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For more information about Dendrochronology contact Jim Speer
Dendrochronology is the science that deals with the dating and studying of annual growth layers in wood.
- Dendron = "tree" (Greek)
- Chronology = "science deals with time and the assignment of dates to particular events."
The Value of Dendrochronology
It is the most accurate dating technique that we use today. It provides annual and even seasonal resolution throughout the entire record. Other records such as varved lake sediments, some ice cores, and coral records can provide annual resolution but it is not as consistently reliable as dendrochronology. Another factor that makes dendrochronology a useful tool is that trees are ubiquitous on the landscape. Most terrestrial-temperate regions of the globe have trees present that can be useful to the techniques of dendrochronology.
Time Frame of Dendrochronology
The time frame of dendrochronology covers anywhere from the present back 10,000 years. But most chronologies are only a few hundred years long. There are some 1,000 year long chronologies scattered around the globe, but they are rare.
Short History and Scope of Dendrochronology
Dendrochronology was developed by A.E. Douglass, founder of the first laboratory entirely devoted to tree-ring research. Douglass' initial interest was the impact of solar cycles on the Earth’s climate. While working in Flagstaff, Arizona in A.D. 1904, he noticed a distinct annual ring pattern in the stems of many ponderosa pine trees, a repeated signature of narrow and wide rings. This now famous pattern, which Douglass subsequently found in trees throughout the region, became known as the Flagstaff signature. Ring-width patterns enable dendrochronologists to precisely and accurately date every individual tree ring in a chronology.
When all trees on a site are limited by a common factor, such as inter-annual variability in climate, the size of their annual growth rings is affected in a similar manner, and a common ring-width pattern emerges across the site or region. Crossdating, i.e., matching the ring patterns in tree-ring samples across a site, can provide an accurate chronological record of the natural history of the stand.
Among other applications, dendrochronology has been used to date:
- Archeological ruins
- Climate change
- Fire history
- Insect outbreaks
- Volcanic eruptions
- Glacier movement
For Past Projects and Lab Presentations please view our Archive Page
Any information for ISU Dendro Lab Archived Projects can be found here.
Equipment and Facilities
The Department of EES (Earth & Environmental Systems) at ISU has among others research laboratories dedicated to Biogeography/ Dendrochronology and Climatology. The Biogeography/Dendrochronology has workspace available for six student workers. The Climatology Laboratory has recently been remodeled and has dedicated space allocated for archiving dendrochronological samples.
A sanding facility and a microscope lab are also available.
The Department of EES(Earth & Environmental Systems) also has the Center for Remote Sensing and Geographic Information Systems. This Center houses 26 computers complete with auxiliary printers and scanners, including a drum printer that can be used for the production of research posters for professional meetings. The Biogeography/Dendrochronology lab has two computers, which can be used for data analysis. The Climatology lab has computers dedicated to the acquisition of climate data.
The Biogeography/Dendrochronology Laboratory currently houses one Velmex Measuring Machine connected to a Stereozoom Microscope on a boom stand and a microcomputer analysis system.
The lab equipment also includes:
13 increment borers
6 stereozoom microscopes
2 belt sanders (4X24")
desktop and laptop computers
1 Stihl Chain saw Stihl 046 with a 24" bar
2 cruiser packs
2 Soil Sampling probes
4 map tubes
Paper straws, Poplar core mounts, skeleton plot paper