Tree rings in a Rocky Mountain Juniper, Yellowstone National Park

A scanned image of Rocky Mountain juniper deadwood sample GGR100 collected in the northern part of Yellowstone National Park under permit YELL-5582.  The full length of this sample covers the time period 723-1792 CE. Since climate influences tree growth and the width of annual rings, the relation between ring widths and recent instrumental climate records (air temperature, precipitation and river discharge) is used to interpret climate variability in the distant past.