Thawing sub‐arctic permafrost: Effects on vegetation and methane emissions

Christensen, Torben R.; Johansson, Torbjörn; Åkerman, H. Jonas; Mastepanov, Mikhail; Malmer, Nils; Friborg, Thomas; Crill, Patrick; Svensson, Bo

doi:10.1029/2003gl018680

Cited by 479 publications

(499 citation statements)

References 21 publications

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“…In northern Sweden, we have previously documented dramatic ecosystem changes as a consequence of the ongoing permafrost thaw (Christensen et al 2004;Johansson et al 2006). A substantial change in the surface hydrology follows the palsa degradation and subsequent increases in CH 4 emissions (Christensen et al 2004) but also in the CO 2 sink strength at the landscape scale has been documented (Johansson et al 2006).…”

Section: Introductionmentioning

confidence: 96%

“…These exchanges are intimately related to temperature and hydrology, and alterations in permafrost coverage, which affect both of those, could have dramatic impacts on the combined climate forcing from these exchanges. Recent studies have shown that palsa mire ecosystems in Sweden are subject to dramatic changes in the distribution of permafrost and vegetation (Christensen et al 2004;Malmer et al 2005;Johansson et al 2006) and also that this is a general phenomenon at least for most of northern Scandinavia (Bosiö et al 2012). These changes are most likely caused by a warming that has been observed during recent decades.…”

Section: Introductionmentioning

confidence: 99%

“…A substantial change in the surface hydrology follows the palsa degradation and subsequent increases in CH 4 emissions (Christensen et al 2004) but also in the CO 2 sink strength at the landscape scale has been documented (Johansson et al 2006). Annual total C budgets have been documented for individual palsa ecosystem components based on automatic chamber measurements and recently the annual dissolved organic carbon (DOC) export terms have been documented from the same parts of the palsa complex .…”

Section: Introductionmentioning

confidence: 99%

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Monitoring the Multi-Year Carbon Balance of a Subarctic Palsa Mire with Micrometeorological Techniques

Christensen

Jackowicz-Korczyński

Aurela

et al. 2012

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This article reports a dataset on 8 years of monitoring carbon fluxes in a subarctic palsa mire based on micrometeorological eddy covariance measurements. The mire is a complex with wet minerotrophic areas and elevated dry palsa as well as intermediate sub-ecosystems. The measurements document primarily the emission originating from the wet parts of the mire dominated by a rather homogenous cover of Eriophorum angustifolium. The CO 2 /CH 4 flux measurements performed during the years [2001][2002][2003][2004][2005][2006][2007][2008] showed that the areas represented in the measurements were a relatively stable sink of carbon with an average annual rate of uptake amounting to on average -46 g C m -2 y -1 including an equally stable loss through CH 4 emissions (18-22 g CH 4 -C m -2 y -1 ). This consistent carbon sink combined with substantial CH 4 emissions is most likely what is to be expected as the permafrost under palsa mires degrades in response to climate warming.

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Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Monitoring the Multi-Year Carbon Balance of a Subarctic Palsa Mire with Micrometeorological Techniques

Christensen

Jackowicz-Korczyński

Aurela

et al. 2012

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“…Vegetation of the area is characterized by a mosaic of subarctic birch forests and wetlands while above the tree line fjäll tundra ecosystems dominate [Malmer et al, 2005]. Various studies report the influence of climate change on the Stordalen mire vegetation [Christensen et al, 2004;Malmer et al, 2005;Svensson et al, 1999], however, there is little known about the local aerosol properties [Svenningsson et al, 2008]. It is expected that depending upon wind direction and meteorology particulate sources from both natural (e.g., oceanic and boreal forest) and anthropogenic (e.g., the port at Narvik and industries on the Barents Sea) sources are expected to perturb the background conditions .…”

Section: Sampling Sitementioning

confidence: 99%

Subarctic atmospheric aerosol composition: 3. Measured and modeled properties of cloud condensation nuclei

et al. 2010

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[1] Aerosol particles can modify cloud properties by acting as cloud condensation nuclei (CCN). Predicting CCN properties is still a challenge and not properly incorporated in current climate models. Atmospheric particle number size distributions, hygroscopic growth factors, and polydisperse CCN number concentrations were measured at the remote subarctic Stordalen mire, 200 km north of the Arctic Circle in northern Sweden. The CCN number concentration was highly variable, largely driven by variations in the total number of sufficiently large particles, though the variability of chemical composition was increasingly important for decreasing supersaturation. The hygroscopicity of particles measured by a hygroscopicity tandem differential mobility analyzer (HTDMA) was in agreement with large critical diameters observed for CCN activation (k % 0.07 -0.21 for D = 50 -200 nm). Size distribution and time-and size-resolved HTDMA data were used to predict CCN number concentrations. Agreement of predictions with measured CCN within ±11% was achieved using parameterized Köhler theory and assuming a surface tension of pure water. The sensitivity of CCN predictions to various simplifying assumptions was further explored: We found that (1) ignoring particle mixing state did not affect CCN predictions, (2) averaging the HTDMA data in time with retaining the size dependence did not introduce a substantial bias, while individual predictions became more uncertain, and (3) predictions involving the hygroscopicity parameter recommended in literature for continental sites (k % 0.3 ± 0.1) resulted in a significant prediction bias. Future modeling studies should therefore at least aim at using averaged, size-resolved, site-specific hygroscopicity or chemical composition data for predictions of CCN number concentrations.Citation: Kammermann, L

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“…In subarctic Fennoscandia, permafrost mires are currently subjected to climate related thawing (Åkerman and Johansson 2008;Callaghan et al 2012) and shift in vegetational and hydrological patterns (Malmer et al 2005;Bosiö et al 2012). These changes exert a significant impact on atmospheric CO 2 sink function and CH 4 emissions (Christensen et al 2004;Johansson et al 2006) and on soil hydrologic dynamics (O'Donnell et al 2012;Jorgenson et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Increased photosynthesis compensates for shorter growing season in subarctic tundra—8 years of snow accumulation manipulations

et al. 2014

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This study was initiated to analyze the effect of increased snow cover on plant photosynthesis in subarctic mires underlain by permafrost. Snow fences were used to increase the accumulation of snow on a subarctic permafrost mire in northern Sweden. By measuring reflected photosynthetic active radiation (PAR) the effect of snow thickness and associated delay of the start of the growing season was assessed in terms of absorbed PAR and estimated gross primary production (GPP). Six plots experienced increased snow accumulation and six plots were untreated. Incoming and reflected PAR was logged hourly from August 2010 to October 2013. In 2010 PAR measurements were coupled with flux chamber measurements to assess GPP and light use efficiency of the plots. The increased snow thickness prolonged the duration of the snow cover in spring. The delay of the growing season start in the treated plots was 18 days in 2011, 3 days in 2012 and 22 days in 2013. Results show higher PAR absorption, together with almost 35 % higher light use efficiency, in treated plots compared to untreated plots. Estimations of GPP suggest that the loss in early season photosynthesis, due to the shortening of the growing season in the treatment plots, is well compensated for by the increased absorption of PAR and higher light use efficiency throughout the whole growing seasons. This compensation is likely to be explained by increased soil moisture and nutrients together with a shift in vegetation composition associated with the accelerated permafrost thaw in the treatment plots.

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Thawing sub‐arctic permafrost: Effects on vegetation and methane emissions

Cited by 479 publications

References 21 publications

Monitoring the Multi-Year Carbon Balance of a Subarctic Palsa Mire with Micrometeorological Techniques

Monitoring the Multi-Year Carbon Balance of a Subarctic Palsa Mire with Micrometeorological Techniques

Subarctic atmospheric aerosol composition: 3. Measured and modeled properties of cloud condensation nuclei

Increased photosynthesis compensates for shorter growing season in subarctic tundra—8 years of snow accumulation manipulations

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