Multiple mechanisms of Amazonian forest biomass losses in three dynamic global vegetation models under climate change

David Galbraith, Peter E. Levy, Stephen Sitch, Chris Huntingford, Peter Cox, Mathew Williams, Patrick Meir

Research output: Contribution to journalArticlepeer-review

Abstract

The large-scale loss of Amazonian rainforest under some future climate scenarios has generally been considered to be driven by increased drying over Amazonia predicted by some general circulation models (GCMs). However, the importance of rainfall relative to other drivers has never been formally examined.

Here, we conducted factorial simulations to ascertain the contributions of four environmental drivers (precipitation, temperature, humidity and CO2) to simulated changes in Amazonian vegetation carbon (C-veg), in three dynamic global vegetation models (DGVMs) forced with climate data based on HadCM3 for four SRES scenarios.

Increased temperature was found to be more important than precipitation reduction in causing losses of Amazonian C-veg in two DGVMs (Hyland and TRIFFID), and as important as precipitation reduction in a third DGVM (LPJ). Increases in plant respiration, direct declines in photosynthesis and increases in vapour pressure deficit (VPD) all contributed to reduce C-veg under high temperature, but the contribution of each mechanism varied greatly across models. Rising CO2 mitigated much of the climate-driven biomass losses in the models.

Additional work is required to constrain model behaviour with experimental data under conditions of high temperature and drought. Current models may be overly sensitive to long-term elevated temperatures as they do not account for physiological acclimation.

Original languageEnglish
Pages (from-to)647-665
Number of pages19
JournalNew Phytologist
Volume187
Issue number3
Early online date19 Jul 2010
DOIs
Publication statusPublished - 1 Aug 2010

Keywords

  • Amazon 'die-back'
  • Amazon drought
  • CO2 fertilization
  • dynamic global vegetation models (DGVMs)
  • elevated temperatures
  • photosynthesis
  • plant respiration
  • TERRESTRIAL BIOSPHERE MODEL
  • CARBON-DIOXIDE ENRICHMENT
  • ABOVEGROUND LIVE BIOMASS
  • GROSS PRIMARY PRODUCTION
  • NET PRIMARY PRODUCTION
  • LAND-SURFACE SCHEME
  • RAIN-FOREST
  • PLANT RESPIRATION
  • TROPICAL FORESTS
  • STOMATAL CONDUCTANCE

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