Figure 1. Title page of Amanda’s thesis including one of the key figures.
Amanda Flory (class of 2025) completed a thesis that investigated the interplay between the pace of the ocean-atmosphere climate in the Northeast Pacific that is dominated by Pacific Decadal Variability along with the volcanically-forced coolings inferred from tree-ring records. Her title page (above) summarizes the results with several known volcanic intervals linked with decade-long coolings. These coolings are inferred from a tree ring-width series located in coastal Southeast Alaska (Dude Mountain, Ketchikan, Alaska). In addition to her thesis work Amanda presented her results at the meeting of the Geological Society of America in the Spring of 2025. The take-home here is that the variability as recorded in the tree-ring record appears to be a combination internal variability of the Northeast Pacific [1] and volcanic forcing [2] contributing to the decadal variability in the climate.

Figure 2. The author (left) cores a yellow cedar (Cupressus nootkatensis) – Nick (middle) and Proto provide support.

Figure 3. Comparisons of Sitka, AK temperature records for the months of December through October of the growth year correlated with the Dude Mountain ring-width record.
This climate/tree-ring comparison (Figure 2) examines the moving correlation over time (since

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The College of Wooster Tree Ring Lab faculty, staff and students have teamed up to publish results of  an analysis of a network of tree-ring sites in Northeast Ohio to ask the question what is driving the changing climate response of the trees. The tree-ring sites include young (100-year-old) white oaks in Secrest Arboretum, Wooster, two sites of post-settlement age (about 200-years old) from Wooster Memorial Park and The Kinney Field Park both in Wooster and four old growth sites (>300 years old) from some of our favorite sites including The College of Wooster campus, Cornerstone Elementary, Browns Lake Bog, David Kline’s (the author) old growth forest on his farm and Johnson Woods the largest tract to old growth white oak forest in Ohio.

The upshot of the study reveals that the one- hundred-year-old white oak stand in Secrest Arboretum, along with two second growth stands have consistently responded positively to summer (June-July) precipitation over the past century, whereas the four nearby old growth sites have lost their moisture sensitivity since about the mid 1970s. This “fading drought signal,” which has been previously reported by Maxwell et al. (2016), appears to be more a result of the legacy of land use

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Wooster Memorial Park has been a great resource for The College of Wooster Earth Sciences (ESCI), Biology among others. Here the ESCI course in Paleoclimate, under permit from the Friends of Wooster Memorial Park, sampled 20 second growth Eastern Hemlock with the aim of determining the climate response of the species in the Park. A recent publication by the Wooster Tree Ring Lab incorporated results from past sampling in the park that was concerned with the changing climate response of white oak trees. This oak study can be found here Wiles et al., 2025.
Lidar Map of Wooster Memorial Park – the green field in the west of the park is the approximate location of tree-ring sampling.
 

The class took advantage of a spectacular day for the sampling.

Nick demonstrating the coring technique using an increment borer.

Another perfect core, once trained, the five groups went into sampling mode.

For most of the group, this was their first experience coring and it was clear some were naturals at the technique.

First-ever core reveal photo – a proud dendrochronologist.

Another first.

Coring for the first time.

Coring and at the same time keeping a sharp eye out for wildlife.

A first – ever core safely archived in a reusable plastic straw.

Even

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