PARENT SESSION
Poster Session #23: Fish, Lakes, Streams, and Wetlands.
Wednesday, August 8, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall

Litterfall production in forested wetlands with contrasting hydrologic regimes.

NEATROUR, MATTHEW^1,2, GOLLADAY, STEVE², BATTLE, JAN², ^{1 2}

ABSTRACT- We examined annual litterfall production in two major types (riparian and depressional) of seasonally-inundated forested wetlands in the Gulf Coastal Plain. Riparian wetlands are periodically inundated by river flooding, which supplies nutrient subsidies, whereas depressional wetlands receive most of their water and nutrients via precipitation. Mean litterfall production was greater in riparian wetlands (625 g m² y^-1) than in depressional wetlands (460 g m² y^-1), although the difference was not significant. This was due, however, to one highly productive depressional wetland (626 g m² y^-1). Taxodium spp. were the dominant contributors to litterfall in both types of wetlands, but litter inputs of Nyssa sylvatica var. biflora were also substantial in depressional wetlands. Litter nitrogen (N) and phosphorus (P) inputs were higher (p<0.01), and nutrient use efficiency (NUE) of N and P was lower (p<0.01) in riparian wetlands than in depressional wetlands. Both wetland types were P-limited as indicated by high N/P ratios and temporal patterns in litter P concentrations. These results suggest that different hydrologic regimes influence litterfall production and P NUE in wetlands of the Gulf Coastal Plain. However, the relationship between litterfall production or NUE, and the timing and/or length of the hydroperiod is complex. Studies are in progress to determine the underlying factors that cause litterfall variability.

KEY WORDS: wetland, litterfall, organic matter