Glob. Change Biol. (2012)

Plant production in northern peatlands is generally nitrogen limited. A key ecological question is whether thawing of permafrost will lead to the release of nitrogen in a form that can be used by plants.

Frida Keuper, from the Department of Ecological Science, VU University Amsterdam, The Netherlands, and co-workers compared plant-available nitrogen pools and fluxes in near-surface permafrost (0–10 cm below the thawfront) with those taken from the current-rooting-zone layer (5–15 cm depth) across five representative peatlands in subarctic Sweden.

Results consistently showed up to seven times more plant-available nitrogen in near-surface permafrost soil compared with the current-rooting-zone layer. Furthermore, a supplementary experiment showed an eightfold larger plant nitrogen uptake from permafrost soil than from other nitrogen sources, such as current-rooting-zone soil or fresh litter substrates. These results demonstrate that near-surface permafrost soil of subarctic peatlands can release a biologically relevant amount of plant-available nitrogen, which may have impacts on plant productivity and species composition.