wetlands, role in ecosystem?
2002b). Some of this demand is met by translocation from belowground reserves but half the aboveground N remains in the standing dead litter, suggesting only half the N has been recovered prior to plant senescence. Therefore, plant demand in the predominant cattail community is about 2.5 g N • m-2 • yr. Burial of organic matter is a major fate of N in this and other marshes and has been estimated at roughly 5 g N • m-2 • yr-1 (Merrill, 1998). Actual estimates of denitrification are rare but estimates for Tivoli North Bay are about 2 g N• m-2 • yr-1 (Merrill, 1998). Clearly the budget is dominated by the tidal input, atmospheric deposition and losses to burial and denitrification. Estimated losses exceed inputs in accordance with the net removal of nitrate from tidal waters. We cannot estimate all the terms in a PO4 budget but again the tidal concentrations imply a net source within the marsh and the high porewater concentrations suggest a sediment source.
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