Mangrove soil phosphorus addition experiment from June 2013 to August 2013 at the mangrove peat soil mesocosms (FCE), Key Largo, Florida

Sea levels in South Florida are conservatively predicted to rise by 0.60 m by 2060. The key mechanisms that maintain coastal peatland elevation against increasing sea level are organic matter accumulation via plant production and mineral sedimentation rates (Smoak et al. 2013). Although coastal mangrove soils are regularly inundated with seawater, little is know about the drivers of carbon sequestration (above or below ground) versus atmospheric efflux under different conditions of salinity and elevated phosphorus (P) associated with sea-level rise and storm surge. A recent study using mangrove peat soils found that seawater inundation reduced soil carbon efflux losses and salinity concentration had little effect on carbon retention or loss pathways. The next logical steps are to understand how plant-soil interactions affect above and below ground carbon processes, as well as how increases in P associated with storm surge from the Gulf of Mexico will influence physical, chemical and biological components of mangrove soils that are associated with above and belowground carbon processes. We will manipulate P in inundated peat soil mesocosms with disturbed and undisturbed red mangrove (Rhizophora mangle) seedlings to identify some of the fundamental mechanisms of soil elevation and carbon cycling given expected increases in seawater-based P availability in South Florida coastal mangroves.