Changes in forest composition in Ohio between Euro-American settlement and the present

In Ohio Euro-American setdement in the late 18th and early 19th centuries subjected forests to large scale disturbances, including widespread clearance. In the subsequent two centuries, some of this land has reforested. To describe changes in forest composition since setdement, we used archival maps of U.S. Public Land Survey records to characterize forest composition just before large scale Euro-American settlement in 27 Ohio counties. We then compared this with modern composition patterns from the U.S. Forest Service's Forest Inventory Analysis. Presetdement forests displayed strong spatial structure and regional differentiation. Counties in northwest Ohio were dominated by beech (Fagus grandifolia; mean relative abundance: 26.9%), whereas southeast Ohio counties were dominated by oaks (Qiiercus spp.; 50.1%). Modern forests, however, had weaker spatial structure and were dominated by oak species in both regions (24.0% and 22.4%, respectively). Overall, we found a decrease in previously dominant species and homogenization across the state. Partial Mantel tests indicated modern forest composition is more closely correlated with modern land use variation than environmental variables, suggesting that forest composition now is driven primarily by land use. Understanding factors influencing forest composition can inform projections of forest response to modern global change, including climate change and land use conversions.
INTRODUCTION Modern day forests are products of complex climatic, ecological, and anthropogenic interactions over time. Anthropogenic influences and legacies increasingly are recognized as important factors affecting species assemblages in forests. [...]