United States -A --A Department of Agriculture Fuel Reduction in Residential Forest Service and Scenic Forests: a Comparison Rocky Mountain Research Station of Three Treatments in a Western Research Paper RMRS-RP-5 Montana Ponderosa Pine Stand May 1998 Joe H. Scott The Author for a particular site, or compatibility with other resource objec- tives may guide the choice of treatment. Joe H. Scott is a Forester with Systems for Environmental Management (P.O. Box 8868, Missoula, MT 59807) and a Consulting Forester specializing in fuel treatments for the wild- Acknowledgments land and urban interface. He received a B.S. degree in forestry This research was supported in part by funding from the and resource management at the University of California at Rocky Mountain Research Station (formerly lntermountain Berkeley in 1990. He completed this study while pursuing an Research Station), Forest Service, U.S. Department of Agricul- M.S. degree in forestry at the University of Montana. ture, through Research Joint Venture Agreement #92685 with the School of Forestry, University of Montana. The assistance Research Summary of Professor Ronald Wakimoto at the University of Montana, Steve Slaughter and Risa Lange-Navarro of the Lolo National Three contrasting thinning treatments to reduce fire hazard Forest's Ninemile Ranger District, Elizabeth Reinhardt of the were implemented in a 100-year-oldponderosa pineIDouglas- lntermountain Fire Sciences Lab (IFSL), and Robert Benson of fir (Pinusponderosa/Pseudotsugamenzesiq stand on the Lolo Systems for Environmental Management has been greatly National Forest, MT. All treatments included a commercial appreciated. Jane Smith of the IFSL, Dave Thomas and Linda thinning designed to reduce crown fuels and provide revenue Wadleigh of U.S. Forest Service lntermounain Region, Jerry to offset costs. The treatments are outlined as follows: Williams of the U.S. Forest Service Northern Region, Phil Weatherspoon of the Pacific Southwest Forest and Range 1. Minimum impact: light commercial thinning from below, Experiment Station, and Robert Benson provided valuable with slash hand-piled and burned. reviews of the draft manuscript. I wish to especially thank 2. Revenue production: moderate commercial thinning Steve Arno of the IFSL for his guidance. from above, whole-tree harvest. 3. Forest restoration: moderate commercial thinning from below, with broadcast burn. Contents Total surface fuel loadings were reduced slightly by all Page treatments, but fine fuel load increased except in Treatment 3. Introduction ........................................................................ 1 All treatments raised crown base height and reduced crown Study Area ......................................................................... 2 bulk density, making crown fires less likely. Methods ............................................................................. 2 All treatments generated income in excess of treatment Treatments ..................................................................... 2 cost. Treatment 2 produced a net income of $832 per acre Fuels and Vegetation .............................. 1...................... 3 treated, Treatment 3 earned a net income of $222 per acre, and Visual Quality .................................................................. 4 Potential Fire Behavior 4 Treatment 1 generated a net income of $1 56 per acre in 1996 . .................................................. dollars. Economic Feasib~l~ty....................................................... 6 Analysis of the aesthetic quality of treated stands revealed Results and Discussion ...................................................... 7 that Treatment 1 was the most preferred, even over the un- Visual Quality .................................................................. 7 treated stand, and Treatment 3 the least preferred. Transitivity Potential Fire Behavior ................................................... 9 of preferences indicates that the preferences were not strong, Economics ....................................................................14 indicating that the treatments actually have similar aesthetic Review of Treatments ......................................................16 value. A severely burned but otherwise untreated stand, when Treatment 1: Minimum Impact ...................................... 16 included in the analysis, was preferred even less than Treat- Treatment 2: Revenue Production ...............................16 ment 3. Treatment 3: Forest Restoration .................................. 18 All treatments used in this demonstration were effective at Cbnclusions .....................................................................18 reducing forest fuels and cost-feasible while maintaining or References ....................................................................... 18 improving aesthetic quality. Individual preference, suitability On the cover: an untreated second-growth ponderosa pine1Douglas-fir stand (left), and the same stand after a moderate thinning followed by prescribed underburn (right). Rocky Mountain Research Station 324 25th Street Ogden, UT 84401 Fuel Reduction in Residential and Scenic Forests: a Comparison of Three Treatments in a Western Montana Ponderosa Pine Stand Joe H. Scott Introduction pine forests due to their high frequency. Today, in contrast, fires in pine forests are much less frequent Forests dominated by ponderosa pine (Pinusponde- but exhibit higher intensity and may become crown rosa) occupy roughly 40 million acres in the Western fires. This change in fire regime (frequency and in- United States (Van Hooser and Keegan 1988), more tensity of fires) can be partially attributed to changes than any other forest type. On roughly half of these in fuel loading and stand structure resulting from acres, ponderosa pine is a climax species that forms historic logging and fire suppression. The quantity of pure stands. As a result of fire exclusion, many climax dead and down fuels has increased, leading to greater pine forests have become overstocked and have devel- surface fire intensity and rate of spread. Stand den- oped thickets of seedlings and saplings. However, they sity has increased, leading to increased likelihood of do not exhibit a shift in species composition over time crown fire and making the trees more susceptible to in the absence of fire. On the other half of its range, fire damage. Also, the thickets of small trees provide a ponderosa pine is a seral species that can be succes- fuel ladder that allows a fire to burn from the surface sionally replaced by more tolerant species such as into the tree crowns. These changes in fuels and stand Douglas-fir (Pseudotsuga menziesii var. glauca) and structure lead to fires that cause more severe effects grand fir (Abiesgrandis). In the past, pine-dominated than in the past. forests persisted in a "fire climax" state despite this The ponderosa pine forest type is not only the most successionalpressure because of the species' ability to extensive and most altered by fire exclusion, but also survive frequent, low-intensity surface fires better one of the most used for residential and recreational than its would-be successors. In the absence of fire, development. Ponderosa pine forests are valued for seral pine forests also become overstocked. In addi- their scenic quality and proximity to urban centers. tion, they often develop an understory of shade-toler- Thinning in ponderosa pine forests will be necessary ant conifers. Sera1 pine forests may also exhibit a to reduce fire hazard and improve tree vigor. Because, compositional shift in favor of the more tolerant asso- there are few documented demonstration studies that ciates of ponderosa pine, making restoration more have applied hazard reduction treatments for residen- difficult. tial and recreational settings, it is difficult to gain the Although many old-growth ponderosa pine and public support necessary to successfully implement Douglas-fir stands were uneven-aged (Amo and oth- such treatments. ers 1995), most second-growth stands are even-aged. Fire hazard in ponderosa pine stands can be lessened Logging in the late 19th century, which removed by prescribed burning, removing understory fuels, nearly all merchantable trees from a stand, created pruning lower branches of small conifers, and thin- ideal conditions for regeneration of even-aged stands. ning the stand to lessen the likelihood of a crown fire The subsequent suppression of fire altered the distur- (Schmidt and Wakimoto 1988). In many cases in the bance regime of frequent, low-intensity fires respon- Western United States, severe wildfires have exhib- sible for creating the uneven-aged, pine-dominated ited reduced fire intensity and severity when they condition in the old growth forests (Arno and others burned into areas treated with prescribed fire 1995).Many pine forests have not experienced afirein the last 75 to 100 years, whereas under a "natural" (Biswell 196% Clark 1990) or thinnirig with fuel re- regime they would have experienced several during moval (McLean 1993). Such treatments generally that time. keep the fire from spreading into tree crowns, thereby These forests are flammable during the warm, dry reducing fire damage and making fire suppression summer months, and also burn under dry conditions more effective. during the spring and fall. The fires of past centuries Whether such a treatment is proposed for a residen- were characteristically of low intensity and severity