Enhancing tree-ring data coverage over the tropical and subtropical Americas

The overall scarcity of observational meteorological data can limit our understanding of Earth’s tropical climate system and our ability to constrain future model projections. Further, little is known regarding the climate sensitivity of tropical forests, which impedes reliable estimates of carbon storage in our warming world. Tree rings register interactions between the atmosphere and the biosphere and are used for reconstructing past climate prior to the existence of instrumental records such as temperature or precipitation. The practice of dating tree rings to the exact calendar year of ring formation is the basis for the science of dendrochronology, a term of Greek origin composed by ‘dendro’ and ‘chronology’ that mean ‘tree’ and ‘time’, respectively. While tree rings have been extensively used in temperate climates, the tropics remain relatively unexplored. Coverage of robust tropical tree-ring chronologies is still very limited across the globe, as shown in the map. Despite previous perception, it is now widely acknowledged that certain tropical tree species do indeed form annual rings. However, tropical tree-ring studies are still not broadly implemented due to the difficulties in identifying well-defined wood layers (tree rings). One of the key challenges of tropical dendrochronology lies in the visualization strategies used to accurately distinguish true annual ring boundaries from false rings. There can be difficulties related to complex anatomical structures or eccentricity across the tree stem. Our recent work has combined traditional methods with relatively novel wood anatomy techniques (see images) and radiocarbon analyses. This interdisciplinary and innovative approach is allowing the discovery of new and promising tree species for application in the field of dendrochronology. Finally, our findings yielded new tools that can be applied by the scientific community to fill current spatial and temporal gaps in tree-ring data across the world’s tropics.