Drained coastal peatlands: A potential nitrogen source to marine ecosystems under prolonged drought and heavy storm events-A microcosm experiment.
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Over the past several decades there has been a massive increase in coastal eutrophication, which is often caused by increased runoff input of nitrogen from landscape alterations. Peatlands, covering 3% of land area, have stored about 12-21% of global soil organic nitrogen (12-20Pg N) around rivers, lakes and coasts over millennia and are now often drained and farmed. Their huge nitrogen pools may be released by intensified climate driven hydrologic events-prolonged droughts followed by heavy storms-and later transported to marine ecosystems. In this study, we collected peat monoliths from drained, natural, and restored coastal peatlands in the Southeastern U.S., and conducted a microcosm experiment simulating coupled prolonged-drought and storm events to (1) test whether storms could trigger a pulse of nitrogen export from drought-stressed peatlands and (2) assess how differentially hydrologic managements through shifting plant communities affect nitrogen export by combining an experiment of nitrogen release from litter. During the drought phase, we observed a significant temporal variation in net nitrogen mineralization rate (NMR). NMR spiked in the third month and then decreased rapidly. This pattern indicates that drought duration significantly affects nitrogen mineralization in peat. NMR in the drained site reached up to 490±110kgha(-1)year(-1), about 5 times higher than in the restored site. After the 14-month drought phase, we simulated a heavy storm by bringing peat monoliths to saturation. In the discharge waters, concentrations of total dissolved nitrogen in the monoliths from the drained site (72.7±16.3mgL(-1)) was about ten times as high as from the restored site. Our results indicate that previously drained peatlands under prolonged drought are a potent source of nitrogen export. Moreover, drought-induced plant community shifts to herbaceous plants substantially raise nitrogen release with lasting effects by altering litter quality in peatlands.
Published Version (Please cite this version)10.1016/j.scitotenv.2016.04.211
Publication InfoWang, Hongjun; Richardson, Curtis J; Ho, Mengchi; & Flanagan, Neal (2016). Drained coastal peatlands: A potential nitrogen source to marine ecosystems under prolonged drought and heavy storm events-A microcosm experiment. Sci Total Environ, 566-567. pp. 621-626. 10.1016/j.scitotenv.2016.04.211. Retrieved from https://hdl.handle.net/10161/15701.
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Visiting Assistant Professor
John O. Blackburn Distinguished Professor
Curtis J. Richardson is Professor of Resource Ecology and founding Director of the Duke University Wetland Center in the Nicholas School of the Environment. Dr. Richardson earned his degrees from the State University of New York and the University of Tennessee. His research interests in applied ecology focus on long-term ecosystem response to large-scale perturbations such as climate change, toxic materials, trace metals, flooding, or nutrient additions. He has specific interests in phosphor
Research Scientist, Senior
My research focuses on C,N,P biogeochemical cycles and the related ecological processes in wetlands, how these key elements dynamically respond to climate change, and how we can use the biogeochemical features to improve the ecological resilience and resistance to climate change and human disturbance, thus mitigating environmental challenges. I also expand my basic research in peatlands to degraded farms and put the resilient mechanism in practice to improve sustainable food, water and agri
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