Phosphorus export from a restored wetland ecosystem in response to natural and experimental hydrologic fluctuations


Autoria(s): Ardón, M; Montanari, S; Morse, JL; Doyle, MW; Bernhardt, ES
Data(s)

01/12/2010

Identificador

Journal of Geophysical Research: Biogeosciences, 2010, 115 (4)

0148-0227

http://hdl.handle.net/10161/4017

0148-0227

http://hdl.handle.net/10161/4017

Idioma(s)

en_US

Relação

Journal of Geophysical Research: Biogeosciences

10.1029/2009JG001169

Journal of Geophysical Research-Biogeosciences

Tipo

Journal Article

Resumo

Wetland restoration is a commonly used approach to reduce nutrient loading to freshwater and coastal ecosystems, with many wetland restoration efforts occurring in former agricultural fields. Restored wetlands are expected to be effective at retaining or removing both nitrogen and phosphorus (P), yet restoring wetland hydrology to former agricultural fields can lead to the release of legacy fertilizer P. Here, we examined P cycling and export following rewetting of the Timberlake Restoration Project, a 440 ha restored riverine wetland complex in the coastal plain of North Carolina. We also compared P cycling within the restored wetland to two minimally disturbed nearby wetlands and an adjacent active agricultural field. In the restored wetland we observed increased soluble reactive phosphorus (SRP) concentrations following initial flooding, consistent with our expectations that P bound to iron would be released under reducing conditions. SRP concentrations in spring were 2.5 times higher leaving the restored wetland than a forested wetland and an agricultural field. During two large-scale drawdown and rewetting experiments we decreased the water depth by 1 m in ∼10 ha of inundated wetland for 2 weeks, followed by reflooding. Rewetting following experimental drainage had no effect on SRP concentrations in winter, but SRP concentrations did increase when the experiment was repeated during summer. Our best estimates suggest that this restored wetland could release legacy fertilizer P for up to a decade following hydrologic restoration. The time lag between restoration and biogeochemical recovery should be incorporated into management strategies of restored wetlands. Copyright 2010 by the American Geophysical Union.