Abstract
Parks Canada, in collaboration with Nova Scotia Lands and Forests and Natural Resources Canada, documented shrub fire behaviour in multiple plots burned over two periods: a spring period in June 2014 and a summer period in July 2017. The study area, located within Cape Breton Highlands National Park, comprised fifteen burn units (20 m by 20 m in size). Each unit was ignited by line ignition and burned under a wide range of conditions. Pre-burn fuel characteristics were measured across the site and used to estimate pre-fire fuel load and post-fire fuel consumption. This fuel complex was similar to many flammable shrub types around the world, results show that this shrub fuel type had high elevated fuel loads (3.17 ± 0.84 kg/m2) composed of exposed live and dead stunted black spruce as well as ericaceous shrubs, mainly Kalmia angustifolia (evergreen) and Rhodora canadensis (deciduous). Data show that the dead moisture content in this fuel complex is systematically lower than expected from the traditional relationship between FFMC and moisture content in the Canadian Fire Weather Index System but was statistically correlated with Equilibrium Moisture Content. A significant inverse relationship between bulk density and fire rate of spread was observed as well as a clear seasonal effect between the spring burns and the summer burns, which is likely attributable to the increase in bulk density in the summer. Unlike most shrub research, wind and dead moisture content did not have a statistically significant association with fire spread rates. However, we believe this to be due to noise in wind data and small dataset. Rate of spread as high as 14 m/min and flame lengths over 4 m were recorded under Initial Spread Index values of 6.4 and relative humidity of 54%. A comparison with a number of well-known shrubland spread rate prediction models was made. An aid to operational fire prediction behaviour is proposed, using a fuel type from the Canadian Fire Prediction System (O-1b) and a modified estimate of fuel moisture of the elevated fuel in the fuel complex.
Highlights
In Nova Scotia, shrublands, known as coastal barrens or highland barrens, represent 6% of the province area and 12% of Cape Breton Highlands National Park (CBHNP) (Figure 1)
Material in 1–7 cm diameter size class mostly remained after the passage of the flaming front, and while it was measured in the resampling, variability was so high that no significant difference from pre-burn load amount in this category could be found
Wind speed is regularly observed to be the primary driver of the observed variability in fire length vs intensity relationship for the NS-1 fuel type similar to the form used by others
Summary
In Nova Scotia, shrublands, known as coastal barrens or highland barrens, represent 6% of the province area and 12% of Cape Breton Highlands National Park (CBHNP) (Figure 1). Intense fire behaviour has been observed in this type of vegetation under weather conditions that would, in other more typical forest stands, be considered low risk. Of different species composition, other shrub types in Australia, New Zealand, Portugal and Scotland exhibit species composition, other shrub types in Australia, New Zealand, Portugal and Scotland exhibit extreme fire behaviour under low fire danger as well [2,3,4,5,6]. The objective of this research project was to carry out and document a series of experimental The objective of this research project was to carry out and document a series of experimental fires in this novel NS-1 fuel type under a range of conditions and to assess the factors that influence fires in this novel NS-1 fuel type under a range of conditions and to assess the factors that influence fire behaviour, spread rate.
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