Dynamics and Fluxes of Nutrients along Environmental Gradients in the Florida Everglades, USA

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USGS research in the Florida Everglades will provide information on how environmental conditions and disturbances impact carbon storage in mangrove systems.

Study sites for Dynamics and Fluxes of Nutrients along Environmental Gradients in the Florida Everglades, USA

Study sites in the Florida Everglades, USA

Science Issue and Relevance: The magnitude and interaction of environmental gradients including regulators (e.g., soil salinity, sulfide), resources (e.g., light, nutrients), and hydroperiod (e.g., frequency, duration and depth of inundation) define a constraint envelope that determines mangrove productivity within a coastal setting. Understanding the allocation of carbon to above- and below-ground biomass and productivity along these environmental gradients is critical to estimating global carbon budgets in mangrove ecosystems. This study aims to examine a long-term (2001-2014) dataset of community structure, above- and below-ground biomass, surface and porewater nutrient concentrations and salinity, and hydroperiod to better understand how biomass and productivity of mangroves respond to the interaction of environmental gradients and disturbance. Results of this study will increase our understanding of how environmental conditions and disturbance impact carbon storage in mangrove systems.

Methodology for Addressing the Issue: In 2000, three mangrove sites were established each along the Shark River and Taylor River basins (25.1006°N, 80.5999°W) in the Florida Everglades. These two sites are markedly different in hydrology and nutrient concentrations, with a pronounced tidal signature and higher nutrient concentrations present at Shark River that are nearly absent at Taylor River. Soil nutrient concentrations were sampled semi-annually (once each during wet and dry seasons), and hydroperiod metrics were calculated from water level measurements obtained hourly at each site. Time-series models (wavelets, Fourier analysis) will be used to identify sources of resources and to characterize hydroperiod, and trends in mangrove productivity along environmental gradients will be quantified.

Illustration of two sites with marked differences in hydrology and nutrient concentrations

Illustration of two sites with marked differences in hydrology and nutrient concentrations

Future Steps: Future efforts will utilize a mass balance approach to quantify carbon imports and exports to the Taylor and Shark River sites in surface water flows.

Location of study: 25.1006°N, 80.5999°W