Nymphaea Rhizome Decomposition in Everglades Wetlands.

Nymphaea is common in the natural, oligotrophic areas of Water Conservation 2a in the Florida Everglades, particularly in the deep water sloughs.  As such, it likely plays a major role in ecosystem function through primary production and decomposition.  The decomposition of its large rhizomes can be rapid and affected by both aerobic and anaerobic processes, as well as availability of nutrients.  Our objective was to assess how fluctuating hydrologic conditions and nutrient enrichment influence decomposition of Nymphaea rhizomes in soil.  Rhizome decomposition proceeded rapidly and led to higher CO₂ and CH₄ production rates compared to soil without rhizomes.  Nutrient enriched sites produced significantly higher decomposition rates than oligotrophic sites under both aerobic and anaerobic conditions.  Aerobic conditions produced higher CO₂ production rates than anaerobic decomposition.  Microbial biomass C, N, and P increased during incubation and corresponded well to decomposition rates.  Higher nutrient levels increased microbial biomass which in turn promoted higher rhizome decomposition rates.  The presence of mycelia growth on decomposing rhizomes in aerobic soils indicated the potential importance of fungi in decomposition processes in sloughs during drought conditions.