Historic Fire Regime of an Upland Oak Forest in South-Central North America

Ryan D. DeSantis,David W. Stahle,Stephen W. Hallgren

doi:10.4996/fireecology.0603045

Ryan D. DeSantis, David W. Stahle + Show 1 more

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https://doi.org/10.4996/fireecology.0603045

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Abstract

Prescribed burning is used in upland oak forests of south-central North America to improve wildlife habitat, reduce fire hazard, restore ecosystem integrity, and maintain biological diversity. However, little is known about the frequency, seasonality, and ignition source of historic fires that shaped these forests. In general, it is believed that fire frequency in upland oak forests of south-central North America was influenced by climate and humans, and decreased since Euro-American settlement; yet there is a dearth of scientific evidence to support this conclusion. The objective of this study was to link the fire history of an upland oak forest in east-central Oklahoma with factors controlling the fire regime. We removed cross-sections from 69 dead post oak (Quercus stellata Wangenh.) trees in a 1 km2 area of old-growth post oak and blackjack oak (Q. marilandica Münchh.) forest, and determined the tree-ring record and exact dates of fire scars from 1750 to 2005, using standard dendrochronological methods. An increase in fire from the eighteenth to early twenty-first centuries appeared to be associated with changes in human occupation, and there was little evidence linking the frequency, severity, or extent of fires to climate factors including drought, lightning, and late-spring frosts. These findings appeared to contradict the belief that fire decreased from the eighteenth to early twenty-first centuries and appeared to emphasize the importance of anthropogenic ignition to the local fire regime.

Highlights

Anthropogenic fire has long played an important role in the ecology of south-central North American oak forests (Pyne 1982, Frost 1998, Bowman et al 2009)
The Kolmogorov-Smirnov Goodness-of-Fit (KS) tests determined that the Weibull distribution did not fit the fire interval data and that fire intervals were not normally distributed, so we report median fire intervals here because they are a better descriptor of central tendency than means with non-normally distributed data: 5.5 yr for the Osage time period, 3 yr for each of the Creek and Pre-Euro-American settlement (EAS) time periods, and 2 yr for each of the Post-EAS and Prescribed Burning time periods
Increasing human population corresponded with decreasing mean fire intervals (MFI) and lightning ignition did not appear to be a major factor

Summary

Introduction

Anthropogenic fire has long played an important role in the ecology of south-central North American oak forests (Pyne 1982, Frost 1998, Bowman et al 2009). Euro-American settlement (EAS) often displaced or replaced indigenous tribes, changing local- and sometimes large-scale impacts on land use (Williams 1989). Fire traditionally played a role in pre-EAS land management techniques used by indigenous tribes but was subsequently reduced or suppressed in south-central North America (Abrams 2005, Courtwright 2007). While some literature suggests that fire frequency decreased in oak forests of south-central North America throughout the nineteenth and twentieth centuries (Abrams 1986, 1992; Van Lear and Watt 1992; Nowacki and Abrams 2008), there is evidence to the contrary (Clark et al 2007). The importance of non-anthropogenic ignitions to fire regimes in North American deciduous forests is relatively unknown (Frost 1998, Peterson and Drewa 2006, Aldrich et al 2010)

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