El Nino drought increased canopy turnover in Amazon forests

Author(s)

Leitold, Veronika ; Morton, Douglas C. ; Longo, Marcos ; dos-Santos, Maiza Nara ; Keller, Michael ; Scaranello, Marcos

• Document type: Journal article
• Source: NEW PHYTOLOGIST; v. 219, n. 3, p. 13-pg., 2018-08-01.

Abstract

Amazon droughts, including the 2015-2016 El Nino, may reduce forest net primary productivity and increase canopy tree mortality, thereby altering both the short- and the long-term net forest carbon balance. Given the broad extent of drought impacts, inventory plots or eddy flux towers may not capture regional variability in forest response to drought. We used multi-temporal airborne Lidar data and field measurements of coarse woody debris to estimate patterns of canopy turnover and associated carbon losses in intact and fragmented forests in the central Brazilian Amazon between 2013-2014 and 2014-2016. Average annualized canopy turnover rates increased by 65% during the drought period in both intact and fragmented forests. The average size and height of turnover events was similar for both time intervals, in contrast to expectations that the 2015-2016 El Nino drought would disproportionally affect large trees. Lidar-biomass relationships between canopy turnover and field measurements of coarse woody debris were modest (R-2 approximate to 0.3), given similar coarse woody debris production and Lidar-derived changes in canopy volume from single tree and multiple branch fall events. Our findings suggest that El Nino conditions accelerated canopy turnover in central Amazon forests, increasing coarse woody debris production by 62% to 1.22 Mg Cha(-1) yr(-1) in drought years . (AU)

• FAPESP's process: 15/07227-6 - Long term effects of forest degradation on carbon cycling in Amazonia
• Grantee: Marcos Longo
• Support Opportunities: Scholarships in Brazil - Post-Doctoral