{"id":3361,"date":"2020-11-03T13:00:00","date_gmt":"2020-11-03T13:00:00","guid":{"rendered":""},"modified":"2025-03-29T15:20:25","modified_gmt":"2025-03-29T15:20:25","slug":"dendrochronology-history-developments-and-methods-9930","status":"publish","type":"post","link":"https:\/\/www.ukessays.com\/essays\/sciences\/dendrochronology-history-developments-and-methods-9930.php","title":{"rendered":"Dendrochronology: History, Developments and Methods"},"content":{"rendered":"

Tree-dating or dendrochronology as it is better known in the academic field, dates back to the 1920s when it was discovered by an astronomer named Andrew Elliscott Douglass.[1]<\/a> This scientific method analyses the growth rings in wood to gather information about the tree’s life that is useful in determining its age (Figure 1).[2]<\/a> Dendrochronology is also found in dendroclimatology, dendroarchaeology, and radiocarbon dating. Focusing more on an artist’s perspective, dendrochronology is helpful in determining information that helps art historians document famous pieces of art, such as the year a piece originated. There are, however, limitations to using dendrochronology on art pieces such as knowing the difference between which artists painted what. This paper will examine dendrochronology, focusing specifically on its history, limitations, and results when used in studying art.<\/p>\n

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Figure 1: Growth rings.<\/p>\n

The biological scientific method of dendrochronology, or ‘tree dating’, determines the terminus post quem or earliest of wood by using the examination of a tree’s growth rings.[3]<\/a> This method has also been used within archaeology to determine the age of architectural artifacts, climatology to detect atmospheric changes in earth, and radiocarbon dating. As Figure 2 illustrates, new growth rings materialise in a layer of cells near the bark during a tree’s growth.[4]<\/a> These new growth rings are produced by ‘vascular cambium,’ where each ring is a new mark of the previous year the tree has lived.[5]<\/a> These rings can change in size and pattern in response to changes in the climate. As a result of this each tree has their own unique pattern and variation of growth rings depending on the local climate and environmental changes. For example, trees that are located in areas where there are more variances in the seasons tend to have more visible rings. In reference to this, the terms ‘early wood’ and ‘late wood’ help to define what season and thus, when during the year, a ring has grown. Additionally, a year with weather conditions providing more moisture results in wider rings, where as a drought year results in narrower rings. Aside from climate conditions, the growth ring structures will differ depending on the tree species as seen when comparing Figures 3, 4, 5, and 6.[6]<\/a><\/p>\n

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Figure 2: The layers underneath bark.<\/p>\n

Trees such as pine, fir, and spruce are composed of ‘tracheids,’ a specific and unique type of cell (Figure 3). Then there are hardwood trees that are separated into two categories known as ‘ring-porous’ and ‘diffuse-porous’. Ring-porous trees, which include oak, ash, and elm trees, have a combination of large vessels for water and smaller vessels with extra fibres to support the stem (Figure 4). Diffuse-porous however, do not have such an extreme difference between their vessels for water and structural support which can be seen in Figure 5. Rather, the vessels in these trees have higher levels of fibres during the end of the growth period which consequently causes better definition between the growth rings. Examples of diffuse-porous trees include beech, limewood, maple, and poplar.<\/p>\n\n\n\n
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Figure 3: Spruce Tree<\/td>\n

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Figure 4: Oak Tree<\/td>\n

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Figure 5: Limewood Tree<\/td>\n

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Figure 6: Tropical Tree<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Determining the date of a piece of wood using dendrochronology is done by measuring the width and pattern of one of its growth rings and comparing it to a piece of documented and measured wood. The process of ‘bridging’, used to establish master chronologies, is a technique that is useful to the dating and matching of individual tree-rings. This process involves overlaying samples of a single type of wood from objects with a known date and location. Shown in Figure 7, these samples are overlaid to synchronise their rings and create master chronologies, essentially a length of growth rings with which a given wooden object could be compared to in order to find its time-range of origin.[7]<\/a><\/p>\n

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Figure 7: The process of bridging to create master chronologies.<\/p>\n

The width of rings in panel paintings are measured straight from the panel itself. These measurements can either be done with or without laboratory equipment (ex. Measuring lope), and they are then recorded and saved for documentation and analysis.[8]<\/a> One of the most important pieces of information for any art historian that can be found from this analysis is the tree’s ‘felling date.’ The felling date of a tree is the exact year that the tree was cut which can be determined by its last ring. This date can help provide a range of when a panel painting was created. Dendrochronology is a useful method for providing a tree’s felling date which in turn provides valuable data about the wood itself, defining the links between the back supports of different paintings (ex. same tree, location, panel).[9]<\/a> However, there limitations to this method of dating the wood from artworks which will be discussed later on.<\/p>\n

Dendrochronology as a scientific method dates back to the 1920s when it was discovered by an astronomer named Andrew Elliscott Douglass. The concept, however, of tree rings dates back further to Greek botanist Theophrastus in 287 BC; he was the first to discover trees had rings marking their growth.[10]<\/a> Throughout history more pieces of information were discovered by multiple artists, scholars, and scientists. Beginning in the 1850s-1890s, the scientific study of tree rings had become more widely practiced and was slowly used to create predictions about changes occurring in the earth’s atmosphere and past observations of the living environment the tree was placed in. It was then in the twentieth century that Astronomer Andrew Elliscott Douglass founded the “Laboratory of Tree-Ring Research at the University of Arizona.”[11]<\/a> Dendrochronology now spans into multiple different fields of study such as art history, climate science, archeology, and more. In art history, as previously discussed dendrochronology is an important method used by art historians for dating artworks incorporating wood and providing other bits of useful information like the region of creation.[12]<\/a> Dendroclimatology refers to past climate changes in trees. The growth rings in trees each year are altered depending on the atmospheric changes in earth. These changes in the climate throughout the year determine the conditions, including the thickness or narrowness, of each ring as it grows. Scientists have been using this particular method to define past global climates changes since the 1870s. Dendroarchaeology refers to the scientific study of artifacts including buildings, furniture, and instruments. Similar to the dendrochronology study of panel paintings, dendroarchaeology studies the wood and finds historical information about an object despite its original physical form. The difference, however, between studying wood from a panel painting and, for example, a building is that the lumber from the tree would have been used during the first year that the last ring grew making it more precise dating than dendrochronology.<\/p>\n

The art piece of the St John Altarpiece is one of the many panel paintings that was analysed by using the method of dendrochronology (Figure 8).[13]<\/a> St John Altarpiece is very similar to the scenes shown in other works such as the Virgin and Child with Saints Catherine of Alexandria and Barbara (Figure 9).[14]<\/a> The St John Altarpiece painting was created in 1479 by Early Netherlandish painter Hans Memling using oil on oak.[15]<\/a> It consists of five paintings; a center panel and two double-sided wings. The central panel includes an image of Virgin and Child surrounded by saints. The left wing shows John the Baptist and his beheading, while the outer side shows St Anthony Abbot (a saint) and St James placed behind two male donors. The right wing is an image of the apocalypse with John the Evangelist writing on an island called Patmos. While the outer side is an image of St Agnes and St Clare placed behind female donors (Figure 10).[16]<\/a> Originally the centre piece of this painting was once missing, but due to the use of dendrochronology and knowledge of the history behind this painting, the centre piece was found and placed with its wings. Art historians were able to make the connection between each piece due to the support panel being the same type of wood (oak) and similar age connection of the growth rings. In terms of connection of paint methods itself, each of the paintings had similar tones in colour (ex. Reds and greens) and paint brush strokes. Once the centre piece was placed with its other matches it was also clear that it connected with the story of Catherine of Alexandria (Figure 11).[17]<\/a> According to history, Catherine Alexandria was a princess and a scholar, later becoming a Christian in her teenager years. In the end of her story she becomes known as a Christian saint and virgin; persuaded by Saint Mary and Baby Jesus. In a debate against Maxentius, Catherine disputed the persecutions by Maxentius and won.[18]<\/a> Angered by the loss of Catherine’s pro-Christian arguments, Maxentius put anyone who converted to death and placed Catherine in imprison to starve to death. Although, Catherine, being watched over by angels, survived and was released. Seeing Maxentius failure once more attempted to propose and marry Catherine. She refused announcing that Jesus Christ was her spouse. Anger risen again, Maxentius beheaded Catherine, but her body lived on in the mountain now known as Mt. Saint Catherine (next to Mount Sinai). The three panels each depict a part of the history behind Catherine of Alexandria. For example, the virgin sites with the Christ baby Jesus surrounded by saints in the center panel, on the left is the beheading, and on the left is the peacefulness of Mt. Saint Catherine. Due to dendrochronology art historians were able to find the missing piece to this great art work.<\/p>\n

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Figure 9: Virgin and Child with Saints Catherine of Alexandria and Barbara.<\/p>\n

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Figure 8: St John Altarpiece.<\/p>\n

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Figure 11: Catherine Alexandria<\/p>\n

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Figure 10: Outside of St. John Altarpiece<\/em><\/p>\n

Even though dendrochronology can tell art historians many pieces of information relating the panel painting being studied, there are still numerous limitations. This method, for example, fails to provide the exact date the painting was created due to the extraction of rings from trimming the bark and the difference of the time it was cut to the completion of the panel and the completion of the painting. Essentially, the felling date for the tree is not exact due to changes in the process of completion of the art work. There is a far spread of statistical range for the production date, especially due to the type of wood used. This being another limitation of the method, the species of trees. Certain locations in the world, more often warmer climate areas, cause species of trees to develop more difficult ring patterns to identify (Figure 12).[19]<\/a> This is due to the fact that areas in the tropics often have a consistent warm weather pattern making the growth rings less distinct. Another limitation of dendrochronology is examination of smaller panels. Due to the size, smaller panels are more difficult to research since the results are not as clear. Many panel paintings are investigated without moving them to avoid damage, which means not all technological devices can be used during the research period. However, for smaller panels technology can be required to be able to achieve accurate results. These limitations show the importance of examining dated works; to establish a more precise master chronology and get more information on the work’s transportation and seasoning.[20]<\/a><\/p>\n

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Figure 12: Seasonal effects on growth rings.<\/p>\n

The biological scientific and historical method of dendrochronology, ‘tree-dating’, is useful in the process of revealing important information of certain wooden objects stemming from panel painting, artifacts, and other environmental findings. It is an important method to art historians in determining multiple factors of paintings, as shown already with the painting called St John Altarpiece. As well as determining the felling date of paintings by the study and comparisons of the growth rings in the wood. Although, dendrochronology still possesses certain limitations to its research in specifying exact factors of panel paintings.<\/p>\n

Bibliography<\/h2>\n