It has been shown that “trees will produce more than one ring in a year. The extra ring is called a ‘false ring’ and it can be the result of drought stress in the middle of a growing season.”
https://www.fs.fed.us/rm/highelevationwhitepines/Education/science-inquire.htm
Until 2013, the oldest individual tree in the world was Methuselah (calculated as a) 4,845-year-old Great Basin bristlecone pine (Pinus longaeva) in the White Mountains of California. Researchers at the Rocky Mountain Tree-Ring Research Group then announced the age of another P. longaeva also located in the White Mountains — this one was (calculated as ) 5,062 years old.
These dates are calculated by summed up by core tree rings. This technique is called ‘crossdating’ where tree rings are ‘matched up’ and added together, going backward into time. Each ring is considered to be one year. While there was no single tree that lived four or five thousand years many lived for over a thousand years. The oldest tree found was found to be 2,435 years old!
https://www.livescience.com/29152-oldest-tree-in-world.html?utm_source=ls-newsletter&utm_medium=email&utm_campaign=20180420-ls
[…] or controlled environments are flawed whether Carbon-14, radio-argon/potassium, ice cores, or even tree rings. When a dating method is carefully observed in a laboratory or field study the results can be […]