Above-ground productivity and litter decomposition in a tidal freshwater forested wetland on Bull Island, SC, USA

Above-ground net primary productivity (NPP), decomposition of water tupelo leaves, and nutrient dynamics were investigated from 2000 to 2002 within a coastal, tidally influenced forested wetland on Bull Island, SC. Flooding of the island is influenced by flooding events of the Pee Dee River (PD) on the western side of the island, Big and Little Bull Creeks (BC) on the eastern side, and daily tidal fluctuations. Above-ground NPP ranged between 477 g/m2 and 1117 g/m2 while mean above-ground NPP was 743 g/m2 when all data were combined regardless of growing seasons or sites. Mean annual litterfall and stemwood production were 463 g/(m2 year) and 279 g/(m2 year), respectively, for all three growing seasons. Analyses also showed that the 3-year average above-ground NPP was significantly higher (p < 0.0001) on the PD side (839 g/(m2 year)) than on the BC side (647 g/(m2 year)). In contrast, water tupelo leaves on the BC side decomposed faster (k = 2.04) than on the PD side (k = 1.59) probably due to microenvironmental factors such as temperature and moisture availability. Nutrient ratios (C:N, C:P, and N:P) indicated continuous N limitation on both sides of the island in respect to litter quality and nutrient deficiency.