Carbon dioxide emissions from periglacial patterned ground under changing permafrost conditions and shrub encroachment in an alpine landscape, Jotunheimen, Norway

Whether Arctic and alpine ecosystems will act as a future net sink or source of carbon remains uncertain. The present study investigates ways in which ecosystem (soil and vegetation) and geomorphological (cryogenic disturbance) factors may control or affect the future release of carbon in an alpine permafrost landscape. Rates of ecosystem respiration (Re) were examined using a portable gas analyzer across an altitudinal transect ranging from mid‐ to high‐alpine vegetation zones underlain by discontinuous to continuous permafrost on Galdhøpiggen (Norway). Measurements were made of Re during the peak growing season on active and relict sorted circles exhibiting varying levels of frost disturbance and shrub encroachment. Re was found to be controlled more strongly by soil microclimate and plant growth forms than by geomorphic indicators of cryoturbation in thawing permafrost or by atmospheric conditions. The results indicate that increasing shrub cover leads to elevated Re, while an increase in surface disturbance has the potential to lower Re. We conclude that vegetation is likely to colonize frost‐disturbed surfaces at progressively higher altitudes as freeze–thaw processes slow down or cease, and this will result in increased Re.