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 at the individual sites rather than tree age. The younger oak stands and their relative sustained drought sensitivity is also related to their history of recently attaining the canopy and similar responses associated with intervals of selective logging. All sites are strongly, negatively correlated with summer (June- July) maximum monthly temperatures.
Paleoclimate class (2021) at Johnson Woods Orrville Ohio. One of the key sites in the paper and one of the key sites in the Midwest. Originally cored by Ed Cook (Lamont-Doherty Tree Ring Lab) in 1980, the site has been updated by The College of Wooster Tree Ring Lab and by Justin Maxwell at the Indiana University Tree Ring Lab. 
Students sampling the remanent white oak stand at Browns Lake Bog a site managed by the Nature Conservancy.
Coring the second-growth white oaks in Wooster Memorial Park.
Another second growth site is within the Wooster city limits at the Kinney Field Park.
The College of Wooster campus maintains an impressive stand of old growth white oaks on its campus. Here members of the Holden Arboretum Tree Corps sample one the the impressive old trees.
Secrest Arboretum (on the Wooster campus of the CFAES) is one of our favorite sites to cores trees. Many of the trees from all around the world have lived in Ohio for over 100 years. Here one of the coauthors cores a white oak planted about 100 years ago.
A final word on this study. Future warming in the Midwest is projected to see increases in spring precipitation, likely decreases in late summer precipitation, which if coupled with an increase in maximum summer temperatures would increase the moisture stress on these trees. Our examination of these varying climate responses with respect to site characteristics and forest age can help future assessments of tree health and the forest’s ability to sequester carbon, as well as facilitate efforts to reconstruct climate by using a range of tree sites for intervals when sensitivity in old growth sites is lost.
These data from the sites in Northeast Ohio are available in the International Tree-Ring Databank maintained by NOAA and many of these records have been incorporated into the North American Drought Atlas contributed to the larger climate science community by Ed Cook and colleagues.
References:
Maxwell, J.T., Robeson, S.M., Harley, G.L., 2016. On the declining relationship between tree growth and climate in the Midwest, United States: the fading drought signal. Clim. Chan. 38, 127–142. https://doi.org/10.1007/s10584-016-1720-3.
Acknowledgements: This work was funded by The College of Wooster, NSF Geopaths and NSF – EAR 2039939 grants.
Fantastic and productive teamwork. A model of student-faculty research. Also a great example of hypothesis-driven science. Congratulations on this paper!