THE NEED AND MEANS TO UPDATE CHRONOLOGIES IN A DYNAMIC ENVIRONMENT

The International Tree-Ring Data Bank (ITRDB) provides public access to over 3000 tree-ring data sets collected over the past century, yet 809 of these sites have end dates between AD 1950 and 1980. These data cannot be calibrated with at least the past 30-40 years of instrumental data when used in climate reconstructions. We developed new tree-ring data sets at five sites in Maine, USA, to update earlier collections. Four of the five collections were successfully updated, with environmental changes at the fifth site limiting our success. Our results highlight the limits to tree longevity in a dynamic world and the need to increase and formalize efforts toward updating chronologies. We initiate a discussion to set forth explicit guidelines that help create consistent efforts to updating chronologies and provide a guide to beginning dendrochronologists who are particularly well suited to contribute to this area of work. The research was carried out through an introductory dendrochronology course taught at the University of Wisconsin-Platteville and offers a model to help direct the increasing availability of human resources to the rapidly growing field of dendrochronology.