Spatiotemporal Complexity of Fire in an Island-Lake Landscape, Border Lakes Region, Minnesota, USA

Abstract

The Border Lakes Region of Minnesota is a unique location to evaluate historical patterns of fire events owing to complex dynamics between the landscape, climate, land use, and role of disturbance. The fragmented landscape and resulting variability in topography may impart important controls on where fire occurs and how fire behaves. My dissertation evaluates how spatial and temporal patterns of historical fire in red pine dominated forests are driven by climate, landscape characteristics, and human land use. My research is aimed at identifying the mechanisms responsible for variations in fire occurrence, such as those that lead to large (synchronous) fire events versus small (asynchronous) fire events. Specifically, I assessed (1) the spatial and temporal patterns of synchronous and asynchronous fire events, (2) the drivers associated with the occurrence of synchronous and asynchronous fires, and (3) evaluate how the tenets of Island Biogeography, area and isolation, help explain patterns in historical fire events in red pine forests of the Border Lakes Region of Minnesota. I have been able to demonstrate that climate, specifically periods of extended drought, are responsible for larger, synchronous fire events while smaller, asynchronous fire events were not related to the variability landscape characteristics and likely related to human land use. In addition, fires were frequent on both islands and mainland sites and the fire event dates between these sites are similar across the landscape. Significant temporal variability in fire events occurred on islands and mainland sites between 1780 and the late 1800s, with fire events accumulating more on islands prior to 1830 and mainland sites accumulating more fire events after 1860. I speculate that fires in the Border Lakes region accumulated more rapidly on islands between 1780 and 1830 due to intense use of the landscape by humans, corresponding to the fur trade era. This result has significant weight regarding management considerations where historically, research has suggested that Indigenous communities have contributed relatively little to the frequency of ignitions. My research argues for the greater integration of traditional practices in resource management, specifically regarding prescribed burning where Indigenous communities likely had a significant effect in red pine forests.