Nitrogen increases early-stage and slows late-stage decomposition across diverse grasslands

Allison Gill, Peter B. Adler, Elizabeth T. Borer, Christopher R Buyarski, Elsa E. Cleland, Carla M. D'Antonio, Kendi F. Davies, Daniel S. Gruner, W. Stanley Harpole, Kirsten S. Hofmockel, Andrew S. MacDougall, Rebecca L. McCulley, Brett A. Melbourne, Joslin L. Moore, John W. Morgan, Anita C. Risch, Martin Schütz, Eric W. Seabloom, Justin P. Wright, Louie H. YangSarah E. Hobbie

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

To evaluate how increased anthropogenic nutrient inputs alter carbon cycling in grasslands, we conducted a litter decomposition study across 20 temperate grasslands on three continents within the Nutrient Network, a globally distributed nutrient enrichment experiment We determined the effects of addition of experimental nitrogen (N), phosphorus (P) and potassium plus micronutrient (Kμ) on decomposition of a common tree leaf litter in a long-term study (maximum of 7 years; exact deployment period varied across sites). The use of higher order decomposition models allowed us to distinguish between the effects of nutrients on early- versus late-stage decomposition. Across continents, the addition of N (but not other nutrients) accelerated early-stage decomposition and slowed late-stage decomposition, increasing the slowly decomposing fraction by 28% and the overall litter mean residence time by 58%. Synthesis. Using a novel, long-term cross-site experiment, we found widespread evidence that N enhances the early stages of above-ground plant litter decomposition across diverse and widespread temperate grassland sites but slows late-stage decomposition. These findings were corroborated by fitting the data to multiple decomposition models and have implications for N effects on soil organic matter formation. For example, following N enrichment, increased microbial processing of litter substrates early in decomposition could promote the production and transfer of low molecular weight compounds to soils and potentially enhance the stabilization of mineral-associated organic matter. By contrast, by slowing late-stage decomposition, N enrichment could promote particulate organic matter (POM) accumulation. Such hypotheses deserve further testing.

Original languageEnglish (US)
Pages (from-to)1376-1389
Number of pages14
JournalJournal of Ecology
Volume110
Issue number6
DOIs
StatePublished - Jun 2022

Bibliographical note

Funding Information:
This work was supported by grants from the National Science Foundation, including the NSF Ecosystems Studies program (NSF DEB-1556529), the Cedar Creek Long Term Ecological Research project (NSF DEB-0620652, DEB-1234162) and the Research Coordination Network program (NSF DEB-1042132). Soil analyses were supported, in part, by USDA-ARS grant 58-3098-7-007 to E.T.B. Additional support for coordination and data management came from the University of Minnesota's Institute on the Environment (DG-0001-13). The authors thank the Minnesota Supercomputer Institute for hosting project data and the Institute on the Environment for hosting Network meetings. Gill was supported by a University of Minnesota College of Biological Sciences Grand Challenges Postdoctoral Fellowship. They are grateful to numerous people who helped construct, deploy, collect and process litter bags, and prepare litter for and conduct laboratory analyses, including, but not limited to, Lori Biederman, Jennifer Firn, Paul Frater, Eric Lind, Bonnie McGill and Viviane Vincent.

Funding Information:
This work was supported by grants from the National Science Foundation, including the NSF Ecosystems Studies program (NSF DEB‐1556529), the Cedar Creek Long Term Ecological Research project (NSF DEB‐0620652, DEB‐1234162) and the Research Coordination Network program (NSF DEB‐1042132). Soil analyses were supported, in part, by USDA‐ARS grant 58‐3098‐7‐007 to E.T.B. Additional support for coordination and data management came from the University of Minnesota's Institute on the Environment (DG‐0001‐13). The authors thank the Minnesota Supercomputer Institute for hosting project data and the Institute on the Environment for hosting Network meetings. Gill was supported by a University of Minnesota College of Biological Sciences Grand Challenges Postdoctoral Fellowship. They are grateful to numerous people who helped construct, deploy, collect and process litter bags, and prepare litter for and conduct laboratory analyses, including, but not limited to, Lori Biederman, Jennifer Firn, Paul Frater, Eric Lind, Bonnie McGill and Viviane Vincent.

Publisher Copyright:
© 2022 The Authors. Journal of Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.

Keywords

  • Nutrient Network (NutNet)
  • grasslands
  • litter decomposition
  • nitrogen
  • nitrogen deposition
  • phosphorus

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