Fine-scale assessment of cross-boundary wildfire events in the western United States

Palaiologos Palaiologou,Cody R. Evers,Michelle A. Day,Max Nielsen-Pincus,Haiganoush K. Preisler,Alan A. Ager

doi:10.5194/nhess-19-1755-2019

Abstract

Abstract. We report a fine-scale assessment of cross-boundary wildfire events for the western US. We used simulation modeling to quantify the extent of fire exchange among major federal, state, and private land tenures and mapped locations where fire ignitions can potentially affect populated places. We examined how parcel size affects wildfire transmission and partitioned the relative amounts of transmitted fire between human and natural ignitions. We estimated that 85 % of the total predicted wildfire activity, as measured by area burned, originates from four land tenures (Forest Service, Bureau of Land Management, private, and state lands) and 63 % of the total amount results from natural versus human ignitions. On average, one-third of the area burned by predicted wildfires was nonlocal, meaning that the source ignition was on a different land tenure. Land tenures with smaller parcels tended to receive more incoming fire on a proportional basis, while the largest fires were generated from ignitions in national parks, national forests, and public and tribal lands. Among the 11 western states, the amount and pattern of cross-boundary fire varied substantially in terms of which land tenures were mostly exposed, by whom, and to what extent. We also found spatial variability in terms of community exposure among states, and more than half of the predicted structure exposure was caused by ignitions on private lands or within the wildland–urban interface areas. This study addressed gaps in existing wildfire risk assessments that do not explicitly consider cross-boundary fire transmission and do not identify the source of fire. The results can be used by state, federal, and local fire planning organizations to help improve risk mitigation programs.

Highlights

Statistical modeling of the ignition cause for simulated fires showed that 63 % of all predicted burned area was generated from natural ignitions (Fig. 2a), mostly originating on Forest Service (FS) (31 % of total area burned by natural ignitions on any land tenure), Bureau of Land Management (BLM) (30 %), private (24 %), and state and tribal lands (4 % each)
Fish & Wildlife Service (FWS) lands were mostly affected by natural ignitions, while city/county lands were mostly affected by human ignitions
When we examined where the major land tenures received most of their incoming fire (Table 2), BLM lands were more exposed to incoming fire ignited on private, FS, and state lands

Summary

Introduction

Most environmental hazard issues span multiple social, ecological, and political boundaries, especially atmospheric and water pollution (Mitchell, 1994; Hills et al, 1998; Uitto and Duda, 2002; Zeitoun and Warner, 2006; Van Eerd et al, 2015; Lyons, 2016; Brack, 2017), habitat conservation (Liu et al, 2017), watershed restoration (Sayles and Baggio, 2017), water supply (Bark et al, 2014; Lara, 2015), and numerous natural disturbances. Palaiologou et al.: Fine-scale assessment of cross-boundary wildfire events in the western US utive orders that address coordinated management across social and political boundaries (US Congress, 2014; USDA Forest Service, 2015a, b, 2018) Implementation of these authorities to perform risk reduction on mixed ownership planning areas has helped demonstrate how crossboundary collaboration can amplify the capacity of risk reduction activities by leveraging the economies of scale, i.e., expand the scale of fuel management (Graham et al, 2010; Ager et al, 2011) and community protection programs (Sexton, 2006; Abrams et al, 2016) commensurate with the scale of wildfire events (Charnley et al, 2016; Fischer et al, 2018; Markus et al, 2018)

Methods

Results

Discussion

Conclusion