A 200-Year Fire History in a Remnant Oak Savanna in Southeastern Wisconsin

Publication Type:Journal Article
Year of Publication:2004
Authors:Wolf, J
Journal:American Midland Naturalist
Date Published:2004
ISBN Number:00030031
Keywords:Canis lupus

In oak (Quercus) savannas in the Midwest region of the United States, fire continues to play a significant role in its persistence within the landscape; however, in southeastern Wisconsin, quantified fire history records are limited. This study documented occurrences of fire for the last 200 y using 16 cross-dated oak sections from an oak savanna remnant in Kenosha County, Wisconsin. Fire history was reconstructed by: (1) obtaining fire-scarred cross sections from cut down oaks in an area planned for an industrial park, (2) preparing sample surfaces to count rings, (3) creating skeleton plots to crossdate samples, (4) dating fire scars, (5) calculating intervals between fires and (6) determining seasonality of the fire. In addition, a master chronology was constructed for the oak savanna using the cross sections to correlate with precipitation. Throughout the entire time series, only 50% of the fire dates were associated with significantly dry years. Although the overall Weibull median interval was 4.59 y, fire frequency fluctuations and gaps reflected specific time periods of human activities. Although some studies report a high fire frequency during Euro-American settlement, in this study the mean fire interval (MFI) was 19.5 y in the early settlement years in 1840-1872 and 4.77 y in the post settlement years in 1873-1979. From 1980 to the present, MFI was 6.7 y. In addition, the data revealed time periods with no fire events: (1) during early Euro-American settlement (1840-1872), (2) land fragmentation and deforestation (1904-1920) and (3) increased industrial zoning (1989-present). Although lightning strikes occur most often during the summer months, the majority of fires that occurred during the dormant season (53%) were set by humans. These data are essential in understanding oak dynamics and in developing management programs for restoration and preservation of remnant areas of oak savanna.

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