Tidal and Nontidal Marsh Restoration: A Trade‐Off Between Carbon Sequestration, Methane Emissions, and Soil Accretion

Details

• Journal Title:
  Journal of Geophysical Research: Biogeosciences
• Personal Author:
  Arias‐Ortiz, Ariane ; Oikawa, Patricia Y. ; Carlin, Joseph ; Masqué, Pere ; Shahan, Julie ; Kanneg, Sadie ; Paytan, Adina ; Baldocchi, Dennis D.
• NOAA Program & Office:
  NWS (National Weather Service)
• Description:
  Support for coastal wetland restoration projects that consider carbon (C) storage as a climate mitigation benefit is growing as coastal wetlands are sites of substantial C sequestration. However, the climate footprint of wetland restoration remains controversial as wetlands can also be large sources of methane (CH4). We quantify the vertical fluxes of C in restored fresh and oligohaline nontidal wetlands with managed hydrology and a tidal euhaline marsh in California's San Francisco Bay‐Delta. We combine the use of eddy covariance atmospheric flux measurements with 210Pb‐derived soil C accumulation rates to quantify the C sequestration efficiency of restored wetlands and their associated climate mitigation service. Nontidal managed wetlands were the most efficient in burying C on‐site, with soil C accumulation rates as high as their net atmospheric C uptake (−280 ± 90 and −350 ± 150 g C m−2 yr−1). In contrast, the restored tidal wetland exhibited lower C burial rates over decadal timescales (70 ± 19 g C m−2 yr−1) that accounted for ∼13%–23% of its annual C uptake, suggesting that the remaining fraction is exported via lateral hydrologic flux. From an ecosystem radiative balance perspective, the restored tidal wetland showed a > 10 times higher CO2‐sequestration to CH4‐emission ratio than the nontidal managed wetlands. Thus overall, tidal wetland restoration resulted in a negative radiative forcing (cooling) through increased soil C accumulation, while nontidal wetland restoration led to an early positive forcing (warming) through increased CH4 emissions potentially lasting between 2.1 ± 2.0 to 8 ± 4 decades.
• Source:
  Journal of Geophysical Research: Biogeosciences, 126(12)
• DOI:
  https://doi.org/10.1029/2021jg006573
• ISSN:
  2169-8953 ; 2169-8961
• Format:
  PDF
• Publisher:
  American Geophysical Union (AGU)
• Document Type:
  Journal Article
• Funding:
  Grant no. NA18NWS4620043B ; Grant no. NA18NWS4620043 B
• Rights Information:
  Other
• Compliance:
  Library
• Main Document Checksum:
  urn:sha-512:f951f12cebc021a01e3b4b2181ebf0b41bb64c20df02dbea5a5fcdcfb06ac74ff5ba9df07e0d24c73556862cc097efa7d468fb3bab0195a89c1d6c0570eeb91b
• Download URL:
  https://repository.library.noaa.gov/view/noaa/65648/noaa_65648_DS1.pdf
• File Type:
  [PDF - 1.77 MB ]