Belowground Biomass Response to Nutrient Enrichment Depends on Light Limitation Across Globally Distributed Grasslands

Elsa E. Cleland, Eric M. Lind, Nicole M. DeCrappeo, Elizabeth DeLorenze, Rachel Abbott Wilkins, Peter B. Adler, Jonathan D. Bakker, Cynthia S. Brown, Kendi F. Davies, Ellen Esch, Jennifer Firn, Scott Gressard, Daniel S. Gruner, Nicole Hagenah, W. Stanley Harpole, Yann Hautier, Sarah E. Hobbie, Kirsten S. Hofmockel, Kevin Kirkman, Johannes KnopsChristopher W. Kopp, Kimberly J. La Pierre, Andrew MacDougall, Rebecca L. McCulley, Brett A. Melbourne, Joslin L. Moore, Suzanne M. Prober, Charlotte Riggs, Anita C. Risch, Martin Schuetz, Carly Stevens, Peter D. Wragg, Justin Wright, Elizabeth T. Borer, Eric W. Seabloom

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


Anthropogenic activities are increasing nutrient inputs to ecosystems worldwide, with consequences for global carbon and nutrient cycles. Recent meta-analyses show that aboveground primary production is often co-limited by multiple nutrients; however, little is known about how root production responds to changes in nutrient availability. At twenty-nine grassland sites on four continents, we quantified shallow root biomass responses to nitrogen (N), phosphorus (P) and potassium plus micronutrient enrichment and compared below- and aboveground responses. We hypothesized that optimal allocation theory would predict context dependence in root biomass responses to nutrient enrichment, given variation among sites in the resources limiting to plant growth (specifically light versus nutrients). Consistent with the predictions of optimal allocation theory, the proportion of total biomass belowground declined with N or P addition, due to increased biomass aboveground (for N and P) and decreased biomass belowground (N, particularly in sites with low canopy light penetration). Absolute root biomass increased with N addition where light was abundant at the soil surface, but declined in sites where the grassland canopy intercepted a large proportion of incoming light. These results demonstrate that belowground responses to changes in resource supply can differ strongly from aboveground responses, which could significantly modify predictions of future rates of nutrient cycling and carbon sequestration. Our results also highlight how optimal allocation theory developed for individual plants may help predict belowground biomass responses to nutrient enrichment at the ecosystem scale across wide climatic and environmental gradients.

Original languageEnglish
Pages (from-to)1466-1477
Number of pages12
Issue number7
StatePublished - Nov 1 2019

Bibliographical note

Funding Information:
This work was generated using data from the Nutrient Network ( experiment, funded at the site-scale by individual researchers. Coordination and data management have been supported by funding to E. Borer and E. Seabloom from the National Science Foundation Research Coordination Network (NSF-DEB-1042132) and Long Term Ecological Research (NSF-DEB-1234162 to Cedar Creek LTER) programs, 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. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the US Government.

Publisher Copyright:
© 2019, Springer Science+Business Media, LLC, part of Springer Nature.


  • Nutrient Network
  • belowground biomass
  • fertilization
  • nitrogen
  • optimal allocation
  • phosphorus
  • roots

ASJC Scopus subject areas

  • Environmental Chemistry
  • Ecology, Evolution, Behavior and Systematics
  • Ecology


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