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

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 km 2 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.