Fuel mass and forest structure following stand-replacement fire and post-fire logging in a mixed-evergreen forest

Abstract

Fuel profiles following fire & post-fire logging Donato et al. Abstract 28Following severe wildfires, managing fire hazard by removing dead trees (post-fire 29 logging) is an important issue globally. Data informing these management actions are relatively 30 scarce, particularly how fuel loads differ by post-fire logging intensity within different 31 environmental settings. In mixed-evergreen forests of Oregon, USA, we quantified fuel profiles 32 3-4 years after stand-replacement fire-assessing three post-fire logging intensities (0%, 25-33 75%, or >75% basal-area cut) across two climatic settings (mesic coastal, drier interior). Stand-34 replacement fire consumed ~17% of aboveground biomass. Post-fire logging significantly 35 reduced standing dead biomass, with high-intensity treatment leaving a greater proportion (28%) 36 of felled biomass on site compared to moderate-intensity treatment (14%) because of less 37 selective tree felling. A significant relationship between logging intensity and resulting surface 38 fuels (0.4-1.2 Mg*ha -1 increase per m 2 *ha -1 basal-area cut) indicated a broadly applicable 39 predictive tool for management. Down wood cover increased by 3-5 times and became more 40 spatially homogeneous after logging. Post-fire logging altered the fuel profile of early-seral 41 stands (standing material removed/transferred, short-term increase in surface fuels, likely 42 reduction in future large fuel accumulation), with moderate-intensity and unlogged treatments 43 yielding surface fuel loads consistent with commonly prescribed levels, and high-intensity 44 treatment resulting in greater potential need for follow-up fuel treatments. 45 46

Modeling the direct effects of salvage logging on long-term temporal fuel dynamics in dry-mixed conifer forests

“…Sites dominated by shrub communities have been shown to be positively correlated with increased re-burn severity when it occurs within a couple decades (Thompson and Spies, 2009;Parks et al, 2013). Salvage logging does not directly target shrub establishment and growth so we expect this fuel layer and resultant fuel inputs to be similar between unmanipulated and salvaged stands (Lopez-Ortiz, 2007), except when salvage logging temporarily slows establishment as heavy machinery kills the initial flush of vegetation (Donato et al, 2013). Understory woody vegetation cover averaged 70% and 2 m in height at our 24 year post-fire field plots.…”

“…Reducing post-fire fuels could mitigate re-burn fire hazard, although there remains a paucity of information regarding postfire temporal fuel dynamics and the direct effect salvage logging has on post-fire hazardous fuels. Some research suggests salvage logging exacerbates fire risk and hazard (Donato et al, 2006(Donato et al, , 2013, reduces hazardous conditions (Monsanto and Agee, 2008), or remains relatively neutral in its effect (McGinnis et al, 2010). Some of these disparate conclusions may result from the type of fuel being evaluated (e.g.…”

“…Salvage logging increases fine woody fuel loadings in early postfire environments (Donato et al, 2013;McGinnis et al, 2010;McIver and Ottmar, 2007), which has been suggested to increase re-burn hazard (Donato et al, 2006). Median fine woody fuel loadings increased by >300% (totaling 6.4 Mg ha À1 ) in salvaged stands relative to unmanipulated stands of southwest Oregon two years post-fire (Donato et al, 2006).…”

“…Salvage logging prescriptions can vary significantly depending on management objectives (Ritchie et al, 2013;Donato et al, 2013) but we have only represented one prescription. Our salvage logging scenario was adapted from salvage logging estimates reported by McIver and Ottmar (2007) in ponderosa pine forests Table 5 The year of maximum fuel loading and predicted values for each fuel layer in unmanipulated and salvaged logged stands for the three simulated stands selected to represent the distribution of pre-fire stand biomass from our sample plots.…”

Tamm Review: Management of mixed-severity fire regime forests in Oregon, Washington, and Northern California

“…Where they are appropriate, salvage operations should focus on the primary fuels that are the reburn concern, i.e., the smaller understory shade-tolerant trees that comprised the ingrowth over the period of fire exclusion (Peterson et al, 2015). Salvaging large trees provides a large economic benefit but has no known ecological benefit, and significant ecological costs (Donato et al, 2013;Lindenmayer et al, 2004;Noss et al, 2006;Long et al, 2014a). One recent study that focused on retaining the basal area of the largest trees was implemented in the severely burned 2003 Cone Fire area (Ritchie et al, 2007).…”