Bridging the Gap From Peat to Ponds: Terrestrial and Aquatic Greenhouse Gas Emissions in an Evolving Permafrost‐Associated Subarctic Peatland
Year: 2026
Type: article
Abstract: Rapid permafrost thaw in peatlands transforms the subarctic landscape into a mosaic of ponds and peat soil, varying in moisture, carbon and nutrients, and time since thaw. As subarctic permafrost degrades, ponds emerge and mature and can gradually infill with Sphagnum peat. These ponds are considered hotspots of methane (CH 4 ) and carbon dioxide (CO 2 ) emissions, but their potential for nitrous oxide (N 2 O) emissions is understudied. Moreover, how greenhouse gas (GHG) fluxes vary between these aquatic and terrestrial environments is unclear, largely because these ecosystems are typically studied separately. We quantified N 2 O, CO 2 , and CH 4 emissions along four transects from a degrading terrestrial palsa to ponds varying in age within a sporadic‐permafrost subarctic peatland near Whapmagoostui‐Kuujjuarapik, QC. We also characterized depth‐dependent GHG concentrations in snow and peat. Waterlogged Sphagnum peat emitted, on average, 361% more C than drier bare peat above permafrost. GHG emissions from Sphagnum peat were comparable to pond emissions, with a greater proportion of CH 4 , suggesting waterlogged systems represent key emission hotspots. Terrestrial N 2 O fluxes were generally low, but the eroding palsa emitted more N 2 O than saturated Sphagnum peat. In ponds, N 2 O was consumed, indicating complete denitrification. Depth profiles of peat and snowpack GHG concentrations indicate likely emissions during winter. Terrestrial GHG fluxes, but not pond fluxes, were strongly associated with nitrogen availability. Our results suggest that future permafrost thaw, leading to bare peat degradation into ponds and the subsequent development of Sphagnum peat with presumably more N 2 fixation potential, will lead to sustained elevated C emissions from peatlands.
DOI: 10.1029/2025jg009509
Language: English
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
SDGs: Climate action, Life on land
Open Access status: hybrid
Estimated APC paid: $4,070
Awards: G2151101085, G2220544987, Étude du rôle des processus microbiens du sol dans les émissions de gaz à effet de serre en milieu aquatique dans les paysages du pergélisol de l’Est du Canada, G4463283056, Intégration du cycle de l'azote et des émissions de gaz à effet de serre dans les écosystèmes d'étangs touchés par le pergélisol dans le nord-est du Canada
OpenAlex ID: W7141939319