Created mangrove wetlands store belowground carbon and surface elevation change enables them to adjust to sea-level rise

Krauss, K. W., et al., 2017. Scientific Reports

Original research (primary data)
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Abstract

Mangrove wetlands provide ecosystem services for millions of people, most prominently by providing storm protection, food and fodder. Mangrove wetlands are also valuable ecosystems for promoting carbon (C) sequestration and storage. However, loss of mangrove wetlands and these ecosystem services are a global concern, prompting the restoration and creation of mangrove wetlands as a potential solution. Here, we investigate soil surface elevation change, and its components, in created mangrove wetlands over a 25 year developmental gradient. All created mangrove wetlands were exceeding current relative sea-level rise rates (2.6 mm yr(-1)), with surface elevation change of 4.2-11.0 mm yr(-1) compared with 1.5-7.2 mm yr(-1) for nearby reference mangroves. While mangrove wetlands store C persistently in roots/soils, storage capacity is most valuable if maintained with future sea-level rise. Through empirical modeling, we discovered that properly designed creation projects may not only yield enhanced C storage, but also can facilitate wetland persistence perennially under current rates of sea-level rise and, for most sites, for over a century with projected medium accelerations in sea-level rise (IPCC RCP 6.0). Only the fastest projected accelerations in sea-level rise (IPCC RCP 8.5) led to widespread submergence and potential loss of stored C for created mangrove wetlands before 2100.

Case studies

Basic information

  • Case ID: INT-102-1
  • Intervention type: Restoration
  • Intervention description:

    created mangrove wetlands from natural transition from marshes newly created intertidal areas that were graded to tidal elevation using a mix of upland soils atop underlying sand, planted with marsh grass (Spartina alterni ora)53, and seeded naturally with mangroves.

  • Landscape/sea scape ecosystem management: No
  • Climate change impacts Effect of Nbs on CCI Effect measures
    Coastal inundation  Positive surface elevation change vertical accretion rate
  • Approach implemented in the field: Yes
  • Specific location:

    Tampa Bay

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

Evidence

  • Notes on intervention effectivness: observation overtime of sediment accretion/elevation change and effectiveness is determined by comparing to a benchmark (rate of sea level rise). they do compare to a 'reference site' which is an undisturbed mangrove but outcomes of comparison only say whether the created mangrove is better/worse/same as a natural habitat, not its effectiveness in of itself. hence the valid effectiveness evaluation is the comparison to the benchmark results are valid ecosystem outcomes as well as they reflect maintenance/health of the habitat
  • 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?: Yes
  • Impacts on GHG: Positive
  • Assess outcomes of the intervention on natural ecosystems: Yes
  • Impacts for the ecosystem: Positive
  • Ecosystem measures: vertical accretion rate surface elevation change
  • 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: