The recent fire history of Barron Township, Algonquin Park

Abstract

The recent fire history of Barron Township (18,600 ha) in Algonquin Park [Ontario, Canada] was studied by examining historical documents and dating past forest fires using dendrochronological techniques. Lightning is still a major ignition source. From 1939-1974, lightning accounted for 48.5% of all fires at a rate of 0.19 fires/yr per 10,000 ha. Dendrochronological data show that 16 fires burned during the 225 yr presuppression interval from 1696 to 1920 for a mean frequency of 14.1 yr. Five major fires (1875, 1864, 1854, 1780 and 1763) each burned at least half of the township with a mean frequency of 45 yr. Meteorological data show that drought prevailed across southern Ontario during 1875, when major fires burned in Barron Township and northern Minnesota [USA], supporting the suggestion that severe fire years correspond with periods of subcontinental drought. Similarly, 1864 appears to have been a major fire year in Barron as it certainly was in Minnesota. The recent fire rotation, i.e., the average time required to burn an area equivalent to the size of the study area, is about 70 yr. Field evidence and increment borings suggest the present vegetation mostly originated as a consequence of the 1875 fire.