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Reconstructing climate and ecology from forests: examples from George Washington’s Mount Vernon plantation and Palmaghatt Ravine
Abstract
Tree-ring records provide insight into past forest dynamics, including forcings from climate, canopy disturbance events, and human land use. This presentation highlights new insights in reconstructing these forcings over space and time at two sites: George Washington’s Mount Vernon agricultural plantation, Virginia, and Palmaghatt Ravine, New York. At Mount Vernon, enslaved labor grew tobacco, wheat, and other produce; however, Washington also described the farm as an English landscape with forests and scattered trees. Comparing tree-ring sampling designs at two spatial scales shows that selecting a similar number of trees across a larger search area is more likely to reconstruct the spatial pattern of forest history of this historical site. LiDAR bare surface elevation shows evidence of cross-plowing, an agricultural method frequently used by Washington, in areas that are now reforested. The preserved record of land use apparent in tree-rings, forest composition, and LiDAR highlights the long duration of land-use legacies from plantation agriculture. At Palmaghatt Ravine, tree-ring records record natural and anthropogenic canopy disturbance events over time that obscure underlying climate responses. Applying age-dependent splines, an offshoot of the detrending splines first developed at Lamont, enables a targeted detrending of canopy release events from tree-ring widths. This method provides an alternative for isolating climate signals in closed-canopy forests and also enables reconstructions of the ecological responses of tree growth to past canopy disturbance events.
Speark's Bio
Daniel Druckenbrod received his Ph.D. in environmental sciences from the University of Virginia in 2003 and currently holds the rank of professor of environmental sciences at Rider University. Prior to this position, Dan was a postdoctoral research associate in the Environmental Sciences Division of Oak Ridge National Lab and an assistant professor at Longwood University. Dan uses tree rings, forest surveys, simulation models, and historical documents to study long-term changes to forests and their environments. His projects include studies of forests and land-use legacies at historical sites, including George Washington’s Mount Vernon and Thomas Jefferson’s Monticello plantations. He is also researching the historical connection between Rider University's woods and Aldo Leopold during his time in Lawrenceville over a century ago. Dan has collaborated on projects studying the growth and water use of eastern deciduous forests in response to air pollution and climate. He is currently collaborating with the Lamont Tree-Ring Lab investigating past climate change from tree rings across Australia, New Zealand, and Southeast Asia. Dan previously served as the Director of Rider's Sustainability Studies Program from 2012 to 2021 and the Chair of the Department of Geological, Environmental, and Marine Sciences from 2021 to 2022.
