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| Titel |
Greenhouse gas balance of a subarctic tundra - importance of carbon dioxide, methane and nitrous oxide from different land cover types |
| VerfasserIn |
M. E. Marushchak, C. Biasi, V. Elsakov, S. Jokinen, S. E. Lind, A. Pitkämäki, T. Virtanen, P. J. Martikainen |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250066059
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| Zusammenfassung |
| The strong warming predicted for the Arctic has increased the need to understand how carbon
(C) balance in tundra will respond to climate change. The large C reservoir of northern
permafrost soils (50% of global belowground soil C pool; Tarnocai et al. 2009) may be
threatened by warming and associated thawing of permafrost, which might lead to increased
release of carbon dioxide (CO2) and methane (CH4) to the atmosphere. Moreover, the recent
findings of high nitrous oxide (N2O) emissions from permafrost soils (Repo et al. 2009,
Elberling et al. 2010) show that the large nitrogen pool in permafrost soils cannot be
neglected anymore when predicting the atmospheric impact of Arctic tundra in
a changing climate. Here we report the annual landscape scale (GHG) balance
of subarctic tundra including all the three most important GHGs: CO2, CH4 and
N2O.
The study was conducted in Northeast European Russia in a heterogeneous landscape
consisting of upland tundra, fens, willow wetlands and massive peat plateau complexes
spotted by thermokarst lakes. Fluxes of CO2, CH4 and N2O were measured during two
growing seasons and the cold season between using different chamber techniques at
terrestrial ecosystems, and combination of gas gradient method and bubble collectors in
thermokarst lakes. The plot scale results were up scaled to the landscape level using a land
cover map based on a high-resolution QuickBird satellite image (Hugelius et al. 2011).
The land cover types studied represent 97% of the whole area study area of 98.6
km2.
On an annual basis the study area acted as a sink of C, but CH4 and N2O emissions caused it
to be a net source of GHGs when considering the global warming potential (GWP; 100-year
time horizon) of all three gases. Willow wetlands, fens and thermokarst lakes (16% of the
landscape) were significant sources of CH4, while CH4 emissions from the rest of the
landscape were negligible. Bare peat surfaces on peat plateaus, peat circles, acted as strong
hotspots of N2O emissions, thus, being unique among pristine northern soils. The peat circles
had also the highest GHG emissions as CO2 equivalents, in contrast to the vegetated part of
the peat plateau that represented the strongest net GHG sink on a unit area basis. Vascular
leaf area index explained well the variability in CO2 fluxes and the total C balance
across all soil and vegetation types, the wetland sites being the largest C sinks. The
climate change will affect on composition and function of arctic landscape in a
complex way, making it difficult to predict the net effect on the landscape scale GHG
balance. |
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