University of Oulu

Risch, A. C., Zimmermann, S., Schütz, M., Borer, E. T., Broadbent, A. A. D., Caldeira, M. C., Davies, K. F., Eisenhauer, N., Eskelinen, A., Fay, P. A., Hagedorn, F., Knops, J. M. H., Lembrechts, J. J., MacDougall, A. S., McCulley, R. L., Melbourne, B. A., Moore, J. L., Power, S. A., Seabloom, E. W. … Ochoa-Hueso, R. (2023). Drivers of the microbial metabolic quotient across global grasslands. Global Ecology and Biogeography, 32, 904–918.

Drivers of the microbial metabolic quotient across global grasslands

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Author: Risch, A. C.1; Zimmermann, S.1; Schütz, M.1;
Organizations: 1Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland
2Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, Minnesota, USA
3Department of Earth and Environmental Sciences, The University of Manchester, Manchester, UK
4Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade de Lisboa, Lisbon, Portugal
5Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado, USA
6German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
7Institute of Biology, Leipzig University, Leipzig, Germany
8Ecology and Genetics Unit, University of Oulu, Oulu, Finland
9Department of Physiological Diversity, Helmholtz Center for Environmental Research – UFZ, Leipzig, Germany
10USDA ARS Grassland Soil and Water Research, Temple, Texas, USA
11Department of Health and Environmental Sciences, Xián Jiaotong-Liverpool University, Suzhou, China
12Plants and Ecosystems (PLECO), University of Antwerp, Antwerp, Belgium
13Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
14Department of Plant and Soil Sciences, University of Kentucky, Lexington, Kentucky, USA
15Arthur Rylah Institute for Environmental Research, Heidelberg, Victoria, Australia
16School of Biological Sciences, Monash University, Clayton, Victoria, Australia
17Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, Australia
18Range Cattle Research and Education Center, University of Florida, Gainesville, Florida, USA
19Facultad de Agronomía, Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura (IFEVA), Consejo Nacional de Investigaciones Científicas y Técnicas. Universidad de Buenos Aires, Buenos Aires, Argentina
20Department of Biology, University of Cádiz, Puerto Real, Spain
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.9 MB)
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Language: English
Published: John Wiley & Sons, 2023
Publish Date: 2023-11-02


Aim: The microbial metabolic quotient (MMQ; mg CO₂-C/mg MBC/h), defined as the amount of microbial CO₂ respired (MR; mg CO₂-C/kg soil/h) per unit of microbial biomass C (MBC; mg C/kg soil), is a key parameter for understanding the microbial regulation of the carbon (C) cycle, including soil C sequestration. Here, we experimentally tested hypotheses about the individual and interactive effects of multiple nutrient addition (nitrogen + phosphorus + potassium + micronutrients) and herbivore exclusion on MR, MBC and MMQ across 23 sites (five continents). Our sites encompassed a wide range of edaphoclimatic conditions; thus, we assessed which edaphoclimatic variables affected MMQ the most and how they interacted with our treatments.

Location: Australia, Asia, Europe, North/South America.

Time period: 2015–2016.

Major taxa: Soil microbes.

Methods: Soils were collected from plots with established experimental treatments. MR was assessed in a 5-week laboratory incubation without glucose addition, MBC via substrate-induced respiration. MMQ was calculated as MR/MBC and corrected for soil temperatures (MMQsoil). Using linear mixed effects models (LMMs) and structural equation models (SEMs), we analysed how edaphoclimatic characteristics and treatments interactively affected MMQsoil.

Results: MMQsoil was higher in locations with higher mean annual temperature, lower water holding capacity and lower soil organic C concentration, but did not respond to our treatments across sites as neither MR nor MBC changed. We attributed this relative homeostasis to our treatments to the modulating influence of edaphoclimatic variables. For example, herbivore exclusion, regardless of fertilization, led to greater MMQsoil only at sites with lower soil organic C (< 1.7%).

Main conclusions: Our results pinpoint the main variables related to MMQsoil across grasslands and emphasize the importance of the local edaphoclimatic conditions in controlling the response of the C cycle to anthropogenic stressors. By testing hypotheses about MMQsoil across global edaphoclimatic gradients, this work also helps to align the conflicting results of prior studies.

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Series: Global ecology and biogeography. A journal of macroecology
ISSN: 1466-822X
ISSN-E: 1466-822X
ISSN-L: 1466-822X
Volume: 32
Issue: 6
Pages: 904 - 918
DOI: 10.1111/geb.13664
Type of Publication: A1 Journal article – refereed
Field of Science: 1181 Ecology, evolutionary biology
Funding: This work was conducted within the Nutrient Network ( experiment, funded at the site scale by individual researchers. The MMQsoil study was funded by an internal competitive WSL grant to ACR, MS, SZ and FH. Coordination and data management are supported by funding to ETB and EWS from the National Science Foundation Research Coordination Network (NSF-DEB-1042132) and Long Term Ecological Research (NSF-DEB-1234162 to Cedar Creek LoTER) programmes, and the Institute on the Environment (DG-0001-13). We also thank the Minnesota Supercomputer Institute for hosting project data and the Institute on the Environment for hosting Network meetings. We are grateful to Roger Köchli and Simon Baumgartner for their help with sample processing and analyses. MCC acknowledges CEF, a research unit funded by FCT, Portugal (UID/AGR/00239/2019) and Compnahia das Lezirias for site access. NE thanks the German Centre for Integrative Biodiversity Research Halle-Jena-Leipzig, funded by the German Research Foundation (FZT 118, 202548816). JJL is grateful to the Research Group Plants and Ecosystems, University of Antwerp, Belgium. Comments by two anonymous referees greatly helped us to improve our manuscript. Dr. Pedro M. Tognetti provided invaluable help with regard to statistical analyses of the data. Open access funding provided by ETH-Bereich Forschungsanstalten.
Copyright information: © 2023 The Authors. Global Ecology and Biogeography published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.