Monday, August 4, 2008: 2:10 PM
104 D, Midwest Airlines Center
Background/Question/Methods As wildfires increase in size and severity, there is an increased need for science-based information regarding the impacts of postfire rehabilitation (e.g. salvage logging) activities on forest structure. Despite this need, few controlled studies exist that compare the ecological impacts of postfire salvage logging within ponderosa pine forests. In August 2000, the Jasper Fire burned ~34,000 ha of ponderosa pine forests in the Black Hills. Following the fire, we identified areas in which no postfire logging would occur and paired them with areas planned for salvage logging. In June 2001, we established 18 – 0.3 ha sites in burned/unsalvaged stands and 18 – 0.3 ha sites in burned/salvaged stands. Nine sites were established in both salvaged and unsalvaged moderate severity stands and nine sites were established in both salvaged and unsalvaged high severity stands. Sites were randomly established within fire severity classes. Salvaged sites were whole-tree harvested and grapple-skidded to landings where they were processed. Using ANOVA with repeated measures, we addressed how postfire salvage logging and fire severity affected the accumulation of hazardous surface fuels, the establishment of regeneration, and the development of understory vegetation over a five year period.
Results/Conclusions Fire-related tree mortality created a large, standing pool of potential fuel in salvaged and unsalvaged sites immediately postfire. In unsalvaged sites, fine woody debris (FWD) and coarse woody debris (CWD) increased ~1380% (0.9 Mg/ha – 13.3 Mg/ha) and ~980% (2.3 Mg/ha – 24.9 Mg/ha) between one and five years postfire, respectively. In contrast, the logging of incipient and delayed mortality in salvaged sites limited the rate of accumulation of FWD to ~110% over the same time period and limited CWD to only 16 Mg/ha after five years. Further accumulation of surface fuels makes increased fire hazard and fire severity a concern for managers, especially in unsalvaged areas where a substantial pool of dead biomass remains standing. In moderate severity sites, regeneration was 75% lower in salvaged than unsalvaged sites, largely due to low seed-tree retention suggesting a re-evaluation of salvage guidelines during future operations. Timely regeneration in high severity sites, regardless of salvage treatment, is unlikely. Logging caused neither a reduction in plant cover nor an increase in the abundance of exotic species five years postfire. Our results suggest the assessment of the potential impacts of salvage logging should be conducted on a site specific basis, integrating ecology, silviculture, and harvest systems.
Results/Conclusions Fire-related tree mortality created a large, standing pool of potential fuel in salvaged and unsalvaged sites immediately postfire. In unsalvaged sites, fine woody debris (FWD) and coarse woody debris (CWD) increased ~1380% (0.9 Mg/ha – 13.3 Mg/ha) and ~980% (2.3 Mg/ha – 24.9 Mg/ha) between one and five years postfire, respectively. In contrast, the logging of incipient and delayed mortality in salvaged sites limited the rate of accumulation of FWD to ~110% over the same time period and limited CWD to only 16 Mg/ha after five years. Further accumulation of surface fuels makes increased fire hazard and fire severity a concern for managers, especially in unsalvaged areas where a substantial pool of dead biomass remains standing. In moderate severity sites, regeneration was 75% lower in salvaged than unsalvaged sites, largely due to low seed-tree retention suggesting a re-evaluation of salvage guidelines during future operations. Timely regeneration in high severity sites, regardless of salvage treatment, is unlikely. Logging caused neither a reduction in plant cover nor an increase in the abundance of exotic species five years postfire. Our results suggest the assessment of the potential impacts of salvage logging should be conducted on a site specific basis, integrating ecology, silviculture, and harvest systems.
