FCE I: Initial FCE research on carbon focused on establishing long-term methods of assessing net ecosystem production at the plot scale and quantifying the quality and fluxes of dissolved and particulate organic carbon in the water and soils. Analysis of annual net primary production datasets showed a wedge of productivity at end of the SRS transect where waters are subsidized by phosphorus delivered in tides and storms from the Gulf of Mexico, while production is highest in the ecotone of the Taylor River transect where brackish marine groundwater supplies phosphorus in the dry season.
FCE II: Our 11+ years of eddy covariance, ground sampling, and landscape data suggest that inter-annual variability in the coastal C balance is largely associated with pulse dynamics of storm disturbance (including cold-fronts), tidal cycles, and groundwater dynamics that influence nutrients, salinity, and inundation - the three features defining the production envelope - for mangrove wetlands. Attempts to balance C budgets find that a significant fraction of the atmospheric CO2 uptake is not accounted for in the measurements of plant primary productivity and there are large uncertainties in the transport and losses by tidal advection of organic and inorganic C into adjacent estuarine waters, downstream mineralization, and air-water CO2 efflux. While our dedicated C cycling research in the SRS mangrove ecotone has moved us closer to balancing the C budget there, we are only just beginning to understand controls on C dynamics in the TS/Ph dwarf mangrove forest and our marsh and seagrass end-members. In the marsh, seasonal and spatial differences in NPP and ecosystem respiration appear to be connected to water residence time and P availability. Longer-term patterns accessible from preliminary soil cores in the TS/Ph ecotone associate mid-20th Century drainage of the Everglades to reduced OM accumulation rates in the marsh, and increased rates in the mangroves consistent with greater groundwater P delivery associated with saltwater intrusion. In the seagrass ecosystem, we have found production dynamics to be linked primarily to variations in P supply and salinity, which are functions of fresh water supply and SLR in Florida Bay.