Spatial Relationships in Frost-Damaged High-Elevation Pines and Links to Major Volcanic Eruptions

  Frost injury in the annual growth rings of pines growing at upper treeline is a consequence of sudden freezing temperatures during the growing season (LaMarche & Hirschboeck 1984). This updated and spatially extensive frost-ring study involves the systematic identification of frost rings in high-elevation pines located in 16 western USA tree-ring sites whose chronologies range from 1692 BC to AD 2000. Several "notable frost events" were identified, based on the criteria of frost damage occurring in greater than 25% of trees at a given site and in two or more sites. The spatial variations between frost events indicate regional variations based on differences in elevation, latitude, and the location of polar outbreaks and their associated upper-level atmosphere circulation patterns. The 17 notable frost events correspond to previous frost ring and light ring evidence, and 13 of them are associated with climatically effective volcanic eruptions.