Sources and Yield of Particulate Organic Carbon and Nitrogen In Managed Headwaters of Mississippi

Author(s): Hatten, J.; Dewey, J.; Mangum, C.; Choi, B.

Managed, forested headwaters in Mississippi constitute a crucial part of watershed dynamics because they comprise more than 60-80% of stream networks and watershed land areas. Headwater streams contribute particulate forms of organic carbon (POC) and nutrients such as nitrogen (PON) to downstream fluvial environments. Flux of these materials from headwaters is difficult to quantify and few studies have examined their source. In particular, the relationships among origin and export of particulate organic carbon and nitrogen with stream discharge represent significant gaps in our understanding of headwater processes. POC and N serve vital function as a regulator of bacterial productivity, dissolved oxygen concentrations, nutrient cycling, and food web productivity however excess terrestrial input of POC and N can contribute to eutrophication and hypoxia in waters that are deficient in DO. This project augments current research efforts concerning hydrologic and hydrologically-mediated functions in managed, forested headwaters of Mississippi. This study quantifies the yield, source, and transport of POC and N within managed watersheds in order to better constrain the flux of OC, nutrients, and contaminants that bind to OM. Objectives are to (1) quantify exports of sediment, POC , and PON, (2) determine whether C and N are derived from a similar source using stable isotope ratios, and (3) determine whether additional process are occurring at a larger scale. Preliminary data linking suspended sediments to soils from 15 months of sampling across four management intensities will be presented. These data will be of value to forested-watershed managers in their efforts to weight the environmental cost vs. nutrient cycling benefit of organic inputs resulting from silvicultural activities.

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Technical Sessions

1 Best Management Practices #1
2 Delta Water Assessment
3 Flood Assessment & Mgmt.
4 Wetlands
5 Watershed Mgmt. #1
6 Non-Point Source Assessment
7 Modeling
8 Water Quality
9 Best Mgt. Practices #2
10 Delta Water Conservation
11 Sedimentation
12 Storm Water
13 Watershed Mgt. #2
14 Public Water Systems
15 Surface Water Assessment & Evaluation

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