Fuel Reduction Treatments Research Articles

Changes in vegetation structure and composition in response to fuel reduction treatments in the South Carolina Piedmont

Fuel reduction treatments are helpful to restore ecosystem structure and function to forests that historically sustained frequent, low-intensity fires. But the impacts of these treatments on Piedmont forests are not well understood. We examined the effects of prescribed burning, thinning, and a combination of burning and thinning on community composition of Pinus taeda/ Pinus echinata forests in the South Carolina Piedmont to identify changes in community structure and species composition. Overstory basal area was reduced across all treatments. The combination of thinning and burning resulted in a substantial increase in sapling density, whereas the burn-only decreased slightly after 3 years. Seedling density for all tree species increased across all treatment units during the same time span. In addition, cover of grasses and forbs increased in the burn-only and thin + burn treatments. Treatments appeared to affect understory life forms differently with the burn-only treatment encouraging forb cover while the thin + burn treatment promoted shrub and graminoid abundance. Non-metric multidimensional scaling (NMS) indicated rapid changes in understory composition for the burn-only and thin + burn treatments, whereas the thin-only treatment showed a more gradual shift over time.

Changes in fuelbed characteristics and resulting fire potentials after fuel reduction treatments in dry forests of the Blue Mountains, northeastern Oregon

In many fire-prone forests in the United States, changes occurring in the last century have resulted in overstory structures, conifer densities, down woody structure and fuel loads that deviate from those described historically. With these changes, forests are presumed to be unsustainable. Broad-scale treatments are proposed to reduce fuels and promote stand development on trajectories toward more sustainable structures. Yet little research to date has identified the effects of these treatments, especially in low elevation dry ponderosa pine ( Pinus ponderosa) and Douglas-fir ( Pseudotsuga menziesii) forests. We report initial fuelbed conditions and changes immediately and 4–6 years after fuel reduction treatments in an operational-scale, replicated ( N = 4), completely randomized experiment in northeastern Oregon. Treatments included a single entry thin from below conducted in 1998, a late season burn conducted in 2000, a thin followed by burning (thin + burn), and a no action treatment which served as a control. Between 1998 and 2004, litter mass declined about 4.4 Mg ha −1 in thin units, about 4.1 Mg ha −1 in thin + burn units, and about 1.5 Mg ha −1 in burn units. Duff mass did not change with treatment. Mass of woody fuels in the 1 and 10 h timelag classes increased in thin units immediately after treatment, but fell to nearly pre-treatment levels by 2004. Mass of woody fuels in the 100 h timelag class increased about 1.6 Mg ha −1 in thin units, and decreased about 0.7 Mg ha −1 in burn units and about 0.1 Mg ha −1 in thin + burn units. There was no difference in the change in total woody fuel mass among all treatments. About 62% of the residual trees in the burn and the thin + burn units were charred; charring extended up the bole about 1.1 m. About 50% of the residual trees in the burn and thin + burn units had scorched lower crowns. Mean scorch height was 4.3 m. Log density was greater in control units compared to actively treated units and greater in the thin units compared to burn or thin + burn units. We used the Fuel Characteristic Classification System (FCCS) to construct a representative fuelbed for each unit from inventoried data and to calculate three indices of fire potential as measures of the change in fire hazard resulting from our treatments: surface fire behavior, crown fire behavior, and fuels available for consumption. Projected flame length, rate of spread, and reaction intensity are derived as metrics of future surface fire behavior. These results are discussed in the context of management options for restoration of ecosystem health in similar low elevation dry ponderosa pine and Douglas-fir forests.

Short‐Term Effects of Fire and Other Fuel Reduction Treatments on Breeding Birds in a Southern Appalachian Upland Hardwood Forest

Abstract: We compared the effects of 3 fuel reduction techniques and a control on breeding birds during 2001‐2005 using 50‐m point counts. Four experimental units, each >14 ha, were contained within each of 3 replicate blocks at the Green River Game Land, Polk County, North Carolina, USA. Treatments were 1) prescribed burn, 2) mechanical understory reduction (chainsaw‐felling of shrubs and small trees), 3) mechanical + burn, and 4) controls. We conducted mechanical treatments in winter 2001‐2002 and prescribed burns in spring 2003. Tall shrub cover was substantially reduced in all treatments compared to controls. Tree mortality and canopy openness was highest in the mechanical + burn treatment after burning, likely due to higher fuel loading and hotter burns; tree mortality increased with time. Many bird species did not detectably decrease or increase in response to treatments. Species richness, total bird density, and some species, including indigo buntings (Passerina cyanea) and eastern bluebirds (Sialia sialis), increased in the mechanical + burn treatment after a 1‐year to 2‐year delay; eastern woodpewees (Contopus virens) increased immediately after treatment. Hooded warblers (Wilsonia citrina), black‐and‐white warblers (Mniotilta varia), and worm‐eating warblers (Helmitheros vermivorus) declined temporarily in some or all treatments, likely in response to understory and (or) leaf litter depth reductions. Densities of most species affected by treatments varied with shrub cover, tree or snag density, or leaf litter depth. High snag availability, open conditions, and a higher density of flying insects in the mechanical + burn treatment likely contributed to increased bird density and species richness. In our study, fuel reduction treatments that left the canopy intact, such as low‐intensity prescribed fire or mechanical understory removal, had few detectable effects on breeding birds compared to the mechanical + burn treatment. High‐intensity burning with heavy tree‐kill, as occurred in our mechanical + burn treatment, can be used as a management tool to increase densities of birds associated with open habitat while retaining many forest and generalist species, but may have short‐term adverse effects on some species that are associated with the ground‐ or shrub‐strata for nesting and foraging.

Mechanical fuel treatment effects on fuel loads and indices of crown fire potential in a south central New Mexico dry mixed conifer forest

The ability of mechanical fuel reduction treatments to mitigate severe fire behavior in dry mixed conifer forests is of interest to land managers as well as the public. We compared fuel loads and indices of crown fire potential to test treatment effectiveness following commercial and non-commercial treatments with differing slash prescriptions in mixed conifer stands at three sites on the Lincoln National Forest in south central New Mexico. Surface and canopy fuels were measured and used to develop custom fuel models in NEXUS 2.0 to estimate torching and crowning indices. Results indicated herbaceous fuel loads were unchanged compared to controls 2 years post-non-commercial and 1 year post-commercial harvest treatment. Sound 1000-h fuels were greater in the scatter and commercial treatments compared to control treatments. The commercial treatment resulted in stand structure closer to historical conditions. Canopy base height increased in all treatments except in stands previously treated 20–30 years ago. Commercial harvest was the only treatment to reduce canopy bulk density and the potential for active crown fire, with the exception of one pile treatment. Non-commercial pile treatments increased the TI. However, due to the danger of crown fire initiation from adjacent stands, further overstory removal is needed in non-commercial treatments to lower crowning potential. Prescribed fire may be used to increase treatment effectiveness in all overstory removal treatments by decreasing surface fuels.

Research Article: Using GIS to Inform a Debate: Land Ownership Patterns and Prioritizing Wildfire Management Options in the Backcountry or near Communities

To prevent wildfires from damaging communities in the American West, many federal wildfire hazard reduction projects in the United States target fuel reduction on federal lands. Current federal policies stress efforts in the 77 million hectares of federally owned land considered to be in need of fuel reduction treatment. There is considerable debate, however, about whether this is more effective than fuel reduction efforts focused directly on the wildland-urban interface around communities. The project reported here uses Geographic Information Systems (GIS) to help provide spatial context and illustrate the approximate relative scales of the options involved. GIS was used to determine ownership patterns of lands in 500 meter buffers around all areas designated by the US Census as populated places in the 11 western states and to determine the amount of federal land most in need of treatment within these buffers. Within these 500 meter buffers, 68% of the lands are privately owned. Only 17.7% of the lands within the buffers are federal lands, while only 15%, or 310,771 hectares, of the buffers are both federally owned and considered to be most in need of treatment. A conclusion is drawn that targeting federal lands for fuel reduction may not sufficiently protect certain communities from wildland fire. Environmental Practice 9:112–118 (2007)

Seeing the forest for the fuel: Integrating ecological values and fuels management

Management of dry forests often involves trade-offs between ecological values, particularly those associated with closed-canopy forests, and reduction of severe wildlife risk. We review principles and our ecological research that can be used to design stand- and landscape-level fuel treatments in dry coniferous forests of western North America. The focus of ecological values is on the ecological web that includes the northern spotted owl ( Strix occidentalis caurina), its two primary prey species the northern flying squirrel ( Glaucomys sabrinus) and bushy-tailed woodrat ( Neotoma cinerea), and the vegetation (live and dead), mycorrhizal fungi, and arboreal lichens that support those prey species. For the landscape level, we describe an ongoing project to develop the FuelSolve computer tool that optimizes the area and location of a fuel treatment by minimizing potential fire behavior and minimizing loss of spotted owl habitat from treatment and potential fire. Some species will gain and some species will lose habitat when stand structure or composition is changed during fuel reduction treatments. Stand-level prescriptions might be altered to maintain or create patchiness of closed-canopy habitat elements, such as snags, down wood, mistletoe-infected trees, and large old trees, and open-canopy habitats can be tailored to ensure creation of suitable composition and structure for wildlife. Allocation of treatments across the landscape might be managed to minimize cumulative effects and impacts on target species populations. General approaches to landscape-level planning of ecologically sound fuel treatments include coarse- and fine-filter approaches. A coarse-filter approach would use some definition of the historical or natural range of variability to define the composition and pattern that might reasonably be expected to sustain the forest ecosystem. Three general approaches can inform fine-filter analysis and development of fuel reduction treatments at the landscape level. Population viability analysis provides sound principles based on attributes of the species population structure, life history and behavior, and environment (habitat) for guiding fine-filter analysis. Fine-filter analysis can be informed by operational modeling of treatment alternatives. Research publications can guide dry forest landscape management. Our FuelSolve optimization model described in this paper differs from other fuel planning models in this class by equally considering multiple optimization objectives for fuel treatment and ecologically important resources. We describe the results of FuelSolve prototype development, an evaluation of outputs for field use, and future development efforts.

Short-term response of shrews to prescribed fire and mechanical fuel reduction in a Southern Appalachian upland hardwood forest

As part of the multidisciplinary National Fire and Fire Surrogate study, we used drift fences with pitfall traps from May to September 2003 and 2004 to determine how three fuel reduction techniques affected shrews in the Southern Appalachian Mountains of North Carolina. Ground-dwelling macroarthropods also were collected from a subset of pitfall traps to assess relative prey availability among the treatments. Four experimental units, each >14 ha were contained within each of three replicate blocks. Treatments were (1) prescribed burning; (2) mechanical felling of shrubs and small trees; (3) mechanical felling + burning; (4) forested controls. Mechanical understory felling treatments were conducted in winter 2001–2002, and prescribed burning was conducted in March 2003. High-intensity fires and high tree mortality increased canopy openness in mechanical felling + burn treatment compared to the others. Burning reduced leaf litter depth in both the burned treatments (burn only and mechanical felling + burn), whereas mechanical understory felling alone increased leaf litter depth in that treatment. Dry biomass of ground-dwelling macroarthropods was similar among the treatments and control. We collected a total of 269 shrews of four species during 2003 and 2004, including northern short-tailed shrews ( Blarina brevicauda), smokey shrews ( Sorex fumeus), pygmy shrews ( S. hoyi), and southeastern shrews ( S. longirostris). Relative abundance of all shrews combined and pygmy shrews was lowest in the mechanical felling + burn treatment, but differed significantly only from the mechanical understory felling treatment where the contrast in leaf litter depth was high. Our results indicate that low-intensity fuel reduction treatments, with minimal change to canopy cover or leaf litter depth, have little impact on shrews. However, high-intensity disturbance, such as prescribed burning that kills trees and dramatically reduces shade and leaf litter depth, can reduce the abundance of some shrew species and all shrews combined, at least in the short term.

Spatial Patterns of Fire Occurrence in the Central Appalachian Mountains and Implications for wildland Fire Management

We investigated spatial variations in the incidence of anthropogenic and natural (lightning-ignited) fire in the central Appalachian Mountains of Virginia and West Virginia using a record of wildland fires that occurred on federal lands between 1970 and 2003. A consideration of spatial variability in wildland fire is important for allocating fire-suppression resources and for informing resource managers who use naturally ignited wildland fires or prescribed fires in ecological restoration efforts and fuel reduction treatments. The central Appalachian region contains three physiographic provinces with distinct climate, terrain, and vegetation characteristics. Comparing ignition density, maximum fire size, and fire cycle among the three provinces indicated that the Appalachian Plateau—the westernmost province and also the highest, coolest, and wettest of the three—was the least fire-prone environment. The Blue Ridge province along the eastern edge of the region was most fire prone. The Ridge and Valley province, which occupies the center of the region, generally was intermediate in fire characteristics, despite having the driest climate and the greatest extent of flammable pine (Pinus L.)-and oak (Quercus L.)-dominated forests. At a finer spatial scale, fire activity varied topographically in all three provinces: ignition density declined with increasing elevation, but showed weaker, less consistent relationships to aspect. Spatial variations in the importance of natural fires may be of particular interest to federal resource managers who are developing plans for permitting natural fires to burn to restore fire-associated ecosystems. The Blue Ridge appears to be a particularly favorable environment for natural ignitions.

Pre-wildfire fuel treatments affect long-term ponderosa pine forest dynamics

The 2002 Rodeo–Chediski fire, the largest wildfire in south-western USA history, burned over treated stands and adjacent untreated stands in the Apache–Sitgreaves National Forest, setting the stage for a natural experiment testing the effectiveness of fuel reduction treatments under conditions of extraordinary fire severity. In seven pairs of treated–untreated study sites measured 2 years after the fire, thinning was strongly associated with reduced burn severity. Treated areas had more live trees, greater survival, and reduced fire intensity as indicated by crown base height and bole char. Ponderosa pine regeneration was patchy but more dense in treated areas. We assessed decade- to century-long effects of the pre-wildfire fuel treatments using the Forest Vegetation Simulator (FVS). Differences between treated and untreated areas were projected to persist for several decades after the fire in terms of stand structure characteristics and for at least 100 years in terms of species composition, with ponderosa pine making up ~60% of basal area in treated areas but only 35% in untreated areas. Future ecosystem development may take the trajectory of recovery to a ponderosa pine/Gambel oak forest or of a shift to an alternative stable state such as an oak-dominated shrubfield, with untreated areas more apt to undergo a shift to a shrubfield state. Current management decisions about fuel treatments have multi-century legacies.

The effects of fuels treatments on soil carbon respiration in a Sierra Nevada pine plantation

Fire-prone forests in the American west are presently slated for extensive fuels reduction treatments, yet the effect on soil CO 2 efflux rates, or soil respiration, has received little attention. This study utilizes the homogeneity of a Sierra Nevada ponderosa ( Pinus ponderosa Dougl. ex P. & C. Laws)–Jeffrey pine ( Pinus jeffreyi, Grev. & Balf.) plantation to investigate changes in soil respiration following mechanical shredding of understory vegetation, or mastication, in 2004; mastication coupled with prescribed burning in 2005; and burning alone also in 2005 as measured over the growing seasons from 2003 to 2005. Soil respiration, soil temperature and soil moisture were measured in two masticated stands which were burned the following year, and in one burned stand; the three of which were compared with two controls stands. Soil respiration response to treatments was detectable even though spatial variability within sites was high (coefficients of variation of 39–66%). Mastication produced short-term reductions in respiration rates, reduced soil moisture by 20%, and mitigated a year-to-year reduction in soil temperature evidenced by controls. Prescribed fire in masticated stands lowered soil respiration from 3.42 to 2.68 μmol m −2 s −1 while fire in the untreated stand raised rates from 3.41 to 3.83 μmol m −2 s −1, although seasonal increases in control sites were greater than those in the untreated stand. Masticated then burned site soil moisture increased by 52% while soil temperature decreased over the span of the growing season. Microclimate variables were not consistently effective in explaining spatial trends. Exponential models using soil temperature and/or moisture to predict temporal trends in respiration were only significant in treated stands, suggesting that treatment implementation increased sensitivity to environmental factors. These results imply that fuels reduction practices in water-stressed forests may have important consequences for ecosystem carbon dynamics.

SMALL MAMMALS AND FOREST FUEL REDUCTION: NATIONAL-SCALE RESPONSES TO FIRE AND FIRE SURROGATES

Forest fuel reduction treatments are increasingly used by managers to reduce the risk of high-severity wildfire and to manage changes in the ecological function of forests. However, comparative ecological effects of the various types of treatments are poorly understood. We examined short-term patterns in small-mammal responses to mechanical thinning, prescribed-fire, and mechanical thinning/prescribed-fire combination treatments at eight different study areas across the United States as a part of the National Fire and Fire Surrogate (FFS) Project. Research questions included: (1) do treatments differ in their effect on small mammal densities and biomass? and (2) are effects of treatments consistent across study areas? We modeled taxa-specific densities and total small-mammal biomass as functions of treatment types and study area effects and ranked models based on an information-theoretic model selection criterion. Small-mammal taxa examined, including deer mice (Peromyscus maniculatus), yellow-pine chipmunks (Tamias amoenus), and golden-mantled ground squirrels (Spermophilus lateralis), as well as all Peromyscus and Tamias species, had top-ranked models with responses varying both by treatment type and study area. In each of these cases, the top-ranked model carried between 69% and 99% of the total weight in the model set, indicating strong support for the top-ranked models. However, the top-ranked model of total small-mammal biomass was a model with biomass varying only with treatment (i.e., treated vs. untreated), not by treatment type or study area; again, this model had strong support, with 75% of the total model weight. Individual species and taxa appear to have variable responses to fuel reduction treatment types in different areas; however, total small-mammal biomass appears generally to increase after any type of fuel reduction. These results suggest that there is substantial variability in taxa-specific responses to treatments and indicate that adaptive management policies may be necessary when applying fuel reduction treatments in areas where management of small-mammal populations is of interest. Adaptive management can be used by managers who are conducting fuel reduction treatments to reduce uncertainty as to which treatments are locally optimal for meeting objectives for the management of small-mammal populations.

Modeling Fuel Treatment Costs on Forest Service Lands in the Western United States

Abstract Years of successful fire suppression have led to high fuel loads on the nation's forests, and steps are being taken by the nation's land management agencies to reduce these fuel loads. However, to achieve desired outcomes in a fiscally responsible manner, the cost and effectiveness in reducing losses due to wildland fire of different fuel treatments in different forest settings must be understood. Currently, prioritizing fuel treatment activities and planning budget expenditures is limited by a lack of accurate cost data. The primary objective of this research was to develop regression models that may be used to estimate the cost of hazardous fuel reduction treatments based on USDA Forest Service Region, biophysical setting, treatment type, and design. A survey instrument was used to obtain activity-specific information directly from fire management officers at Forest Service Ranger Districts for treatments occurring between 2001 and 2003. For both prescribed burns and mechanical activities, treatment size described the largest amount of variation in cost per acre, with increased size reducing cost per acre, on average. We confirmed that data on Forest Service fuel treatment activities maintained in the National Fire Plan Operations and Reporting System were not sufficiently accurate for reasonable cost analysis and modeling.

Response of white-footed mice ( Peromyscus leucopus) to fire and fire surrogate fuel reduction treatments in a southern Appalachian hardwood forest

An experiment conducted as part of the multidisciplinary National Fire and Fire Surrogate Study was designed to determine effects of three fuel reduction techniques on small mammals and habitat structure in the southern Appalachian mountains. Four experimental units, each >14-ha were contained within each of three replicate blocks at the Green River Game Land, Polk County, NC. Treatments were (1) prescribed burning (B); (2) mechanical felling of shrubs and small trees (M); (3) mechanical felling + burning (MB); (4) controls (C). Mechanical understory felling treatments were conducted in winter 2001–2002, and prescribed burning was conducted in March 2003. After treatment, there were fewer live trees, more snags, and greater canopy openness in MB than in other treatments. Leaf litter depth was reduced by burning in both B and MB treatments, and tall shrub cover was reduced in all fuel reduction treatments compared to C. Coarse woody debris pieces and percent cover were similar among treatments and controls. We captured 990 individuals of eight rodent species a total of 2823 times. Because white-footed mice composed >79% of all captures, we focused on this species. Populations in experimental units increased 228% on average between 2001 and 2002, but there was no evidence of an effect of the mechanical treatment. From 2002 to 2003, all units again showed an average increase in relative population size, but increases were greater in MB than in the other treatments. Age structure and male to female ratio were not affected by the fuel reduction treatment. Average adult body weight declined from 2001 to 2002, but less so in M than in units that remained C in both years. The proportion of mice captured near coarse woody debris was similar to the proportion captured in open areas for all treatments, indicating that white-footed mice did not use coarse woody debris preferentially or change their use patterns in response to fuel reduction treatments. Land managers should understand possible effects of different fuel reduction treatments on white-footed mouse populations, as they are an important component of the fauna and food chain of deciduous southern Appalachian forests.

The effects of mechanical fuel reduction treatments on the activity of bark beetles (Coleoptera: Scolytidae) infesting ponderosa pine

Selective logging, fire suppression, forest succession and climatic changes have resulted in high fire hazards over large areas of the western USA. Federal and state hazardous fuel reduction programs have increased accordingly to reduce the risk, extent and severity of these events, particularly in the wildland–urban interface. In this study, we examined the effects of mechanical fuel reduction treatments on the activity of bark beetles in ponderosa pine, Pinus ponderosa Dougl ex. Laws., forests located in Arizona and California, USA. Treatments were applied in both late spring (April–May) and late summer (August–September) and included: (1) thinned biomass chipped and randomly dispersed within each 0.4 ha plot; (2) thinned biomass chipped, randomly dispersed within each plot and raked 2 m from the base of residual trees; (3) thinned biomass lopped-and-scattered (thinned trees cut into 1–2 m lengths) within each plot; (4) an untreated control. The mean percentage of residual trees attacked by bark beetles ranged from 2.0% (untreated control) to 30.2% (plots thinned in spring with all biomass chipped). A three-fold increase in the percentage of trees attacked by bark beetles was observed in chipped versus lopped-and-scattered plots. Bark beetle colonization of residual trees was higher during spring treatments, which corresponded with peak adult beetle flight periods as measured by funnel trap captures. Raking chips away from the base of residual trees did not significantly affect attack rates. Several bark beetle species were present including the roundheaded pine beetle, Dendroctonus adjunctus Blandford (AZ), western pine beetle, D. brevicomis LeConte (AZ and CA), mountain pine beetle, D. ponderosae Hopkins (CA), red turpentine beetle, D. valens LeConte (AZ and CA), Arizona fivespined ips, Ips lecontei Swaine (AZ), California fivespined ips, I. paraconfusus Lanier (CA) and pine engraver, I. pini (Say) (AZ). Dendroctonus valens was the most common bark beetle infesting residual trees. A significant correlation was found between the number of trees chipped per plot and the percentage of residual trees with D. valens attacks. A significantly higher percentage of residual trees was attacked by D. brevicomis in plots that were chipped in spring compared to the untreated control. In lopped-and-scattered treatments, engraver beetles produced substantial broods in logging debris, but few attacks were observed on standing trees. At present, no significant difference in tree mortality exists among treatments. A few trees appeared to have died solely from D. valens attacks, as no other scolytids were observed in the upper bole. In a laboratory study conducted to provide an explanation for the bark beetle responses observed in this study, monoterpene elution rates from chip piles declined sharply over time, but were relatively constant in lopped-and-piled treatments. The quantities of β-pinene, 3-carene, α-pinene and myrcene eluting from chips exceeded those from lopped-and-piled slash during each of 15 sample periods. These laboratory results may, in part, explain the bark beetle response observed in chipping treatments. The implications of these results to sustainable forest management are discussed.

Considerations for characterizing fuels as inputs for fire behavior models

Active crown fires affect forest ecosystem structure and function, and the livelihood of the surrounding human communities. Researchers and managers use simulation models to understand fire behavior and predict fire hazard. Accurate predictions depend on the capacity of simulation models to represent the processes that control fire behavior and on the quality of the data used. The data required to predict crown fire hazard include surface and canopy fuel characteristics. Because these variables are difficult to measure, fire behavior specialists categorize surface fuels into standard Surface Fuel Models, and calculate canopy fuel variables based on assumptions (e.g., canopy base height (CBH), canopy bulk density (CBD)). Our objectives were: (1) to analyze the sensitivity of CBH and CBD to assumptions made in their calculations, and (2) to determine the consequences for crown fire hazard due to variability in CBH, CBD and among Fuel Models. We calculated a range of values of CBH and CBD for 14 ponderosa pine stands in the Colorado Front Range, USA, by varying the assumptions made in their calculations. We found that CBH and CBD were sensitive to crown shape. If shapes were observed in the field, these metrics would better represent canopy structure. We used NEXUS, a spreadsheet model, to predict crown fire hazard at the 14 sites, using the above-mentioned range of CBH and CBD values, and four different Surface Fuel Models commonly used in montane forests. NEXUS predicted that more extreme weather was generally needed for wildfires to reach the crowns of trees than for the fires to actively spread once they had crowned. The selected fuel model was the main variable affecting crown fire hazard. Seven sites burned in 2002, after our field data were collected. Correspondence between burn severity and NEXUS predictions of fire behavior was generally high. Where this correspondence was weak, the differences could be assigned to variation in weather conditions or the presence of hard to quantify ladder fuels. Our results demonstrate that researchers and managers need to estimate inputs fire behavior models carefully to enhance their predictive capacity. They also suggest that prescribed fires are likely effective fuel reduction treatments.

Fuel reduction treatment and wildfire influence on carabid and tenebrionid community assemblages in the ponderosa pine forest of northern Arizona, USA

We investigated the response of community assemblages of carabids (Coleoptera: Carabidae) and tenebrionids (Coleoptera: Tenebrionidae) from June to August in 2003 and 2004 on ponderosa pine forest stands of various conditions that were created by fuel reduction treatments (thinning, and thinning plus prescribed burning) and wildfires between 1987 and 1996 in northern Arizona. We found that richness and abundance increased for carabids but decreased for tenebrionid significantly from June (the driest season of the year) to August (wet monsoon season of the year), a temporal partition for ecological niches in ponderosa pine forests. For both taxa, wildfire burned stands had the highest species richness and diversity; whereas the thinned stands had the highest species evenness. Both fuel reduction treatment and wildfire resulted in significantly different community assemblages of carabids and tenebrionids compared to unmanaged stands. Results showed that carabids from the genera of Amara, Anisodactylus, Cicindela, Harpalus, Radine, and tenebrionids in the genus of Eleodes were ecological indicators for wildfire stands. However, Synuchus dubius, and Coelocnemis spp.1 were indicator species for thinned stands, and unmanaged stands, respectively. We concluded that the richness and diversity of both taxa tended to increase after fuel reduction treatment and wildfire, and that some species from both taxa were suitable as ecological indicators for the structural change of ponderosa pine forests. Creating a mosaic of heterogeneous landscape through mechanical fuel reduction treatments is an important management strategy to maintain high invertebrate species diversity in ponderosa pine forest ecosystems in the southwestern US.

Investments in Fuel Removals to Avoid Forest Fires Result in Substantial Benefits

Abstract Forest fuel reduction treatments are needed, as shown by the increased number and cost of devastating crown fires in overly dense forests. Although large trees can be removed for valuable products, the market value for the smaller logs may be less than the harvest and hauling charges, resulting in a net cost for thinning operations. However, failure to remove these small logs results in the retention of ladder fuels that support crown fires with destructive impacts to the forest landscape. A cost/benefit analysis broadened to include market and nonmarket considerations indicates that the negative impacts of crown fires are underestimated and that the benefits of government investments in fuel reductions are substantial.

Forest landowner decisions and the value of information under fire risk

We estimate the value of three types of information about fire risk to a nonindustrial forest landowner: the relationship between fire arrival rates and stand age, the magnitude of fire arrival rates, and the efficacy of fuel reduction treatment. Our model incorporates planting density and the level and timing of fuel reduction treatment as landowner decisions. These factors affect, among other things, the loss a landowner incurs should fire arrive before harvesting. The value of information depends on the nature and combination of mistakes a landowner makes, the relationship between fire arrival and stand age, and on whether the landowner undertakes fuel treatment and values nontimber benefits. Information of various types is of most value to a landowner who does not undertake fuel treatment. The value of information about the magnitude of fire risk is also more than twice as high when the landowner underestimates fire risk, rather than overestimating it. For a landowner who undertakes fuel treatment but makes multiple mistakes, the asymmetry between overestimating and underestimating fire risk and efficacy of fuel reduction is even more pronounced.

Effects of post-fire conditions on germination and seedling success of diffuse knapweed in northern Arizona

Introduction of exotic plant species is confounding treatments designed to reduce unnaturally high tree densities in ponderosa pine ( Pinus ponderosa P. & C. Lawson) forests of the western United States. Also, the recent increase in large, stand-replacing wildfires may promote introduction and spread of species, such as diffuse knapweed ( Centaurea diffusa Lam.), which may lead to reduced forage and land values and major ecosystem changes. We hypothesized that diffuse knapweed germination and seedling growth would respond positively to burned conditions in northern Arizona ponderosa pine forests. Our first field study was based on a May 2002 wildfire near Flagstaff, Arizona (Site I). For the field study at Site I, we buried diffuse knapweed seeds in sealed mesh packets in four forest floor conditions: severely burned, moderately burned, unburned bare soil and unburned. We removed packets monthly and measured percent germination. Germination under severely burned conditions at Site I (overall average 76%) was higher than in unburned conditions (59%) ( P = 0.017). Our second field study was based on a fuel reduction treatment with slash piles burned in February 2003 (Site II). Germination in seed packets was higher ( P = 0.003) in pile burn scars (67%) than in adjacent unburned locations (38%) at Site II. In fall 2002, we planted knapweed seeds in pots containing intact soil cores from Site I from unburned and severely burned conditions. We allowed competition to grow in half the pots, and removed competition in the other half. Diffuse knapweed biomass/pot was greater ( P = 0.035) in soil from the severely burned (2.6 g) compared to the unburned condition (0.6 g) from Site I. Knapweed biomass/pot also appeared greater when grown in soil from pile burn scars (3.3 g) compared with unburned locations (2.5 g) from Site II, although the difference was not significant ( P = 0.317). We conclude that severe wildfire or pile burning can promote germination and seedling growth of diffuse knapweed in northern Arizona pine forests. Moreover, diffuse knapweed may also threaten unburned forests, as average germination was 48% in unburned locations. Failure to consider exotic invasive species in fuel reduction and wildfire rehabilitation may result in trading one undesirable condition for another.

The Impact of Forest Density on Property Values

Abstract We applied a simple hedonic price model to determine the benefits of fuel reduction treatments reflected in residential housing values in Flagstaff, Arizona, in hopes of finding a way to address increasing treatment costs. Results show that the fuel reduction treatments that convert high canopy closure would increase property values significantly ($190 per 1,000 m2 per home). The treatments that lower forest density are not only one means to reduce wildfire hazard but also to enhance scenic beauty and improve residential property values.