A TALE OF TWO: RECONSTRUCTING CLIMATE FROM TREE-RINGS OF THE NORTH AEGEAN, AD 1089-1989, AND LATE PLEISTOCENE TO PRESENT: DENDROCHRONOLOGY IN UPSTATE NEW YORK

Carol Bliss Griggs, Ph.D. Cornell University 2006 In the first two chapters, oak samples from the north Aegean (39-42 degrees N, 22-37 degrees E) are used in dendroclimatological research. In the first chapter, the precipitation of May and June is shown to be the primary limiting factor in annual ring growth and is reconstructed from a tree-ring chronology of historic building and modern forest samples, AD 1089 to 1989. Removing all but the high-frequency variability plus normalizing the oak data sets gives an accurate regional precipitation reconstruction.
The low-frequency variance in the same chronology filtered with a 24-kernel Gaussian filter explains 91.6% of the variance in the filtered North Atlantic Oscillation (NAO) May index, 1915-1967, but not before that period. In the second chapter, the oak chronology is divided into three grids, west to east. The May NAO is recorded in the western grid chronology from 1833-1967. Using the similarities and differences in the three grids' filtered oak chronologies over time as indicators of the effect of the May NAO on the region, the low-frequency May NAO is reconstructed for AD 1181 to 1967.
The third and fourth chapters examine the tree-ring record of samples collected in New York State (41-45 degrees N, 73-80 degrees W). Over 30 tree-ring chronologies that represent various windows of time from 15,000 years ago to the present have been constructed from tree-ring measurements of wood collected from six modern woodlands, seven historical structures and timbers, and eight river, stream, and pond sediments. Chapter 3 focuses on the oldest samples dating from the late Pleistocene Epoch, including wood sections found in three mastodon excavations in New York State. The oldest wood macrofossils are spruce and their respective radiocarbon dates reflect the southeast to northwest retreat of the ice sheet and subsequent migration of arboreal species across New York State. Chapter four is a compendium of the collected wood samples from the Holocene Epoch. Regional modern and historic chronologies date from AD 1625 to 2004 for oak, AD 1593 to 2003 for hemlock, and AD 1681 to 1848 for pine. Floating chronologies date throughout the Holocene, from ca. 9500 BC to the mid-fourteenth century AD.