Spatial Distribution in Everglades Nutrient Budgets and Their Effects on Biogeochemical Processes.

The dynamics of soil C storage and cycling has been a major focus of the United States Environmental Protection Agency (USEPA) Everglades Regional Environmental Monitoring Assessment Program ( EVR R-EMAP) for several reasons including: the importance of wetlands peat to the global carbon cycle, the loss of Everglades peat due to subsidence, and the implications of restored (increased) hydrology on peat soil preservation and accretion. The respiration of soil organic matter (OM) is dependent on several factors including hydrology, nutrient availability, and the lability of the stored organic matter. It was hypothesized that physicochemical conditions will, at least partially, control the mineralization of organic carbon and OC that may be recalcitrant under a given condition could become labile as conditions change.

To determine the spatial distribution of nutrients and carbon stocks across the Greater Everglades Ecosystem (GEE) the most recent iteration of the larger EVR R-EMAP project (wet season 2014) 119 sites distributed across the GEE were sampled for environmental compartments including Soil, Flocculent detrital organic matter (floc), periphyton, surface water, and vegetation (Sawgrass, Cladium jamaicense Crantz) and analyzed for physicochemical parameters. Solid materials were analyzed for bulk density, moisture, ash contents, and total carbon, nitrogen and phosphorus (TC, TN, TP) concentrations. Surface water was analyzed for total and soluble nutrients.

Additionally, twenty five sites were “semi-randomly selected” based on expected soil characteristics, before sampling, to represent each of five “sub eco-regions”. There were five “replicate” sites in each of the five areas that represented Northern Peats (Water Conservation Area-1, WCA-1), Impacted Peats (WCA-2), Central Glades (WCA-3), Southern Peats (Shark River Slough in Everglades National Park, ENP), and Marl Soils (ENP short hydroperiod marshes). Fresh soil from these selected sites were assayed to determine the influence of added P and the lability of soil C on soil OM decomposition (measured via CO₂ efflux). Soils were unamended controls or augmented with 0.4 mmole P (KH₂PO₄) g^-1 dry weight soil or 1.2 mmole C (glucose) g^-1 dw soil or the combination. Samples were incubated at room temperature in the dark for 24 to96 hours after which the headspace gases were analyzed for CO₂ content. Initial findings suggest that despite of spatial differences in C and P content across the GEE, there was no significant effect on nutrient mechanisms in controlling microbial respiration.