1 History 2 Growth rings 3 Dendrochronological equation 4 Sampling and dating 5 Reference sequences 6 Applications
7 Related chronologies 8 See also 9 References 10 External links
The Greek botanist
This section has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these template messages)
This section relies too much on references to primary sources. Please improve this section by adding secondary or tertiary sources. (November 2014) (Learn how and when to remove this template message)
This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (November 2014) (Learn how and when to remove this template message)
(Learn how and when to remove this template message)
Further information: Wood
Diagram of secondary growth in a tree showing idealised vertical and horizontal sections. A new layer of wood is added in each growing season, thickening the stem, existing branches and roots, to form a growth ring.
Horizontal cross sections cut through the trunk of a tree can reveal growth rings, also referred to as tree rings or annual rings. Growth rings result from new growth in the vascular cambium, a layer of cells near the bark that botanists classify as a lateral meristem; this growth in diameter is known as secondary growth. Visible rings result from the change in growth speed through the seasons of the year; thus, critical for the title method, one ring generally marks the passage of one year in the life of the tree. Removal of the bark of the tree in a particular area may cause deformation of the rings as the plant overgrows the scar. The rings are more visible in trees which have grown in temperate zones, where the seasons differ more markedly. The inner portion of a growth ring forms early in the growing season, when growth is comparatively rapid (hence the wood is less dense) and is known as "early wood" (or "spring wood", or "late-spring wood"); the outer portion is the "late wood" (sometimes termed "summer wood", often being produced in the summer, though sometimes in the autumn) and is denser.
Many trees in temperate zones produce one growth-ring each year, with the newest adjacent to the bark. Hence, for the entire period of a tree's life, a year-by-year record or ring pattern builds up that reflects the age of the tree and the climatic conditions in which the tree grew. Adequate moisture and a long growing season result in a wide ring, while a drought year may result in a very narrow one. Direct reading of tree ring chronologies is a complex science, for several reasons. First, contrary to the single-ring-per-year paradigm, alternating poor and favorable conditions, such as mid-summer droughts, can result in several rings forming in a given year. In addition, particular tree-species may present "missing rings", and this influences the selection of trees for study of long time-spans. For instance, missing rings are rare in oak and elm trees. Critical to the science, trees from the same region tend to develop the same patterns of ring widths for a given period of chronological study. Researchers can compare and match these patterns ring-for-ring with patterns from trees which have grown at the same time in the same geographical zone (and therefore under similar climatic conditions). When one can match these tree-ring patterns across successive trees in the same locale, in overlapping fashion, chronologies can be built up—both for entire geographical regions and for sub-regions. Moreover, wood from ancient structures with known chronologies can be matched to the tree-ring data (a technique called cross-dating), and the age of the wood can thereby be determined precisely. Dendrochronologists originally carried out cross-dating by visual inspection; more recently, they have harnessed computers to do the task, applying statistical techniques to assess the matching. To eliminate individual variations in tree-ring growth, dendrochronologists take the smoothed average of the tree-ring widths of multiple tree-samples to build up a ring history, a process termed replication. A tree-ring history whose beginning- and end-dates are not known is called a floating chronology. It can be anchored by cross-matching a section against another chronology (tree-ring history) whose dates are known. A fully anchored and cross-matched chronology for oak and pine in central Europe extends back 12,460 years,[non-primary source needed] and an oak chronology goes back 7,429 years in Ireland and 6,939 years in England. Comparison of radiocarbon and dendrochronological ages supports the consistency of these two independent dendrochronological sequences.[non-primary source needed] Another fully anchored chronology that extends back 8500 years exists for the bristlecone pine in the Southwest US (White Mountains of California).[non-primary source needed] Dendrochronological equation
A typical form of the function of the wood ring width in accordance with the dendrochronological equation.
A typical form of the function of the wood ring (in accordance with the dendrochronological equation) with an increase in the width of wood ring at initial stage.
Dendrochronological equation defines the law of growth of tree rings. The equation was proposed by Russian biophysicist Alexandr N. Tetearing in his work "Theory of populations"  in the form:
Δ L ( t ) =
( t )
displaystyle Delta L(t)= frac 1 k_ v ,rho ^ tfrac 1 3 , frac d big ( M^ tfrac 1 3 (t) big ) dt ,
displaystyle Delta L
is width of annual ring,
is time (in years),
is density of wood,
displaystyle k_ v
is some coefficient,
M ( t )
is function of mass growth of the tree.
With the neglection of natural sinusoidal oscillations in tree mass, the formula of the changes in the annual ring width is:
Δ L ( t ) = −
displaystyle Delta L(t)=- dfrac c_ 1 e^ -a_ 1 t +c_ 2 e^ -a_ 2 t 3k_ v rho ^ tfrac 1 3 (c_ 4 +c_ 1 e^ -a_ 1 t +c_ 2 e^ -a_ 2 t )^ tfrac 2 3
displaystyle c_ 1
displaystyle c_ 2
displaystyle c_ 4
are some coefficients,
displaystyle a_ 1
displaystyle a_ 2
are positive constants. The formula is useful for correct approximation of samples data before data normalization procedure.
The typical forms of the function
Δ L ( t )
displaystyle Delta L(t)
of annual growth of wood ring are shown in the figures.
Sampling and dating
A portrait of Mary Queen of Scots, determined to date from the 16th century by dendrochronology.
cliff dwellings of Native Americans in the arid U.S. Southwest. The Fairbanks House in Dedham, Massachusetts. While the house had long been claimed to have been built circa 1640 (and being the oldest wood-framed house in North America), core samples of wood taken from a summer beam confirmed the wood was from an oak tree felled in 1637–8. An additional sample from another beam yielded a date of 1641, thus confirming the house had been constructed starting in 1638 and finished sometime after 1641 as wood was not seasoned before use in building at that time in New England. The burial chamber of Gorm the Old, who died c. 958, was constructed from wood of timbers felled in 958.
This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (November 2014) (Learn how and when to remove this template message)
Similar seasonal patterns also occur in ice cores and in varves (layers of sediment deposition in a lake, river, or sea bed). The deposition pattern in the core will vary for a frozen-over lake versus an ice-free lake, and with the fineness of the sediment. Some columnar cactus also exhibit similar seasonal patterns in the isotopes of carbon and oxygen in their spines (acanthochronology). These are used for dating in a manner similar to dendrochronology, and such techniques are used in combination with dendrochronology, to plug gaps and to extend the range of the seasonal data available to archaeologists and paleoclimatologists. A similar technique is used to estimate the age of fish stocks through the analysis of growth rings in the otolith bones. See also
Baumkuchen, cake that resembles growth rings
^ a b Grissino-Mayer, Henri D. (n.d.), The Science of
R. A. Studhalter (April 1956) "Early history of crossdating",
Tree-Ring Bulletin, 21 : 31–35. Available on-line at:
University of Arizona
Leonardo da Vinci, Trattato della Pittura ... (Rome, (Italy): 1817), p. 396. From p. 396: "Li circuli delli rami degli alberi segati mostrano il numero delli suoi anni, e quali furono più umidi o più secchi la maggiore o minore loro grossezza." (The rings around the branches of trees that have been sawn show the number of its years and which [years] were the wetter or drier [according to] the more or less their thickness.) Sarton, George (1954) "Queries and Answers: Query 145. — When was tree-ring analysis discovered?", Isis, 45 (4): 383–384. Sarton also cites a diary of the French writer Michel de Montaigne, who in 1581 was touring Italy, where he encountered a carpenter who explained that trees form a new ring each year.
^ du Hamel & de Buffon (27 February 1737) "De la cause de l'excentricité des couches ligneuses qu'on apperçoit quand on coupe horisontalement le tronc d'un arbre ; de l'inégalité d'épaisseur, & de different nombre de ces couches, tant dans le bois formé que dans l'aubier" Archived 2015-05-09 at the Wayback Machine. (On the cause of the eccentricity of the woody layers that one sees when one horizontally cuts the trunk of a tree ; on the unequal thickness, and on the different number of layers in the mature wood as well as in the sapwood), Mémoires de l'Académie royale des science, in: Histoire de l'Académie royale des sciences ..., pp. 121–134. ^ du Hamel & de Buffon (4 May 1737) "Observations des différents effets que produisent sur les végétaux les grandes gelées d'hiver et les petites gelées du printemps" Archived 2015-05-09 at the Wayback Machine. (Observations on the different effects that the severe frosts of winter and the minor frosts of spring produce on plants), Mémoires de l'Académie royale des science, in: Histoire de l'Académie royale des sciences ..., pp. 273–298. Studhalter (1956), p. 33, stated that Carl Linnaeus (1745, 1751) in Sweden, Friedrich August Ludwig von Burgsdorf (1783) in Germany, and Alphonse de Candolle (1839–1840) in France subsequently observed the same tree ring in their samples. ^ Alexander C. Twining (1833) "On the growth of timber — Extract of a letter from Mr. Alexander C. Twining, to the Editor, dated Albany, April 9, 1833" Archived May 14, 2015, at the Wayback Machine., The American Journal of Science, 24 : 391–393. ^ See:
(Anon.) (1835) "Evening meeting at the Rotunda" Archived 2015-05-14 at
the Wayback Machine., Proceedings of the Fifth Meeting of the British
Association for the Advancement of Science held in Dublin during the
week from the 10th to the 15th of August, 1835, inclusive, pp.
Jacob Kuechler ( August 6, 1859) "Das Klima von Texas" (The climate of Texas), Texas Staats-Zeitung [Texas state newspaper] (San Antonio, Texas), p. 2. "The droughts of western Texas", The Texas Almanac for 1861, pp. 136–137 ; see especially p. 137. Archived 2015-11-02 at the Wayback Machine.
^ J. T. C. Ratzeburg, Die Waldverderbniss oder dauernder Schade,
welcher durch Insektenfrass, Schälen, Schlagen und Verbeissen an
lebenenden Waldbäumen entsteht. [The deterioration of forests or
lasting damage that arises from feeding by insects, debarking,
felling, and gnawing on living forest trees.], vol. 1, (Berlin,
(Germany): Nicolaische Verlag, 1866), p. 10. Archived 2015-10-01 at
the Wayback Machine. From p. 10: "Die beiden, auf Taf. 42, Fig. 6 (mit
dem Durchschnitt Fig. 7) und Fig. 1 (mit dem Durchschnitt Fig. 2)
dargestellten Zweige hatten in dem Frassjahre 1862 einen doppelt so
starken Jahrring als in dem vorhergehenden angelegt, und auch der
(hier nicht abgebildete) Ring des jährigen Triebes war bei den
gefressenen stärker as der eines nicht gefressenen." (Both branches
that are presented in plate 42, fig. 6 (with the cross-section in fig.
7) and fig. 1 (with the cross-section in fig. 2) had produced, in the
defoliation year of 1862, a growth ring that was twice as strong as in
the preceding one, and so was the ring of the year-old shoot (not
illustrated here) stronger in the case of the defoliated tree than one
that was not defoliated.)
^ Franklin Benjamin Hough, The Elements of
Seckendorff, Arthur von (1881) "Beiträge zur Kenntnis der
Schwarzföhre Pinus austriaca Höss" [Contributions to our knowledge
of the black pine Pinus austriaca Höss], Mitteilung aus dem
forstlichen Versuchswesen Oesterreichs [Report from the Austrian
^ Speer (2010), p. 36–37. ^ See:
Шведов, Ф. (Shvedov, F.) (1892) "Дерево, как летопись засух" (The tree as a record of drought), Метеорологический Вестник (Meteorological Herald), (5) : 163–178. Speer (2010), p. 37.
^ "Early wood" is used in preference to "spring wood", as the latter
term may not correspond to that time of year in climates where early
wood is formed in the early summer (e.g. Canada) or in autumn, as in
some Mediterranean species.
^ Capon, Brian (2005). Botany for Gardeners (2nd ed.). Portland, OR:
Timber Publishing. pp. 66–67.
ISBN 0-88192-655-8. [better source needed]
^ The only recorded instance of a missing ring in oak trees occurred
in the year 1816, also known as the "Year Without a Summer".Lori
Martinez (1996). "Useful
The Wikibook Historical
Wikimedia Commons has media related to Growth rings.
Nottingham Tree-Ring Dating Laboratory
Video & commentary on Medullary Rays, heart wood and tree rings.
Video & commentary on
v t e
Analog forestry Bamboo forestry Close to nature forestry Community forestry Ecoforestry Energy forestry Mycoforestry Permaforestry Plantation forestry Social forestry Sustainable forestry Urban forestry
Ecology and management
Arboriculture Controlled burn Dendrology Ecological thinning Even-aged management Fire ecology Forest
informatics IPM inventory governance law old-growth pathology protection restoration secondary transition
ATFS CFS FSC PEFC SFI SmartWood Woodland Carbon Code
Growth and yield modelling Horticulture
Silviculture Sustainable management Tree
crown girth height volume
chitemene slash-and-burn slash-and-char svedjebruk
Timber recycling Wildfire Wilding
lumber plywood pulp and paper sawmilling
biochar biomass charcoal non-timber palm oil rayon rubber tanbark
engineered fuel mahogany teak
Forester Arborist Bucker Choker setter Ecologist Feller Firefighter
handcrew hotshot lookout smokejumper
v t e
Archaeology Astronomy Geology History Paleontology Time
Ab urbe condita
Anno Domini / Common Era
Hindu units of time
Long Count Short Count Tzolk'in Haab'
Canon of Kings Lists of kings Limmu
Chinese Japanese Korean Vietnamese
Pre-Julian / Julian
Pre-Julian Roman Original Julian Proleptic Julian Revised Julian
Gregorian Proleptic Gregorian Old Style and New Style dates Adoption of the Gregorian calendar Dual dating
Lunisolar Solar Lunar Astronomical year numbering
Chinese sexagenary cycle Geologic Calendar Hebrew Iranian Islamic ISO week date Mesoamerican
Cosmic Calendar Ephemeris Galactic year Metonic cycle Milankovitch cycles
Deep time Geological history of Earth Geological time units
Chronostratigraphy Geochronology Isotope geochemistry Law of superposition Luminescence dating Samarium–neodymium dating
Amino acid racemisation Archaeomagnetic dating Dendrochronology Ice core Incremental dating Lichenometry Paleomagnetism Radiometric dating
Radiocarbon Uranium–lead Potassium–argon
Tephrochronology Luminescence dating Thermoluminescence dating
Fluorine absorption Nitrogen dating Obsidian hydration Seriation Stratigraphy
Chronicle New Chronology Periodization Synchronoptic view Timeline Year zero Circa Floruit Terminus post quem ASPRO chrono