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Title: Gross primary production responses to warming, elevated CO 2 , and irrigation: quantifying the drivers of ecosystem physiology in a semiarid grassland

Determining whether the terrestrial biosphere will be a source or sink of carbon (C) under a future climate of elevated CO2 (eCO2) and warming requires accurate quantification of gross primary production (GPP), the largest flux of C in the global C cycle. We evaluated six years (2007-2012) of flux-derived GPP data from the Prairie Heating and CO2 Enrichment (PHACE) experiment, situated in a mixed prairie grassland in Wyoming (USA). The GPP data were fitted to a mixed effects model that extended a light response model to include the effects of environmental (soil water content, vegetation greenness, nitrogen) and meteorological data (air temperature, vapor pressure deficit, photosynthetically active radiation) at current and past times. The stimulation of the cumulative six-year GPP by warming (20%, P=0.06) and eCO2 (19%, P=0.14) were primarily driven by enhanced C uptake during spring (96%, P=0.003) and fall (115%, P=0.001), respectively. These enhancements were consistent across each year, suggesting mechanisms for extending the growing season. Vapor pressure deficit from 1-3 days prior was the most significant predictor of temporalvariability in GPP and for explaining treatment differences in GPP, suggesting that atmospheric drought plays an important role for predicting GPP now and under future climate conditions.
ORCiD logo [1] ;  [2] ;  [3] ;  [4] ; ORCiD logo [5] ; ORCiD logo [6] ;  [7] ;  [8] ;  [8] ;  [9] ;  [10] ;  [11] ;  [12] ;  [12] ;  [13] ;  [14] ;  [15] ;  [16]
  1. Lancaster Environment Centre (United Kingdom)
  2. Northern Arizona Univ., Flagstaff, AZ (United States). School of Informatics, Computing, and Cyber Systems; Northern Arizona Univ., Flagstaff, AZ (United States). Dept. of Biological Sciences
  3. Northern Arizona Univ., Flagstaff, AZ (United States). Dept. of Biological Sciences
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division and Climate Change Science Inst.
  5. Macquarie Univ., NSW (Australia). Dept. of Biological Sciences
  6. Univ. of Western Sydney, NSW (Australia). Hawkesbury Inst. for the Environment
  7. Univ. of Wyoming, Laramie, WY (United States). Dept. of Botany
  8. Colorado State Univ., Fort Collins, CO (United States). Natural Resource Ecology Lab.
  9. Univ. Paris-Saclay, Gif-sur-Yvette (France). Lab. des Sciences du Climat et de l'Environnement (LSCE)
  10. Univ. of Exeter (United Kingdom). College of Engineering, Mathematics, and Physical Sciences
  11. Commonwealth Scientific and Industrial Research Organization (CSIRO), Ocean and Atmosphere, Aspendale, Vic. (Australia)
  12. Max Planck Inst. for Biogeochemistry, Jena (Germany). Biogeochemical Integration Dept.
  13. Univ. of Illinois, Urbana, IL (United States). Dept. of Atmospheric Sciences
  14. Senckenberg Biodiversity and Climate Research Centre, Frankfurt (Germany)
  15. Univ. of Oklahoma, Norman, OK (United States). Dept. of Microbiology & Plant Biology; East China Normal Univ. (ECNU), Shanghai (China). Research Center for Global Change and Ecological Forecasting
  16. Univ. of Western Sydney, NSW (Australia). Hawkesbury Inst. for the Environment; Univ. of Wyoming, Laramie, WY (United States). Dept. of Botany
Publication Date:
Grant/Contract Number:
AC05-00OR22725; SC0006973; DEB#1021559
Accepted Manuscript
Journal Name:
Global Change Biology
Additional Journal Information:
Journal Volume: 23; Journal Issue: 8; Journal ID: ISSN 1354-1013
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1400811