Determinig fire history from old white pine stumps in an oak-pine forest

Fire scars on stumps of white pine (Pinus strobus L.) in a red oak (Quercus rubra L.) white pine forest near Bracebridge, Ontario, were dated using dendrochronological methods. A chronological record of fires that caused basal scarring is preserved in the remnant white pine stumps, which were estimated to be up to 135 years old. Large cross-sections (1.4 to 0.75 m in diameter) were cut from the solid portion of the stump. Over 100 annual rings per stump facilitated the cross-dating of 72% of the cross-sections. A tree ring chronology between 1664 and 1852 from 21 dated fire scars found in the 1-km2 study area. The mean fire return intervals ranged from more than 76 years (between 1664 and 1740) to 5 years (betwwen 1741 and 1810). An abrupt increase in fire frequency after 1741 is attributed to increases in human population levels as Natives and European reoccupied the area. The frequent fires between 1741 and 1810 are hypothesized to have advanced the regeneration and dominace of red oak over sugar maple (Acer saccharum Marsh.) and contributed to the present dominace of red oak in the overstory.