VEGETATION SENSITIVITY DURING THE MID-HOLOCENE WARMING IN WESTERN OHIO

There has been a growing interest in prairie reconstruction in western Ohio, yet there are few recent academic sources supporting the claim that prairies appeared in western Ohio during the mid-Holocene. During the hypsithermal, the warmest and driest part of the Holocene, prairie peninsulas appeared interfingered with forests from Minnesota to western Indiana. If prairie did appear in Ohio, it would have occurred during the mid-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. 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 replaced the previous dominant taxa. Betula, Fagus, Ulmus, Alnus, Fraxinus and Juglans appeared at 1675 cm and remained stable around 10% throughout. A 47% peak in Acer occurred at 1370 cm. Following the Acer peak, Quercus became the dominant taxa, fluctuating between 61% and 39% until the top of the core. Carya appeared around 10% throughout the core, but experienced an increase to 20% concurrently with the Quercus spike at 1325 cm. Starting at 1385 cm, Pinus returned at levels below 5%. Poaceae and Cyperaceae remained below 10% throughout the core. Similarly, Ambrosia remained below 10% throughout the majority of the core until 1175 cm, where it jumped to 35%.

There are no identifiable spikes in Poaceae and Cyperaceae exceeding 10%, suggesting that prairie grassland was not present around Crystal Lake. The spike of Ambrosia near the top of the core likely represents the beginning of homesteading activity in the area. 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.