106-10 Preliminary Reconstruction of Shoulder Season Temperatures Using a Tsuga canadensis (Eastern Hemlock) Tree-Ring Chronology (1696-2024) in the Northwestern Adirondack Mountains

Session: 37th Annual Undergraduate Research Exhibition Sponsored by Sigma Gamma Epsilon (Posters)

Presenting Author:

Authors:

Abstract:

Assessing how mean shoulder-season temperatures (the shift into and out of the growing season) affect conifer growth may improve predictions of their response to a warming climate. Due to the limited availability of instrumental climate records in the northwestern Adirondack Mountains, we used dendroclimatological methods to conduct a preliminary reconstruction of mean temperature in the shoulder seasons (Mar, Apr; Sep, Oct) using tree-ring width measurements from Tsuga canadensis (Eastern Hemlock). An exploratory chronology was developed from 16 trees located along the edge of Fox Fen, an ecologically sensitive wetland, to leverage their heightened climate sensitivity. This resulted in 31 samples that were mounted and sanded to prepare for microscopic analysis followed by digitization using CooRecorder. Data analyses were conducted using CDendro and COFECHA, revealing a 300+-year chronology (1696-2024) with a correlation coefficient of 0.54. This chronology was subsequently detrended in ARSTAN using an age-dependent spline with a stiffness of 30 years to remove age-related growth trends and retain decadal signals. Using DendroClim2002, we conducted a climatological analysis, determining that mean temperature in the shoulder seasons (Mar, Apr; Sep, Oct) exhibited the strongest correlation with radial growth. Lastly, using PCreg, we developed a model reconstructing mean shoulder-season temperatures extending back to 1696 CE based on a 46-year calibration period. Though the model explains a modest portion of variance (R2=0.229, r=0.478), the statistically significant relationship (p<.05) suggests that Tsuga canadensis may hold promise as a regional climate proxy, particularly with further replication and refinement. This working reconstruction reveals substantial decadal variability, including a well-documented mid-19th-century cooling period from 1839-1863 (cf., Mann et al., 1999), possibly originating from a volcanically induced decrease of radiative forcing (e.g., Crowley, 2000). While this reconstruction was primarily designed to gain experience and refine methodology, our findings may contribute to a longer-term understanding of climate variability in the northwestern Adirondacks, including a possible future streamflow reconstruction.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-10244

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