ALASKA’S FIRST WESTERN RED CEDAR TREE-RING CHRONOLOGY

Western red cedar (Thuja plicata) is a long-lived conifer tree that occurs in the temperate rainforests in the Pacific Northwest of North America. Here we report on Alaska’s first tree-ring chronology of this species, near the northernmost edge of its geographical range. The ring-width record (1621-2021) consists of twenty cores from Kake, a Tlingit village in southeastern Alaska. The ring-width variability is sensitive to winter temperatures, which is unusual for dendroclimatology in Northern North America. The ecophysiological reasons for this cold season signal are uncertain, however, its discovery offers a strong potential for further insights into coastal ocean-atmospheric phenomena, which are primarily expressed in winter.

A strong marker year in 1876 offers potential teleconnections with a well-recognized, widespread drought interval linked with famine. This year includes the lowest growth index value in the chronology, as well as the coldest recorded average winter temperature from Sitka, AK, 85 km North of Kake. While the specific drivers behind this temperature excursion are unclear, it corresponds with climatic anomalies in other parts of the world. For example, the phases of the PDO (Pacific Decadal Oscillation) and ENSO (El Niño Southern Oscillation) have been linked to major droughts in East Asia, South America, and Africa between 1875 and 1878. Future collections of Western red cedar and the development of ring-width records in tree populations that are winter-temperature responders can further contribute to our understanding of air-sea interactions in the North Pacific and to the development of tree ring-based drought atlases.