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Plant carbon allocation drives turnover of old soil organic matter in permafrost tundra soils

Street, LE; Garnett, MH; Subke, J-A; Baxter, R; Dean, JF; Wookey, PA

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LE Street

MH Garnett

J-A Subke

JF Dean

PA Wookey


Carbon cycle feedbacks from permafrost ecosystems are expected to accelerate global climate change. Shifts in vegetation productivity and composition in permafrost regions could influence soil organic carbon (SOC) turnover rates via rhizosphere (root zone) priming effects (RPEs), but these processes are not currently accounted for in model predictions. We use a radiocarbon (bomb‐14C) approach to test for RPEs in two Arctic tall shrubs, alder (Alnus viridis (Chaix) DC.) and birch (Betula glandulosa Michx.), and in ericaceous heath tundra vegetation. We compare surface CO2 efflux rates and 14C content between intact vegetation and plots in which below‐ground allocation of recent photosynthate was prevented by trenching and removal of above‐ground biomass. We show, for the first time, that recent photosynthate drives mineralization of older (>50 years old) SOC under birch shrubs and ericaceous heath tundra. By contrast, we find no evidence of RPEs in soils under alder. This is the first direct evidence from permafrost systems that vegetation influences SOC turnover through below‐ground C allocation. The vulnerability of SOC to decomposition in permafrost systems may therefore be directly linked to vegetation change, such that expansion of birch shrubs across the Arctic could increase decomposition of older SOC. Our results suggest that carbon cycle models that do not include RPEs risk underestimating the carbon cycle feedbacks associated with changing conditions in tundra regions.


Street, L., Garnett, M., Subke, J., Baxter, R., Dean, J., & Wookey, P. (2020). Plant carbon allocation drives turnover of old soil organic matter in permafrost tundra soils. Global Change Biology, 26(8), 4559-4571.

Journal Article Type Article
Acceptance Date Apr 6, 2020
Online Publication Date Jun 17, 2020
Publication Date 2020-08
Deposit Date Apr 6, 2020
Publicly Available Date Jun 25, 2020
Journal Global Change Biology
Print ISSN 1354-1013
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 26
Issue 8
Pages 4559-4571


Published Journal Article (Advance online version) (1.7 Mb)

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Copyright Statement
Advance online version © 2020 The Authors. Global Change Biology published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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