Informing climate models with rapid chamber measurements of forest carbon uptake

Abstract

Models predicting ecosystem carbon dioxide (CO2) exchange under future climate change rely on relatively few realworld tests of their assumptions and outputs. Here, we demonstrate a rapid and cost-effective method to estimate CO2 exchange from intact vegetation patches under varying atmospheric CO2 concentrations. We find that net ecosystem CO2 uptake (NEE) in a boreal forest rose linearly by 4.7 +/- 0.2% of the current ambient rate for every 10 ppm CO2 increase, with no detectable influence of foliar biomass, season, or nitrogen (N) fertilization. The lack of any clear short-term NEE response to fertilization in such an N-limited system is inconsistent with the instantaneous downregulation of photosynthesis formalized in many global models. Incorporating an alternative mechanism with considerable empirical support -diversion of excess carbon to storage compounds -into an existing earth system model brings the model output into closer agreement with our field measurements. A global simulation incorporating this modified model reduces a long-standing mismatch between the modeled and observed seasonal amplitude of atmospheric CO2. Wider application of this chamber approach would provide critical data needed to further improve modeled projections of biosphere-atmosphere CO2 exchange in a changing climate.

Keywords

boreal forest; earth system model; model-data integration; nutrient limitation; photosynthetic downregulation; Pinus sylvestris

Published in

Global Change Biology
2017, volume: 23, number: 5, pages: 2130-2139

SLU Authors

• Metcalfe, Daniel

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Palmroth, Sari

  • Duke University

• Campbell, Catherine

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    

• Hurry, Vaughan

  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    

• Keel, Sonja G.

  • Agroscope

• Linder, Sune

  • Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences
    

• Näsholm, Torgny

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    
  • Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences
    

• Ohlsson, Anders

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Blackburn, Meredith

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

• Oren, Ram

  • Duke University

Global goals (SDG)

SDG13 Climate action

UKÄ Subject classification

Forest Science

Publication identifier

• DOI: https://doi.org/10.1111/gcb.13451

Permanent link to this page (URI)

https://res.slu.se/id/publ/81109