Tree-ring analysis, the science that deals with study of annual tree rings, allows scientists to develop precisely dated records of annually or seasonally resolved data commonly extending 300 or more years into the past. In regions with short records of instrumental data, tree growth can be used as a substitute for streamflow because many of the same factors that affect streams, such as precipitation and runoff, also influence the growth of trees. Unlike the western and central United States, the eastern United States has limited tree-ring records suitable for millennial-length reconstructions of streamflow and climate. A new source of climate history for eastern United States may be derived from isolated stands of old-growth eastern redcedar growing near the headwaters of the Potomac River in West Virginia. Additionally, in the eastern broadleaf forest tens of tree species grow together across a variety of sites, each with a different response to climate, allowing for additional climate information to be extracted. This research will utilize old-growth eastern redcedar and the multitude of broadleaf tree species to learn more about the history of streamflow and climate in the Basin. Current management and modeling strategies in the Potomac River Basin are constrained by the limited length and variability of the instrumental records of streamflow and precipitation. The primary outcomes of the project will be 1) tree-ring reconstructions of the streamflow and precipitation of the Potomac River Basin for the last 1000 years using eastern redcedar tree-ring widths, 2) a multi-species tree-ring reconstruction used to increase the seasonal knowledge of climate for the last 300 years, 3) an evaluation of the instrumental record of streamflow in the context of the past 1000 years of the tree-ring record, and 4) the integration of tree-ring data into water resource modeling efforts in the eastern United States.
This Doctoral Dissertation Research will generate one of the few ultra-long (1000 years) tree-ring chronologies for eastern North America. The Potomac River is the primary water resource for the Washington, DC metropolitan area, supplying approximately 75 percent of the water demand. The climate reconstructions will aid water resource managers at the Interstate Commission on the Potomac River Basin plan for future drought events by placing the instrumental records of streamflow and precipitation within the context of natural climatic variability of the past millennium. The tree-ring records of precipitation and streamflow will be integrated into an existing water supply and demand model to assess the ability of the water system to meet demand under past drought conditions. The multi-species approach will aid tree-ring scientists in climate reconstructions in other regions where multiple species are present and will promote the use of existing tree-ring data to investigate water resource management issues in locations with limited instrumental records. As a Doctoral Dissertation Research Improvement award, this award also will provide support to enable a promising student to establish a strong independent research career.
