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| Dendrochronologists determined the age of the trees by cross-dating. The photo shows a sample of juniper. Photo Credit: Rashit Khantemirov |
A group of dendrochronologists from Italy, Denmark, Germany and Russia has discovered the longest-lived woody plant in the Arctic. It was the common juniper (Juniperus communis). The oldest juniper bush, which was found in the north of Finland, is 1647 years old. In the Polar Urals, the oldest juniper bush lived half as long, yet it is the longest-living organism in the Urals. Scientists told about the long-lived junipers in an article in the journal Ecology.
"Many species in the genus Juniperus are long-lived woody plants. But there was a lack of reliable data on the most common species, the common juniper. There are legends about junipers that are two thousand years old, but there was no reliable evidence. Counting the number of annual rings, rather than estimating the age by trunk thickness, shrub size and other indirect signs, can be considered reliable evidence," explains Rashit Khantemirov, co-author of the paper, a member of the Laboratory of Natural Science Methods in Humanities at Ural Federal University and the Laboratory of Dendrochronology and IER&J of the Ural Branch of the Russian Academy of Sciences.
Moreover, simple counting the rings does not always give the correct figure, the researcher adds. Some rings may be missing, called "dropouts", and so-called false rings may form in some years. The exact age can only be established by comparing the pattern of the year rings of many individuals, i.e. by using the cross-dating method.
"The cross-dating method is the main method in dendrochronology. With its help it is possible not only to identify fallen and false rings, but also to determine with absolute accuracy the year of formation of each ring. This makes it possible to determine both the age and the time of life of dead trees and shrubs. But for cross dating it is necessary to measure the width of all rings in all the studied trees or shrubs," says Rashit Khantemirov.
A group of dendrochronologists working in circumpolar regions, from Greenland in the west to the Polar Urals in the east, cross-dated almost 2,000 juniper bushes, both living and withered. The oldest juniper in northern Finland turned out to be the oldest. Dendrochronologists counted 1647 rings in one of them at the base of a branch cut from a bush. This individual grew from 260 to 1906 years, it is the oldest woody plant for the whole Europe, not only its polar part. Prior to that, the challenger for the title of the oldest woody plant in Europe was considered to be a representative of the Bosnian pine, growing in southern Italy. This tree even has its own name - Italus. Its age is estimated at 1230 years. But the annual rings in it counted "only" 1070. The central rings in the trunk of this tree have rotted away, and the number of missing rings was determined with the help of various tricks.
Four more shrubs, both living and withered, with a life expectancy of more than 1,000 years were found in northern Finland. Two more shrubs, both alive and over 1000 years old, were found in northern Sweden.
"The third in the ranking of areas where centuries-old junipers can be found was the Polar Urals. The oldest juniper, discovered in 1999 by Stepan Shiyatov, was alive and was 840 years old at the time. It is the oldest woody plant in the Urals. On the territory of Russia only Kayander larch can live longer, the modern representative of which grew in Yakutia for 945 years. And among the dried trunks of larch trees, specimens that have lived for more than 1000 years have been found," adds Rashit Khantemirov.
Determining the maximum age of the common juniper is important for understanding the history of this species, its survival strategy, and for developing measures to protect it, the scientists explain.
"For dendrochronologists, first of all, information about the potential of a given species to reconstruct the history of the natural environment is important. One of the important parameters in assessing this potential is the longevity of individual individuals and the preservation of wood from branches of long-dead junipers. In this respect, the Polar Urals offer more opportunities than areas in the north of Sweden and are almost as good as the north of Finland. In the mountains of the Polar Urals, dried juniper branches can be preserved for many centuries. Therefore, with the help of annual rings of Polar Urals juniper it is possible to reconstruct the climate history for almost 1,350 years, starting from the year 641," says Rashit Khantemirov.
The staff of the laboratory of dendrochronology of the Institute of Plant and Animal Ecology of the Ural Branch of the Russian Academy of Sciences found out a quarter of a century ago that the width of the rings of this species reflects changes in early-year temperatures quite well. Especially valuable was the discovered property of juniper rings to react sensitively to extreme temperature events during the entire life of the shrub, while in trees the sensitivity to extremes decreases with age.
Published in journal: Ecology
Title: Common juniper, the oldest nonclonal woody species across the tundra biome and the European continent
Authors: Marco Carrer, Raffaella Dibona, Davide Frigo, Ludmila Gorlanova, Rashit Hantemirov, Lucrezia Unterholzner, Signe Normand, Urs Albert Treier, and Angela Luisa Prendin
Source/Credit: Ural Federal University | Anna Marinovich
Reference Number: eco020425_01
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