Carbon loss from northern circumpolar permafrost soils amplified by rhizosphere priming

• Published in: Nature geoscience 2020-08, Vol.13 (8), p.560-565
• Main Authors: Keuper, Frida, Wild, Birgit, Kummu, Matti, Beer, Christian, Blume-Werry, Gesche, Fontaine, Sébastien, Gavazov, Konstantin, Gentsch, Norman, Guggenberger, Georg, Hugelius, Gustaf, Jalava, Mika, Koven, Charles, Krab, Eveline J., Kuhry, Peter, Monteux, Sylvain, Richter, Andreas, Shahzad, Tanvir, Weedon, James T., Dorrepaal, Ellen
• Format: Article
• Language: English
• Subjects: 704/106/694; 704/158/2165; 704/47/4113; Amplification; Anthropogenic factors; Boreal ecosystems; Carbon; Climate change; Climate Research; Decomposition; Earth and Environmental Science; Earth and Related Environmental Sciences; Earth Sciences; Earth System Sciences; Emissions; Empirical analysis; Environmental Sciences; Geochemistry; Geology; Geophysics/Geodesy; Geovetenskap och miljövetenskap; Global Changes; Global temperatures; Global warming; Greenhouse effect; Greenhouse gases; Klimatforskning; Markvetenskap; Melting; Microorganisms; Organic carbon; Organic soils; Permafrost; Permafrost soils; Plant roots; Priming; Respiration; Rhizosphere; Roots; Soil; Soil erosion; Soil loss; Soil respiration; Soil Science; Soils; Stocks; Temperature rise; Thawing
• ISSN: 1752-0894; 1752-0908; 1752-0908
• DOI: 10.1038/s41561-020-0607-0

As global temperatures continue to rise, a key uncertainty of climate projections is the microbial decomposition of vast organic carbon stocks in thawing permafrost soils. Decomposition rates can accelerate up to fourfold in the presence of plant roots, and this mechanism—termed the rhizosphere priming effect—may be especially relevant to thawing permafrost soils as rising temperatures also stimulate plant productivity in the Arctic. However, priming is currently not explicitly included in any model projections of future carbon losses from the permafrost area. Here, we combine high-resolution spatial and depth-resolved datasets of key plant and permafrost properties with empirical relationships of priming effects from living plants on microbial respiration. We show that rhizosphere priming amplifies overall soil respiration in permafrost-affected ecosystems by ~12%, which translates to a priming-induced absolute loss of ~40 Pg soil carbon from the northern permafrost area by 2100. Our findings highlight the need to include fine-scale ecological interactions in order to accurately predict large-scale greenhouse gas emissions, and suggest even tighter restrictions on the estimated 200 Pg anthropogenic carbon emission budget to keep global warming below 1.5 °C. Plant roots in thawing permafrost soils act to enhance microbial decomposition and the loss of soil organic carbon, according to an analysis of observational data and a rhizosphere priming model.