A REVISED ESTIMATED AGE FOR THE BENNETT JUNIPER FROM TREE-RING AND RADIOCARBON DATES

The Bennett Juniper (Juniperus grandis R.P.Adams, Cupressaceae) in the Sierra Nevada Mountains of California is the largest known individual juniper tree of any species, and thought to be the oldest. I present a revised estimated age for the tree based on an extrapolation of mean annual radial growth rate of ring widths measured from a long increment core containing 1221 rings (769–1989 CE), extended back in time to an inferred pith position based on half of the tree diameter. The pith date estimated from growth extrapolation is 140 BCE, making the tree 2129 yr old when sampled in 1989 CE, or 2164 yr old in 2024 CE when it is still alive. I also obtained radiocarbon dates on three pieces of wood that had been excavated from inside the tree bole by marmots. Radiocarbon dates are all younger than the extrapolated pith date from the increment core, with calibrated dates ranging from 105–280 CE. These dates provide minimum ages for the tree and support for an older pith date. Inexactitude in extrapolating early growth rates coupled with an uncertain pith position relative to where the long core was collected leads me to propose a revised estimated age range for the Bennett Juniper of between 2000–2300 yr. This is younger than an age of 3000 yr often assigned to the tree and younger than another Sierra Juniper known to be 2675 yr old at the time it was cored. However, regardless of inaccuracy inherent in extrapolation methods used here, the Bennett Juniper is undoubtedly one of the oldest known individual trees of any species to be found anywhere in the world.