Fires increase Amazon forest productivity through increases in diffuse radiation

A. Rap (1) , D. V. Spracklen (1) , L. Mercado (2) , C. L. Reddington (1) , J. M. Haywood (2) , R. J. Ellis (3) , O. L. Phillips (1) , P. Artaxo (4) , Damien Bonal (5) , Natalia Restrepo-Coupe (6) , N. Butt (7)

1 University of Leeds
2 University of Exeter
3 Centre for Ecology and Hydrology
4 USP - Universidade de São Paulo = University of São Paulo
5 EEF - Ecologie et Ecophysiologie Forestières [devient SILVA en 2018]
6 UTS - University of Technology Sydney
7 USQ - University of Southern Queensland

Atmospheric aerosol scatters solar radiation increasing the fraction of diffuse radiation and the efficiency of photosynthesis. We quantify the impacts of biomass burning aerosol (BBA) on diffuse radiation and plant photosynthesis across Amazonia during 1998-2007. Evaluation against observed aerosol optical depth allows us to provide lower and upper BBA emissions estimates. BBA increases Amazon basin annual mean diffuse radiation by 3.4-6.8% and net primary production (NPP) by 1.4-2.8%, with quoted ranges driven by uncertainty in BBA emissions. The enhancement of Amazon basin NPP by 78-156TgCa(-1) is equivalent to 33-65% of the annual regional carbon emissions from biomass burning. This NPP increase occurs during the dry season and acts to counteract some of the observed effect of drought on tropical production. We estimate that 30-60TgCa(-1) of this NPP enhancement is within woody tissue, accounting for 8-16% of the observed carbon sink across mature Amazonian forests.

Domaines: Sciences du Vivant [q-bio]

A. Rap, D. V. Spracklen, L. Mercado, C. L. Reddington, J. M. Haywood, et al.. Fires increase Amazon forest productivity through increases in diffuse radiation. Geophysical Research Letters, 2015, 42 (11), pp.4654-4662. ⟨10.1002/2015GL063719⟩. ⟨hal-01269165⟩