Fire, Drought, and Humans in a Heterogeneous Lake Superior Landscape

Abstract

We used dendrochronology and historic data to examine spatial and temporal variation in the historic fire regime of a complex landscape adjacent to Lake Superior in the Huron Mountains, Michigan, USA. Across the study area, 330 dated fire scars were identified and cross-dated from 115 trees and seven sites, spanning the years 1439–2005. Most of the fires were small in spatial extent; larger fires were infrequent and occurred primarily in level landscape positions within 1.5 km of Lake Superior. Small, frequent fires also occurred at the higher elevations attributable to lightning ignitions. The mean fire interval (MFI) from 1439–1751 was 49 yr and then abruptly shortened to 18.5 yr until the 1900s, during which time the MFI across all sites was greater than 78 yr. From 1752–1900s, high fire frequency occurred even in relatively wet years, suggesting an increased human influence. We interpret these patterns in fire intervals in the context of topography and changes in human population, land use, and cultural perspectives on fire.