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| Titel |
Thaw pond dynamics and carbon emissions in a Siberian lowland tundra landscape |
| VerfasserIn |
Ko van Huissteden, Monique Heijmans, Josh Dean, Ove Meisel, Arne Goovaerts, Frans-Jan Parmentier, Gabriela Schaepman-Strub, Luca Belelli Marchesini, Alexander Kononov, Trofim Maximov, Alberto Borges, Steven Bouillon |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250142086
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| Publikation (Nr.) |
 EGU/EGU2017-5661.pdf |
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| Zusammenfassung |
| Arctic climate change induces drastic changes in permafrost surface wetness. As a result of
thawing ground ice bodies, ice wedge troughs and thaw ponds are formed. Alternatively,
ongoing thaw may enhance drainage as a result of increased interconnectedness of thawing
ice wedge troughs, as inferred from a model study (Liljedahl et al., 2016, Nature Geoscience,
DOI: 10.1038/NGEO2674). However, a recent review highlighted the limited predictability of
consequences of thawing permafrost on hydrology (Walvoord and Kurylyk, 2016,
Vadose Zone J., DOI:10.2136/vzj2016.01.0010). Overall, these changes in tundra
wetness modify carbon cycling in the Arctic and in particular the emissions of CO2
and CH4 to the atmosphere, providing a possibly positive feedback on climate
change.
Here we present the results of a combined remote sensing, geomorphological, vegetation
and biogechemical study of thaw ponds in Arctic Siberian tundra, at Kytalyk research station
near Chokurdakh, Indigirka lowlands. The station is located in an area dominated by
Pleistocene ice-rich ’yedoma’ sediments and drained thaw lake bottoms of Holocene age. The
development of three types of ponds in the Kytalyk area (polygon centre ponds, ice wedge
troughs and thaw ponds) has been traced with high resolution satellite and aerial
imagery.
The remote sensing data show net areal expansion of all types of ponds. Next to formation
of new ponds, local vegetation change from dry vegetation types to wet, sedge-dominated
vegetation is common. Thawing ice wedges and thaw ponds show an increase in area and
number at most studied locations. In particular the area of polygon centre ponds increased
strongly between 2010 and 2015, but this is highly sensitive to antecedent precipitation
conditions. Despite a nearly 60% increase of the area of thawing ice wedge troughs, there is
no evidence of decreasing water surfaces by increasing drainage through connected ice
wedge troughs.
The number of thaw ponds shows an equilibrium between newly formed and disappearing
ponds, although their net area increased by 16%. The disappearing of ponds was mostly the
result of vegetation succession, rather than drainage. This vegetation succession results from
an invasion by sedges, followed by establishment of Sphagnum and seedlings of dwarf
shrubs.
The formation of thaw ponds and troughs resulting from small-scale permafrost collapse
results in a drastic change of CH4 and CO2 emissions, from near-zero emission or uptake to
high emission. New water surfaces with drowned dry tundra vegetation show the highest
emission. However, rapid vegetation succession may mitigate these emissions over time, in
particular in the relatively shallow thaw ponds. In contrast, the polygon centre ponds with a
stable, oligotrophic vegetation show modest and constant CH4 emission and CO2 uptake. |
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