T123 The Stories of Geoheritage

Monday, 16 October 2023
1:30 PM - 5:30 PM
320

THE INTERSECTION OF ORAL HISTORIES AND TREE RING CHRONOLOGIES IN SOUTHEAST ALASKA

Paper number: T123-9
Program: Technical Sessions
Time: 3:20 PM – 3:35 PM

Authors

Abstract

The Wooster Tree Ring Lab (WTRL) has partnered with the Alaskan Youth Stewards (AYS) from Hoonah, Kake, Angoon and Prince of Wales Island, Alaska for the past four years. Each summer the WTRL has collaborated with one of the communities in Southeast Alaska with the aim of developing field and research skills centered on tree-ring analysis. The main goal of the summer 2023 trip to Hoonah was to increase the sample size of a ring width chronology of mountain hemlock originally sampled in 2020 by AYS. Additionally, students further developed and analyzed the climate signal of yellow and red cedar from Kake sampled in collaboration with AYS in the summer of 2022.

This previous sampling in Kake yielded two cedar chronologies, one from a yellow cedar decline, and the other from the northernmost known stand of red cedar, both located in Kake. The leading hypothesis for yellow cedar decline is increasing winter temperatures melting the insulative snowpack causes the shallow roots of the yellow cedar to be damaged during subsequent frost events. The yellow cedar ring width series based on 20 cores dates to 1108 C.E. and shows a release indicating increased ring widths over the past ~100 years. Yellow cedar ring widths are strongly correlated with May through September minimum temperatures. This release in ring widths is likely due to a combination of an increase in light and nutrient resources due to the death of surrounding yellow cedars and warming minimum temperatures over the past century. The red cedar ring width series is based on 51 cores and spans 506 years (1516-2022 C.E.). Red cedar shows the highest correlations with January through May temperatures. The varying response of the cedar sites at Kake along with new collections from Hoonah can begin to add detail to regional climate history.

Our long-term goal seeks to further establish a relationship between reconstructed climate using tree ring chronologies and Tlingit oral histories in Southeast Alaska. For example, oral histories report an interval of winter following winter, when summer temperatures became unseasonably cold for one to two consecutive years and may have impacted local food resources around the time Hoonah was being settled. Further climate reconstruction in the region may help to place these oral histories more firmly in time using the calendar-dated tree ring series.

Geological Society of America Abstracts with Programs. Vol. 55, No. 6

doi: 10.1130/abs/2023AM-392714

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