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

Date

2010

Authors

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

Journal Title

Journal ISSN

Volume Title

Publisher

Cambridge University Press

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 (Cveg), 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 Cveg 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 Cveg 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.

Description

Keywords

Keywords: carbon; rain; carbon dioxide; climate change; dieback; drought; fertilizer application; general circulation model; numerical model; photosynthesis; phytomass; rainfall; rainforest; respiration; article; biological model; biomass; Brazil; cell respiration; Amazon 'die-back'; Amazon drought; CO2 fertilization; Dynamic global vegetation models (DGVMs); Elevated temperatures; Photosynthesis; Plant respiration

Citation

Source

New Phytologist

Type

Journal article

Book Title

Entity type

Access Statement

License Rights

DOI

10.1111/j.1469-8137.2010.03350.x

Restricted until

2037-12-31