树轮年代学

树轮年代学，又称树木年轮学、树轮学（英语：Dendrochronology^[1]）是一种通过对树木年轮进行科学分析而测定年代的方法。这门学科是20世纪上半叶由亚利桑那大学教授，树轮研究实验室的创办人A. E. 道格拉斯（英语：A. E. Douglass）发展起来的。在考古学、美术史、树木气候学（英语：Dendroclimatology）领域有重要应用价值。

树轮取样和计数工具

树轮年代学用于确定样本的精确年代，特别常用于确定因为年代较近，用放射性测年仅能给出大致时段，无法确定精确年代的样本。然而，为了精确给出一棵死亡树木的年代，需要获得包含树木外沿的完整样本——大多数经过加工的木板无法满足这样的要求。这种方法还能用来确定某些事件发生的时间或环境变化速率（大多数时候与气候变化有关），或者确定考古发掘的木材、工艺品或建筑的年代，比如古代版画的年代。这种方法也用于检查放射性测年的数据，以校准碳同位素测年的精度。^[2]

树上新生的细胞会在靠近树皮处形成一层。一棵树的生长速率会因为当年的气候变化而发生有规律的变化，在树干上生成可见的生长轮。树干的每一轮都标志着一个树木经过了一个完整的季节周期或者一年的变化。^[3] 直到2020年，准确的北半球树木年轮数据已经回溯至13,910年之前。^[4]目前还有一种较新的测年方法，利用每一个年轮的氧同位素之变化来测年。这种方法称为“同位素树木年轮法”（isotope dendrochronology），可以用于测定因为年轮太少或过于相似，不适于使用传统树木年轮法测定的样本。^[5]

历史

希腊植物学家泰奥弗拉斯托斯首次提出树木具有轮线。^[6][7]达芬奇 (1452–1519)在《绘画论》中则第一次指出树木的轮线乃是年轮，其厚度有树木发生的条件决定。^[8]1737年，法国博物家Henri-Louis Duhamel du Monceau 与布丰考察了生长条件与树木年轮形状之关系。^[9]他们发现，1709的严冬造成了独特的深色树轮，成为后来欧洲诸多自然学家的参考数据。^[10]在美国，Alexander Catlin Twining (1801–1884)在1933年提出，树木年轮的模式可以用来同步各种树木的年代，因此可以用于重建整个地区从前的气候条件。^[11]英国博物学家查尔斯·巴贝奇（Charles Babbage）提出，可以使用树木年轮学来定年泥碳沼中残余的树木甚至地层(1835, 1838)。^[12]

19世纪后半叶，关于树轮的科学研究与树木年轮学的应用逐渐多了起来。1859年，德国-美国裔的土地测量员Jacob Kuechler (1823–1893) 使用交叉定年法检查了橡树 (Quercus stellata)的年轮，试图以此分析西得克萨斯州的气候。^[13]1866年，德国植物学家、昆虫学家和森林学家Julius Ratzeburg (1801–1871)观察到树木年轮可能受到昆虫侵害的影响。^[14]到了1882年，这一观察就已经写入了森林学教科书。^[15]1870年代，荷兰天文学家雅各布斯·卡普坦 (1851–1922) 使用交叉定年法重建了荷兰和德国的气候。1881年，瑞士-奥地利森林学家Arthur von Seckendorff-Gudent (1845–1886)也开始使用交叉定年法。^[16]从1869到1901年，德国森林病理学教授Robert Hartig (1839–1901)撰写了一系列论文，讨论树木年轮的解剖学和生态学问题。^[17]1892年,俄国物理学家Fedor Nikiforovich Shvedov (Фёдор Никифорович Шведов; 1841–1905) 写到，他已经使用树木年轮预测了1882至1891年期间的干旱。^[18]

20世纪初，天文学家A. E. Douglass 在亚利桑那大学创建了树木年轮研究所。Douglass希望更好地理解太阳黑子活动与周期对地球气候的影响，而气候的变化则进一步记录在树木年轮之中(换句话说，太阳黑子 → 气候 → 树轮)。

注释

1. 词源解释：源自古希腊语：δένδρον，树木；χρόνος，时间；-λογία，学科。
2. The term "dendrochronology" was coined in 1928 by the American astronomer Andrew Ellicott Douglass (1867–1962). Douglass, A.E. (1928). Climatic Cycles and Tree Growth. Vol. II. A Study of the Annual Rings of Trees in relation to Climate and Solar Activity. Washington, D.C., USA: Carnegie Institute of Washington. p. 5. From p. 5: "One can see that in all this we are measuring the lapse of time by means of a slow-geared clock within trees. For this study the name "dendro-chronology" has been suggested, or "tree-time."
3. Grissino-Mayer, Henri D. (n.d.), The Science of Tree Rings: Principles of Dendrochronology, Department of Geography, The University of Tennessee, archived from the original on November 4, 2016, retrieved October 23, 2016
4. van der Plecht, J; Bronck Ramsey, C; Heaton, T. J.; Scott, E. M.; Talamo, S (August 2020). "Recent Developments in Calibration for Archaeological and Environmental Samples". Radiocarbon. 62 (4): 1095–1117. doi:10.1017/RDC.2020.22.
5. Loader, Neil J.; Mccarroll, Danny; Miles, Daniel; Young, Giles H. F.; Davies, Darren; Ramsey, Christopher Bronk (August 2019). "Tree ring dating using oxygen isotopes: a master chronology for central England". Journal of Quaternary Science. 34 (6): 475–490. Bibcode:2019JQS....34..475L. doi:10.1002/jqs.3115.
6. Theophrastus with Arthur Hort, trans., Enquiry into Plants, volume 1 (London, England: William Heinemann, 1916), Book V, p. 423. From p. 423: "Moreover, the wood of the silver-fir has many layers, like an onion; there is always another beneath that which is visible, and the wood is composed of such layers throughout." Although many sources claim that Theophrastus recognized that trees form growth rings annually, this is not true.
7. For the history of dendrochronology, see: (Condensed from: James H. Speer, Fundamentals of Tree-ring Research (Tucson, Arizona: University of Arizona Press, 2010), Chapter 3: History of Dendrochronology, pp. 28–42.
8. See: - 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.
9. 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.
10. 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.
11. 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.
12. 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. 116–117. - Charles Babbage (1838) "On the age of strata, as inferred from rings of trees embedded in them" Archived 2015-05-15 at the Wayback Machine, The Ninth Bridgewater Treatise: A Fragment, 2nd ed. (London, England: John Murray, 1838), pp. 256–264.
13. See: - 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
14. 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.)
15. Franklin Benjamin Hough, The Elements of Forestry (Cincinnati, Ohio: Robert Clarke and Co., 1882), pp. 69–70. Archived 2015-10-01 at the Wayback Machine
16. See: - 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 Department of Forestry Research] (Vienna, Austria: Carl Gerold Verlag, 1881), 66 pages. - Speer (2010), p. 36.
17. Speer (2010), p. 36–37.
18. 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.