A Tree-Ring Fire History Of The Upper Bois Brule River, Northwest Wisconsin

Abstract

The Bois Brule River is a 44-mile-long, northward flowing Wisconsin waterway. From 1650 – 1830 the river served as part of a popular fur trade route, used by the Ojibwe, the British, and the French, that connected Lake Superior to the Mississippi River. The route eventually reached such prominence that it was termed “The Historic Highway”. I developed fire histories at three discrete sites along the Upper Bois Brule River in Northwest Wisconsin in order to (A) determine the rate of historic fire along the Upper Bois Brule River, (B) provide fire history information within the context of changes in Native American and European American land use, (C) investigate the influence of seasonal drought patterns on fire occurrence and (D) provide crucial and necessary baseline information to be used in land management decision-making. The fire history is comprised of 60 fire scarred trees, 344 individual fire scars and 68 unique fire years. The mean fire interval ranged from 15.7 – 22.4 and the mean fire interval for the entire region was 5.1. The rate of fires began to slow in the early 1900s, before eventually ceasing in 1918. There was no consistent relationship between fire events and regional climate patterns when each site was considered individually. When all fire years were considered in aggregate there was a significant relationship between the event year and regional drought. Results suggest that lighting, as a lone ignition source, cannot fully explain the reconstructed fire regime. It seems likely that human land use activities may have influenced the rate of fire along the Upper Bois Brule River. These findings have important implications for future land management and can be used as a guide to achieve site specific goals.