Short-term impact of post-fire salvage logging on regeneration, hazardous fuel accumulation, and understorey development in ponderosa pine forests of the Black Hills, SD, USA

Abstract

We examined the impacts of post-fire salvage logging on regeneration, fuel accumulation, and understorey vegetation and assessed whether the effects of salvage logging differed between stands burned under moderate and high fire severity following the 2000 Jasper Fire in the Black Hills. In unsalvaged sites, fire-related tree mortality created a large standing pool of available fuel, resulting in a rapid increase in surface fuel loads. After 5 years, fine woody debris (FWD) and coarse woody debris (CWD) increased ~1380% and 980% in unsalvaged sites, resulting in FWD and CWD loads of 13 and 25 Mg ha–1, respectively. In contrast, salvage logging limited the rate of accumulation of FWD to ~110% over the same time period and total accumulation of CWD to 16 Mg ha–1. In moderate-severity sites, regeneration was 75% lower in salvaged sites owing to low seed-tree retention, suggesting a re-evaluation of salvage guidelines during future operations in the Black Hills. The likelihood of timely regeneration in high-severity sites, regardless of salvage treatment, is low. We found no discernible effect of salvage logging on understorey development 5 years after fire. Logging caused neither a reduction in total plant cover nor an increase in the abundance of exotic species.

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

“…fine woody fuels, coarse woody fuels, and regenerating vegetation) are evaluated. Reducing fuel loadings and their influence on re-burn hazard requires thoughtful manipulation of current and future fuel inputs, including dead biological legacies and recovering vegetation (Raymond and Peterson, 2005;Keyser et al, 2009). The benefits post-fire hazardous fuels treatments have on maintaining ecosystem resilience must be weighed against the negative effects it has on the structure and function of these postfire environments if resilient landscapes remain the management goal.…”

“…This shrub layer could persist for decades more or gradually collapse as trees out-compete shrubs (Nagel and Taylor, 2005), continuing to contribute to fine woody fuel loadings. Eventually live vegetation will control fine and coarse woody fuel inputs (Hall et al, 2006;Keyser et al, 2009;Harmon, 2009), reducing the influence of dead-biological legacies on fire hazard.…”

Ten years after wildfires: How does varying tree mortality impact fire hazard and forest resiliency?

“…In mixed conifer forests severe fires may lead to increased surface fuel loading and thus high-intensity reburning in the future, especially in managed forests (Thompson et al, 2007;Odion et al, 2004). However, the few studies following wildfires in drier forest types such as ponderosa pine (Pinus ponderosa) suggest that fuel loadings in severely burned ponderosa pine types may not present a severe fire hazard (Passovoy and Fulé, 2006;Keyser et al, 2009). Further, even though most wildfires result in a mosaic of burn severities (Van Wagner, 1983), few studies have documented changes in stand structure and fuel complexes through time across the range of fire severity.…”

“…Productive ecosystems also require the maintenance of both coarse and fine surface fuel loadings. Whereas some coarse woody debris (CWD; woody material >7.62 cm) is needed to maintain wildlife habitat and soil productivity, high CWD can present excessive fire hazard (Brown et al, 2003) and these concerns often lead to post-fire logging (Donato et al, 2006;McIver and Ottmar, 2007;Thompson et al, 2007;Keyser et al, 2009). In addition to CWD, fine fuels are essential for forest productivity and to allow for the spread of surface fires (Zimmerman, 2003).…”

The efficacy of salvage logging in reducing subsequent fire severity in conifer-dominated forests of Minnesota, USA

“…The latter finding may be attributed to forest-floor alterations by harvesting equipment, which made the forest floor more susceptible to damage from heating. These results point to the importance of considering multiple criteria (here tree crown and forest floor), as well as details of the salvage operation (e.g., timing, equipment used, and amount of fuels left on site) when evaluating the ecological consequences of salvage logging (Greene et al 2006, Keyser et al 2009). In particular, the harvesting equipment used dictates the amount of forest-floor disturbance (Greene et al 2006), and the amount of slash remaining on-site post-salvage determines fire hazard, given that these fine fuels largely govern ignition, spread rate, and fire-line intensity (Dodge 1972, Rothermel 1972.…”