What are my recent activities? In summer 2000 I joined the University of Nevada in Reno to teach and conduct research in the areas of ecoclimatology, environmental change, and quantitative methods. My dissertation work on forest growth trends in Arizona had both regional and global relevance. Regionally, it provided evidence for the impact of fire suppression on the ecology of southwestern conifer forests, ultimately contributing to landscape conservation plans. Globally, it showed the importance of placing twentieth-century patterns into a longer historical perspective to disentangle the impact of land use changes (in this case, European settlement) from stand dynamics and other factors. From 1994 to 2000 I conducted research at Scripps Institution of Oceanography on past climate using proxy records from terrestrial tree rings and oceanic sediments (varves). Based on such records, I have suggested that sudden inter-decadal change occurred near A.D. 1600 over marine and land systems of the American West Coast. At Scripps I also established a research program in dendroclimatology, and assembled the tree-ring laboratory that I then transferred to UNR. My recent studies deal with quantifying climate and tree growth variability from mountain ecosystems in the Great Basin of North America, in western Mexico, and in Italy. Special emphasis is placed on understanding responses to disturbance (wildfire, land use changes) in relation to climate dynamics and to the distribution of woody species at the watershed level.
From 2008 to 2013 I was the statewide lead for the Ecological Change component of an NSF-EPSCoR project entitled “Nevada Infrastructure for Climate Change Science, Education and Outreach”, which was funded for a total of $15 million. As part of the research infrastructure funded by this large multi-investigator project, we established the Nevada Climate-ecohydrological Assessment Network (NevCAN), which includes valley-to-peak instrumental transects designed to measure changes in atmospheric, hydrologic, and ecologic variables, including the spatial and temporal processes that control, and are recorded by, wood growth of lower and upper treeline species.
Thanks to the science infrastructure provided by NevCAN, I am now involved in multiple research projects aimed at understanding the environmental drivers of intra-annual tree-ring features. Extramurally-funded studies performed by the DendroLab are focused on examining the connection between wood form and function in conifer species of the western US. We use automated point dendrometers, wood anatomy, and cellular phenology to uncover the exquisitely intricate connections between dendrochronology, wood science, tree physiology, forest ecology, mensuration, and allometry. These new activities also include domestic and international collaborations, the latter with scientists in Canada, Germany, France, Finland, and Italy.
As public and private management agencies strive to develop robust indicators of changing ecological state at multiple temporal scales, tree-ring records hold great promise because they provide long, continuous, and absolutely dated information on annual tree growth. Dendrochronology is an ideal tool for clearly understanding the natural range of variability in environmental patterns and processes, and this long-term information can reduce uncertainty associated with risk assessment.