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Research article - Peer-reviewed, 2021

Contribution of microbial photosynthesis to peatland carbon uptake along a latitudinal gradient

Hamard, Samuel; Cereghino, Regis; Barret, Maialen; Sytiuk, Anna; Lara, Enrique; Dorrepaal, Ellen; Kardol, Paul; Kuttim, Martin; Lamentowicz, Mariusz; Leflaive, Josephine; Le Roux, Gael; Tuittila, Eeva-Stiina; Jassey, Vincent E. J.


Phototrophic microbes, also known as micro-algae, display a high abundance in many terrestrial surface soils. They contribute to atmospheric carbon dioxide fluxes through their photosynthesis, and thus regulate climate similar to plants. However, microbial photosynthesis remains overlooked in most terrestrial ecosystems. Here, we hypothesise that phototrophic microbes significantly contribute to peatland C uptake, unless environmental conditions limit their development and their photosynthetic activity. To test our hypothesis, we studied phototrophic microbial communities in five peatlands distributed along a latitudinal gradient in Europe. By means of metabarcoding, microscopy and cytometry analyses, as well as measures of photosynthesis, we investigated the diversity, absolute abundance and photosynthetic rates of the phototrophic microbial communities. We identified 351 photosynthetic prokaryotic and eukaryotic operational taxonomic units (OTUs) across the five peatlands. We found that water availability and plant composition were important determinants of the composition and the structure of phototrophic microbial communities. Despite environmental shifts in community structure and composition, we showed that microbial C fixation rates remained similar along the latitudinal gradient. Our results further revealed that phototrophic microbes accounted for approximately 10% of peatland C uptake. Synthesis. Our findings show that phototrophic microbes are extremely diverse and abundant in peatlands. While species turnover with environmental conditions, microbial photosynthesis similarly contributed to peatland C uptake at all latitudes. We estimate that phototrophic microbes take up around 75 MT CO2 per year in northern peatlands. This amount roughly equals the magnitude of projected peatland C loss due to climate warming and highlights the importance of phototrophic microbes for the peatland C cycle.


algae; carbon cycle; metabarcoding; microbial diversity; peatland; photosynthesis; phototrophs; primary productivity

Published in

Journal of Ecology
2021, volume: 109, pages: 3424-3441
Publisher: WILEY

Authors' information

Hamard, Samuel
Universite Toulouse III - Paul Sabatier
Cereghino, Regis
Universite Toulouse III - Paul Sabatier
Barret, Maialen
Universite Toulouse III - Paul Sabatier
Sytiuk, Anna
Universite Toulouse III - Paul Sabatier
Lara, Enrique
Consejo Superior de Investigaciones Cientificas (CSIC)
Dorrepaal, Ellen
Umea University
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Kuttim, Martin
Tallinn University
Lamentowicz, Mariusz
Adam Mickiewicz University
Leflaive, Josephine
Universite Toulouse III - Paul Sabatier
Le Roux, Gael
Universite Toulouse III - Paul Sabatier
Tuittila, Eeva-Stiina
University of Eastern Finland
Jassey, Vincent E. J.
Universite Toulouse III - Paul Sabatier

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