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The impact of sea-level rise on organic matter decay rates in Chesapeake Bay brackish tidal marshes

September 3, 2013

The balance between organic matter production and decay determines how fast coastal wetlands accumulate soil organic matter. Despite the importance of soil organic matter accumulation rates in influencing marsh elevation and resistance to sea-level rise, relatively little is known about how decomposition rates will respond to sea-level rise. Here, we estimate the sensitivity of decomposition to flooding by measuring rates of decay in 87 bags filled with milled sedge peat, including soil organic matter, roots and rhizomes. Experiments were located in field-based mesocosms along 3 mesohaline tributaries of the Chesapeake Bay. Mesocosm elevations were manipulated to influence the duration of tidal inundation. Although we found no significant influence of inundation on decay rate when bags from all study sites were analyzed together, decay rates at two of the sites increased with greater flooding. These findings suggest that flooding may enhance organic matter decay rates even in water-logged soils, but that the overall influence of flooding is minor. Our experiments suggest that sea-level rise will not accelerate rates of peat accumulation by slowing the rate of soil organic matter decay. Consequently, marshes will require enhanced organic matter productivity or mineral sediment deposition to survive accelerating sea-level rise.

Citation Information

Publication Year 2013
Title The impact of sea-level rise on organic matter decay rates in Chesapeake Bay brackish tidal marshes
DOI 10.5194/bg-10-1869-2013
Authors M.L. Kirwanm, J.A. Langley, Gleen R. Guntenspergen, J.P. Megonigal
Publication Type Article
Publication Subtype Journal Article
Series Title Biogeosciences
Index ID 70047953
Record Source USGS Publications Warehouse
USGS Organization Patuxent Wildlife Research Center