Joseph M. Marschall

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

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.

Fire history reflects human history in the Pine Creek Gorge of north-central Pennsylvania

ABSTRACT Fire history studies are important tools for understanding past fire regimes and the roles humans played in those regimes. Beginning in 2010, we conducted a fire history study in the Pine Creek Gorge area of north-central Pennsylvania to ascertain the number of fires and fire-free intervals, their variability through time, and the role of human influences. We collected 93 cross sections from fire-scarred red pine (Pinus resinosa) snags, stumps, and living trees at three separate sites along the western rim of Pine Creek Gorge. From these, we found 79 fire years and 11 multidecadal fire-free intervals between 1600 and 2010. The three fire histories were quite synchronous; their fire years and fire-free periods mirrored one another despite being 12 to 14 km apart. Before 1791, fires were rare, suggesting a low population of American Indians and (or) little woodland burning by the tribes. A prolonged fire-free interval from 1650 to 1735 coincided with the Beaver Wars and the introduction of European diseases. Another fire-free period coincided with the American Revolutionary War. After that, fires became quite common with nearly all of them occurring within the next 125 years while Pine Creek Gorge was intensively logged. Since logging ended and fire control started in the 1910s, fires have been virtually absent from the three sites. Based on the fire and human histories, we conclude that human activities and culture are the driving forces behind the fire regimes of Pine Creek Gorge.

Spatial patterning of fuels and fire hazard across a central U.S. deciduous forest region

Information describing spatial and temporal variability of forest fuel conditions is essential to assessing overall fire hazard and risk. Limited information exists describing spatial characteristics of fuels in the eastern deciduous forest region, particularly in dry oak-dominated regions that historically burned relatively frequently. From an extensive fuels survey of unmanaged forest lands (1,446 plots) we described fuel loadings and spatial patterns of fine and coarse fuels. We attempted to explain the variability in fuel loading of each time-lag fuel class using landscape and seasonal variables through a multiple regression modeling approach. Size class distributions of woody fuels were generally homogeneous across the region except in the glaciated portions of Illinois where loadings appeared lower. Temporally, litter depths progressively decreased from leaffall (November). A fire hazard model that combined seasonal changes in litter depth and fuel moisture content depicted the degree of regional spatial variability during the transition between extreme dry and wet conditions. In the future, fire hazard indices could be paired with ignition probabilities in order to assess spatio-temporal variability of fire risk within the region.