Decadal vegetation changes in a northern peatland, greenhouse gas fluxes and net radiative forcing

• Published in: Global change biology Vol. 12; no. 12; pp. 2352 - 2369
• Main Authors: JOHANSSON, TORBJÖRN, MALMER, NILS, CRILL, PATRICK M, FRIBORG, THOMAS, ÅKERMAN, JONAS H, MASTEPANOV, MIKHAIL, CHRISTENSEN, TORBEN R
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.12.2006; Blackwell Publishing Ltd
• Subjects: aerial CIR photography; Biologi; Biological Sciences; Biology; carbon balance; Carbon dioxide; change; Climate change; Earth and Related Environmental Sciences; Ecology; Ecosystems; Ekologi; Geovetenskap och miljövetenskap; Greenhouse gases; GWP; Infrared imaging systems; Natural Sciences; Naturgeografi; Naturvetenskap; northern; northern Sweden; peatland; permafrost; Physical Geography; radiative forcing; sub-Arctic; Sweden; vegetation; vegetation change
• ISSN: 1354-1013; 1365-2486; 1365-2486
• DOI: 10.1111/j.1365-2486.2006.01267.x

Thawing permafrost in the sub-Arctic has implications for the physical stability and biological dynamics of peatland ecosystems. This study provides an analysis of how permafrost thawing and subsequent vegetation changes in a sub-Arctic Swedish mire have changed the net exchange of greenhouse gases, carbon dioxide (CO₂) and CH₄ over the past three decades. Images of the mire (ca. 17 ha) and surroundings taken with film sensitive in the visible and the near infrared portion of the spectrum, [i.e. colour infrared (CIR) aerial photographs from 1970 and 2000] were used. The results show that during this period the area covered by hummock vegetation decreased by more than 11% and became replaced by wet-growing plant communities. The overall net uptake of C in the vegetation and the release of C by heterotrophic respiration might have increased resulting in increases in both the growing season atmospheric CO₂ sink function with about 16% and the CH₄ emissions with 22%. Calculating the flux as CO₂ equivalents show that the mire in 2000 has a 47% greater radiative forcing on the atmosphere using a 100-year time horizon. Northern peatlands in areas with thawing sporadic or discontinuous permafrost are likely to act as larger greenhouse gas sources over the growing season today than a few decades ago because of increased CH₄ emissions.