Wednesday, May 28, 2008 - 9:30 AM
370

Phosphorus retention processes in a large-scale wetland restoration project under a changing climate

Marcelo Ardon1, Shaena Montanari2, Jennifer L. Morse1, Martin W. Doyle3, and Emily S. Bernhardt1. (1) Department of Biology, Duke University, Box 90338, Durham, NC 27708, (2) Department of Geography, University of North Carolina, Chapel Hill, NC 27599, (3) Department of Geography, University of North Carolina- Chapel Hill, CB 3220, Chapel Hill, NC 27599

To ameliorate present and future coastal eutrophication, management agencies are increasingly turning to wetland restoration of former agricultural fields. Restoring wetland hydrology is thought to be followed by recovery of functional benefits. However, climate change predictions of prolonged droughts punctuated by severe storms will create new challenges to restoring functioning ecosystems. We examined phosphorus retention in a large (400+ ha) wetland restoration project in the coastal plain of NC, by combining a mass balance budget with soil and soil solution chemistry. After an increase in P export following initial restoration of flooded conditions, the site functioned primarily as a P sink (retaining 0.02 kg SRP ha-1 mo-1 during summer). Release of soil P declined as suggested by decreasing concentrations of soil solution P after initial flooding (P declined from 22 µg SRP L-1 to below detection limit). In the laboratory soils retained 60-80% of P added, with concentrations of Al and Fe explaining most of the variation (r2 = 0.70). Drought conditions during summer and fall punctuated by rain events caused increases in P export. Our results caution that while former agricultural fields converted to wetlands can serve as P sinks, storms can lead to P export to coastal ecosystems.


Web Page: Phosphorus, restoration, wetland

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