Facilitation shifts paradigms and can amplify coastal restoration efforts

Silliman, B. R., et al., 2015. Proceedings of the National Academy of Sciences of the United States of America

Original research (primary data)
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Restoration has been elevated as an important strategy to reverse the decline of coastal wetlands worldwide. Current practice in restoration science emphasizes minimizing competition between out-planted propagules to maximize planting success. This paradigm persists despite the fact that foundational theory in ecology demonstrates that positive species interactions are key to organism success under high physical stress, such as recolonization of bare substrate. As evidence of how entrenched this restoration paradigm is, our survey of 25 restoration organizations in 14 states in the United States revealed that >95% of these agencies assume minimizing negative interactions (i.e., competition) between outplants will maximize propagule growth. Restoration experiments in both Western and Eastern Atlantic salt marshes demonstrate, however, that a simple change in planting configuration (placing propagules next to, rather than at a distance from, each other) results in harnessing facilitation and increased yields by 107% on average. Thus, small adjustments in restoration design may catalyze untapped positive species interactions, resulting in significantly higher restoration success with no added cost. As positive interactions between organisms commonly occur in coastal ecosystems (especially in more physically stressful areas like uncolonized substrate) and conservation resources are limited, transformation of the coastal restoration paradigm to incorporate facilitation theory may enhance conservation efforts, shoreline defense, and provisioning of ecosystem services such as fisheries production.

Case studies

Basic information

  • Case ID: INT-081-1
  • Intervention type: Restoration
  • Intervention description:

    Salt marsh restoration based on two different designs of planting transplants: (1) In clumped treatments, nine transplant plugs were planted in the middle of each plot so that all plugs were touching. (2) In dispersed treatments, nine plugs were planted at equal distances from each other (50 cm in all directions). Trans- plant plugs were 10 × 10 × 10 cm and consisted of the dominant marsh grass Spartina alterniflora

  • Landscape/sea scape ecosystem management: No
  • Climate change impacts Effect of Nbs on CCI Effect measures
    Biomass cover loss  Positive For the planted saltmarsh species: Aboveground biomass % survivorship mean total plot stem density (including all stems in original plantings and emergent runners and thus a measurement of clump expansion) maximum expansion / maximal runner length (reflecting dispersal potential)
  • Approach implemented in the field: Yes
  • Specific location:

    Gulf of Mexico at Fort DeSoto, Tampa, Florida (N 27°36′56′′, W 82°44′09′′)

  • Country: United States of America
  • Habitat/Biome type: Saltmarsh |
  • Issue specific term: Not applicable


  • Notes on intervention effectivness: Look at growth and survivorship after intervention implemented to assess effectiveness note that focus of study is to compare the two ways in which the restoration intervention could be implemented (spatial configuration of plantings) and to see which one will have the maximum success. Nonetheless it shows that the intervention restores the saltmarsh regardless of configuration. (these were not coded for separately b/c not a different intervention type per se but variations of the same)
  • Is the assessment original?: Yes
  • Broadtype of intervention considered: Not applicable
  • Compare effectivness?: No
  • Compared to the non-NBS approach: Not applicable
  • Report greenhouse gas mitigation?: No
  • Impacts on GHG: Not applicable
  • Assess outcomes of the intervention on natural ecosystems: Yes
  • Impacts for the ecosystem: Positive
  • Ecosystem measures: Same as climate impact: salt marsh plant survivorship, biomass, density, expansion *relevant ecosystem effect b/c restoring habitat important for conservation as well*
  • Assess outcomes of the intervention on people: No
  • Impacts for people: Not reported
  • People measures:
  • Considers economic costs: No
  • Economic appraisal conducted: No
  • Economic appraisal described:
  • Economic costs of alternative considered: No
  • Compared to an alternative: Not reported

Evaluation methodology

  • Type of data: Quantitative
  • Is it experimental: No
  • Experimental evalution done: Not applicable
  • Non-experimental evalution done: Empirical case study
  • Study is systematic: