Tundra landscape heterogeneity, not interannual variability, controls the decadal regional carbon balance in the Western Russian Arctic
Treat, C.C.; Marushchak, M.E.; Voigt, C.; Zhang, Y.; Tan, Z.; Zhuang, Q.; Virtanen, T.A.; Räsänen, A.; Biasi, C.; Hugelius, G.; Kaverin, D.; Miller, P.A.; Stendel, M.; Romanovsky, V.; Rivkin, F.; Martikainen, P.J.; Shurpali, N.J.
Global Change Biology 24(11): 5188-5204
ISSN/ISBN: 1354-1013 PMID: 30101501 DOI: 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.