Human vs. Lightning Ignition of Presettlement Surface Fires in Coastal Pine Forests of the Upper Great Lakes

Loope, Walter; Anderton, John

Thirty-nine patches of coastal pine forest along the shores of Lakes Superior, Michigan, and Huron were examined for the presence of fire scarred, logging era stumps. Red pine (Pinus resinosa) stumps and living, fire scarred P. resinosa (rare) were sectioned for fire scars. Post-logging era, living trees (large diameter trees with unburned, lower branches) were cored with an increment borer. Evidence of fire was found at all 39 sites, and 29 patches contained multiple fire scars that provided data about fire intervals. Pre-logging era fire intervals averaged less than 22 yrs compared to an average post-logging era fire interval of more than 75 yrs. Frequency of lightening strikes (from data from other researchers) in the upper Great Lakes region varies from 0.2 to 1.9 lightening fires/year/100,000 hectares. It is hypothesized that lightening is too infrequent to have been the ignition source for all the pre-logging fires and that planned or accidental burning by native Americans (Anishnabeg) at their seasonal camps was the source for most or all of the pre-logging era (1750-1900) fires in the pine patches. Maps indicate locations of coastal pine forest pockets along the southern coast of Lake Superior and the northern coast of Lake Michigan. Sites at Pictured Rocks National Lakeshore are featured in separate map.

Human vs. Lightning Ignition of Presettlement Surface Fires in Coastal Pine Forests of the Upper Great Lakes

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