HYDROPERIOD INFLUENCES ON NUTRIENT DYNAMICS IN DECOMPOSING LITTER OF A FLOODPLAIN FOREST

Lack of clarity regarding the relationship between hydroperiod and dec omposition dynamics has long been a barrier to the development of a cl ear understanding of floodplain biogeochemistry. Relationships between hydroperiod and decomposition processes were investigated using a con trolled, field approach on the Ogeechee River floodplain in south Geor gia. The study intent was to develop cause-effect relationships betwee n specific flooding regimes and decomposition parameters. Microcosms d esigned to manipulate flooding regimes were installed and used in comb ination with litterbags containing abscised foliage. Treatments were d esigned to mimic realistic hydroperiod-nutrient inflow scenarios and i ncluded: a nonflooded control, hooded for 6 mo, flooded for 3 mo, hood ed intermittently for 4 mo, hooded for 3 mo with elevated P inflow, an d hooded for 3 mo with elevated N inflow. Mass, C, N, and P dynamics w ere studied for a 106-wk period. Flooding stimulated mass, C, N, and P loss. The data suggest that single, brief fiooding regimes may stimul ate mass and C loss to the greatest extent. The proportion of N and P remaining after 106 wk was only marginally different among flooding re gimes. However, temporal patterns of immobilization-mineralization wer e strongly influenced by the nature of the flooding regime.