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The Importance of Biological N2-fixation in Peatlands Across Northern Latitudes

Melanie Vile1, R. Kelman Wieder1, Dale H. Vitt2, Lucy J. Sheppard3, Luca Braggaza4, Dennis D. Wykoff1
1 Department of Biology, Villanova University, Villanova, PA 19085, USA
2 Department of Plant Biology, University of Southern Illinois, Carbondale, IL, USA
3 C.E.H. Edinburgh, Bush Estate Penicuik, Midlothian, EH26 0QB, Scotland
4 WSL & EPFL, Switzerland, and University of Ferrara, Italy

Invited Talk 10 in Links between the N cycle and other elements

17.07.2014, 11:10-11:40, H20

Globally, boreal peatlands cover a mere 3-4 % of the Earth’s land surface, yet store ~ 30% of the world’s soil carbon and ~9-16% of global soil nitrogen.  A long standing peatland paradigm holds that bogs, which are ombrotrophic, receive external inputs of nitrogen solely from atmospheric deposition. Amongst pristine regions, inputs of atmospheric deposition to boreal bogs in western Canada anchor the lowest rates found globally (< 1 kg N ha-1 yr-1). Despite historically low inputs of atmospheric nitrogen deposition, we have shown that bogs of western Canada have accumulated approximately 20-30 times more N in peat than can neither be explained by inputs from atmospheric deposition, nor by recycling of N. Biogeochemical theory predicts that biological nitrogen fixation, the conversion of di-nitrogen gas in the atmosphere to plant available ammonium, should dominate in ecosystems where nitrogen is scarce.  We have demonstrated that rates of biological N2-fixation by diazotrophs associated with Sphagnum mosses can fully account for the missing and overlooked input of nitrogen to western Canadian systems causing us to re-evaluate the importance of this process on the global scale.



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last modified 2014-05-12