Changes in climate, land use, and disturbance regimes are affecting tropical forest ecosystems worldwide by driving variations in how trees die, grow, and reproduce. However, there is high uncertainty on the magnitude and direction of these effects and how forests will continue to respond to future environmental changes. One of the main sources of this uncertainty is attributed to a poor knowledge of the mechanisms driving variability in tree mortality across space and over time.

Over the last decade, studies have reported an increase in tree mortality in forests worldwide. However, evidence from tropical forests, which play a major role in global biodiversity, biogeochemical cycles, and climate regulation, is geographically restricted and has mostly evaluated the impact of extreme events such as droughts, blowdowns, or fires. The few studies addressing tree mortality trends in the tropics have mostly been focused on moist old-growth, lowland forests, and have shown contrasting results. While tree mortality and associated biomass losses have been reported to have increased over the past decades in the Amazon and across the Australian moist tropics, no clear trends were found across the African moist tropics, and extensive tree mortality assessments are scarce in tropical Asia, as well as in mountain, secondary, and dry tropical forests. The lack of large-scale and long-term evaluations of tree mortality across different types of tropical forests hampers our ability to draw conclusions on the overall vulnerability of these ecosystems. 

While several international research networks have made significant contributions to the understanding of tropical tree mortality over the past decades, a comprehensive pantropical perspective is still lacking. This symposium aims to present preliminary results from a multi-network collaboration across 15 forest networks in the tropics, the Tropical Forest Mortality Working Group (ATFS-MWG). The session will begin with an introduction to the symposium and working group, emphasizing their objectives, philosophy to ensure fair representation of scientists across career stages and tropical countries. The symposium will then showcase the first cross-network study on the drivers of spatial variation in tropical tree mortality across the pantropics, followed by presentations from invited speakers from different plot networks. These talks will explore mortality assessments across forest types (dry/wet, montane/lowland, and secondary forests), spatial scales (regional and pantropical) and temporal scales.
The session will end with 10 min of open discussion with the audience on the challenges and opportunities highlighted by the symposium for the future of Tropical Tree Mortality Research.