Impacts of Thawing Permafrost on Nitrogen in Subarctic Peatlands
Keuper, F., van Bodegom, P.M., Dorrepaal, E., Weedon, J.T., van Hal, J., van Logtestijn, R.S.P. and Aerts, R. 2012. A frozen feast: thawing permafrost increases plant-available nitrogen in subarctic peatlands. Global Change Biology 18: 1998-2007.
Results indicated that "all extraction methods, across all peatlands, consistently showed up to seven times more plant-available N in near-surface permafrost soil compared to the current rooting zone layer," and they say that "these results were supported by the bioassay experiment, with an eightfold larger plant N-uptake from permafrost soil than from other N-sources such as current rooting zone soil or fresh litter substrates." In addition, they note that "net mineralization rates were much higher in permafrost soils compared to soils from the current rooting zone layer (273 mg N/m2 and 1348 mg N/m2 per growing season for near-surface permafrost at 0.5°C and 11°C, respectively, compared to -30 mg N/m2 for current rooting zone soil at 11°C)."
The six Swedes and their lone Dutch collaborator conclude that their results "demonstrate that near-surface permafrost soil of subarctic peatlands can release a biologically relevant amount of plant available nitrogen, both directly upon thawing as well as over the course of a growing season through continued microbial mineralization of organically bound N." Therefore, given the nitrogen-limited nature of northern peatlands, they confidently conclude that "this release may have impacts on both plant productivity and species composition," which we presume would likely consist of significant increases in productivity and ecosystem species richness.