January 15, 2020

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Ability of Ecosystems to Absorb CO2 from Atmosphere Limited by Nitrogen and Phosphorus Availability in Soils

Nitrogen and phosphorus constrain the CO2 fertilization of global plant biomass.

The Science

To predict the effects of rising atmospheric carbon dioxide (CO2) levels, scientists perform elevated COexperiments at local and regional scales to simulate the response of plants at a global scale. Although there is strong evidence from these experiments that elevated CO2 levels enhance photosynthesis, there are conflicting results for ecosystem-level responses. By globally extrapolating the local results, it becomes evident that the ecosystem-level responses are a function of nutrient availability and nutrient cycling habits.

The Impact

The convergence of past observation with the globally synthesized retrospective predictions of this model supports its future predictions. Despite nutrient limitations, the model indicates that the same key ecosystems will still be responsible for most of the global greening and carbon uptake and forests will continue positive growth trends at CO2 levels expected in 2100. Ultimately, this study highlights the importance of maintaining forests as one of the most important contributions toward limiting global climate change.

Summary

This paper synthesizes observational evidence at local scales and captures a global view of the elevated CO2 effect on plant growth. Data from 138 local elevated COexperiments with 56 potential predictors of CO2 effect were considered for the creation of this model. The model is used to predict plant growth response to elevated CO2 globally. It confirms that soil nutrients are the limiting factors on plant growth and the contrasting growth response of the individual elevated COexperiments can be explained by the differing nutrient cycle habits of various types of forest.

Principal Investigator

Joshua Fisher
University of California, Los Angeles
joshbfisher@gmail.com

Program Manager

Daniel Stover
U.S. Department of Energy, Biological and Environmental Research (SC-33)
Environmental System Science
daniel.stover@science.doe.gov

Funding

The project was funded by the Terrestrial Ecosystem Science program of the Office of Biological and Environmental Research (BER) within the U.S. Department of Energy (DOE) Office of Science and by the National Science Foundation’s (NSF) Ecosystem Science Cluster.

References

Terrer, C., R. B. Jackson, I. C. Prentice, and T. F. Keenan, et al. "Nitrogen and phosphorus constrain the CO2 fertilization of global plant biomass". Nature Climate Change 9 684–689  (2019). https://doi.org/10.1038/s41558-019-0545-2.