Tundra landscape heterogeneity, not inter-annual variability, controls the decadal regional carbon balance in the Western Russian Arctic
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CitationTreat, CC. Marushchak, ME. Voigt, C. Zhang, Y. Tan, Z. Zhuang, Q. Virtanen, TA. Räsänen, A. Biasi, C. Hugelius, G. Kaverin, D. Miller, PA. Stendel, M. Romanovsky, V. Rivkin, F. Martikainen, PJ. Shurpali, NJ. (2018). Tundra landscape heterogeneity, not inter-annual variability, controls the decadal regional carbon balance in the Western Russian Arctic. GLOBAL CHANGE BIOLOGY, [Epub ahead of print 9 Sept 2018], 10.1111/gcb.14421.
Across the Arctic, the net ecosystem carbon (C) balance of tundra ecosystems is highly uncertain due to substantial temporal variability of C fluxes and to landscape heterogeneity. We modeled both carbon dioxide (CO2) and methane (CH4) fluxes for the dominant land cover types in a ~100‐km2 sub‐Arctic tundra region in northeast European Russia for the period of 2006–2015 using process‐based biogeochemical models. Modeled net annual CO2 fluxes ranged from −300 g C m−2 year−1 [net uptake] in a willow fen to 3 g C m−2 year−1 [net source] in dry lichen tundra. Modeled annual CH4 emissions ranged from −0.2 to 22.3 g C m−2 year−1 at a peat plateau site and a willow fen site, respectively. Interannual variability over the decade was relatively small (20%–25%) in comparison with variability among the land cover types (150%). Using high‐resolution land cover classification, the region was a net sink of atmospheric CO2 across most land cover types but a net source of CH4 to the atmosphere due to high emissions from permafrost‐free fens. Using a lower resolution for land cover classification resulted in a 20%–65% underestimation of regional CH4 flux relative to high‐resolution classification and smaller (10%) overestimation of regional CO2 uptake due to the underestimation of wetland area by 60%. The relative fraction of uplands versus wetlands was key to determining the net regional C balance at this and other Arctic tundra sites because wetlands were hot spots for C cycling in Arctic tundra ecosystems.