EGU23-2946, updated on 28 Feb 2023
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

­­Carbon Costs of Plant Nutrient Acquisition Improve Present-Day Carbon Cycle Estimates and Limit CO2 Fertilization Effect

Renato K. Braghiere1,2, Joshua Fisher3, Kara Allen4, Edward Brzostek5, Mingie Shi6, Xiaojuan Yang7, Daniel Ricciuto7, Rosie Fisher8, Qing Zhu9, Richard Phillips10, Benjamin Sulman7, Brian Steidinger11, Nadejda Soudzilovskaia12, Jing Liang13,14, Kabir Peay11, and Thomas Crowther15
Renato K. Braghiere et al.
  • 1Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA (
  • 2Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA (
  • 3Schmid College of Science and Technology, Chapman University, Orange, CA 92866, USA
  • 4Manaaki Whenua—Landcare Research, Lincoln, New Zealand
  • 5Department of Biology, West Virginia University, Morgantown, WV, USA
  • 6Pacific Northwest National Laboratory, Richland, WA, USA
  • 7Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, USA
  • 8Center for International Climate Research, Oslo, Norway
  • 9Climate and Ecosystem Sciences Division, Climate Sciences Department, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
  • 10Department of Biology, Indiana University, Bloomington, IN, USA
  • 11Department of Biology, Stanford University, Stanford, CA, USA
  • 12Department of Environmental Biology, Leiden University, Institute of Environmental Sciences, Leiden, The Netherlands
  • 13Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, USA
  • 14Research Center of Forest Management Engineering of State Forestry and Grassland Administration, Beijing Forestry University, Beijing, China
  • 15Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland

Most Earth system models (ESMs) do not explicitly represent the carbon (C) costs of plant nutrient acquisition, which leads to uncertainty in predictions of the current and future constraints to the land C sink. While plants acquire nutrients through different uptake pathways, such as from mycorrhizae, direct root uptake, retranslocation from senescing tissues, and biological fixation in the case of nitrogen (N), they usually have different associated C costs. Determining the amount of nutrients acquired through each uptake pathway and the associated C cost could increase understanding of the global C and nutrient cycles, as well as the predictive skills of ESMs.

Here, we integrate a plant productivity-optimizing nutrient (N and phosphorus (P)) acquisition model (Fixation & Uptake of Nutrients, FUN) into the Energy Exascale Earth System (E3SM) Land Model (ELM) to simulate the global C and nutrient cycles (Braghiere et al., 2022). We benchmarked the model with observations (in-situ, remotely sensed, and integrated using artificial intelligence), and other ESMs from CMIP6; we found significant improvements in present C cycle variables estimates. We also examine the impact of mycorrhizal spatial distributions on the global C cycle, since most plant species predominantly associate with a single type of mycorrhizal fungi and uncertainties in mycorrhizal distributions are non-trivial, with current estimates disagreeing in up to 50% over 40% of the land area (Braghiere et al., 2021). Global Net Primary Productivity (NPP) is reduced by 20% with N costs and 50% with NP costs, while modeled and observed nutrient limitation agreement increases when N and P are considered together. Even though NPP has been growing globally in response to increasing CO2, as soil nutrient progressively becomes more limiting, the costs to NPP for nutrient acquisition have increased at a faster rate. This suggests that nutrient acquisition will increasingly demand a higher portion of assimilated C to support the same productivity.

Braghiere, et al. (2022)

Braghiere, et al. (2021)

How to cite: Braghiere, R. K., Fisher, J., Allen, K., Brzostek, E., Shi, M., Yang, X., Ricciuto, D., Fisher, R., Zhu, Q., Phillips, R., Sulman, B., Steidinger, B., Soudzilovskaia, N., Liang, J., Peay, K., and Crowther, T.: ­­Carbon Costs of Plant Nutrient Acquisition Improve Present-Day Carbon Cycle Estimates and Limit CO2 Fertilization Effect, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-2946,, 2023.