Swetnam, Thomas

Swetnam, Thomas
University of Arizona

Dr. Swetnam’s research focuses on understanding forest disturbances and dynamics, and how they are influenced by climate and humans. He uses tree-rings and documentary sources to reconstruct disturbance histories of forest fires, insect outbreaks and tree demographics (i.e., natality and mortality) at local scales of forest stands and watersheds, to broad scales at regional to global scales. In addition to his interest in basic ecological questions about forests, disturbances, and climate, the practical applications of this work for resource management have been a key interest and emphasis. His recent projects have involved compilation and analyses of extensive fire-scar chronology networks that enable synthetic fire climatology investigations at multiple scales. The parallel of this work in tree-ring studies is the compilation of vast networks of tree-ring width and density chronologies by dendroclimatologists, and the resulting reconstructions of climatic indices spanning centuries to millennia, and continents to hemispheres. Swetnam, his students and colleagues have been capitalizing in recent years on the availability of these long climate reconstructions in comparative analyses with the tree-ring based disturbance history networks. Their results have important implications for the understanding of past and present climate changes in driving disturbance and ecosystem changes at regional to global scales.

A continuing goal of Swetnam’s research and teaching is to foster and contribute to the development of the fields of dendrochronology and fire climatology, and their applications in global change studies and resource management. To this end, he has taken a leadership role in a number of efforts, including helping to create an international data bank for archiving and making accessible fire history data sets, organizing multiple national and international workshops on fire climatology, editing books and special issues of scientific journals on these topics, and mentoring graduate students, post docs and young faculty with these specialties at U of A and at other institutions. At the same time, he has also been working with graduate students and colleagues on clarifying the basic understanding of how disturbance processes and events are manifested in tree rings, particularly using modern (i.e., 20th – 21st century) disturbance, climate, and tree-ring records. Ultimately, Swetnam envisions a continued expansion of the geographic coverage and temporal depth of the tree-ring based disturbance history networks that are developing worldwide in temperate and boreal ecosystems. These data networks, combined with improved and expanded climate reconstructions, improved analytical techniques, and modeling approaches are likely to provide new and useful insights about the responses of past and current ecosystem to climate change.