Quantifying the effect of forest age in annual net forest carbon balance

Research output: Contribution to journalLetter


Forests dominate carbon (C) exchanges between the terrestrial biosphere and the atmosphere on land. In the long term, the net carbon flux between forests and the atmosphere has been significantly impacted by changes in forest cover area and structure due to ecological disturbances and management activities. Current empirical approaches for estimating net ecosystem productivity (NEP) rarely consider forest age as a predictor, which represents variation in physiological processes that can respond differently to environmental drivers, and regrowth following disturbance. Here, we conduct an observational synthesis to empirically determine to what extent climate, soil properties, nitrogen deposition, forest age and management influence the spatial and interannual variability of forest NEP across 126 forest eddy-covariance flux sites worldwide. The empirical models explained up to 62% and 71% of spatio-temporal and across-site variability of annual NEP, respectively. An investigation of model structures revealed that forest age was a dominant factor of NEP spatio-temporal variability in both space and time at the global scale as compared to abiotic factors, such as nutrient availability, soil characteristics and climate. These findings emphasize the importance of forest age in quantifying spatio-temporal variation in NEP using empirical approaches.


  • Simon Besnard
  • Nuno Carvalhais
  • M. Altaf Arain
  • Andrew Black
  • Sytze De Bruin
  • Nina Buchmann
  • Alessandro Cescatti
  • Jiquan Chen
  • Jan G.P.W. Clevers
  • Ankur R. Desai
  • Christopher M. Gough
  • Katerina Havrankova
  • Martin Herold
  • Lukas Hörtnagl
  • Martin Jung
  • Alexander Knohl
  • Bart Kruijt
  • Lenka Krupkova
  • Beverly E. Law
  • Asko Noormets
  • Olivier Roupsard
  • Rainer Steinbrecher
  • Andrej Varlagin
  • Caroline Vincke
  • Markus Reichstein
External organisations
  • Max Planck Institute for Biogeochemistry
  • Wageningen University
  • McMaster University
  • University of British Columbia
  • ETH Zürich
  • European Commission
  • Michigan State University
  • University of Wisconsin-Madison
  • University of Virginia
  • University of Göttingen
  • Oregon State University
  • North Carolina State University
  • Texas A and M University
  • Agricultural research for develompent (CIRAD)
  • University of Montpellier
  • Karlsruhe Institute of Technology
  • A.N. Severtsov Institute of Ecology and Evolution, RAS
  • Global Change Research Centre of the Czech Academy of Sciences
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Physical Geography


  • carbon cycle, climate, eddy covariance, net ecosystem production, empirical modeling, forest age, soil properties
Original languageEnglish
Article number124018
JournalEnvironmental Research Letters
Issue number12
Publication statusPublished - 2018 Dec
Publication categoryResearch