A high-resolution record of late-Holocene moisture variability from a Michigan raised bog, USA.

Testate amoeba from Minden Bog, Michigan sediment core. A high-resolution record of late-Holocene moisture variability from a Michigan raised bog, USA.
Volume 13, Issue 6, pp. 863-876, November 2003.

Robert K. Booth1 and Stephen T. Jackson

Department of Botany, University of Wyoming, Laramie, WY 82071-3165

1 Present address:
Center for Climatic Research, Room 1153 Atmos/Ocn & Space Science Bldg.
1225 W. Dayton Street, Madison, WI 53706-1695

We reconstructed the late-Holocene surface-moisture history and vegetation dynamics of a raised bog in Michigan using testate amoebae, peat humification, pollen, stomata and plant macrofossils. Our primary objective was to compare bog palaeohydrology with the water-level history of Lake Michigan, and to regional and local vegetation changes. Hydrologic histories inferred from testate amoebae and humification show similar trends, and correspond with records of past water-level variability in Lake Michigan. The bog clearly shows effective-moisture increases during the Algoma highstand (~3200-2300 cal. BP) and a later unnamed highstand (~1900-1300 cal. BP). Some higher-frequency fluctuations are also similar. The good correspondence indicates that bog hydrology and the water levels of Lake Michigan have been driven by changes in large-scale atmospheric circulation patterns for at least the past 3500 years. Climate during the Algoma highstand may have been spatiotemporally complex, with increasing moisture occurring several hundred years earlier in the northern portion of the western Great Lakes basin. Locally, the expansion and contraction of Picea populations on the bog surface was probably directly related to moisture conditions. The well-documented decline in Fagus populations in the central Great Lakes region after 1000 cal. BP is contemporaneous with a major shift towards drier conditions, suggesting that relative dryness caused the decline.
Download the amoeba assemblage data and water table reconstruction from the WDC Paleo Archive.

Water Table reconstruction
Testate amoeba-inferred water table depth reconstruction of Minden Bog compared to the sedimentologically derived water-level history of Lake Michigan (Baedke and Thompson, 2000).
Minden Bog, Michigan Minden Bog, an ombrotrophic peatland in eastern Michigan, USA.

To read or view the full study, please visit the Ingenta website.
It was published in Holocene, Volume 13, Issue 6, pp. 863876, November 2003.
The research was funded by student grants to R.K. Booth from the Society of Wetlands Scientists and The Paleobiological Fund, as well as a C.S. Mott Scholarship from the International Association of Great Lakes Research. Additional funding came from a USGS-BRD Cooperative Agreement (143498HQAG2181) to S.T. Jackson.

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16 October 2003