Recent Crown Thinning in a Boreal Black Spruce Forest Does Not Reduce Spread Rate nor Total Fuel Consumption: Results from an Experimental Crown Fire in Alberta, Canada

Abstract

<jats:p>A 3.6 ha experimental fire was conducted in a black spruce peatland forest that had undergone thinning the year prior. After 50 m of spread in a natural stand at 35–60 m min−1, the crown fire (43,000 kW m−1 intensity using Byram’s method) encountered the 50% stem removal treatment; spread rates in the treatment were 50–60 m min−1. Fuel consumption in the control (2.75 kg m−2) was comparable to the treatment (2.35 kg m−2). Proxy measurements of fire intensity using in-stand heat flux sensors as well as photogrammetric flame heights had detected intensity reductions to 30–40% of the control. Crown fuel load reductions (compensated by higher surface fuel load) appear to be the most significant contributor to the decline in intensity, despite drier surface fuels in the treatment. The burn depth of 5 cm in moss and organic soil did not differ between control and treatment. These observations point to the limited effectiveness (likely reductions in crown fire intensity but not spread rate) of stem removal in boreal black spruce fuel types with high stem density, low crown base height and high surface fuel load. The observed fire behaviour impacts differ from drier conifer forests across North America.</jats:p>

Study of Fuel-Smoke Dynamics in a Prescribed Fire of Boreal Black Spruce Forest through Field-Deployable Micro Sensor Systems

“…Spikes in PM 2.5 concentrations in the north and northeast locations within 15 min of the fire-ignition are indicative of smoke generation from flaming combustion of canopy fuels. Combustion of canopy fuels occurred during the time when the fire front swept through unit 5 (the burn area) from the ignition line in the south towards the northern perimeter in about six minutes [27]. The timespan of canopy fuel combustion is in agreement with the time period when continued enhancements in PM 2.5 concentrations were recorded at the north and northeast micro-stations.…”

“…Smoke created by the smoldering phase of fires, mostly by the surface fuels, on the other hand, are shown to have a slower ground level propagation and are likely to result in sustained enhancements in particulate levels in ambient air. Although fuel loading from ground fuels contributing to smoldering in our study is estimated to be only 35% of total fuel [27], they contributed to higher particulate concentrations in air in downwind locations and for longer durations of time. This may be a key consideration in cases of wildland fires or preventive prescribed fires that may occur in close vicinity of communities.…”

“…The fire behavior and the spread to the north direction was recorded through in-situ measurements. Details can be found in Thompson et al [27]. Five micro-stations were deployed at downwind locations of the prescribed fire zone.…”

Effects of Prescribed Burn on Nutrient and Dissolved Organic Matter Characteristics in Peatland Shallow Groundwater

“…The area drains into a first-order beaver-impacted stream to the north. More details about the site can be found in [18]. The objective of the prescribed burn at this site was to test the effectiveness of stem removal fuel treatment in a black spruce forest [18].…”

Navigating the Wildfire–Pandemic Interface: Public Perceptions of COVID-19 and the 2020 Wildfire Season in Arizona

“…COVID-19 has drastically altered U.S. wildfire management and associated organization efforts, predominantly due to concerns about infection rates among firefighting crews and in fire camps that might reduce agency capacity to provide rapid suppression response [5,6]. This is particularly challenging as some incident response efforts depend on shared resources and personnel, and evolving travel restrictions may restrict opportunities to request aid both nationally and internationally for larger incidents [7,8].…”