A Large Amazonian Peatland Carbon Sink Was Eliminated by Photoinhibition of Photosynthesis and Amplified Ecosystem Respiration

New research by SWAC professor Tim Griffis and colleagues shows that a palm swamp peatland in the Peruvian Amazon can shift from being a carbon sink to being carbon neutral after prolonged periods of both higher light intensities and a lower water table.

Peatlands store about one third of global soil carbon despite occupying less than 5% of the land area. Recent estimates show that tropical peatlands store much more carbon than previously thought. There are considerable gaps in knowledge regarding the interannual variability of carbon budgets in tropical peatlands and the way that changing environmental conditions influence the carbon cycling in these ecosystems. We show that a palm swamp peatland in the Peruvian Amazon is sensitive to changes in environmental conditions and can flip from a large carbon sink to carbon neutral when there are prolonged periods with (a) clear skies and higher light intensities that impair canopy photosynthesis and (b) a lower water table that increases peat decomposition. These findings show that the carbon budgets of these ecosystems are highly sensitive to environmental variability.