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| Titel |
Environmental correlates of peatland carbon fluxes in a thawing landscape: do transitional thaw stages matter? |
| VerfasserIn |
A. Malhotra, N. T. Roulet |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 10 ; Nr. 12, no. 10 (2015-05-29), S.3119-3130 |
| Datensatznummer |
250117952
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| Publikation (Nr.) |
 copernicus.org/bg-12-3119-2015.pdf |
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| Zusammenfassung |
| Peatlands in discontinuous permafrost regions occur as a mosaic of wetland
types, each with variable sensitivity to climate change. Permafrost thaw
further increases the spatial heterogeneity in ecosystem structure and
function in peatlands. Carbon (C) fluxes are well characterized in end-member
thaw stages such as fully intact or fully thawed permafrost but remain
unconstrained for transitional stages that cover a significant area of
thawing peatlands. Furthermore, changes in the environmental correlates of C
fluxes, due to thaw, are not well described – a requirement for modeling
future changes to C storage of permafrost peatlands. We investigated C fluxes
and their correlates in end-member and a number of transitional thaw
stages in a sub-arctic peatland. Across peatland-lumped CH4 and CO2
flux data had significant correlations with expected correlates such as water
table depth, thaw depth, temperature, photosynthetically active radiation and
vascular green area. Within individual thaw states, bivariate correlations as
well as multiple regressions between C flux and environmental factors changed
variably with increasing thaw. The variability in directions and magnitudes
of correlates reflects the range of structural conditions that could be
present along a thaw gradient. These structural changes correspond to changes
in C flux controls, such as temperature and moisture, and their interactions.
Temperature sensitivity of CH4 increased with increasing thaw in
bivariate analyses, but lack of this trend in multiple regression analyses
suggested cofounding effects of substrate or water limitation on the apparent
temperature sensitivity. Our results emphasize the importance of
incorporating transitional stages of thaw in landscape level C budgets and
highlight that end-member or adjacent thaw stages do not adequately describe
the variability in structure-function relationships present along a thaw
gradient. |
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