The Impacts of Droughts in Tropical Forests
Publication stage: In Press Corrected Proof
Tropical forests exchange more carbon dioxide (CO2) with the atmosphere than any other vegetation type and, thus, form a crucial component of the global carbon cycle. However, the impacts of anthropogenic climate change on drought occurrence and intensity could weaken the tropical forest carbon sink, with resulting feedback to future climates. We urgently need a better understanding of the mechanisms and processes involved to predict future responses of tropical forest carbon sequestration to climate change. Recent progress has been made in the study of drought responses at the molecular, cellular, organ, individual, species, community, and landscape levels. Although understanding of the mechanisms is incomplete, the models used to predict drought impacts could be significantly improved by incorporating existing knowledge.
Forecasts from climate models suggest an increased risk of droughts in tropical forests over the next few decades, potentially threatening the large existing carbon sink.
Natural droughts and rainfall exclusion experiments result in decreased tree growth and increased mortality, with large trees most affected in both cases.
Mechanisms at the tree level are still incompletely understood. Hydraulic failure seems to be robustly associated with tree death, but other failure modes, including carbon starvation and phloem failure, may also be significant.