The influence of hydrologic variations onphosphorus cycling and retention in a swamp stream ecosystem

The fluxes and retension of filterable reactive phosphorus (FRP),
filterable unreactive phosphorus (FUP), and particulate phosphorus (PP)
in a floodplain swamp in eastern North Carolina varied in response to the
seasonality of inundation and yearly variations in runoff from the
upstream watershed. High runoff and floodplain inundation typically
occurred during the cool season when decomposition rates were low.
During the flooded period, the floodplain forest floor had a high
absorption capacity for runoff-derived FRP that was both temperature
and water FRP concentration dependent. The FUP, on the other hand,
was released from the forest floor in approximate proportion to the
volume of floodwaters. During the warm season, when decomposition
rates were faster and standing water concentrations of phosphorus were
relatively high, little or no runoff occurred; thus there was no significant
loss of phosphorus from the ecosystem. Loss of FUP from the ecosystem
and imports of PP were correlated with yearly variations in runoff. The PP exports remained constant during the 2 years of the study; this
resulted in large net retention during the year of high runoff. Overall, 30
to 56% of total phosphorus inputs were retained by the swamp ecosystem
during the 2 years of study