Bristlecone pines (BCP) are possibly the oldest trees on Earth, with he oldest living specimen of bristlecone pine reputed to be approximately 4,900 years old. However the largest BCP, the Patriarch tree is estimated to be a mere 1500 years old. The "oldest" trees come from extreme environments with short cool summers with a growing season thought to be only several weeks long, desert-like aridity (250 mm of precipitation per year, mostly as snow), and strong winds coupled with air that in the summer is said to be the driest on earth, and the rocky ‘soil’ (where there is any ’soil’), means that what little rain does fall will evaporate or drain away quickly. Many trees grow out of little more than cracks in dolomitic rocks.
Trees in such stressed conditions are known to form additional rings. Sometimes these can be identified as such but where rings are thin, as in these BCPs , they are often indistinguishable from annual rings. Glock et al. demonstrated that in dry climates, not only are ‘false’ rings common in many species, but the bands of ‘false’ dark-wood can have outer boundaries that are every bit as distinct as the outer boundaries of a true annual ring. They found that multiplicity was more than twice as common as annularity, and conclude that probably very few annual increments, over the entire tree, consist of only one growth layer.
However BCP's growing nearby but where moisture conditions are better, as in valley areas where a decent soil can accumulate, do not reach the ancient ‘ages’, ‘No old bristlecone pines are found in the valley bottom, which is a sheltered area with deep colluvial soil and gentle surface slope.’
Researchers have found that in the central area of a stand of BCP trees, where growing conditions are the best, the trees do not have more than several hundred rings. But at the margins of the stand, where the soil thins and growing conditions become progressively poorer, the trees with the most rings are found. It seems more probable that all the trees in the stand are about the same age, but that the trees growing at the margins are starved for water and grow multiple rings to conserve water.
So although some researchers do consider each ring as an annual ring there is good evidence for a significant number as being false rings. Biblical dating would put the flood at ~2349BC., or ~4350 before present. 11% false rings would put the age as less than the time to the flood. 25% would put starting date after the post flood ice age. If Glock et al. are correct in their estimates of the frequencey of false rings the trees could be much younger.
Top Customer Reviews 4.0 out of 5 starsAmazing summary of research into sub-annual ring-growth patterns ByDavid M. Barkeron October 3, 2013 Format: Paperback|Verified Purchase
So often we hear of "annual tree-rings" yet few people are aware of sub-annual rings, and multiple rings. This is a scholarly research report of experiments and studies showing that under some circumstances trees can and do grow more than one ring within a year. Profound!
 So far I haven't been able to access a copy. Do you have a link I could use or perhaps I could borrow yours.