Global Change Feedbacks on Trace Gas Fluxes in Wetlands

     My lab has focused on numerous experiments that examine if and to what extent that climate change in wetlands will enhance fluxes of the two major greenhouse gases, carbon dioxide and methane.  This has been a major focus of our whole-ecosystem climate change experiments (Updegraff et al. 2001, White et al. 2008) (see: Manipulative Climate Change Experiment on Peatlands in Minnesota).

     We also have examined soil carbon mineralization rates as carbon dioxide and methane in laboratory incubations and in situ in 17 peatlands in Minnesota, North Carolina, and Florida.  These experiments have related gas production in the peat to soil carbon quality and other environmental variables in order to gain a better understanding of controls over inherent differences in the abilities of different peats and their microbial communities to mineralize carbon as carbon dioxide and methane (Bridgham et al. 1998).

     Former Ph.D. student, Jason Keller (currently Chapman University) focused his dissertation research on elucidating the relative importance of the acetoclastic versus autotrophic pathways of methanogenesis in a bog, acidic fen, and alkaline fen in northern Michigan (Keller and Bridgham 2007).  He also examined the relative contribution of different terminal electron acceptors to anaerobic carbon mineralization, finding a large unexplained production of anaerobic carbon dioxide that we ascribed to humic acids as terminal electron acceptors.  A recently funded project will expand on providing a mechanistic understanding of pathways of anaerobic carbon degradation and the efficiency of methane production in northern wetlands (under Current Projects see:  Why does the efficiency of methane production vary dramatically among wetlands?).  In two separate projects, he examined how short-term and  long- term fertilization with nitrogen and phosphorus and liming of peatlands affected methane production and consumption in peatlands (Keller et al. 2005, 2006).

     Former Ph.D. student Melanie Vile (currently Villanova University) examined the role of atmospheric sulfur deposition in a pristine bog in central Alberta, Canada and two bogs in the Czech Republic with very high sulfur deposition on rates of sulfate reduction, methanogenesis, fermentation, and overall anaerobic carbon mineralization (Vile et al. 2003 a and b).

See curriculum vitae for relevant publications.