Cooperative Ecosystem Studies Unit, Piedmont-South Atlantic CESU

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The National Research Program (NRP) of the USGS Water Resources Discipline seeks to provide financial assistance for multidiscipline environmental research to further our understanding on how floodplain forests help to buffer society from water quality degradation and rising atmospheric CO2 when hydrological connections to adjacent streams and rivers remain intact. As depositional sites, floodplains trap material from anthropogenic activities that may drive increases in sediment export upstream and consequent deposition downstream. The main objective of this research is to estimate and interpret the forest net primary productivity (NPP), species composition, and structure relations among elevated sedimentation and key drivers of material trapping (nitrogen and phosphorus dynamics), C sequestration, and biogeochemical dynamics. This basic understanding is being used to predict the effects of floodplain sedimentation on ecosystem services. 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.

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