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This content will become publicly available on September 6, 2018

Title: Terrestrial biosphere models underestimate photosynthetic capacity and CO 2 assimilation in the Arctic

Terrestrial biosphere models (TBMs) are highly sensitive to model representation of photosynthesis, in particular the parameters maximum carboxylation rate and maximum electron transport rate at 25°C (V c,max.25 and J max.25, respectively). Many TBMs do not include representation of Arctic plants, and those that do rely on understanding and parameterization from temperate species. We then measured photosynthetic CO 2 response curves and leaf nitrogen (N) content in species representing the dominant vascular plant functional types found on the coastal tundra near Barrow, Alaska. The activation energies associated with the temperature response functions of Vc,max and Jmax were 17% lower than commonly used values. When scaled to 25°C, Vc,max.25 and J max.25 were two- to five-fold higher than the values used to parameterize current TBMs. This high photosynthetic capacity was attributable to a high leaf N content and the high fraction of N invested in Rubisco. Leaf-level modeling demonstrated that current parameterization of TBMs resulted in a two-fold underestimation of the capacity for leaf-level CO 2 assimilation in Arctic vegetation. Our study highlights the poor representation of Arctic photosynthesis in TBMs, and provides the critical data necessary to improve our ability to project the response of the Arctic to global environmentalmore » change.« less
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [2]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States). Environmental and Climate Sciences Dept.
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Environmental Sciences Division
Publication Date:
Report Number(s):
BNL-114195-2017-JA
Journal ID: ISSN 0028-646X; R&D Project: 80821; YN1901000
Grant/Contract Number:
SC0012704; AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
New Phytologist
Additional Journal Information:
Journal Volume: 216; Journal Issue: 4; Journal ID: ISSN 0028-646X
Publisher:
Wiley
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; maximum carboxylation capacity; maximum electron transport rate; photosynthesis; rubisco; tundra; temperature response function
OSTI Identifier:
1392220
Alternate Identifier(s):
OSTI ID: 1378802; OSTI ID: 1394319