Stand-Level Fuel Reduction Treatments and Fire Behaviour in Canadian Boreal Conifer Forests

Abstract

Stand-level fuel reduction treatments in the Canadian boreal zone are used predominantly in community protection settings to alter the natural structure of dominant boreal conifer stands such as black spruce (Picea mariana (Mill.) BSP), jack pine (Pinus banksiana Lamb.) and lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia). The aim of these fuel treatments is to inhibit the development of fast-spreading, high-intensity crown fires that naturally occur in boreal forest ecosystems. We document fuel treatment design standards used in boreal forests in Canada and review data requirements and methodological approaches for investigating fuel treatment effects on fire behaviour. Through a series of illustrative examples and summaries of empirical observations, we explore the implications of data and modelling assumptions used to estimate fire behaviour in fuel-treated areas and identify insights about fuel treatment effectiveness in boreal conifer stands. Fuel treatments in black spruce, jack pine and lodgepole pine stands were generally effective at reducing modelled and observed fire behaviour and inhibiting crown fire development and spread under low to moderate fire weather conditions. Evidence suggests that fuel treatments in these fuel types will be ineffective when rates of spread and wind speeds are very high or extreme. High surface fuel loads combined with the relatively short stature of boreal conifer trees can further undermine fuel treatment efforts. Priority areas for future study include examining alternatives for managing surface fuel loads in treated stands, exploring the viability of alternative horizontal fuel reduction protocols such as clumped fuel configurations, and integrating suppression and containment strategies within the fuel treatment planning and design process.

Escalating carbon emissions from North American boreal forest wildfires and the climate mitigation potential of fire management

“…Fuel treatments, similar to those used in temperate forests of the western United States, may not modify and, in some cases, may actually increase carbon loss when implemented in boreal forests ( 49 , 50 ). Conversely, these same treatments are an important climate adaptation tool in boreal communities, where fuel modification can temper fire behavior and enhance defensibility during low to moderate fire weather ( 51 , 52 ). On a landscape scale, however, these treatments would be incongruent with the historical occurrence of fire in these ecosystems.…”

Fifty years of wildland fire science in Canada

“…At stand scales, uneven-aged silvicultural systems traditionally used to promote tree growth and enhance wildlife habitat are being renewed as fuel mitigation treatments to reduce wildland fire risk (Agee and Skinner 2005). Particular emphasis is placed on the wildland-urban interface, where treatments tailored to specific forest types have potential local benefits (Johnston and Flannigan 2018;Beverly et al 2020). At landscape scales, strategic location and configuration of fuel treatments aim to modify fire behaviour and mitigation of the wildland-urban interface (Finney 2001;Parisien et al 2007).…”

Fuel reduction treatments reduce modeled fire intensity in the sagebrush steppe

“…Despite the need for designing and employing effective fuel treatments to mitigate wildfire, there has been little research on the effects or longevity of fuel reduction treatments on potential fire behavior in sagebrush ecosystems. Relatively more literature exists with emphasis on forested ecosystems (i.e., Beverly et al, 2020; Johnston et al, 2021; Pique & Domenech, 2018) and on risk assessment (i.e., Syphard et al, 2011). Here, we used a long‐term and broad‐scale data set to describe fuel structure and accumulation for 10 years following fire, mechanical, and herbicide treatments in Wyoming big sagebrush communities across the northern Great Basin and quantified how those patterns impacted potential future fire behavior (flame length, rate of spread, and reaction intensity).…”