Improving age estimates for late Holocene glacial landforms using dendrochronology – Some examples from Garibaldi Provincial Park, British Columbia

Abstract

Dating of late Holocene landforms below treeline in high mountains is commonly done using dendrochronology. Four factors can reduce the accuracy of ages obtained by dendrochronology: (1) locating the oldest living tree on a surface; (2) the method of counting the rings; (3) the age-height correction factor; and (4) ecesis, which is the time it takes trees to successfully germinate on a bare surface. A review of published studies from the western Cordillera of the Americas shows that some of these issues have not been fully addressed. Research in Garibaldi Provincial Park in the southern Coast Mountains of British Columbia shows that the accuracy of tree-ring ages can be improved if (1) crossdating and chronology construction, rather than simple ring counts, are done; (2) individual age-height correction factors are applied; and (3) site-specific ecesis estimates are made. While these suggestions are not always necessary to their fullest extent, researchers should at least report their methods in more detail and provide uncertainties in their age estimates that take into account age-height and ecesis corrections.