The USGS Water Resources Discipline is offering this grant to conduct multidisciplinary environmental research on floodplain forest ecosystems to understand their role in water quality, carbon sequestration, and biogeochemical dynamics.

The recipient institution will be responsible for collecting, processing, and analyzing samples necessary to determine the net aboveground primary productivity and composition of forest sites across a sedimentation gradient within the Congaree National Park. This includes an examination of the nature of relationships that exist between past and current aboveground net primary productivity, sedimentation rates, and species specific dynamics. The recipient must have extensive experience measuring primary productivity and species composition in floodplain wetland ecosystems, as well as sufficient laboratory instrumentation, field equipment, and personnel to conduct the work. While this research should have applications for forested riparian wetlands throughout the southeastern U.S., emphasis should be placed on the Congaree River (South Carolina) and its floodplain in the vicinity of Congaree National Park. The specific objectives of this funding opportunity include:

1. The estimation of aboveground net primary productivity in forests as the sum of litterfall combined with stemwood increment less branch and stem mortality. Within each sampling zone, fifteen 0.01-ha circular plots will be established and inventoried in terms of over- and understory species composition and diameters at breast height (DBH). Litterfall will be collected using three randomly placed 0.25 m2 littertraps with 1 mm mesh fiberglass screen bottoms. The traps will be mounted on styrofoam sections to prevent inundation during flood events and will be emptied monthly or every other month depending upon season. Leaves, reproductive parts, and small branches will be separated, dried, and weighed after each litter collection period. Total annual litterfall will represent leaf biomass production.

2. All trees in each plot will be remeasured for DBH at the end of each growing season. Total tree biomass (stem, branch, and bark) for each year will be estimated from DBH using general allometric equations. Stems > 1 m tall but < 10 cm DBH will be identified to species and measured (DBH or basal diameter depending on size) in a 5 m x 5 m subplot. Biomass of the smaller stems will be estimated using allometric equations. Differences in production among the sites will be tested using ANOVA repeated measures techniques.