Nutrient, carbon, and water dynamics of a titi shrub swamp ecosystem in Apalachicola, Florida

The main components and processes of a titi shrub swamp were quantified for incorporation into a simulation model to predict their long-term responses to wastewater discharge. The main components were vegetation, water, and soil; and the processes were carbon, nitrogen and phosphorus cycling, and water flow.; Quantification of model compartments indicated that (1) aboveground biomass is in the low to intermediate range of values cited for forested wetlands, (2) precipitation is the principal source of water and nutrients to this system, and (3) relative concentrations of nitrogen and phosphorus in precipitation, surface water and groundwater indicate that nutrients are conserved within the system. Therefore, small amounts of nutrients were cycled within this system and low nutrient input limited the simulated productivity.; The simulated response to increased nutrients was an increase in annual biomass and litter and increased storage of nutrients in biomass, litter and soil, and the rates of these increases decreased with time. Wastewater discharged to wetlands with a N:P ratio similar to that stored in vegetation would maximize the lifetime of the system for phosphorus assimilation. Therefore, nutrient loading criteria should be based on maximizing the longevity of the system, which can be estimated by determination of the phosphorus adsorption capacity of the soil.; Mineral soils dominated by titi had a low capacity for phosphorus adsorption while organic soils dominated by black gum had a higher capacity for phosphorus adsorption. The adsorption capacities of these soils were related to the content and availability of amorphous and poorly crystalline oxides of aluminum.; Sweetbay had low rates of transpiration per leaf area relative to other forested wetland species. An increase occurred from the individual to the community level due to high leaf area index in the bay swamp. This community transpires at a rate greater than open water evaporation when water is readily available as indicated by the pan ratio. There is variability among forested wetland communities and among seasons and these systems evapotranspire at low rates when water is scarce and at higher rates when water is readily available. Therefore, these systems are adapted for water conservation during dry periods.