the most critical nutrients are Carbon
  and Nitrogen.
• Good retention of these nutrients increases the
  chance of recovery for a disturbed area

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Additional Benefits of Nutrient Retention

• Nutrient Retention is not only necessary for
  plant survival, but offers many benefits to the
  ecosystem.
• One experiment focused on the effects of
  macrophyte species richness on wetland function.
• The increase in macrophyte diversity helped the
  wetland to retain additional amounts of
  Phosphorus, an environmental pollutant

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Biotic Interactions

• The successful establishment of biotic
  interactions may be one of the most important
  steps in the restoration process.
• For many restored areas the reassembly of the
  plant population is enough to trigger
  colonization by various animal species.
• The interactions of a few key species, though,
  may determine the ultimate success of the
  community

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Biotic interactions and Key Species

• Key species are those species that have a large
  impact on a community.
• Key species can be seen as ecosystem engineers.
• If key species are removed or do not returned to
  a restored area, large changes in ecosystem
  function will result

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The influence of Biotic Interactions

• Experiments on species co-existence in temperate
  forests have offered some valuable insight into
  the role of biotic interactions.
• Biotic interactions are incredible important
  in the time frame from reproduction to
  establishment of a seedling
• These interactions include the role of
  pollinators and other critical species

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Valuable Biotic Interactions

• Birds play a major role in seed dispersal
• Mycorrhizal interactions can provide the seedling
  with various nutrients
• Different species of tree have different
  advantages at different stages

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Ewels Criteria in Action

• Case Study 1
• Restoring Enriched Grassland Effects of Mowing
  on Species Resistance, Productivity, and Nutrient
  Retention
• By John Maron

• Case Study 2
• Dispersal Limitation, Invasion Resistance, and
  the Structure of Pond Zooplankton Communities
• By Jonathan Shurin

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Case Study One

• In this experiment, scientists examined the
  effects of nitrogen enrichment on species- rich
  grasslands.
• Nitrogen enrichment has become an increasing
  problem due to the build up of nitrogen oxides in
  the atmosphere and soil
• The areas of nitrogen enrichment are prone to
  invasion by exotic species, increases in biomass,
  and loss of species diversity.

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Case Study One

• The scientists hypothesized that removal of
  biomass through repeated mowing of the research
  area would lead to a drop in Nitrogen levels.
• Also it was hypothesized that the mowing would
  increase native species diversity, through the
  removal of nitrogen- fixing invaders such as bush
  lupine.

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Results of Case Study One

• Mowing and the removal of biomass resulted in a
  dramatic change in species assembly
• The population shifted from exotic species to a
  mixture of exotic and native forbs community.
• Due to biomass removal and the shift in species,
  there were changes in nitrogen retention

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Results of Case Study One

• The mowing ,though useful in increasing species
  diversity and productivity, did not succeed in
  reducing Nitrogen levels.
• In fact, the switch to the combination of exotic
  and native forbs due to mowing, actually resulted
  in increased nitrogen retention.

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Case Study Two

• This experiment highlights the invasion
  resistance capabilities of a pond community
• The scientist introduced a sample of non-native
  zooplankton in several fishless ponds

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Case Study Two

• In cases were native species diversity was high,
  the introduced invaders could not establish a
  foothold in the community.
• In fact, the success rate of introduction was low
  with many of the invaders becoming extinct.
• For those that became established, they had no
  impact on the overall community, since their
  total numbers were very low.

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Results of Case Study Two

• The pattern established in this experiment
  supports the hypothesis that an increase in
  species diversity confers invasion resistance.
• The increase in biotic interactions among the
  natives also reduced the chance of invasion

• The same experiment conducted a test on the
  effects of introduced invaders on a community
  with limited diversity.
• In this test, the invaders did become
  established in the community.

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Final Thoughts

• Both experiments illustrated the importance of
  nutrient retention, biotic interactions,
  invasibility, and productivity on the
  construction of a sustainable community.
• While one experiment failed to achieve its main
  goal and the other succeed, the overall knowledge
  of the interactions in a community was increased,
  making the efforts part of a win-win situation