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Current Projects

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Tree-Ring Dating of Logs on the President Abraham Lincoln Boyhood Home in Hodgenville, Kentucky, U.S.A.

Maegen L. Rochner, Zachary T. Merrill, Laura G. Smith, and Henri D. Grissino-Mayer

LTRS students sampling the Abraham Lincoln Boyhood Home in Hodgenville,Kentucky.

In 1812, Thomas Lincoln relocated his family, including future President Abraham Lincoln, from the Sinking Springs farm location to the Knob Creek site 10 miles north of Hodgenville, Kentucky, where they lived until moving again in 1816. The Knob Creek site is where Abraham Lincoln had his earliest memroies, planting crops, playing with his childhood friends, and attending school. But this cabin is not the original cabin built by Thomas Lincoln. Our tree-ring dating of the logs on this cabin will provide dates for when the trees were harvested to construct this cabin, which likely is a cabin that was built by the Gollaher family, who lived nearby the Lincolns during the same period.

Absolute Dating of Tree Rings on a Dugout Canoe Uncovered during Hurricane Irma in Cocoa, Florida, U.S.A.

Laura G. Smith and Henri D. Grissino-Mayer

the dugout canoe exposed when Hurricane Irma rattled Florida in September 2017.

On September 10, 2017, Hurricane Irma made a second landfall, in southern Florida, and would continue its rampage up the central-eastern half of the Florida peninsula over the coming days as a Category 3 hurricane. While over Florida, turbulent winds and surf were kicked up, accompanied by torrential rains, both off the coast and on inland waterways. As it passed near Cocoa, Florida near the Kennedy Space Center at Cape Canaveral, the turbulent winds and surf caused a wooden dugout canoe to be loosened from the bottom of the Indian River, likely in the marginal area near the river edge. We have been contracted to do the dendrochronological analysis on this canoe to determinemore precisely when it was built!

Dendrochronological Analyses on the Effects of Moose Herbivory on Forests of Isle Royale National Park, Lake Superior, U.S.A.

Zachary A. Merrill and Henri D. Grissino-Mayer

Zach shows off two white spruce saplings that have been browsed by moose

Ph.D. student Zach Merrill already knows Isle Royale National Park well, having interned there several summers ago. For his Ph.D. research, Zach will collect hundreds of cores and cross sections from balsam fir and white sprice to investigate the temporal and spatial dynamics of moose herbivory on tree growth. From this, Zach can then learn of changes in moose populations over time and space and from this learn about changes in wolf populations, the island's top predator. The ruggedness and isolation of the island requires considerable and extended hikes with full packs to reach the randomly located plots for this research, but the beauty of this least-visited national park is remarkable!

Century-Scale Climate Forcing of Temporal and Spatial Patterns in Whitebark Pine Ecosystems

Maegen L. Rochner and Henri D. Grissino-Mayer

Maegen takes notes at her study site in the Beartooth Mountains, Wyoming.

Ph.D. student Maegen Rochner will use her expertise in geomorphology and paleoclimatology to help solve a major question concerning the impacts of major climate episodes in the past on the current spatiotemporal patterns of high-elevation whitebark pine communities in the Beartooth Mountains of northwestern Wyoming. For example, are the dead standing whitebark pines attributable to the deteriorating temperatures during the Little Ice Age? Do current populations of these pines reflect the differential effects of elevation on snow and ice accumulation? During which periods did the tree islands of Engelmann spruce and whitebark pine establish?

Tree-Ring Dating of Timbers from the Gonzalez-Alvarez and Tovar Houses, St. Augustine, Florida, U.S.A.

Maegen L. Rochner and Henri D. Grissino-Mayer

The Tovar House (left) and Gonzalez-Alvarez House (right) in St. Augustine.

The St. Augustine Historical Society contacted the LTRS and asked if we could attempt to date the timbers found in two of the most important and oldest buildings in historic Old St. Augustine, Florida: the Tovar House and the Gonzalez-Alvarez House. Both were believed to have been built in teh early 1700s and then renovated by adding a second floor during the first British Period in the mid-1700s. Our goal was to determien (1) if the buildings were indeed that old, and (2) determine if floor joists on the second floors do indeed support the mid-1700s renovations.

Absolute Dating of Timbers from the Blount Mansion Complex, Knoxville, Tennessee, U.S.A.

Maegen L. Rochner and Henri D. Grissino-Mayer

LTRS students sample a floor joist in the Blount Mansion main building.

The Blount Mansion Historical Association contacted the LTRS to see if we could use tree-ring dating techniques to date when the various buildings on the Blount Mansion complex were constructed. Governor William Blount was the first govermor of the State of Tennessee, holding office in the early to late 1790s. Supposedly, the main building weas constructed from 1792 to 1795, but will the tree rings confirm this? And when were the East Wing and West Wing buildings constructed and added? It took several trips to collect all the core samples, but hopfully these will provide answers to help learn the history of this famous structure in downtown Knoxville, Tennessee.

Absolute Tree-Ring Dating of Two Longleaf Pine Dugout Canoes, Laurinburg, North Carolina, U.S.A.

Maegen L. Rochner and Henri D. Grissino-Mayer

A dugout canoe in the Museum of Scotland County, Laurinburg, North Carolina.

A very cool tree-ring project, the first of its kind in the United States, in which we're tasked with finding out when two dugout canoes were fashioned from old-growth longleaf pines growing in the Coastal Plain region of North Carolina. One challenge we faced was that few longleaf pine chronologies exist for this region, and even fewer that could be long enough to date the floating tree-ring series. We were elated recently when we were able to date the tree rings with absolute certainty against a reference tree-ring chronology we had developed earlier from pines sampled in a crib dam in nearby Hope Mills. What were the dates? Check for a publication soon to come out from this research!

(Re-)Dating the Thomas Pate House, Colonial National Historic Park, Yorktown, Virginia

Henri D. Grissino-Mayer and Maegen L. Rochner

LTRS students pose outside before beginning to core the Thomas Pate House in Yorktown, Virginia.

In 1999, dendrochonologist Herman "Jack" Heikkenen collected 11 samples from the Thomas Pate House and dated the year of construction of this house to 1731. The only problem is that this house had already been built about 1700 by ferryman Thomas Pate, well documented in historical records! The original dating of this structure caused the National Park Service to rename the house as the Cole Digges House after the person who had owned the property in 1731. Our mission is to determine if the original dating of the timbers from this structure was accurate, and if so, why would timbers used in the house post-date the known date of construction?

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