Current and Past Research Interests

Fire History of the Bigwoods, Minnesota

The Bigwoods were a large area of deciduous forest surrounded by prairie that occupied much of south-central Minnesota (see recent article in MNPS Plant Press or picture below). The existence of this tongue of forest surrounded by prairie -- and its associated fires -- was the cause of much discussion in the 19th century and has been the subject of several research projects.

J. McAndrews in the 1960s and E. Grimm again in the 1980s reconstructed the long-term history of the Bigwoods based on pollen analysis and changes in sedimentation. Both suggested that a reduction in fire frequency coincident with the onset of the 'Little Ice Age' only 300-400 years BP was the trigger for the expansion of the Big Woods; a competing hypothesis is that a reduction in Native American populations due to disease was responsible for a drop in fires but there is very little data to address this hypothesis directly. Grimm showed that the borders of the Bigwoods corresponded with the location of rivers and lakes and other features of the landscape that would have acted as fire breaks.

My students and I are trying to better understand the relationship of fire to the rise of the Big Woods, examining charcoal, pollen, sediment magnetic susceptibility, and sediment composition from the sediments of 20+ lakes in and around the Bigwoods area. We have a manuscript in review right now describing this work.

I have also been working with Phil Camill (Carleton), Christoph Geiss (Trinity College), and Becky Teed (LRC, University of MInnesota) on cores from two lakes in the Bigwoods both of which have sediment records that extend 10-12000 years. We have a paper in press in Journal of Paleolimnology describing some of this work as well as several manuscripts in review or in preparation. One interesting conclusion is that this area has remained a mix of forest and prairie throughout the past 10000 years -- even at the height of the mid-Holocene dry period (8000 BP).

Fire History of the Northern Great Plains

Fires have been a historical component of the ecology of the northern Great Plains for the past 10000 years. The accounts of 19th and early 20th century settlers and explorers are replete with stories of these fires but we know very little about the long term history of fire. I've been looking at charcoal deposited in lake sediments in North and South Dakota and Montana. Charcoal (+120 microns in length) is abundant (picture to right). The charcoal record indicates an extended period of increased fires just before european settlement, possibly due increased ignition sources, and extended periods of high and low charcoal deposition over the past 10000 years.