Amazonian rainforest tree mortality driven by climate and functional traits

Tree mortality appears to be increasing in moist tropical forests 1 , with potentially important implications for global carbon and water cycles 2 . Little is known about the drivers of tree mortality in these diverse forests, partly because long-term data are lacking 3 . The relative importance of climatic factors and species functional traits as drivers of tropical tree mortality are evaluated using a unique dataset in which the survival of over 1,000 rainforest canopy trees from over 200 species has been monitored monthly over five decades in the Central Amazon. We found that drought, as well as heat, storms and extreme rainy years, increase tree mortality for at least two years after the climatic event. Specific functional groups (pioneers, softwoods and evergreens) had especially high mortality during extreme years. These results suggest that predicted climate change will lead to higher tree mortality rates, especially for short-lived species, which may result in faster carbon sequestration but lower carbon storage of tropical forests. Fifty years of monthly observation of rainforest canopy trees in the Central Amazon reveals that drought, heat, storms and extreme rain can all increase tree mortality. Pioneers, softwoods and evergreen functional groups were particularly vulnerable.