A LAKE RECORD OF ENVIRONMENTAL CHANGE IN NORTHEASTERN OHIO SINCE EUROPEAN COLONIZATION

A half meter of wind-blown silt within meter-long lake cores from Browns Lake in Northeast Ohio records the post-settlement history of the region. This core shows the most severe changes in the landscape since the glacial transition approximately 14 thousand years ago. These land use changes included deforestation, draining of surrounding wetlands, intensive agriculture coupled with climate shifts all contributing to a dustbowl like environment. These dramatic transitions likely exacerbated drought during time of a natural and volcanically forced drying in the early decades of the 19th Century. Dust lofted by these land use transformations had the potential of modifying surface and atmospheric conditions as well as the biogeochemistry of ecosystems facilitating landscape transitions.

Lead 210 profiles, Cesium-137 and radiocarbon ages provide the lake sediment chronology and nearby moisture-sensitive tree-ring chronologies within the basin are records of climate and logging. Logging about 1820 and again in 1950 is evident in the tree growth and in the lake sediments. The recovery of the dust-dominated landscape is recorded with increasing organic content in the lake, reflecting changing farming practices and increasingly pluvial conditions. The recovery in the basin is also marked by a rebound in diatom communities seen in increases in diatom abundance and diversity over recent decades. Pending grain size and nutrient analyses will help us better understand the role of wind-blown silt in changing nutrient conditions and contributing to the shift from a bog to forest environment over the last 100 years. This study highlights the utility of lake sediment analyses for better understanding the relative roles of naturally occurring events like droughts and pluvials along with anthropogenic drivers and feedbacks that all impact ecosystems.