Through tree-ring cross-referencing, they have been shown to be more than five millennia old.A clonal colony can survive for much longer than an individual tree.For example, they depend on ancient records of rare astronomical phenomena, such as the solar eclipse during the ninth year of Ashur Dan III of Assyria, to determine the age of historical events.In the absence of such records, standard radiocarbon measurements provide the best estimates, but these are still often only accurate to within 200 to 300 calendar years.In a new paper, the authors explain how harvesting such data could revolutionise the study of ancient civilisations such as the Egyptian and Mayan worlds.Until now scholars have had only vague evidence for dating when events happened during the earliest periods of civilisation, with estimates being within hundreds of years.
The current record-holders for individual, non-clonal trees are the Great Basin bristlecone pine trees from California and Nevada, in the United States.
As with all long-lived plant and fungal species, no individual part of a clonal colony is alive (in the sense of active metabolism) for more than a very small fraction of the life of the entire clone.
Some clonal colonies may be fully connected via their root systems, while most are not actually interconnected, but are genetically identical clones which populated an area through vegetative reproduction.
In addition, tree ages are derived from a variety of sources, including documented "tree-ring" count core samples, and from estimates.
For these reasons, this article presents three lists of "oldest trees," each using varying criteria.
Ages for clonal colonies, often based on current growth rates, are estimates.