Trajectories of coastal wetland ecosystem recovery Thanks to an NSF CAREER grant, we will be examining the resilience of forested wetlands in the coast of North Carolina. This project will combine remote sensing, long-term monitoring, field manipulations, and citizen science to understand the response of coastal wetlands to a changing climate and rising seas. You can find a description of the project here
Salinization of inland waters Starting in January 2015, with funding from NSF Coastal SEES, we will be examining the human and ecological consequences of saltwater intrusion in the Albemarle-Pamlico Peninsula of North Carolina. This is an interdisciplinary collaborative project with Ryan Emanuel (NCSU), Emily Bernhardt (Duke), Justin Wright (Duke), and Todd BenDor (UNC Chapel Hill). You can find a description of the project here. You can find the project website here. See ECU coverage of the grant here See other coverage of this project here
Consequences of saltwater intrusion on nutrient cycling in a coastal plain wetland
In collaboration with Drs. Emily Bernhardt (Duke), Geoff Poole, Clem Izurieta, Robert Payn (University of Montana), and Amy Burgin (University of Nebraska), we are examining the consequences of drought-induced saltwater intrusion on the coupled cycling of carbon, nitrogen and sulfur in the Timberlake Wetland Restoration project. Our work combines long-term field measurements, laboratory experiments of soil anaerobic metabolic pathways, mesocosms and simulation modeling. I have been conducting microcosm experiments examining the role of drought and saltwater on greenhouse gas emissions and soil solution nutrients. We documented large increases in ammonium release due to increased salinity (Ardon et al. 2013). This work was supported by NSF.
Biogeochemical tradeoffs in wetland restoration
As a postdoc I examined the water quality benefits of the Timberlake Wetland Restoration Project. We were interested in examining potential tradeoffs associated with wetland restoration, particularly: 1) is there a N benefit at a P cost for water quality? 2) is there a water quality benefit at a greenhouse gas cost? In the first two years after restoration the site functioned as a NO3sink, while being a source of NH4, DON and TP to downstream ecosystems (Ardón et al. 2010 a). To examine hydrologic control over P export, we conducted two large-scale draw-down experiments where we drained 10 ha of the site. We found 4x fold increases in P concentrations in soil solution and surface water in summer but no changes in winter (Ardón et al. 2010 b). We also found that the restored site emitted less greenhouse gases than an active agricultural field or two reference wetlands. (Morse et al. 2012). Collaborators: J.L. Morse, M.W. Doyle, E.S. Bernhardt
Long-term patterns in tropical stream biogeochemistry
In collaboration with Drs. Cathy Pringle (UGA), Alonso Ramirez (University of Puerto Rico), John Duff (US Geological Survey) and Gaston Small (University of Minnesota), we are examining long-term patterns in stream biogeochemistry at La Selva Biological Station in Costa Rica. We have observed that ENSO-related changes in dry season rainfall lead to increases in stream water P and episodic pH drops (Triska et al. 2006, Small et al. 2012). The episodic pH drops are not the same in all streams through out La Selva, due to very different buffering capacity provided by interbasin groundwater inputs into some of the streams. (Ardón et al 2013). This work is supported by an NSF-LTREB.
Carbon processing in tropical and temperate streams
I am a part of a group conducting a Meta-Analysis & SynthesiS of Leaf decomposition in StreamS (MASS-LOSS). This is in collaboration with Jennifer Follstad-Shah (Utah State University), John Kominoski (UGA) and others. This group is examining the role of temperature, litter chemistry, and biota on decomposition rates of leaf litter in streams worldwide. For my dissertation I examined how interactions between leaf litter chemistry and stream water nutrients affect leaf litter breakdown rates. I found that structural compounds were more important than secondary compounds in determining leaf breakdown rates (Ardón and Pringle 2008). My data also showed that leaf litter quality determined the magnitude of microbial response to enhanced nutrients (Ardón et al. 2006, Ardón and Pringle 2007). And, contrary to common misconceptions in the literature, leaves from temperate tree species can have more secondary compounds than leaves from tropical species (Ardón et al. 2009).