Strategically placed landscape fuel treatments decrease fire severity and promote recovery in the northern Sierra Nevada

Abstract

Strategically placed landscape area treatments (SPLATs) are landscape fuel reduction treatments designed to reduce fire severity across an entire landscape with only a fraction of the landscape treated. Though SPLATs have gained attention in scientific and policy arenas, they have rarely been empirically tested. This study takes advantage of a strategically placed landscape fuel treatment network that was implemented and monitored before being burned by a wildfire. We evaluated treatment efficacy in terms of resistance, defined here as the capacity to withstand disturbance, and recovery, defined here as regeneration following disturbance. We found that the treated landscape experienced lower fire severity than an adjacent control landscape: in the untreated control landscape, 26% of land area was burned with >90% basal area mortality, according to the remote-sensing-derived relative differenced Normalized Burn Ratio (RdNBR), while in the treated landscape only 11% burned at the same severity. This difference was despite greater pre-treatment fire risk in the treatment landscape, as indicated by FARSITE fire behavior modeling. At a more local scale, monitoring plots within the treatments themselves saw greater regeneration of conifer seedlings two years following the fire than plots outside the treatments. Mean seedling densities for all conifer species were 7.8 seedlings m-2 in treated plots and only 1.4 seedlings m-2 in control plots. These results indicate that SPLATs achieved their objective of increasing forest resistance and recovery.

Wildfire controls on evapotranspiration in California’s Sierra Nevada

“…Similar trends have been reported across the Western United States (Dennison et al 2014;Miller and Safford 2012;Westerling 2016). These increases have been attributed to overly dense forests with a buildup of surface and ladder fuels (Stephens et al 2012;Stephens et al 2009;Stevens et al 2017;Tubbesing et al 2019), and a longer fire season with drier and warmer summers and earlier spring snowmelt (Westerling et al 2006).…”

Fostering collective action to reduce wildfire risk across property boundaries in the American West

“…From an ecological standpoint, wildfires can burn large areas (>40 000 ha) and wildfire transmission occurs across land ownerships , Hessburg et al 2015, Palaiologou et al 2019. It is neither practical nor necessary to treat hazardous fuels everywhere to reduce wildfire risk; nevertheless, thousands of hectares must be treated to change fire behavior and reduce its severity (Finney et al 2007, North et al 2012, Krofcheck et al 2017, Tubbesing et al 2019. To be most effective, treatments should be strategically-placed and target high-hazard locations where wildfires are most likely to ignite and to burn (Finney et al 2007, Tubbesing et al 2019.…”

“…It is neither practical nor necessary to treat hazardous fuels everywhere to reduce wildfire risk; nevertheless, thousands of hectares must be treated to change fire behavior and reduce its severity (Finney et al 2007, North et al 2012, Krofcheck et al 2017, Tubbesing et al 2019. To be most effective, treatments should be strategically-placed and target high-hazard locations where wildfires are most likely to ignite and to burn (Finney et al 2007, Tubbesing et al 2019. Uncoordinated fuels treatments on individual land ownerships do not necessarily add up to, or optimize, landscape-scale wildfire risk reduction (Finney et al 2007, North et al 2012, Loudermilk et al 2014, Hessburg et al 2015, Palaiologou et al 2019.…”

Local forest structure variability increases resilience to wildfire in dry western U.S. coniferous forests

“…Severity patterns at a landscape scale (e.g., for a whole fire) may represent cross-scale emergences of the local influence of forest structure variability on fire effects (Peters et al 2004;Rose et al 2017). For instance, forest management actions (e.g., prescribed fire, use of wildfire under mild conditions) that reduce fuel loads and increase structural variability can be effective at reducing fire severity across broader spatial extents than the direct footprints of those actions (Graham et al 2004;Stephens et al 2009;Tubbesing et al 2019).…”