Plant roots increase carbon emission from permafrost soils

Date:
July 20, 2020
Source:
Umea University
Summary:
A key uncertainty in climate projections is the amount of carbon
emitted by thawing permafrost in the Arctic. Plant roots in soil
stimulate microbial decomposition, a mechanism called the priming
effect. An international research team shows that the priming
effect alone can cause emission of 40 billion tonnes carbon from
permafrost by 2100.



FULL STORY ==========================================================================
A key uncertainty in climate projections is the amount of carbon emitted
by thawing permafrost in the Arctic. Plant roots in soil stimulate
microbial decomposition, a mechanism called the priming effect. An international research team co-lead by Frida Keuper from INRAE and Umeaa University and Birgit Wild from Stockholm University shows that the
priming effect alone can cause emission of 40 billion tonnes carbon from permafrost by 2100. The study was published today in Nature Geoscience.


========================================================================== Permafrost is permanently frozen ground which stores as much carbon as
there is in all plants on Earth and in the atmosphere together. The
surface of the permafrost thaws in summer, allowing plant and soil
life to thrive. When microorganisms breathe, they emit greenhouse
gases. Scientists have previously anticipated that rapidly rising
temperatures will drive the emission of 50-100 billion ton permafrost
carbon by 2100. On top of that, plant roots feed sugar to the
microorganisms in the soil, which the microbes can use to break down
more soil organic matter -- the priming effect -- resulting in even
higher greenhouse gas emissions.

"We have known about the priming effect since the 1950's, but we did
not know whether or not this small-scale ecological interaction had a significant impact on the global carbon cycle," says Research Scientist
Frida Keuper, affiliated with the French National Research Institute
for Agriculture, Food and Environment, INRAE, and with Umeaa University, Sweden.

The team of researchers combined maps of plant activity and data on soil
carbon content from the Northern Circumpolar Soil Carbon Database with
an extensive literature survey on priming and plant root properties, to estimate the priming effect in permafrost ecosystems and its influence
on greenhouse gas emissions.

They show that the priming effect increases soil microbial respiration by
12 percent, which causes the additional loss of 40 billion ton carbon by
2100 compared to current predictions for permafrost. This equals almost
a quarter of the remaining 'carbon budget' for human activities to limit
global warming to max 1.5DEGC.

"These new findings demonstrate how important it is to consider
small-scale ecological interactions, such as the priming effect, in
global greenhouse gas emission modelling," says Birgit Wild, Assistant Professor at Stockholm University.


========================================================================== Story Source: Materials provided by Umea_University. Original written
by Anna-Lena Lindskog.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Frida Keuper, Birgit Wild, Matti Kummu, Christian Beer, Gesche
Blume-
Werry, Se'bastien Fontaine, Konstantin Gavazov, Norman Gentsch,
Georg Guggenberger, Gustaf Hugelius, Mika Jalava, Charles Koven,
Eveline J.

Krab, Peter Kuhry, Sylvain Monteux, Andreas Richter, Tanvir
Shahzad, James T. Weedon, Ellen Dorrepaal. Carbon loss from
northern circumpolar permafrost soils amplified by rhizosphere
priming. Nature Geoscience, 2020; DOI: 10.1038/s41561-020-0607-0 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200720112335.htm

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