Dendrochronology

Dendrochronology is the dating and study of annual rings in trees. Tree-ring chronologies provide unique archives of environmental history and have many inter-disciplinary applications. Tree-ring chronologies are based on small core samples extracted non-destructively from living trees and cross-sections cut from dead logs. Using these methods scientists can perform the reconstructions of past climate and stream flow, the socioeconomic impacts of past climatic extremes, the dating of historic structures, and the identification and mapping of ancient forests. For an idea of how long a tree species may live, one good source is the OLDLIST at: http://www.rmtrr.org/oldlist.htm This list contains confirmed tree ages from around the world, but not specifically from Pennsylvania.

What are the oldest trees in Pennsylvania? We have started a compilation of the oldest trees know from Pennsylvania and will present it on this website as we progress. For now a couple of references to whet the appetite:

	The diagram below is taken from the monograph: The Ecology and Silvics of Forest in the High Plateaus of Pennsylvania by A.F. Hough and R. D. Forbes, Ecological Monographs, Vol 13, No. 3, July 1943. The diagram shows a section across the East Tionesta Creek Valley in north central Pennsylvania. They didn't use strict dendro methods; ages are determined by ring counting, so they could contain significant errors in age. Initial comparison with ages of trees using modern dendro methods indicate that Hough and Forbes ages are pretty good [Pederson, D'Amato and Orwig; accepted].
	Ed Cook has a network of at least 42 hemlock populations from the northern AL to Nova Scotia over to MI. The oldest intact hemlock he cored is from Tionesta, PA and dates to 1425 (cored in the 1980's). He reported those trees were relatively small. His primary paper on the species is: Cook, E. R. and Cole, J. 1991. Predicting the response of forests in eastern North America to future climatic change. Climatic Change 19:271-282.
	This spring a large Cucumbertree fell in Cook Forest State Park. A preliminary count indicates the tree has over 425 rings - making it the oldest know cucumbertree yet to have been found. (photo above) http://www.nativetreesociety.org/fieldtrips/penna_cook_forest/cook_nov18_2005/cook_forest_cucumber.htm Cook Forest Cucumber
	Schall's Gap: This small stand of old growth hemlocks was investigated by PSU forestry students a few years ago. A graduate student did some coring and counted 540 rings on one of the biggest trees in the stand, placing it at roughly the same age as the oldest of the Alan Seeger hemlocks. Eastern White Pine Versatility in the Presettlement Forest Issn: 0006-3568 Journal: BioScience Volume: 51 Issue: 11 Pages: 967-979 Authors: Abrams, Marc D. DOI: 10.1043/0006-3568(2001)051<0967:EWPVIT>2.0.CO;2 Also see this reference on the site: http://etda.libraries.psu.edu/theses/approved/WorldWideFiles/ETD-396/etd.pdf
	Neil Pederson reports from intensive database searches and other sources on the oldest oaks: "As for the oldest oaks in the east. Checking all the sources I could (Calling Dave Stahle, Dave Orwig, going through the modern tree-ring analysis lit), the oldest oak is a white oak Ed Cook cored in 1983 along the Blue Ridge Parkway in central VA. This sample was too suppressed for his work (drought reconstruction) and had been sitting in our lab undated for almost 20 years. I spent more than a day trying too cross-date this sample. It was very suppressed for > 200 years. The inner ring date is 1519 making this tree 464 years when cored. We don't know if this tree is still alive. There are several other white oaks in Ed's collection 420+ years of age. The second oldest white oak in Ed's collection was 433 yrs old in the early-1980s. The oldest chestnut oaks, btw, are 427 years old; 1 in SE PA, 1 in N NJ. I visited both of these trees in July 2005, so these trees are now 430 years old. Interestingly, these are many, 7-10, chestnut oaks along the northern Appalachian Mountains 420+ years old."
	The international Tree Ring Data Bank at: http://www.ncdc.noaa.gov/paleo/ftp-treering.html can be searched to locate tree ring data from Pennsylvania. It lists 14 samples from Pennsylvania, all hemlocks collected by Dr. Ed Cook in the 1980's.

Ultimate Tree-Ring web pages, http://web.utk.edu/~grissino/
designed to be the ULTIMATE source for information on the science of Dendrochronology. I've designed these pages to be easily understood by people at all levels of education, from elementary school students to high school students, from first grade teachers to college professors. You won't find anything fancy here - I want these pages to be readable, enjoyable, and (most of all) educational. My goal is to make available as much information about dendrochronology as I can possibly find on the Internet, from the basics of tree-ring dating, to reference and bibliographic information, to products and supplies, to books, and more!

University of Arkansas Tree Ring Laboratory http://www.uark.edu/misc/dendro/ The Tree-Ring Laboratory (TRL) was established in 1979 and concentrates on the development of exactly-dated annual tree-ring chronologies from ancient forests worldwide. These tree-ring chronologies are based on small non-destructive core samples taken from living trees, and cross-sections cut from dead logs. Tree-ring chronologies provide unique archives of environmental history, and have important applications to climatology, ecology, hydrology, seismology, archaeology, and history.

The Laboratory of Tree Ring Research http://tree.ltrr.arizona.edu/ The primary mission of the Laboratory of Tree-Ring Research is to apply dendrochronology (the study of tree rings) to improve understanding of natural environmental variability in climatic, hydrologic, geomorphic, and ecological systems and their interactions with human societies. Located at The University of Arizona in Tucson, Arizona, the LTRR was the first dendrochronology laboratory anywhere in the world, first established in 1937 by A.E. Douglass. Today, it serves as one of the premier tree-ring research facilities with nearly 90 personnel investigating nearly all topics in dendrochronology. Current research efforts are directed toward the quantification of tree-ring parameters, the establishment of new tree-ring chronologies throughout the world, the use of tree rings in the study of forest ecosystems, the reconstruction of paleohydrologic and paleoclimatic variables, and the documentation and development of prehistoric chronological controls.

Rocky Mountain Tree Ring Research, Inc. -Old List http://www.rmtrr.org/oldlist.htm OLDLIST is a database containing maximum ages of trees by species. The purpose of the database is to serve as a baseline for the maximum known ages of different species, such that individual trees of exceptional ages may be recognized. A portion of the database listing the oldest trees of 30 different species is given. The oldest species in the database is Pinus longaeva, with the oldest individual tree at 4,844 years old. The oldest angiosperm tree in the database is a Quercus alba at 407 years old. A request is made to interested scientists to contribute to the database.

Tree-Ring Laboratory of Lamont-Doherty Earth Observatory http://www.ldeo.columbia.edu/res/fac/trl/ LAMONT-DOHERTY EARTH OBSERVATORY OF COLUMBIA UNIVERSITY. ROUTE 9W, PALISADES, NEW YORK 10964 Voice: (845) 365-8517, Fax: (845) 365-8152