How Old Are These Trees?

I was working with a colleague in Paradise Valley, Utah last week, collecting forest stand data.  We were working in the pinyon-juniper, measuring heights, diameters, crowns, etc.  When we could find a good tree—meaning one that was not too old and twisted—we also estimated stand age by taking cores and counting rings.  The majority of the trees we were able to core were 60 to 70 years old.  There were sections of forest that were older, much older, probably 250 to 300 years older, but a significant portion of the pinyon-juniper forest in the project area originated around the end of WWII.  It seems likely that this forest expansion coincided with a period of much improved rangeland fire suppression, as well as a couple of good seasons of seed production and germination.  As you can see from the picture, the trees we cored were six to eight inches in diameter.  The core with the reddish heartwood (at top) is juniper and the longer core is pinyon.  (If you can't tell by looking at them, you can always tell by sniffing them—they each have a unique smell.)