Development of Vegetation and Surface Fuels Following Fire Hazard Reduction Treatment

Abstract

Abstract:In dry western Unites States forests where past resource management has altered the ecological role of fire and stand characteristics alike, mechanical thinning and prescribed burning are commonly applied in wildfire hazard abatement. The reduced surface fuel loads and stand structures resulting from fuels modifications are temporary, yet few studies have assessed the lifespan of treatment effects. We sampled forest fuels and vegetation following fuels reduction in a chronosequence of time since treatment in the northern Sierra Nevada and southern Cascade regions of California. Treatments altered overstory characteristics including stand density, basal area, and species composition. These effects were still present on the oldest treatment sites (8-15 years post-treatment). Other stand characteristics, particularly timelag fuel loads, seedling density, and shrub cover, exhibited substantial variability, and differences between treatment age classes and between treatment and control groups were not statistically significant. OPEN ACCESSForests 2012, 3 701

UC Cooperative Extension works with fire safe councils to reduce wildfires

“…Figure 2 shows that 8 years and more after fuel reduction, the treatments are still projected by fire models to greatly reduce the chance of a crown fire compared to untreated forest. The study findings (Chiono et al 2012) "suggest that in the forest types characteristic of the northern Sierra Nevada and southern Cascades, treatments for wildfire hazard reduction retain their effectiveness for more than 10-15 years and possibly beyond a quarter century. "…”

Effects of fuel treatments on California mixed-conifer forests

“…During thinning operations, fire-intolerant species (e.g., fir) are often targeted and the composition of residual surviving trees can be shifted toward fire-tolerant species, like pines (Chiono et al 2012); however, prescribed fire on its own does not necessarily shift tree species composition, because it rarely kills the large trees which contribute most of the seeds (van Mantgem et al 2011). Abundance of tree seedlings generally decreases in the years immediately following treatments (Schwilk et al 2009;Stevens et al 2014) but recovers over time (Chiono et al 2012).…”

“…There is evidence that mechanical thinning, prescribed fire, or a combination of the two can reduce shrub cover (Collins et al 2007;Wayman and North 2007) or have no effect (Chiono et al 2012;Collins et al 2007;Stevens et al 2014) over a span of 1 to 5 years posttreatment. Shrubs may respond positively to treatments over longer time periods by resprouting and regenerating from seed (Kane et al 2010;Stevens et al 2014), particularly when prescribed fire is used, as fire scarifies the seeds of many common montane chaparral species .…”

Quantifying Ladder Fuels: A New Approach Using LiDAR

“…Reported treatments covered 3999 ha, or 18% of the total study area (see Figure 1 for spatial arrangement) and were implemented primarily between 2003 and 2008 (10% of treatments were completed between 1999 and 2002). Treatment longevity has been estimated to be between 8 and 15 years in similar areas [14,15], so we were confident in including treatments up to 10 years old in the study sample.…”

“…These treatments have been shown to be effective in ameliorating fire behavior and reducing tree mortality through both modeled simulations [4,5] and when encountered by real wildfires [3,[6][7][8][9][10][11][12][13]. Recent studies suggest the duration for reduction in potential fire behavior and effects, or treatment longevity, can exist for up to 8-15 years in the Sierra Nevada [14,15]. Some have argued that fuel reduction treatments are the most cost-effective solution in the face of our current fire suppression expenditures because treating the forest will keep fire in check more economically than suppression alone [16].…”