VEGETATION SENSITIVITY DURING THE MID-HOLOCENE WARMING IN WESTERN OHIO

There has been a growing interest in prairie reconstruction in Ohio, yet there are no recent academic sources supporting the claim that western Ohio had prairies in the past. During the hypsithermal, the warmest and driest part of the Holocene, prairie peninsulas appeared interfingered with forests in Minnesota and Indiana. If prairie did appear in western Ohio, it would have occurred during the Holocene hypsithermal. The goal of this study was to determine if western Ohio experienced a prairie period during the hypsithermal using pollen as a proxy for past regional vegetation.

An 8.4m sediment core was collected from Crystal Lake, Clark County, OH; the bottom four meters of the core have been analyzed. Sediment was sampled at 10-15 m intervals. From the base of the core to 1675 cm, Pinus and Picea were dominant taxa, with Picea reaching 75%-85%. At 1705 cm, Quercus, and Acer replace the previous dominant taxa. Acer percentages decrease at 1615 cm, while Quercus increases slightly. Betula, Ulmus, Alnus, Fraxinus and Juglans appear starting at 1675 cm and remain stable below 10%. Fagus appears around the same time, but remains low until a spike to 14% at 1570 cm. Poaceae, Cyperaceae, and Ambrosia appear at the base of the core but disappear until 1725cm, with all three taxa remaining below 10%.

There are no identifiable spikes in grass or sedge exceeding 10%, suggesting that prairie grassland was not present in this region. Other studies in the area show similar patterns in the percentages of Betula, Carya, Cyperaceae over time. Studies of pollen in western Ohio are important in completing the Holocene record for the state, but also give insight into what taxa will dominate western Ohio during modern climate changes.