Temporal variability of carbon and nutrient burial, sediment accretion, and mass accumulation over the past century in a carbonate platform mangrove forest of the Florida Everglades
Joshua L. Breithaupt1, Joseph M. Smoak2, Thomas J. Smith III3, and Christian J. Sanders4
Citation: Breithaupt, J. L., J.M. Smoak, T. J. Smith III, and C. J. Sanders (2014), Temporal variability of carbon and nutrient burial, sediment accretion, and mass accumulation over the past century in a carbonate platform mangrove forest of the Florida Everglades, J. Geophys. Res. Biogeosci., 119, doi:10.1002/2014JG002715.
The objective of this research was to measure temporal variability in accretion and mass sedimentation rates (including organic carbon (OC), total nitrogen (TN), and total phosphorous (TP)) from the past century in a mangrove forest on the Shark River in Everglades National Park, USA. The 210Pb Constant Rate of Supply model was applied to six soil cores to calculate annual rates over the most recent 10, 50, and 100 year time spans. Our results show that rates integrated over longer timeframes are lower than those for shorter, recent periods of observation. Additionally, the substantial spatial variability between cores over the 10 year period is diminished over the 100 year record, raising two important implications. First, a multiple-decade assessment of soil accretion and OC burial provides a more conservative estimate and is likely to be most relevant for forecasting these rates relative to long-term processes of sea level rise and climate change mitigation. Second, a small number of sampling locations are better able to account for spatial variability over the longer periods than for the shorter periods. The site average 100 year OC burial rate, 123 ± 19 (standard deviation) g m-2 yr-1, is low compared with global mangrove values. High TN and TP burial rates in recent decades may lead to increased soil carbon remineralization, contributing to the low carbon burial rates. Finally, the strong correlation between OC burial and accretion across this site signals the substantial contribution of OC to soil building in addition to the ecosystem service of CO2 sequestration.
1College of Marine Science, University of South Florida, St. Petersburg, Florida, USA, 2Department of Environmental Science, Policy, and Geography, University of South Florida, St. Petersburg, Florida, USA, 3U.S. Geological Survey, Southeast Ecological Science Center, St. Petersburg, Florida, USA, 4Centre for Coastal Biogeochemistry Research, School of Environment, Science & Engineering, Southern Cross University, Lismore, New South Wales, Australia
Correspondence to: J. L. Breithaupt, email@example.com