The University of Tennessee, Knoxville


Current and Past Projects of
the Laboratory of Tree-Ring Science

Fire History and Stand Dynamics on Rainy Mountain,
Chattahoochee National Forest, Georgia

Alex W. Dye and Henri D. Grissino-Mayer

Alex with fire scarred section

The north Georgia mountains are one of the few areas in the U.S. where no tree-ring research has been conducted. For his master's project, Alex hopes to develop a 300-year long chronology from old-growth shortleaf pines and investigate the fire history and stand dynamics of forests on Rainy Mountain in extreme northeastern Georgia. The area does have abundant fire-scarred pine stumps that we hope to develop the first fire history for Georgia.

Stand Dynamics of the "Pygmy Forests" on the McCarty's Lava Flow,
El Malpais National Monument, New Mexico

Sarah J. Jones and Henri D. Grissino-Mayer


One of the great mysteries of the malpais region is the existence and perpetuation of the so-called "pygmy forest" found only on McCarty's Lava Flow in the malpais region. Why do these ponderosa pine, pinyon pine, and juniper trees only grow to be no more than 20 feet tall yet live to be hundreds of years old? Sarah's master's research seeks to answer those questions by conducting an extensive analysis of the ages and disturbance history of these rare and endangered forests.

Did the 2008 TVA Coal Ash Spill Have an Effect on Growth of Surviving Trees?
Niki A. Garland and Henri D. Grissino-Mayer

TVA Project

In December 2008, one of the nation's worst environmental diasters occurred when an impoundment dam at the TVA Fossil Plant in Harriman Tennessee failed, spilled millions of cubic meters of coal ash into the pristine environment. Once the area was safe enough for researchers, Niki Garland, for her master's project, initiated a project to evaluate whether or not the survising trees on two islands in the Emory River showed any adverse effects of this disaster. She found that the surviving trees showed no reduction in tree growth rates post-spill, although many trees had already succumbed to the effects of the coal ash.

Stand Dynamics of Ponderosa Pine Forests in Relation to Past Wildfire Activity,
El Malpais National Monument, New Mexico
Alex J. Pilote and Henri D. Grissino-Mayer


For Alex Pilote's master's research, we initiated a project that complements the extensive fire-scar based fire history at El Malpais in New Mexico. To better understand the possible influence of moderate to high severity fires, we collected cores from over 600 trees at three sites in the area to evaluate the age structure and successional patterns of the ponderosa pine forests where we had previously reconstructed fire history. Possible pulses of establishment could indicate higher severity fires in the past.

The Historical Dendroarchaeology of Four Log Structures at the
Anderson-Doosing Farm, Catawba Valley, Virginia
Henri D. Grissino-Mayer and the NADEF 2011 Archaeology Group

Sampling an old barn

Perhaps one of the greatest achievements on research on log structures, members of the NADEF 2011 Archaeology Group intensely sampled four log structures at a historic farm complex just north of Blacksburg, Virginia. We found that a dilapidated cabin nearby was built in 1809-1810, the double pen cantilever barn (above) was built in 1830-1831, and the standing cabin and smokehouse were built simultaneously in 1838-1839. This research was subsequently published in the Journal of Archaeological Science in 2012.

Evaluating Shortleaf Pine Logs from a Timber Crib Dam in Fredericksburg, Virginia
Henri D. Grissino-Mayer, Grant L. Harley, Alex Dye, and Dorothy Rosene

We were very fortunate to be contacted by a wood worker in Fredericksburg, Virginia about some logs he had salvaged from a dismantled crib dam that was built across the Rhappahannock River in 1855. We collected over 40 cross sections from these logs and hope to build a long floating chronology spanning back to the 1500s from these samples to help shed light on past climate in a region virtually devoid of long pine chronologies.

Climate History from Old-Growth Ponderosa Pines,
El Morro National Monument, New Mexico
Niki A. Garland, Grant L. Harley, Sarah J. Jones, and Henri D. Grissino-Mayer

This project will focus on the extensive stands of old-growth ponderosa pine trees that exist in the sheltered environs of Inscription Rock at El Morro National Monument. These immense pines grow within the Box Canyon surrounded by the north and south mesa tops. Niki and Sarah will analyze the climate response of these trees and reconstruct climate using this climate signal, in the hope that these trees provide additional climate information than that gathered at nearby El Malpais.

Tree-Ring Dating of Timbers Extracted from a Spanish Mission Era Church,
Fountain of Youth Historic Park, St. Augustine, Florida
Niki A. Garland and Henri D. Grissino-Mayer

Fountain of Youth project

We were quite surprised when contacted by the Florida Museum of Natural History who asked if we could attempt tree-ring dating on two timbers extracted from the original site of a Spanish Mission church constructed in the earliest decades of settlement by Pedro Menendez in St. Augustine, Florida. We found that one pine timber had conclusive dating with a reference chronology from Lake Louise and dated to the late 17th century.

Fire History and Vegetation Dynamics in the Lower Florida Keys, U.S.A.
Grant L. Harley, Henri D. Grissino-Mayer, and Sally P. Horn

Henri Grissino-Mayer and Grant Harley (right) discuss strategy for collecting fire history samples on Big Pine Key at the North Watson Hammock site. This project focuses on disturbance history of endangered pine rocklands so that the U.S. Fish and Wildlife Service can learn more about the forest dynamics on the Key Deer National Wildlife Refuge. So far, we've collected over 100 fire-scarred samples and cored numerous slash pines for this project, which makes up the dissertation research of Grant Harley.

The Impact of Oceanic-Atmospheric Oscillation Change in the Southeastern United States Abstracted from Tree-Ring Network Data
Nancy Li and Henri D. Grissino-Mayer

For this project, Nancy investigated the climate response of trees along an east to west gradient here in the Southeastern U.S., across the southern Appalachian Mountains. She focused primarily on the longer-term decadal oscillations, such as the Atlantic Multidecadal Oscillation, the North Atlantic Oscillation, and the El Nino-Southern Oscillation. Here, Here, Nancy is coring a Table Mountain pine at her Linville Gorge site in North Carolina.

Fire-Climate Relationships in Ponderosa Pine Forests
of the Zuni Mountains, New Mexico
Monica T. Rother and Henri D. Grissino-Mayer

An extension to our research on fire history in the malpais region of New Mexico, this project investigated the spatial dynamics of past wildfires from tree-ring data to better understand the influence of topography and fuel loadings in the Zuni Mountains on fire regimes immediately to the south in El Malpais National Monument. Monica also investigated climate drivers of wildfire activity by evaluating relationships between these past fires and longer-term climate oscillations.

Fire History of Xeric Mixed Pine-Oak Hardwood Forests in
Great Smoky Mountains National Park, Tennessee, U.S.A.
Lisa B. LaForest, Henri D. Grissino-Mayer, and Charles W. Lafon

Lisa LaForest Sampling at Gold Mine Trail

In 2006, we initiated a project in Great Smoky Mountains National Park to reconstruct the history of wildfires using the fire-scar record as well as the age structure and stand dynamics of xeric mixed pine-oak forests found exclusively in the western end of the park. Led by Ph.D. student (now Dr.) Lisa LaForest, we found that fire was quite frequent at three sites, aveaging about one fire every 5 to 7 years. Equally important, we found that fire-dependent yellow pines are not regenerating because of changes in fire regimes caused by human activities in the last 70 years. Forests in the future will likely consist of fire-intolerant tree species as fire continues to be less a factor in forest development.

The Historical Dendroarchaeology of the Ximénez-Fatio House,
St. Augustine, Florida, U.S.A.
Henri D. Grissino-Mayer and Leda N. Kobziar

The Ximénez-Fatio House is one of the oldest standing structures in St. Augustine, Florida, the first city established by Europeans in the U.S. in 1565. During renovations, we were able to extract numerous cores from beams in this house, and our data do corroborate the 1798-1799 construction date. In addition, our results indicate that the wing to the right was actually built when owned by Louisa Fatio, around 1855-1858.

Fire History at Two Sites near Cades Cove,
Great Smoky Mountains National Park, U.S.A.
Ian C. Feathers and Henri D. Grissino-Mayer

A central question we have about the fire regimes in Great Smoky Mountains National Park concerns how variable fire activity is in such a topographically diverse area. Ian collected fire-scarred samples and stand inventory data from two sites, one nearly bordering Cades Cove and the other about 3 miles down Cooper Road trail away from the cove. He found that the two fire histories were very distinct and found that fire activity in the "deep" site may have been impacted more by human activities.

Fire History In Idaho: Does Fire Affect the Climate Signal in Ponderosa PIne Trees?
Jessica D. Slayton and Henri D. Grissino-Mayer

Group at Idaho

A central question concerns whether or not fire activity has an effect on the climate signal found in ponderosa pine trees, one of the most heavily sampled species in the western U.S. This master's project by Jessica Slayton (center) evaluated the climate signal of pines in areas with frequent fire activity as well as areas with little fire activity, and she found little effect of fire on tree growth patterns.

The Dendroarchaeology of Two Log Structures at the
Marble Springs Historic Site, Knox County, Tennessee
Jessica D. Slayton and Henri Grissino-Mayer

Walker Springs Cabin, Knox County, Tennessee

We were asked by the Tennessee Historical Commission to determine if a cabin at the Marble Springs Historic Site in Knox County, Tennessee could have been constructed by the State's first governor, General John Sevier in the late 18th century. We additionally sampled the Walker Springs cabin, shown above, which had been relocated to the site from west Knoxville. We found that the cabin above was built in 1829, while the John Sevier cabin was constructed in the early 1830s, long after his death.

Stand Dynamics and Fire History in
Whitebark Pine Communities of Western Montana
Evan R. Larson and Henri Grissino-Mayer

We conducted a comprehensive study of the complex stand dynamics, disturbance regimes, and the effects of climate change on the whitebark pine ecosystem in western Montana. Dendroecological techniques and analyses were used to provide high-quality, temporally precise information on the ecological status of this declining keystone species. For more information of the complex interactions between whitebark pine, grizzly bear and black bear populations, and Clark’s nutcrackers, please visit

Dendroecology of the Endangered Torreya taxifolia in Northwestern Florida, USA
Elizabeth A. Atchley and Henri D. Grissino-Mayer

This project is perhaps one of the most significant yet conducted in our laboratory. Here, Beth Atchley holds a log of one of the most endangered conifer species in the world -- only 150 individuals of this species are left in northwestern Florida and extreme southwestern Georgia. Until recently, no one really knew why this species is dying, but Beth's research has shed light on possible changes in environmental factors that may be responsible. Primary among these changes are changes in the upland pine forests caused by logging and conversion to slash pine plantations. This change may have changed the light and temperature regime of the coves in which this species exists.

Fire Regimes of Forested Kipukas in El Malpais National Monument, New Mexico
Daniel B. Lewis and Henri D. Grissino-Mayer

Michael Armbrister steadies a log on Mesita Blanca while Daniel Lewis saws off a fire-scarred section. Daniel's thesis research has gathered information on the fire history of relict areas where human disturbances have been minimal. Daniel found that fire was very frequent on these isolated kipukas and saw little change in fire frequency into the 20th century. Daniel also conducted a comprehensive age structure analysis on two of these kipukas and found that the ages nonetheless indicated major disturbances during the 20th century. No evidence was found that high-severity wildfires occurred in these sites.

Fire Regimes of Pinus pungens Lamb. in Great Smoky Mountains National Park, Tennessee, USA
Michael R. Armbrister and Henri D. Grissino-Mayer

The status of Table Mountain pine as a component of forests in the southern Appalachian Mountains is unknown, because the species is largely dependent on fire (notice the fire scar on the snag). Fire has been nearly non-existent in this park since about 1934. table Mountain pine, however, largely depends on recurrent wildfires for its very existence. Michael was able to find out that fires had occurred with regular frequency prior to the park's establishment, about once every 7-10 years. More importantly, Michael found out that the maximum length of time the park could go without fire was about 80 years, and the park is fast approaching this critical fire-free interval.

Gap Phase Dynamics in Great Smoky Mountains National Park, Tennessee, USA
Jacob J. Cseke and Henri D. Grissino-Mayer

This national park contains perhaps the most diverse system of forests anywhere in the world. Approximately two-thirds of the park contains old-growth forests, and Jake's research concerns the importance of gaps in closed-canopy forests for helping maintain this diversity. Jake sampled trees growing within and around about 18 gaps in various habitat settings, as well as the outer rings from the gapmaker itself. Jake found that the majority of gaps was associated with major ice storm events during the latter half of the 20th century.

Oxygen Isotope Ratios of Longleaf Pines as a Proxy of Past Hurricane Activity
along the Atlantic Seaboard
Whitney L. Nelson, Henri D. Grissino-Mayer, and Claudia I. Mora

Here, Whitney confers with Tom Harlan of the tree-ring lab in Tucson. Whitney's project is an extension of the project begun by Dana Miller, and involves isolating a hurricane signal from tree rings of longleaf pines growing in South Carolina. Whitney hopes to provide high resolution information on hurricane activity by further subdividing the tree-ring data into smaller portions for isotopic analysis.

Past Trends in Decadal-Scale Climate Inferred from
Old-Growth Longleaf Pine Stands in the Southeastern U.S.
Joseph P. Henderson and Henri D. Grissino-Mayer

This picture shows Lieutenant Colonel Joseph P. Henderson, who recently completed his Ph.D. at the Laboratory of Tree-Ring Science, kneeling next to a section cut from a longleaf pine stump that had been logged sometime in the past 10 years in Eglin Air Force Base near Pensacola, Florida. This one tree goes back to the early 1500s, and Joe collected over 100 similar samples from the area. Joe has also collected extraordinary samples from remnant longleaf pine trees in Texas and South Carolina. In his dissertation, Joe demonstrated how these pines revealed past trends in climate phenomena such as the El Nino-Southern Oscillation, the Atlantic Multidecadal Oscillation, and even the Pacific Decadal Oscillation.

Oxygen Isotope Ratios in Longleaf Pines as Proxy Indicators
of Past Tropical Cyclone Activity
Dana L. Miller, Henri D. Grissino-Mayer, and Claudia I. Mora

Tropical cyclones are known to cause depletions of oxygen-18 and therefore changes in oxygen isotope (18O/16O) ratios. If we can extract an isotopic record from the tree rings of longleaf pines growing in coastal locations, we could perhaps reconstruct land-falling hurricanes for hundreds of years for the coastal plain region of the Southeastern U.S. Dana's project is attempting to reconstruct hurricane activity for the past 200 years (and perhaps longer) from longleaf pine tree rings that came from a site in extreme southern Georgia (Lake Louise).

A Millennial-Length Reconstruction of Spring Rainfall
from Western Juniper in South Central Oregon, USA
Christopher A. Underwood and Henri D. Grissino-Mayer

In 2001, Daniel Lewis and I collected over 100 cross sections from dead and downed juniper logs from trees that once had grown at Frederick Butte in southern-central Oregon. This site contains some of the most remarkable long-lived trees and dead wood anywhere in the U.S. Some of these trees are over 1000 years old, and the region around the butte is full of dead and downed remnant wood. Sadly, most of this wood makes its way to fireplaces in campsites. Chris has already dated some of these samples back to about AD 800.

Assessing the Dendrochronological Potential of Pinus occidentalis
in the Cordillera Central of the Dominican Republic
James H. Speer, Kenneth H. Orvis, Henri D. Grissino-Mayer, and Sally P. Horn

Here, Henri cuts a small cross section from a standing snag of West Indian pine with a chain saw in the Conuco del Diablo ("Cornfield of the Devil") at approximately 3000 meters on the northern slope of Loma La Pelona. Our initial study investigated the potential of this species to yield past climatic information for a subtropical location. The block field contains hundreds of remnant pieces of well-preserved wood that should push the record back several more centuries. We've also sampled nearly 100 trees (mostly dead and downed) that contain a very clear record of past wildfires, and eventually we hope to push the fire history back for several centuries.

A 600-Year Reconstruction of Spring Precipitation from Longleaf Pines
in South-Central Georgia, USA
Henri D. Grissino-Mayer

We found an incredible area of relict longleaf pine stumps and remnants at Lake Louise, a research site owned by Valdosta State University in southern Georgia. We were surprised to find stumps that had remained intact since logging occurred around the turn of the 20th century. One reason these were so intact is because these trees had been turpentined previously, and the stumps were impregnated with resin. These samples have already provided a continuous well-replicated chronology back to AD 1421!

Climatic Variability in 20th Century Pacific Teleconnections
in the Southeastern U.S.
Kevin J. Anchukaitis and Henri D. Grissino-Mayer

Here, Kevin is coring an eastern white pine in western North Carolina at a site called Brush Hollow. Kevin then analyzed other tree-ring chronologies from the Southeastern U.S. and found that these trees revealed a strong relation to Pacific Ocean teleconnections (ENSO and PDO) that appears to change over time.

Alfred's Cabin at The Hermitage: Slave Cabin or Freedman's Cabin?
Daniel B. Lewis, Whitney L. Nelson, Henri D. Grissino-Mayer, and Edward R. Cook

Alfred was born on Andrew Jackson's Hermitage Plantation about 1815 and lived there until his death in 1901. The staff at The Hermitage would like to furnish the cabin for interpretive programs but needs to know if the double-pen, saddlebag cabin was built by Alfred while he was a slave or later when he was a freedman. The cabin is rare, constructed exclusively with eastern redcedar logs, the first such structure we've encountered in Tennessee. We extracted about 90 cores from the cabin and successfully dated the construction of this cabin to the year 1843.

Tree-Ring Dating the Joseph Hoskins' Log House, Tannenbaum State Park,
Greensboro, North Carolina
Joseph P. Henderson and Henri D. Grissino-Mayer

This two-story, clapboard-sided structure is the main feature at Tannenbaum State Park in Greensboro, North Carolina, believed to have been built around 1780 by Joseph Hoskins. The state park now occupies the location where the highly significant battle of the Guilford County Courthouse was fought in 1781 during the Revolutionary War. We extracted about 60 half-inch wide cores from most logs on both floors of this structure and should eventually be able to date its year of construction.

Tree-Ring Dating of Abraham Lincoln's Birthplace Log Cabin,
Hodgenville, Kentucky
Henri D. Grissino-Mayer and Dwight T. Pitcaithley

This cabin is housed in a beautiful memorial building, but some believe the cabin may not contain a single log associated with Abraham Lincoln. The tree rings in these logs could provide information on when the logs were cut. Eventually, we found several logs that dated to the 1840s and 1850s, but none that dated to the early 1800s. It's likely that not a single log in this cabin dates to the birth year of Abraham Lincoln (1809).

The Dendroarchaeology of the Swaggerty Blockhouse, Cocke County, Tennessee
David F. Mann, Henri D. Grissino-Mayer, John B. Rehder, and Charles Faulkner

The Swaggerty Blockhouse is a historic structure reportedly built in 1787. The cabin is built from large red oaks that were sampled by David with an increment borer. He also collected ceramics, nails, and window glass in a dendroarchaeological study like no other. David found what some had thought previously. This was not a blockhouse but was instead a small cantilever barn. It was not built in 1787 but rather had been built about 1859/1860. Furthermore, it was used for hog raising and slaughtering by the farmer who built the structure, Jacob Stevens.

Dendrochronological Dating of Musical Instruments made by Antonio Stradivari
Henri D. Grissino-Mayer, Paul R. Sheppard, and Malcolm K. Cleaveland

One of the most exciting projects I've ever been involved with. Some contend the "Messiah" violin could not have been made by Stradivari based on stylistic grounds. Funded by the Violin Society of America, we took our instruments to England to find out. Are the tree-ring dates contemporary with Stradivari? We found that indeed the tree rings dated to Stradivari's time (1577-1687) and therefore could not have been made by a copyist at a later time.

Tree-Ring Analysis of Boxwoods from
Thomas Jefferson's Poplar Forest, Lynchburg, Virginia
Henri D. Grissino-Mayer and David F. Mann

An interesting project concerns the shrubs encircling the front carriage circle, seen to the right in the photo. If they were likely planted by Thomas Jefferson, they stay. If not, they could go. David and I spent two afternoons collecting small cross sections from as many dead stems as we could find. We found that the average age of a single stem was about 90 years, and each shrub contained third generation stems. This meant that the shrubs could indeed been planted by Thomas Jefferson.

Dendrochronological Dating of the Devault Cabin, Johnson City, Tennessee
Henri D. Grissino-Mayer, David F. Mann, Bill Reding, and Daniel B. Lewis

The Devault Cabin is believed to have been built in the late 1700s and likely served as a corn crib or other outbuilding as it was too small for human habitation. The dominance of pine logs, however, suggests a later date in the 1860s. Nonetheless, the rings could extend the tree-ring record for the area back to the 1600s and help date other nearby structures, such as the log structures at Rocky Mount a few miles north in Piney Flats, Tennessee.

Analysis of Wood Samples from a Crime Scene using
Laser-Induced Breakdown Spectroscopy (LIBS)
Henri D. Grissino-Mayer and Madhavi Z. Martin

In April 2004, we were contacted to help solve a homicide in Collin County, Texas. The victim's body had been burned under a pile of mesquite logs (upper left of photo) in an attempt to conceal evidence. Soon after, the sheriff's office found similar mesquite wood in a fireplace (lower right in photo) and people who attended the gathering around the fireplace knew from whom the wood came. If we could connect the two sets of wood, then the prosecutor's office would have convincing evidence that could help convict the suspect. To do so would require a relatively new technique called Laser-Induced Breakdown Spectroscopy.

The University of Tennessee, Knoxville. Big Orange. Big Ideas.

Knoxville, Tennessee 37996 | 865-974-1000
The flagship campus of the University of Tennessee System