NCEAS Working Groups
Progressive nitrogen limitation of plant and ecosystem responses to elevated CO2
Project Description
This working group will address the issue: why don't most field experimental results support model
predictions that progressive ecosystem nitrogen (N) limitation leads to downregulation of primary
production in elevated CO2?
Ecosystem models that link nutrient cycling with plant production generally predict long-term
photosynthetic downregulation and reduced stimulation in plant production caused by progressive N
constraints in elevated CO2. The conceptual model is that increased carbon (C) influx under elevated
CO2 will immobilize more N in plant biomass and soil organic matter, progressively leading to less N
available for plant uptake. However, the predicted downregulation in primary production has not been
confirmed by most of the free-air CO2 enrichment (FACE) and open-top chamber (OTC) experiments.
The discrepancy between model predictions and experimental data apparently results from a
fundamental knowledge gap concerning ecosystem C and N interactions, which lie at the core of
ecosystem ecology. The proposed working group will address the issue of progressive N limitations by
(1) compilation and synthesis of experimental data from the on-going FACE and OTC projects as well
as from the literature; (2) synthesis of published modeling results and comparison of mechanisms
incorporated into various models; (3) identification of possible mechanisms causing the discrepancy
between model predictions and experimental results; and (4) defining future research need for both
experimental and modeling studies.
This project has the potential to make a critical contribution to ecosystem ecology. Moreover,
a solid understanding of C:N interactions extends beyond ecology. Models increasingly applied to
policy questions appear to have major problems matching the aspects of experimental results. The latter
are most relevant to the policy applications. The ability of the ecological community to provide useful
information on the future carbon dynamics of the terrestrial biosphere (including the terrestrial sink)
depends critically on resolving the question of progressive N limitation.

Principal Investigator(s)
Yiqi Luo, Christopher B. Field
Project Dates
Start: May 10, 2001
End: June 21, 2002
completed
Participants
- Gregory P. Asner
- University of Colorado
- Aihua Bian
- University of Oklahoma
- William S. Currie
- University of Maryland Center for Environmental Science
- Jeffrey S. Dukes
- Carnegie Institution
- Christopher B. Field
- Carnegie Institution
- Adrien Finzi
- Boston University
- Ueli Hartwig
- Institute of Plant Sciences
- Bruce A. Hungate
- Northern Arizona University
- Ilkka Leinonen
- University of Oklahoma
- Yiqi Luo
- University of Oklahoma
- Ross McMurtrie
- University of New South Wales
- Belinda E. Medlyn
- University of New South Wales
- Ram Oren
- Duke University
- William J. Parton
- Colorado State University
- Diane Pataki
- University of Utah
- M. Rebecca Shaw
- Stanford University
- Lianhai Wu
- University of Oklahoma
- Donald R. Zak
- University of Michigan
Products
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Journal Article / 2003
Nitrogen and climate change
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Presentations / 2003
Progressive nitrogen limitation of plant and ecosystem responses to rising atmospheric CO2 concentration
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Journal Article / 2004
Progressive nitrogen limitation of ecosystem responses to rising atmospheric carbon dioxide
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Journal Article / 2006
Elevated CO2 stimulates net accumulations of carbon and nitrogen in land ecosystems: A meta-analysis
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Data Set / 2006
Elevated CO2 stimulates net accumulations of carbon and nitrogen in land ecosystems: a meta-analysis database