doi: 10.1093/forestscience/56.1.1pmid: N/A
This content is only available as a PDF. © 2010 by the Society of American Foresters
McIver, James D.; Fettig, Christopher J.
doi: 10.1093/forestscience/56.1.2pmid: N/A
This content is only available as a PDF. © 2010 by the Society of American Foresters
McIver, James Duncan; Weatherspoon, Charles Phillip
doi: 10.1093/forestscience/56.1.4pmid: N/A
The National Fire and Fire Surrogate (FFS) study is described, from its conceptual stage in early 1996 to the completion of its short-term phase in May 2006. Comprising 12 sites, the FFS study is a comprehensive multidisciplinary experiment designed to evaluate the economics and ecological consequences of alternative fuel reduction treatments in seasonally dry forests of the United States. The FFS study uses a common experimental design across the 12-site network, with each site consisting of a fully replicated experiment that compares four treatments: an unmanipulated control, prescribed fire, mechanical treatments, and mechanical + fire. We measured operational costs and variables within several components of the ecosystem, including vegetation, the fuel bed, soils, bark beetles, tree diseases, and wildlife in the same 10-ha experimental units. This design allowed us to assemble a fairly complete picture of ecosystem response to treatment at the site scale, and to compare treatment response across sites representing a wide variety of conditions. We offer the FFS study as a model for conducting a complex multidisciplinary management experiment focused on natural resource issues. We then discuss why we believe it was successful and how it could be improved. We discuss seven key features that we believe must be considered to conduct a successful multidisciplinary experiment: funding, design, partnerships, organization, standardization, data management, and outreach. Although experiments such as the FFS study are difficult to execute, they may be our best hope for answering some of our more pressing questions in the field of natural resource management.
Fiedler, Carl E.; Metlen, Kerry L.; Dodson, Erich K.
doi: 10.1093/forestscience/56.1.18pmid: N/A
Crown fires that burned thousands of ha of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) forests in recent years attest to the hazardous conditions extant on the western landscape. Managers have responded with broad-scale implementation of fuel reduction treatments; however. because threats to pine forests extend beyond fire, so too must the approaches to address them. This western Montana study evaluated four treatments in a randomized complete block experiment for their effects on stand structural characteristics, growth increment, and crown fire potential. Evaluation of control, burn-only, thin-only, and thin-burn treatments showed that the combined thin-burn treatment had the greatest number of desired effects, the burn-only had the fewest, and the thin-only was intermediate. The thin-burn significantly reduced stand density, canopy cover, torching hazard, and crowning hazard and increased average diameter, height-to live-crown, and basal area increment; the thin-only reduced stand density, canopy cover, and crowning hazard and increased average diameter and basal area increment; and the burn-only reduced torching hazard and increased height-to-live crown. These structural and growth effects are related to or influence numerous stand/ecosystem properties at our site, including diameter distributions, species composition, large-tree development potential, overall tree vigor, potential for shade-intolerant tree regeneration, and resiliency to fire. Results demonstrate that well-designed restoration treatments can promote key short-term stand and ecosystem responses while significantly reducing crown fire potential.
Waldrop, Thomas; Phillips, Ross A.; Simon, Dean A.
doi: 10.1093/forestscience/56.1.32pmid: N/A
This study tested the success of fuel reduction treatments for mitigating wildfire behavior in an area that has had little previous research on fire, the southern Appalachian Mountains. A secondary objective of treatments was to restore the community to an open woodland condition. Three blocks of four treatments were installed in a mature hardwood forest in western North Carolina. Fuel reduction treatments included chainsaw felling of small trees and shrubs (mechanical treatment), two prescribed fires 3 years apart, a combination of mechanical and burning treatments, and an untreated control. Mechanical treatment eliminated vertical fuels but without prescribed burning; the mechanical treatment added litter (11%) and woody fuels (1 hour 167%; 10 hours 78%) that increased several measures of BehavePlus4-simulated fire behavior (rate of spread, flame length, spread distance, and area burned) for 5 years. Prescribed burning reduced litter mass by 80% and reduced all simulated fire behavior variables for 1 year but had no residual effect by the third year. The combined mechanical and burning treatments had hot prescribed fires (mean temperature of 517°C at 30 cm aboveground) during the first burn that killed some overstory trees, resulting in increased amounts of woody fuels on the forest floor. All active treatments (fire, mechanical, and combined) reduced simulated wildfire behavior, even after a severe ice storm that added fine fuels. Prescribed burning in combination with the mechanical treatment was the most effective in reducing all measures of fire behavior and advancing restoration objectives. Each of the active treatments tested must be repeated to reduce fuels and lower wildfire behavior, but prescribed burning must be repeated frequently.
doi: 10.1093/forestscience/56.1.46pmid: N/A
Western United States land managers are conducting fuel reduction and forest restoration treatments in forests with altered structural conditions. As part of the National Fire and Fire Surrogate (FFS) study, thinning and burning treatments were evaluated for changing forest structure. Shifts between pretreatment and posttreatment diameter distributions at seven western FFS study sites were determined by assessing live tree diameter frequency distributions and the 10th and 90th percentile and mean diameter. Diameter distributions were based on 31,517 live trees within 76 pretreatment units and 25,061 live trees within 85 posttreatment units. Cross-site comparisons were made using meta-analysis. Values for 10th percentile diameter increased at two sites, values for 90th percentile diameter increased at six sites, and values for mean diameter increased at five sites (P < 0.05) after active treatments (thin, burn, or thin + burn) compared with control sites. Across the seven western FFS study sites, the overall effect size of the thin treatment increased for 90th percentile and mean diameter, the overall effect size of the burn treatment increased for 10th percentile, 90th percentile, and mean diameter, and the overall effect size of the thin + burn treatment increased for 10th percentile, 90th percentile, and mean diameter. This work indicates that although each of the active treatments was effective in shifting diameter distributions toward larger trees, no single treatment or entry will probably mitigate nearly a century of fire exclusion and fuel accumulation in dry coniferous forests of the western United States.
Fettig, Christopher; Borys, Robert; Dabney, Christopher
doi: 10.1093/forestscience/56.1.60pmid: N/A
We examined bark beetle responses to fire and fire surrogate treatments 2 and 4 years after the application of prescribed fire in a mixed-conifer forest in northern California. Treatments included an untreated control (C), thinning from below (T), and applications of prescribed fire (B) and T + B replicated three times in 10-ha experimental units. A total of 1,822 pine and fir trees (5.1% of all trees) were killed by bark beetles. Mountain pine beetle (Dendroctonus ponderosae Hopkins) was found infesting ponderosa pine (Pinus ponderosa Dougl. ex Laws.), sugar pine (Pinus lambertiana Dougl.), and lodgepole pine (Pinus contorta Dougl. ex Loud.); western pine beetle (Dendroctonus brevicomis LeConte) was found infesting ponderosa pine; and fir engraver (Scolytus ventralis LeConte) was found infesting white fir (Abies concolor [Gord. & Glend.] Lindl. ex Hildebr.). Significantly higher rates of bark beetle-caused tree mortality occurred on B (9.2%) than on C (3.2%), T (<1%), or T + B (3.3%) cumulatively during the 4-year period. A total of 723 pines (4.4% of all pines) were killed by bark beetles, primarily mountain pine beetle. Attacks resulted in significantly more pine mortality on B (5%) than on C, T, or T + B (all <1%) 2 years after the application of prescribed fire. No significant treatment effects were found during the second sample period or cumulatively during the 4-year period. A total of 1,098 white fir trees (5.8% of all white fir) were killed by the fir engraver. Attacks resulted in significantly higher rates of fir mortality on T + B than on T during both sample periods but not cumulatively during the 4-year period. Overall, bark beetle-caused tree mortality was concentrated in the smaller diameter classes. The implications of these and other results to forest management are discussed.
Hessburg, Paul F.; Povak, Nicholas A.; Salter, R. Brion
doi: 10.1093/forestscience/56.1.74pmid: N/A
Mechanical thinning and prescribed burning practices are commonly used to address tree stocking, spacing, composition, and canopy and surface fuel conditions in western US mixed conifer forests. We examined the effects of these fuel treatments alone and combined on snag abundance and spatial pattern across 12 10-ha treatment units in central Washington State. A snag census was conducted before and immediately after treatments on each unit where all snags were measured and classified as either “new” (<1 year as a snag) or “old” (>1 year as a snag) mortality, and bark beetle species were censused on the bottom 3-m of the bole. Before treatment, snags were found in all units and more than two-thirds of the snags were ponderosa pine. Burning (burn-only and thin + burn combined) treatments led to increases in total snag abundance in all but the largest diameter class. Snag abundance in the large snag class (>60 cm dbh) decreased in most treatment units indicating that units with high abundance before treatment had the potential to lose more snags with treatment or time. Treatments also affected the spatial distribution of snags. The thin-only treatment reduced clumpiness, leading to a more random snag distribution, whereas the burn-only and thin + burn treatments generally retained or enhanced a clumped snag distribution. Bark beetles attacked >75% of snags across all units before and after treatments, and red turpentine beetle (Dendroctonus valens LeConte) occurrence tended to increase after prescribed burning. Managers can use this information to tune silvicultural prescriptions to meet stocking, spacing, and fuel reduction objectives while retaining or recruiting snags, thereby increasing the utility of conditions for certain wildlife species.
Gaines, William; Haggard, Maryellen; Begley, James; Lehmkuhl, John; Lyons, Andrea
doi: 10.1093/forestscience/56.1.88pmid: N/A
We monitored the short-term (<3 years) response of land birds to restoration treatments (thin, burn, and thin-burn) in dry forests located on the eastern slope of the Cascade Range in Washington. Overall avian community composition did not change among the treatments. However, individual species responses varied with the chipping sparrow showing lower density in treatments, whereas hermit thrush, mountain chickadee, white-headed woodpecker, western bluebird, American crow, and common raven increased in treatment units. Daily survival rates of nesting guilds were similar in treated versus control stands; however, burn-only showed lower daily survival rates compared with other treatments. Additional research is needed to validate this result. Cavity-nesters (mountain chickadee, red-breasted nuthatch, and house wren) and foliage-nesters (chipping sparrow) used trees that were larger in diameter than available regardless of the treatment. Our results, in combination with other results from this study area, provide important implications for managers: (1) thin-burn treatments were effective at restoring habitat for several avian focal species; (2) spring burn treatments should be carefully designed to achieve desired restoration objectives; (3) large trees provide important habitat functions and are a key component for maintaining or restoring the viability of focal avian species; and (4) additional research is needed to better understand the effects of spring burning and the long-term effects of dry forest restoration treatments.
Farris, Kerry L.; Zack, Steve; Amacher, Andrew J.; Pierson, Jennifer C.
doi: 10.1093/forestscience/56.1.100pmid: N/A
We examined the short-term response of the bark-foraging bird community to mechanical thinning, prescribed fire, and thinning/prescribed fire combination treatments designed to reduce fuel loads at study sites throughout the continental United States as part of the national Fire and Fire Surrogate (FFS) project. We modeled the effects of study site, treatment, treatment category, and time since treatment on the foraging encounter rate of four individual species (red-breasted nuthatch [Sitta canadensis], mountain chickadee [Poecile gambeli], hairy woodpecker [Picoides villosus], and brown creeper [Certhia americana]) and assessed the relative importance of several tree and snag characteristics in the selection of foraging trees by these same species. The foraging encounter rate of all four species responded inconsistently across both treatment categories and study sites. Substrate diameter was the strongest and most consistent characteristic positively influencing the selection of foraging habitat structures for all species across all treatment categories. Other influential variables included the presence of bark beetles for red-breasted nuthatches, hairy woodpeckers, and brown creepers in control and burn-only treatment areas and tree species for brown creepers in burn-only and thin-only treatment areas. Although this study did not detect any major negative treatment response by any species, our results suggest that there is substantial variability in the reaction of this particular bird community to fuel reduction treatments and that managers may need to evaluate the effects of these treatments on a site-by-site and species-by-species basis.
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