Dendrochrono­logy

Dendrochronology as a service

Dendrochronology is a scientific method for determining the exact age of wooden samples on the basis of a comparison of the annual ring width measurement series of a sample with an annual ring width chronology.

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The dendrochronology method goes back to Douglass (Arizona, 1908). The maintenance of the dendrochronological heritage of Prof. Huber, the founder of dendrochronology in Europe, is an important concern of the Chair of Forest Utilization and the Dendro-Institute (with Prof. Bues, Prof. Roloff, Prof. Röhle and others) in Tharandt. Research Associates of the Chair of Forest Utilization and the Dendro-Institute Tharandt carry out scientifically sound research and provide services in the field of dendrochronology for applied building and historical research in Central Germany.

Building and monument preservation

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In cooperation with recognized centers of tree-ring research, Tharandt works on research topics in the field of dendrochronology and provides services, particularly in Brandenburg, Saxony, Saxony-Anhalt and Thuringia.
In the past few years, contract work has been carried out for small and medium-sized companies, as well as for dating roof constructions in the Albrechtsburg Meißen or for the preservation of monuments in the central German region.
Samples can be taken by employees of the Chair or the Dendro Institute.

If the client carries out the selection, collection and documentation of the samples himself, the following guidelines on sample quality and sample numbers should be observed:

• The basis for dating is a measurable tree ring sequence. Each sample to be dated should contain at least 50 growth rings. Pieces of wood with shorter ring sequences carry the risk of not being datable and may only be dated in conjunction with reliable mean curves (sufficient number of samples). Samples with less than 25 growth rings cannot be dated with certainty. The following tree species are processed: oak, pine, fir, spruce, ash, beech, possibly also alder and elm.
• As a rule, about 5 different individual samples are needed to answer a specific question. Several samples usually enable reliable dating. Normally, about 2-8 cm thick slices (cross-sections of trunk wood or beams sawn perpendicular to the direction of growth) are processed. The samples should be as regular and knot-free as possible. The presence of the forest edge (the last growth ring of the tree before felling) is important for determining the year of felling.
• Drill cores (diameter: 16 - 25 mm) are taken from installed timber elements after consultation. If necessary and if the wood is in good condition, a 10 mm increment borer can also be used. For objects that must not be damaged, it is possible to measure the annual ring widths using photos of the wood cross-sections.