The Fire and Fire Surrogate Study in the Sierra Nevada: Evaluating restoration treatments at Blodgett Forest and Sequoia National Park

Eric E. Knapp¹, Scott L. Stephens², James D. McIver³, Jason J. Moghaddas², and Jon E. Keeley¹

(¹US Geological Survey, Sequoia and Kings Canyon Field Station, 47050 Generals Highway, Three Rivers, CA 93271; ²Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720; ³Forestry and Range Sciences Lab, PNW Research Station, USDA Forest Service, 1401 Gekeler Lane, La Grande, OR 97850)

Paper Summary: The Fire and Fire Surrogate (FFS) study is a national research effort to evaluate the economics and ecological effects of alternative fuel reduction methods to reduce wildfire hazard. Funded by the Joint Fire Science Program, USDA Competitive Grants, and the National Fire Plan, the study consists of a network of 13 sites located in forested ecosystems across the country, each characterized by a historical regime of frequent low to moderate intensity fire. Two of these sites - Blodgett Forest Research Station and Sequoia National Park – are located in the Sierra Nevada. The consequences of four management options are being assessed at Blodgett Forest: mechanical treatment alone, prescribed fire alone, mechanical + prescribed fire, and untreated control. Treatments at the Sequoia National Park site are early season prescribed fire, late season prescribed fire, and untreated control. All sites in the network are collecting data on the same suite of variables, including overstory and understory vegetation, fuel and fire behavior, soils and the forest floor, wildlife, entomology, pathology, treatment costs, and utilization economics. Treatments at the Sequoia National Park site were completed in June of 2002, and all but the prescribed burns had been conducted at Blodgett Forest by October 2002. Post-treatment results from Blodgett Forest are only available for the period after thinning and prior to burning. The majority of post-treatment data collection at both sites will not occur until 2003 and 2004. Post-treatment data from both sites should be considered preliminary.

Blodgett Forest Research Station

· Mechanical thinning and mastication reduced total fuel loads from 150.0 tonnes/ha to 101.9 tonnes/ha. This may be explained by disturbance and burial of some of the litter and duff under soil with mechanical treatment.

· Mechanical thinning and mastication increased the proportion of woody fuel in small diameter size classes and increased fuel depth.

· How these changes to the fuel bed affect rate of spread and flame length in surface fires was not yet determined but it is expected that the desired fire hazard reduction goal was not met by thinning and mastication alone.

Sequoia National Park

• Very high pre-treatment fuel loading (192.8 tonnes/ha) was reduced 66% and 79% after early season and late season burns, respectively.
• Lower fuel consumption was likely due to the higher fuel moisture levels during the early season. Moisture in thousand-hour and duff fuels averaged 24% and 38%, respectively, at the time of the early season burns and 10% and 12%, respectively, at the time of the late season burns.
• Seventy one percent of the plot area was estimated to have burned within the early season units and 85% of the plot area was estimated to have burned within the late season units. Islands of unburned habitat may be important for post-fire recolonization by some plant and animal species.
• Initial (first season post-fire) mortality of trees smaller than 50 cm dbh was significantly less within early season burn units than late season burn units. Mortality of trees greater than 50 cm dbh did not differ between the burning season treatments.