Persistent effects of a severe drought on Amazonian forest canopy

Recent Amazonian droughts have drawn attention to the vulnerability of tropical forests to climate perturbations. Satellite and in situ observations have shown an increase in fire occurrence during drought years and tree mortality following severe droughts, but to date there has been no assessment o...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2013-01, Vol.110 (2), p.565-570
Main Authors: Saatchi, Sassan, Asefi-Najafabady, Salvi, Malhi, Yadvinder, Aragão, Luiz E. O. C., Anderson, Liana O., Myneni, Ranga B., Nemani, Ramakrishna
Format: Article
Language:English
Subjects:
Artificial satellites
Biological and medical sciences
Biological Sciences
Brazil
Drought
Droughts
Dry seasons
Fires
Forest canopy
Forestry
Fundamental and applied biological sciences. Psychology
General forest ecology
Generalities. Production, biomass. Quality of wood and forest products. General forest ecology
Geographic Mapping
Microwaves
Moisture
Physical Sciences
Pixels
Radar
Rain
Rainforests
Satellites
Time Factors
Time series
Trees - growth & development
Tropical Climate
Tropical forests
Tropical rain forests
Vegetation
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Summary:Recent Amazonian droughts have drawn attention to the vulnerability of tropical forests to climate perturbations. Satellite and in situ observations have shown an increase in fire occurrence during drought years and tree mortality following severe droughts, but to date there has been no assessment of long-term impacts of these droughts across landscapes in Amazonia. Here, we use satellite microwave observations of rainfall and canopy backscatter to show that more than 70 million hectares of forest in western Amazonia experienced a strong water deficit during the dry season of 2005 and a closely corresponding decline in canopy structure and moisture. Remarkably, and despite the gradual recovery in total rainfall in subsequent years, the decrease in canopy backscatter persisted until the next major drought, in 2010. The decline in backscatter is attributed to changes in structure and water content associated with the forest upper canopy. The persistence of low backscatter supports the slow recovery (>4 y) of forest canopy structure after the severe drought in 2005. The result suggests that the occurrence of droughts in Amazonia at 5–10 y frequency may lead to persistent alteration of the forest canopy.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1204651110