Fire history and recent fire rotation periods in the Nova Scotia Acadian Forest

Abstract

Descriptive records of wildfires since the earliest writings and quantitative provincial fire records since 1915 have been used to produce a synthesis of fire history for the Province of Nova Scotia, Canada. Large annual burns were common up to the mid-1930's. Annual burns totalling over 15 000 ha occurred in each of the years 1918, 1920, 1921, 1930, 1934, 1944, and 1947, and annual burns totalling over 30 000 ha occurred in each of the years 1920 and 1921. Lightning has accounted for 1% of the number of fires (three per year). Thirty percent of the fires have occurred in the month of May; however, fires have been recorded for all months. Fire rotation periods for the province as a whole were 1000 or 2500 years, using the mean annual burn or median annual burn, respectively, for all burns in the years 1915 to 1975. In contrast, calculations of burned areas on maps produced at the turn of the century gave presuppression fire rotation periods of just over 200 years. Vegetation types have had widely varying fire rotation periods. The vegetation of Cape Breton Island has been subjected to almost no fires over 20 ha, whereas the vegetation type with the shortest fire rotation period (in the interior of western Nova Scotia) has been subjected to fire rotation periods as low as 65 years at the turn of the century, to about 2000 years for the years 1958 to 1975. A summary of fire rotation periods for the Boreal, Great Lakes – St. Lawrence, and Acadian Forest Regions found in the literature is presented for comparison with the Nova Scotia data, and more detailed comparisons are made between the fire rotation periods of the similar vegetation types in New Brunswick and Nova Scotia.