129-57 250 Years of American Old Growth: Tracing European Settlement and the Black Swamp with Dendrochronology of Ohioan Witness Trees

Abstract:

Old growth trees growing in Ohio (>250 years old) have been witness to natural and anthropogenic changes. A little over a 140 years ago, northwest Ohio witnessed the erasure of one of its largest wetlands, the Great Black Swamp. Initially a barrier for early Euro-American settlers, the Black Swamp was profoundly changed and the extant trees were witness to the land-use changes in addition to the changing climate. By analyzing tree ring records in Northwest Ohio, from Goll Woods State Nature Preserve (a remnant of the Black Swamp) Shagbark Hickory, White Oak and Burr Oaks sampled by the Indiana University Tree Ring Lab show a positive relationship to summer precipitation and a negative one with maximum summer temperatures. They also show evidence of witnessing land-use change throughout the mid-late 19^th century. During the 1820s-1880s, as vegetation declined from land clearing, the remaining vegetation faced a profound change in ecology. Growth releases in the trees can be dated using tree-ring analysis. The land clearing in the Maumee Valley region appears non-uniform as the growth releases from the various sites in Goll Woods vary in time. The oaks show early releases with the White Oak and Burr Oak releasing in the 1850s and 1820s, respectively. The Hickory exhibits a sudden release within the early 1870s, with a subtle decline during the 1900s. Sorting out the natural and anthropogenic signals in the trees is a challenge as to some extent the profound changes in land use and hydrology driven by settlement could also feedback on and contribute to changes in climate. This dendrohistorical case study from Northwest Ohio can be applied more broadly across Ohio to include the other nine old-growth sites. We will extract additional climatic and settlement history from the witness trees of these sites on the 250^th anniversary of the nation.

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