Separation of net ecosystem exchange into assimilation and respiration using a light response curve approach: critical issues and global evaluation

Abstract The measured net ecosystem exchange (NEE) of CO 2 between the ecosystem and the atmosphere reflects the balance between gross CO 2 assimilation [gross primary production (GPP)] and ecosystem respiration (R eco ). For understanding the mechanistic responses of ecosystem processes to environmental change it is important to separate these two flux components. Two approaches are conventionally used: (1) respiration measurements made at night are extrapolated to the daytime or (2) light–response curves are fit to daytime NEE measurements and respiration is estimated from the intercept of the ordinate, which avoids the use of potentially problematic nighttime data. We demonstrate that this approach is…

• NS
  National Science Foundation
• UD
  U.S. Department of Energy

  Awards: DE-FG02-04ER63911, FG02-04ER63911, DE-FG02-, FG02-04ER63917, DE-FG02, DE-FG02-04ER63917
• CF
  Canadian Foundation for Climate and Atmospheric Sciences
• AS
  Austrian Science Fund

  Awards: P17560, P19849
• OO
  Office of Science
• NS
  Natural Sciences and Engineering Research Council of Canada
• NR
  Natural Resources Canada