A long-term shift in forest canopy properties following intense drought in Amazonia

Sassan Saatchi, CALTECH/JPL, sassan.saatchi@jpl.nasa.gov (Presenter)
Salvi Asefi, UCLA, asefi@ucla.edu
Yadvinder Malhi, Oxford University, ymalhi1@googlemail.com
Luiz Aragao, University of Exeter, l.aragao@exeter.ac.uk
Ranga Babu Myneni, Boston University, rmyneni@bu.edu
Ramakrishna R. Nemani, NASA ARC, rama.nemani@nasa.gov

Recent Amazonian droughts have drawn attention to the vulnerability of tropical forests to severe climate perturbations. Tree mortality and fires are shown to increase following drought years, but, to date there has been no assessment of long-term impacts of these droughts. Here, we use satellite microwave observations of rainfall and canopy backscatter, to show that more than 70 million ha of forests in western Amazonia experienced a strong water deficit during the dry season of 2005 and a closely corresponding decline in canopy backscatter. Remarkably, and despite the recovery in rainfall in subsequent years, the decrease in backscatter persisted until the next major drought in 2010. The decline in backscatter has been attributed to loss of canopy water content and tree mortality. The persistence of low canopy water content suggests long-lived changes in canopy structure, from widespread loss of branches or mortality of canopy and emergent trees3. The long recovery time from the 2005 drought suggests that occurrence of droughts in Amazonia at 5-10 year frequency would lead to permanent alteration of the forest canopy.

Presentation Type:  Poster

Session:  Global Change Impact & Vulnerability   (Tue 11:30 AM)

Associated Project(s): 

• Saatchi, Sassan: Vegetation Structure Studies ...details

Poster Location ID: 280