Wetland development, permafrost history and nutrient cycling inferred from late Holocene peat and lake sediment records in subarctic Sweden

Kokfelt, Ulla; Reuss, Nina; Struyf, Eric; Sonesson, M.; Rundgren, Mats; Skog, Göran; Rosén, Peter; Hammarlund, Dan

doi:10.1007/s10933-010-9406-8

Cited by 85 publications

(115 citation statements)

References 34 publications

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“…In Stordalen, peat hollow has been dominated by spaghum communities since the onset of peat formation (Malmer and Wallen, 1996). However, the peat in the hummocks developed from a carex dominated fen peat with woody debris into a drier ombrotrophic peat with Calluna and Spaghnum (Malmer and Wallen, 1996;Kokfelt et al, 2010). Such vegetation change is expected to give rise to a depth trend similar to the type 3 trend in Fig.…”

Section: Change In Vegetationmentioning

confidence: 94%

Stable carbon isotopes as indicators for environmental change in palsa peats

et al. 2011

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Abstract. Palsa peats are unique northern ecosystems formed under an arctic climate and characterized by a high biodiversity and sensitive ecology. The stability of the palsas are seriously threatened by climate warming which will change the permafrost dynamic and induce a degradation of the mires.We used stable carbon isotope depth profiles in two palsa mires of Northern Sweden to track environmental change during the formation of the mires. Soils dominated by aerobic degradation can be expected to have a clear increase of carbon isotopes (δ 13 C) with depth, due to preferential release of 12 C during aerobic mineralization. In soils with suppressed degradation due to anoxic conditions, stable carbon isotope depth profiles are either more or less uniform indicating no or very low degradation or depth profiles turn to lighter values due to an enrichment of recalcitrant organic substances during anaerobic mineralisation which are depleted in 13 C.The isotope depth profile of the peat in the water saturated depressions (hollows) at the yet undisturbed mire Storflaket indicated very low to no degradation but increased rates of anaerobic degradation at the Stordalen site. The latter might be induced by degradation of the permafrost cores in the uplifted areas (hummocks) and subsequent breaking and submerging of the hummock peat into the hollows due to climate warming. Carbon isotope depth profiles of hummocks indicated a turn from aerobic mineralisation to anaerobicCorrespondence to: C. Alewell (christine.alewell@unibas.ch) degradation at a peat depth between 4 and 25 cm. The age of these turning points was 14 C dated between 150 and 670 yr and could thus not be caused by anthropogenically induced climate change. We found the uplifting of the hummocks due to permafrost heave the most likely explanation for our findings. We thus concluded that differences in carbon isotope profiles of the hollows might point to the disturbance of the mires due to climate warming or due to differences in hydrology. The characteristic profiles of the hummocks are indicators for micro-geomorphic change during permafrost up heaving.

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Section: Change In Vegetationmentioning

confidence: 94%

Stable carbon isotopes as indicators for environmental change in palsa peats

et al. 2011

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“…It is a subarctic peatland with discontinuous permafrost. Peat formation at the mire occurred at about 5000 cal BP (Rosswall et al, 1975;Kokfelt et al, 2010). This area has a continental climate, with an annual mean air temperature of 0.07 • C and an average annual precipitation of 308 mm from 1986 to 2006 according to the observations at ANS (Callaghan et al, 2010).…”

Section: The Study Area and Field Observationsmentioning

confidence: 99%

Assessing effects of permafrost thaw on C fluxes based on multiyear modeling across a permafrost thaw gradient at Stordalen, Sweden

Deng

Frolking

et al. 2014

Biogeosciences

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Abstract. Northern peatlands in permafrost regions contain a large amount of organic carbon (C) in the soil. Climate warming and associated permafrost degradation are expected to have significant impacts on the C balance of these ecosystems, but the magnitude is uncertain. We incorporated a permafrost model, Northern Ecosystem Soil Temperature (NEST), into a biogeochemical model, DeNitrificationDeComposition (DNDC), to model C dynamics in highlatitude peatland ecosystems. The enhanced model was applied to assess effects of permafrost thaw on C fluxes of a subarctic peatland at Stordalen, Sweden. DNDC simulated soil freeze-thaw dynamics, net ecosystem exchange of CO 2 (NEE), and CH 4 fluxes across three typical land cover types, which represent a gradient in the process of ongoing permafrost thaw at Stordalen. Model results were compared with multiyear field measurements, and the validation indicates that DNDC was able to simulate observed differences in seasonal soil thaw, NEE, and CH 4 fluxes across the three land cover types. Consistent with the results from field studies, the modeled C fluxes across the permafrost thaw gradient demonstrate that permafrost thaw and the associated changes in soil hydrology and vegetation not only increase net uptake of C from the atmosphere but also increase the annual to decadal radiative forcing impacts on climate due to increased CH 4 emissions. This study indicates the potential of utilizing biogeochemical models, such as DNDC, to predict the soil thermal regime in permafrost areas and to investigate impacts of permafrost thaw on ecosystem C fluxes after incorporating a permafrost component into the model framework.

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“…In a reed-dominated small freshwater tidal marsh and given the high solubility of biogenic silica, more than 40% of DSi export can be attributed to reed decomposition (Struyf et al, 2007). Moreover, the transport of Si through boreal watersheds could be impacted by silica storage originating from diatoms accumulation in peat layers (Kokfelt et al, 2009(Kokfelt et al, , 2010.…”

Section: Si In Soil-plant Systemsmentioning

confidence: 99%