LB1998

1. Effectiveness of Fuels Management at Reducing Area Burned and Carbon Loss from Wildfires Natural Resources Natural Resources Ressources naturelles Ressources naturelles Canada Canada Canada Canada Canadian Forest Canadian Forest Service canadien Service canadien Service Service des forêts des forêts LB1998 BU2098 BU2178 Area burned NW winds SE winds 5500 Scenarios Scenarios FS2098 FS2098 FS2178 FS2178 FB1998 FB1998 LB1998 LB1998 BU2098 BU2098 BU2178 BU2178 5000 FB1998 FS2098 FS2178 4500 4000 3500 3000 2500 2000 1500 1000 500 0 ENVIRONMENT K. Hirsch, V.Kafka, B. Todd, B. Amiro Introduction There are years in which forest fires play a significant role in the carbon budget. For example, during severe fire seasons, carbon released by wildfires can equal 75% of that emitted from fossil fuel combustion in Canada. In the boreal mixedwood forests, it may be possible to reduce area burned, and hence carbon emissions, from wildfires through the use of ‘fire-smart’ forest management techniques. Minimizing area burn from unwanted wildfire could not only contribute to lowering the future carbon emissions but also help to reduce the possibility of timber shortages and facilitate the inclusion of ecological goals in forest management. This exploratory analysis was conducted in the context of developing procedures and techniques for integrating fire and forest management In this study, we assessed the impact of using strategically located fuel treatments (fuel conversion and reduction) on the area burned and total fuel consumption by wildfires. Using the equations of the Canadian Forest Fire Behavior Prediction (FBP) System and a landscape fire growth model, wildfires were simulated in a 200,000 ha area of central Alberta. Fire size and fuel consumption were compiled for each fire to determine the vulnerability of each landscape to large fires and the potential effects on direct carbon loss. • Methods • Through consultation with local forest managers, a forest management scenario was developed in an attempt to reduce the chance of having large fires while maintaining timber production goals. This fire-smart scenario, which combines strategically located fuel treatments and intensive silviculture, was compared to a business-as-usual (i.e., two-pass) management approach by converting projected vegetation types of the future landscapes to FBP System fuel types at each 10-year interval for a 200-year period. Then, an hourly time-step, cellular propagation fire growth model was used to simulate fires on a few selected landscapes produced by the two methods. Ignition points were randomly located within a 5 km x 5 km stratified grid. One hundred and forty-six fires were grown for 13 hours under historical extreme spring-time fire weather conditions and for two dominant wind directions. Statistics for area burned and fuel consumption were obtained and the two scenarios were compared at different points in time. In addition, we compared the landscapes to one that was produced by simply superimposing the fuel breaks over the landbase in 1998. Fig.3. Examples of 3 simulated fires under the same weather conditions and ignition locations for the landbase in 1998 (LB1998) and landbase with superimposed fuel breaks (FB1998). Note the smaller area burned by the wildfires on the FB1998. Deciduous/mixed (some conifer) Deciduous/mixed Conifer production Conversion to mixed Conversion to conifer Intensive conifer production Mixed/deciduous (some conifer) Mixed/deciduous Maintain current • Results • There is a considerable decrease (25-30%) in average area burned and average fuel consumption when fuel breaks are added on the landbase in 1998 as well as between the BU2078 and FS2078 (Fig. 4). However, some large fires can still occur in the fire-smart scenario, only the likelihood of large fires has been reduced (Fig. 5). • The effectiveness of the fire-smart scenario takes several decades to be established and varies in time thereafter due to different proportions and spatial arrangement of fuels and to the harvesting of the fuel breaks. For example, the area burned is slightly larger in the FS2178 compared to BU2178. • In the study area, both scenarios result in the creation of a high proportion of grass and this results in higher potential area burned in the future. Note also that more grass may also decrease direct carbon loss from an individual fire but may actually increase fire frequency and total carbon loss over time. UNTREATED LANDSCAPES Fig.1. Compartments and objectives as designed by the forest managers in order to create the fire-smart scenario. Fuel consumption NW winds SE winds Fuel types (and flammability) Spruce-lichen woodland (moderate) Boreal spruce (high) Mature jack or lodgepole pine (moderate) Immature jack or lodgepole pine (high) Aspen (very low) [FUEL BREAK] Boreal mixedwood (30% D:70% C) (moderate) Boreal mixedwood (50% D:50% C) (low-moderate) [FUEL BREAK] No data or fuel Grass (moderate-high) Ponderosa pine-Douglas-fir (low-moderate) Fire size class (ha) < 5000 5000-10,000 10,00-15,000 Area burned (ha) Fuel consumption (kg/m2) Number of fires 15,000-20,000 > 20,000 TREATED LANDSCAPES Fig. 4. Average area burned and fuel consumption for wildfires in each landscape Fig. 5. Distribution of fire sizes in each landscape • Implications • It seems feasible to strategically change the landscape fuel continuity and arrangement with new forest management techniques to achieve goals of reducing the area burned. • The potential for reducing carbon loss needs further investigation due to the effect of fire frequency and indirect emissions from decomposition after wildfires. • The fire-smart method needs to be optimized to be more effective through time (i.e. the addition of spatially conscious constraints and dynamic fuel breaks). • Landscape fuels management techniques have to be applied on a larger area and comply with ecological, social, and economic goals. • The fire-smart method could have further benefits as an adaptive measure by counteracting a possible increase in fire danger associated with climate change. kilometers 20 0 20 Contact Information: Natural Resources Canada Canadian Forest Service Northern Forestry Centre 5320 - 122 Street Edmonton, AB T6H 3S5 780-435-7319 Collaborators Fig.2. FBP System fuel type landscapes and proportions for the landbase in 1998 (LB1998), landbase with superimposed fuel breaks (FB1998), business-as-usual approach in 2098 (BU2098) and 2178 (BU2178), and fire-smart approach in 2098 (FS2098) and 2178 (FS2178).