Nature 519, 78–82 (2015)

Credit: XAVIFERRANDO/THINKSTOCK

The mechanisms through which tropical forests respond to drought remain poorly resolved and this also limits understanding of the implications of drought events for the carbon cycle. This is particularly problematic in forested tropical regions where droughts are expected to increase in frequency and severity.

Christopher Doughty, from the University of Oxford, and co-workers use measurements of net primary production, autotrophic respiration and heterotrophic respiration from a network of forest monitoring plots spread throughout South America to develop a better understanding of the mechanisms of forest response to the 2010 drought. They find that drought suppresses photosynthesis and that trees compensate for reductions in energy by prioritizing growth at the expense of investment in tissue maintenance and defence. The authors propose that this reduced investment in maintenance and defence may be responsible for the observed increase in tree mortality in the years following the 2010 Amazonian drought.