Rhizosphere allocation by canopy-forming species dominates soil CO2 efflux in a subarctic landscape

In arctic ecosystems, climate change has increased plant productivity. As arctic carbon (C) stocks predominantly are located belowground, the effects of greater plant productivity on soil C storage will significantly determine the net sink/source potential of these ecosystems, but vegetation control...

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Bibliographic Details
Published in:New Phytologist
Main Authors: Parker, Thomas C., Clemmensen, Karina E., Friggens, Nina L., Hartley, Iain P., Johnson, David, Lindahl, Bjorn D., Olofsson, Johan, Siewert, Matthias B., Street, Lorna E., Subke, Jens-Arne, Wookey, Philip A.
Format: Article in Journal/Newspaper
Language:English
Published: Umeå universitet, Institutionen för ekologi, miljö och geovetenskap 2020
Subjects:
Arctic
ectomycorrhizal fungi
girdling
rhizosphere
shrub expansion
soil CO2 efflux
treeline
Botany
Botanik
Climate change
Northern Sweden
Subarctic
Online Access:http://urn.kb.se/resolve?urn=urn:nbn:se:polar:diva-8521
https://doi.org/10.1111/nph.16573
Description
Summary:In arctic ecosystems, climate change has increased plant productivity. As arctic carbon (C) stocks predominantly are located belowground, the effects of greater plant productivity on soil C storage will significantly determine the net sink/source potential of these ecosystems, but vegetation controls on soil CO2 efflux remain poorly resolved. In order to identify the role of canopy‐forming species in belowground C dynamics, we conducted a girdling experiment with plots distributed across 1 km2 of treeline birch (Betula pubescens ) forest and willow (Salix lapponum ) patches in northern Sweden and quantified the contribution of canopy vegetation to soil CO2 fluxes and belowground productivity. Girdling birches reduced total soil CO2 efflux in the peak growing season by 53%, which is double the expected amount, given that trees contribute only half of the total leaf area in the forest. Root and mycorrhizal mycelial production also decreased substantially. At peak season, willow shrubs contributed 38% to soil CO2 efflux in their patches. Our findings indicate that C, recently fixed by trees and tall shrubs, makes a substantial contribution to soil respiration. It is critically important that these processes are taken into consideration in the context of a greening arctic because productivity and ecosystem C sequestration are not synonymous.

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