High-severity fire: evaluating its key drivers and mapping its probability across western US forests
Document Type: Journal
Author(s): Sean A. Parks ; Lisa M. Holsinger ; Matthew Panunto ; W. Matt Jolly ; Solomon Z. Dobrowski ; Gregory K. Dillon
Publication Year: 2018

Cataloging Information

Alberta; Apache Highlands; Arizona - New Mexico Mountains; British Columbia; California central coast; California north coast; California south coast; Canadian Rockies; Colorado Plateau; ecoregional maps; extreme fire weather; fire management; fire severity; fuel reduction treatments; fuels management; high severity fire; Idaho; Landsat; live fuels; Middle Rockies; moderate fire weather; Montana; Nebraska; Nevada; North Dakota; Oregon; RBR - relativized burn ratio; South Dakota; Southern Rockies; Texas; topography; Utah - Wyoming Rockies; Utah High Plateaus; Washington; western Cascades
Record Maintained By:
Record Last Modified: September 12, 2018
FRAMES Record Number: 25960


Wildland fire is a critical process in forests of the western United States (US). Variation in fire behavior, which is heavily influenced by fuel loading, terrain, weather, and vegetation type, leads to heterogeneity in fire severity across landscapes. The relative influence of these factors in driving fire severity, however, is poorly understood. Here, we explore the drivers of high-severity fire for forested ecoregions in the western US over the period 2002–2015. Fire severity was quantified using a satellite-inferred index of severity, the relativized burn ratio. For each ecoregion, we used boosted regression trees to model high-severity fire as a function of live fuel, topography, climate, and fire weather. We found that live fuel, on average, was the most important factor driving high-severity fire among ecoregions (average relative influence = 53.1%) and was the most important factor in 14 of 19 ecoregions. Fire weather was the second most important factor among ecoregions (average relative influence = 22.9%) and was the most important factor in five ecoregions. Climate (13.7%) and topography (10.3%) were less influential. We also predicted the probability of high-severity fire, were a fire to occur, using recent (2016) satellite imagery to characterize live fuel for a subset of ecoregions in which the model skill was deemed acceptable (n = 13). These 'wall-to-wall' gridded ecoregional maps provide relevant and up-to-date information for scientists and managers who are tasked with managing fuel and wildland fire. Lastly, we provide an example of the predicted likelihood of high-severity fire under moderate and extreme fire weather before and after fuel reduction treatments, thereby demonstrating how our framework and model predictions can potentially serve as a performance metric for land management agencies tasked with reducing hazardous fuel across large landscapes.

Online Link(s):
Parks Sean A., Holsinger Lisa M., Panunto Matthew H., Jolly W. Matt, Dobrowski Solomon Z., Dillon Gregory K. 2018. High-severity fire: evaluating its key drivers and mapping its probability across western US forests. Environmental Research Letters 13(4):044037.