Pine species from California, famous for its longevity and one of those used to develop an exceptionally long, arid-site, tree-ring chronology. The oldest living specimens date back more than 4600 years, but cross-dating these with remnants of dead bristlecone pines has extended the arid-site chronology to more than 8200 BP. A 5500-year chronology has been developed for bristlecone pines at the upper tree limit. These pines are also used to calibrate the radiocarbon-dating method to allow for fluctuations in atmospheric 14C:12C ratios as revealed by measuring 14C:12C ratios of individual tree rings in the long, absolutely dated, tree-ring series. P. longaeva is Great Basin bristlecone pine and P. aristata is mountain bristlecone pine. Both are used for dating. See also dendrochronology.
Subjects: Earth Sciences and Geography.