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BackgroundIn seed-obligate conifer forests of the western US, land managers need a better understanding of the spatiotemporal variability in post-fire recovery to develop adaptation strategies. Successful establishment of post-fire seedlings requires the arrival of seeds and favorable environmental conditions for germination, survival, and growth. We investigated the spatiotemporal limitations to post-fire seedling establishment and height growth in dry to moist mixed conifer forests with and without post-fire forest management treatments (salvage logging, grass seeding) in areas burned from low to high severity. In 2011, we measured post-fire seedling establishment year, juvenile density (seedlings and saplings), and height growth (annual and total) in 50 plots with six conifer species in the School Fire (2005), Blue Mountains, WA, USA. In 2021, we remeasured the plots for post-fire juvenile density and height growth.ResultsPost-fire juvenile tree densities appeared sufficient for self-replacement of forest (> 60 stems ha−1) in 96% of plots in 2021 (median 3130 stems ha−1), but densities were highly variable (range 33–100,501 stems ha−1). Annual seedling establishment was positively correlated with cooler, wetter climate conditions during the summer of germination (July–September) and the growing season of the subsequent year (April–September) for multiple tree species. We found lower juvenile densities at greater distances to seed sources and with higher grass cover, while salvage logging had no effect. Annual height growth was shorter on warmer, drier topographic positions for three species, whereas annual height growth was associated with climate variability for one species. Shifts in height class structure from 2011 to 2021 were, in part, explained by differences among species in annual height growth.ConclusionsAbundant and widespread tree seedling establishment for multiple conifer species after fire was strong evidence that most burned sites in the present study are currently on a trajectory to return to forest. However, post-fire establishment may be constrained to brief periods of cooler, wetter climate conditions following future fires. Long-term monitoring of post-fire recovery dynamics is needed to inform management activities designed to adapt forests to climate change and future disturbances, which will collectively shape future forest structure and composition.

As the size and extent of wildfires has increased in recent decades, so has the cost and extent of post-fire management, including seeding and salvage logging. However, we know little about how burn severity, salvage logging, and post-fire seeding interact to influence vegetation recovery long-term. We sampled understory plant species richness, diversity, and canopy cover one to six years post fire (2006 to 2009, and 2011) on 72 permanent plots selected in a stratified random sample to define post-fire vegetation response to burn severity, post-fire seeding with native grasses, and salvage logging on the 2005 School Fire in eastern Washington. Understory vegetation responded rapidly post fire due, in part, to ample low intensity rainfall events in the first post-fire growing season. Vegetation was more diverse with greater plant species richness and diversity (Shannon-Wiener index) in low and moderate burn severity plots in 2006 (species richness 18; diversity 2.3) compared to high burn severity plots (species richness 10; diversity 1.8), with species richness on the high severity plots reaching 19 in the sixth post-fire year, similar to the initial values on the low and moderate burn severity plots. Plants that commonly resprout from rhizomes, bulbs, and other surviving belowground sources were abundant post fire, while those establishing from off-site seed sources, including non-native species, were present but not abundant. Plots seeded with native grass post fire and not salvage logged had the highest canopy cover of graminoid species: more than 30 % six years after the fire (in 2011), with low forb (15 %) and shrub (1 %) canopy cover and species richness. For comparison, high severity plots that were not seeded and not salvage logged had 3 % graminoid cover, 14 % forb cover, and 26 % shrub cover. Plots that had been salvage logged from one to three years after the fire produced less canopy cover of shrubs and forbs, but three times more canopy cover of graminoids on the high burn severity plots by 2011. High severity plots that were salvage logged and not seeded with native grasses had the lowest species richness, diversity, and cover. Very few non-native species were found, regardless of salvage logging and seeding. Rapid post-fire growth dominated by native plants of high diversity suggests that this forest’s vegetation and soils are highly resilient to disturbance. Overall, burn severity and post-fire seeding with native grasses were more influential than salvage logging on understory plant abundance one to six years after fire.

Post-fire mulch and seeding treatments, often applied on steep, severely burned slopes immediately after large wildfires, are meant to reduce the potential of erosion and establishment of invasive plants, especially non-native plants, that could threaten values at risk. However, the effects of these treatments on native vegetation response post fire are little studied, especially beyond one to two years. We compared species richness, diversity, and percent canopy cover of understory plants one, two, three, four, and six years after immediate post-fire application of wood strand mulch, agricultural wheat straw mulch, hydromulch + seed with locally adapted native grasses, seed only with locally adapted native grasses with no mulch, and untreated (no mulch or grass seeding) after the 2005 School Fire in Washington, USA. For wood strand mulch treatments, mean canopy cover of grasses and forbs was low, varying from 3 % to 20 % in post-fire years two through six; whereas wheat straw mulch had the lowest mean cover of grasses, 29 % in post-fire years two through six. Plots hydromulched and seeded with grass, and those seeded with grass but not mulched, tended to have higher grass cover than other treatments and untreated plots over the six years. Species richness and diversity was highest for the hydromulch + seed treatment. Ten non-native species were found, but never with more than 2 % canopy cover, each. Although the inference of our small-plot work is limited, our results suggest that post-fire rehabilitation treatments apparently altered the abundance and diversity of native perennial understory plants for one to six years post fire—effects that could persist for decades.

Prescribed and resource benefit fires are used to manage fuels in fire-prone landscapes in the Southwest. These practices, however, typically occur under different conditions, potentially leading to differences in fire behavior and effects. The objectives of this study were to investigate the effects of recent prescribed fires, resource benefit fires, and repeated fires in ponderosa pine forests, as well as recent resource benefit fires in pinyon-juniper woodlands. The Gila National Forest was the study area because it has a rich history of using fire as a restoration tool. In each vegetation type, fuels and stand structure were sampled using random plots stratified by burn severity in resource benefit fires. In ponderosa pine, sampling and analysis also included prescribed fire and areas subject to repeated resource benefit fires. To assess potential fire behavior, we used the crown fire behavior prediction model Nexus using ninetieth percentile weather conditions. In ponderosa pine forests, surface fuels were similar between prescribed fires and low severity resource benefit fires. However, resource benefit fires significantly reduced basal area, resulting in lower loading of canopy fuels and crown fire potential. Additionally, effects of resource benefit fire on stand structure and fuels seem to be sustained in areas that burned in two or three resource benefit fires in the last century. In pinyon-juniper woodlands, resource benefit low severity fires had no effect on surface or canopy fuel loads. Moderate severity resource benefit fires, on the other hand, did significantly reduce surface and canopy fuel loads. Results from this study are pertinent to fire and fuels managers throughout the southwestern United States who utilize prescribed and resource benefit fire to reduce fuel loads and restore historical forest conditions.

The Cooney Ridge Fire Experiment conducted by fire scientists in 2003 was a burnout operation supported by a fire suppression crew on the active Cooney Ridge wildfire incident. The fire experiment included measurements of pre-fire fuels, active fire behavior, and immediate post-fire effects. Heat flux measurements collected at multiple scales with multiple ground and remote sensors illustrate the spatial and temporal complexity of the fire progression in relation to fuels and fire effects. We demonstrate how calculating cumulative heat release can provide a physically based estimate of fuel consumption that is indicative of fire effects. A map of cumulative heat release complements estimates of ground cover constituents derived from post-fire hyperspectral imagery for mapping immediate post-fire ground cover measures of litter and mineral soil. We also present one-year and 10-year post-fire measurements of overstory, understory, and surface conditions in a longer-term assessment of site recovery. At the time, the Cooney Ridge Fire Experiment exposed several limitations of current state-of-science fire measurement methods, many of which persist in wildfire and prescribed fire studies to this day. This Case Report documents an important milestone in relating multiple spatiotemporal measurements of pre-fire, active fire, and post-fire phenomena both on the ground and remotely.

We apply a combination of suppression and release criteria to reconstruct the disturbance history of a ponderosa pine – Douglas-fir stand in central Idaho. In this stand, disturbance, likely fire, induced growth releases in some trees, and sudden, severe suppressions in others. To characterize growth release following disturbance, we developed boundary-line release criteria for Douglas-fir and ponderosa pine. Suppression criteria were applied to identify disturbances defined as a growth reduction of more than 1.8 standard deviations sustained for a minimum of five years. To prevent confusing a true release event with growth increases associated with recovery from suppression, release events were not tallied for at least fifteen years following a suppression event. Release and suppression events were combined to create a disturbance chronology characterized by a high frequency of disturbance between 1820 and 1920. This period of disturbance likely reflects post-European settlement land uses such a...

Large wildfires are common in many western coniferous forests, and these fires can affect woodpecker reproduction and habitat use. Our objectives were to examine nesting densities, reproductive parameters, and species-specific habitat selection of woodpeckers in a recently burned region of the Black Hills in South Dakota, USA, between 2001 and 2004. Postfire nesting densities were greatest in areas dominated by high prefire canopy cover, and reproductive success averaged >70%. For some species of woodpeckers, factors such as diameter at breast height, burn severity, and distance to unburned patches were important for nest-site selection. Our data indicated that nesting densities of many woodpeckers in the Black Hills were lower than what has been recorded elsewhere following recent, large wildfires in ponderosa pine (Pinus ponderosa) forests. Management activities that simulate mixed-severity fire effects and retain higher numbers of large snags are likely to benefit cavity nesters in this region.

The Differenced Normalized Burn Ratio (ΔNBR) is widely used to map post-fire effects in North America from multispectral satellite imagery, but has not been rigorously validated across the great diversity in vegetation types. The importance of these maps to fire rehabilitation crews highlights the need for continued assessment of alternative remote sensing approaches. To meet this need, this study presents a first preliminary comparison of immediate post-fire char (black ash) fraction, as measured by linear spectral unmixing, and ΔNBR, with two quantitative one-year post-fire field measures indicative of canopy and sub-canopy conditions: % live tree and dry organic litter weight (gm-2). Image analysis was applied to Landsat 7 Enhanced Thematic Mapper (ETM+) imagery acquired both before and immediately following the 2000 Jasper Fire, South Dakota. Post-fire field analysis was conducted one-year post-fire. Although the immediate post-fire char fraction (r 2 = 0.56, SE = 28.03) and ΔNBR (r 2 = 0.55, SE = 29.69) measures produced similarly good predictions of the % live tree, the standard error in the prediction of litter weight with the char fraction method (r 2 = 0.55, SE = 4.78) was considerably lower than with ΔNBR (r 2 = 0.52, SE = 8.01). Although further research is clearly warranted to evaluate more field measures, in more fires, and across more fire regimes, the char fraction may be a viable approach to predict longer-term indicators of ecosystem recovery and may potentially act as a surrogate retrospective measure of the fire intensity.

The Forest Service Remote Sensing Applications Center (RSAC) and the U.S. Geological Survey Earth Resources Observation and Science (EROS) Data Center produce Burned Area Refl ectance Classifi cation (BARC) maps for use by Burned Area Emergency Response (BAER) teams in rapid response to wildfi res. BAER teams desire maps indicative of fi re effects on soils, but green and nonphotosynthetic vegetation and other materials also affect the spectral properties of post-fi re imagery. Our objective was to assess how well satellite image-derived burn severity indices relate to a suite of immediate post-fi re effects measured on the ground. We measured or calculated fi re effects variables at 418 plots, nested in 50 fi eld sites, located across the full range of burn severities observed at the 2003 Black Mountain, Cooney Ridge, Robert, and Wedge Canyon wildfi res in western Montana, the 2003 Old and Simi wildfi res in southern California, and the 2004 Porcupine and Chicken wildfi res in interior Alaska. We generated the Normalized Burn Ratio (NBR), differenced Normalized Burn Ratio (dNBR), Relative dNBR (RdNBR), Normalized Difference Vegetation Index (NDVI), and differenced NDVI (dNDVI) burn severity indices from Landsat 5 Thematic Mapper (TM) imagery across these eight wildfi res. The NBR correlated best with the fi re effects measures but insignifi cantly, meaning other indices could act as suitable substitutes. The overstory (trees in Montana and Alaska, shrubs in California) measures appear to correlate best to the image variables, followed by understory and surface cover measures. Exposed mineral soil and soil water repellency were poorly correlated with the image variables, while green vegetation was most highly correlated. The BARC maps are more indicative of post-fi re vegetation condition than soil condition. We conclude that the NBR and dNBR, from which BARC maps of large wildfi res in the United States are currently derived, are sound choices for rapid assessment of immediate

Wildfire effects on the ground surface are indicative of the potential for post-fire watershed erosion response. Areas with remaining organic ground cover will likely experience less erosion than areas of complete ground cover combustion or exposed mineral soil. The Simi and Old fires burned ∼67,000 ha in southern California in 2003. Burn severity indices calculated from pre- and post-fire multispectral imagery were differenced (i.e., differenced Normalized Burn Ratio (dNBR)) to highlight fire-induced changes to soil and vegetation. Aerial and field hyperspectral data were also collected together with field ground cover measurements soon after the fires. Spectral endmembers representing green vegetation, nonphotosynthetic vegetation (NPV), charred NPV, and charred and uncharred inorganic materials (soil, ash, and rock) were used in a constrained linear spectral unmixing process to determine the post-fire fractional ground cover of each component on the ground surface. The spectral unmixing results, dNBR, and a Relative dNBR (RdNBR) were validated using field-measured fractional ground cover estimates to determine which product best predicted the conditions on the ground. The spectral unmixing results were significantly correlated to all classes of charred and uncharred organics and inorganics, and the dNBR was the best indicator of charred soil and green vegetation. The RdNBR had several significant correlations with the ground data, yet did not consistently correlate well with any specific ground cover types. A map of post-wildfire ground cover and condition, especially exposed soil and remaining vegetative cover, is a good indicator of the fire’s effect on the ground surface and the resulting potential for hydrologic response.

Vegetation response and burn severity were examined following eight large wildfires that burned in 2003 and 2004: two wildfires in California chaparral, two each in dry and moist mixed-conifer forests in Montana, and two in boreal forests in interior Alaska. Our research objectives were: 1) to characterize one year post-fire vegetation recovery relative to initial fire effects on the soil surface that could potentially serve as indicators of vegetation response (and thus, ultimately longer-term post-fire ecosystem recovery), and 2) to use a remotely-sensed indicator of burn severity to describe landscape patterns in fire effects. We correlated one-year post-fire plant species richness and percent canopy cover to burn severity and to soil surface cover immediately after the fires. For all eight wildfires, plant canopy cover and species richness were low and highly variable one year post-fire. We found a greater number of forbs when compared to other plant life forms, independent of burn severity. Plant cover was dominated by grasses in chaparral systems, by forbs in mixed-conifer forests, and by shrubs in boreal forests, similar to the unburned vegetation. Fine-scale variability in post-fire effects on soils, the diversity of pre-fire vegetation, and the resilience of plants to fire likely explain the high variation observed in post-fire vegetation responses across sites and burn severities. On most low and moderate burn severity sites, >30% of the soil surface was covered with organic material immediately post-fire, and one year later, the canopy cover of understory vegetation averaged 10% or more, suggesting low risk to post-fire erosion. In California chaparral and the two Montana mixed conifer sites, 5% or less of the area within the fire perimeter burned with high severity, while in Alaska, 58% was mapped as high burn severity; we think this is characteristic in Alaska, but uncharacteristic of chaparral fires, especially given the high proportion of non-native species post-fire in our chaparral sites. All fires had a mosaic of different burn severities (as indicated by delta Normalized Burn Ratio, dNBR) with highly variable patch size (mean 1.3 ha to 14.4 ha, range from

While nadir-viewing passive multispectral sensors have limited utility for characterizing the full dimensionality of forest canopies, multi-angle remote sensors such as the Multi-angle Imaging SpectroRadiometer (MISR) may improve detection of canopy architecture, canopy cover, and leaf area index (LAI) of forest canopy versus understory vegetation. Our objective was to determine whether data from the MISR sensor could improve estimates of LAI across a post-fire ponderosa pine forest located in the Black Hills of South Dakota. We measured LAI during the 2002 and 2003 growing seasons and created continuous LAI maps using Landsat TM and ETM+ data (mean R 2 =0.81). We fit linear regression models of total and canopy LAI, using a series of MISR at-nadir and off-nadir or anisotropic vegetation indices as predictor variables, for each of five sampling periods. We found the best LAI model fits using either a new hotspot-adjusted normalized difference vegetation index, NDVIHS, NDVI calculated from the −60° view angle, or NDVI at-nadir and either the Hotspot–DarkSpot Index (HDS) or the normalized difference anisotrophic index (NDAX) (R 2 =0.56–0.91). However, differences in fits of these best models and those including NDVI at-nadir ranged from only 1 to 8%. Reflectance anisotropy patterns related strongly to understory vegetation phenology. We found that the relationships among NDVI or the enhanced vegetation index (EVI) and canopy or total LAI showed little variation across view angles when the understory vegetation was senesced and significant anisotropy when understory green LAI was greatest. These findings demonstrate the value of multi-temporal measurements during periods of understory phenological change, even if the overstory LAI is relatively stable. We also evaluated the performance of the MISR LAI product and found moderate fits between the MISR LAI and our field- and Landsat-derived canopy LAI (R 2 =0.21–0.44).

Abstract Red-headed Woodpecker (Melanerpeserythrocephalus) populationsare declining at a continental scale, yet little isknown about their nest-site selection and reproductionwithin burned forests. We measured reproductiveparameters and nest-site characteristics at 17Red-headed Woodpecker nests and 17 random sitesbetween 2001 and 2004 in the Black Hills, SouthDakota. The average date the first egg was laid was 17June, and the average clutch size was 5.4 ±0.4. The daily nest survival rate averaged 0.98(overall nest success = 47%), and predation was the major cause ofnest failure. Red-headed Woodpecker nests occurredfarther from grassland edges in large diameter snagswithin severely burned quaking aspen(Populustremuloides) stands.High-severity fire within these aspen stands resultedin a combination of snag and understorycharacteristics that differed from the surroundingpine forest matrix. Interactions between cover typeand burn severity may have important ecologicalconsequences for Red-headed Woodpeckers in a mixedconifer forest.

We compared patch structure, fire-scar formation, and seedling regeneration in patches of low, moderate, and high burn severity following the large (~34 000 ha) Jasper fire of 2000 that occurred in ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws.) forests of the Black Hills of South Dakota, USA. This fire created a patchy mosaic of effects, where 25% of the landscape burned as low, 48% as moderate, and 27% as high severity. Dead cambium on a significant portion of tree circumference in a tree with live cambium and a vigorous crown was taken as evidence of incipient fire-scar formation. Tree mortality was approximately 21%, 52%, and 100% in areas of low, moderate, and high burn severity, respectively. Dead cambium was detected on approximately 24% and 44% of surviving trees in low and moderate burn severity patches, respectively. Three years postfire, regeneration densities were ~612 and 450 seedlings·ha–1 in low and moderate burn severity patches, respectively, and no regeneration was observed in the interior of high burn severity patches. Fire-scars will be found on 73% of the area burned in this fire, and large patches of multicohort forest will be created. Mixed-severity fire may have been common historically in the Black Hills, and in conjunction with frequent surface fire, played an important role in shaping a spatially heterogeneous, multicohort ponderosa pine forest.

We collected field and remotely sensed data spanning 10 years after three 2003 Montana wildfires to monitor ecological change across multiple temporal and spatial scales. Multiple endmember spectral mixture analysis was used to create post-fire maps of: char, soil, green (GV) and non-photosynthetic (NPV) vegetation from high-resolution 2003 hyperspectral (HS) and 2007 QuickBird (QB) imagery, and from Landsat 5 and 8 imagery collected on anniversary dates in 2002, 2003 (post fire), 2004, 2007 and 2013. Initial estimates of char and NPV from the HS images were significantly correlated with their ground-measured counterparts (ρ=0.60 (P=0.03) and 0.68 (P=0.01) respectively), whereas HS GV and Landsat GV were correlated with canopy GV (ρ=0.75 and 0.70 (P=0.003) respectively). HS imagery had stronger direct correlations with all classes of fine-scale ground data than Landsat and also had stronger predictive correlations with 10-year canopy data (ρ=0.65 (P=0.02) to 0.84 (P=0.0003)). There was less than 5% understorey GV cover on the sites initially, but by 2013, it had increased to nearly 60% regardless of initial condition. The data suggest it took twice as long for understorey GV and NPV to replace char and soil as primary ground cover components on the high-burn-severity sites compared with other sites.

Many scientists and managers have an interest in describing the environment following a fire to understand the effects on soil productivity, vegetation growth, and wildlife habitat, but little research has focused on the scientific rationale for classifying the post-fire environment. We developed an empirically-grounded soil post-fire index (PFI) based on available science and ecological thresholds. Using over 50 literature sources, we identified a minimum of five broad categories of post-fire outcomes: (a) unburned, (b) abundant surface organic matter ( > 85% surface organic matter), (c) moderate amount of surface organic matter ( ≥ 40 through 85%), (d) small amounts of surface organic matter ( < 40%), and (e) absence of surface organic matter (no organic matter left). We then subdivided each broad category on the basis of post-fire mineral soil colors providing a more fine-tuned post-fire soil index. We related each PFI category to characteristics such as soil temperature and duration of heating during fire, and physical, chemical, and biological responses. Classifying or describing post-fire soil conditions consistently will improve interpretations of fire effects research and facilitate communication of potential responses or outcomes (e.g., erosion potential) from fires of varying severities.

Methods for evaluating the impact of fires within tropical forests are needed as fires become more frequent and human populations and demands on forests increase. Short- and long-term fire effects on soils are determined by the prefire, fire, and postfire environments. We placed these components within a fire-disturbance continuum to guide our literature synthesis and develop an integrated soil burn severity index. The soil burn severity index provides a set of indicators that reflect the range of conditions present after a fire. The index consists of seven levels, an unburned level and six other levels that describe a range of postfire soil conditions. We view this index as a tool for understanding the effects of fires on the forest floor, with the realization that as new information is gained, the index may be modified as warranted.

Rapid Response Research is conducted during and immediately after wildland fires, in coordination with fire management teams, in order to collect information that can best be garnered in situ and in real-time. This information often includes fire behavior and fire effects data, which can be used to generate practical tools such as predictive fire models for managers. Drawing upon lessons learned from fire managers and researchers working on active wildland fires, we identify challenges including high costs, logistics, and safety; understanding and fitting into the fire management organization; building relationships with managers and other researchers; and science delivery. Our recommendations for safer and more effective Rapid Response Research are that researchers must understand the fire organizations and their objectives because a fire manager’s primary responsibility is to manage the fire safely, not support research. In addition, researchers must be prepared with equipment, a “red card” signifying sufficient training and fitness, and appropriate knowledge when arriving to do research on a fire. Further, researchers must have and follow an operations plan. We recommend using a liaison to build strong relationships with managers and sharing what was learned. Science guided by questions that are important to managers is essential to improving both the understanding of wildland fire dynamics and developing strategies to address fire risk, rehabilitation, and restoration, yet researchers must be aware of the challenges of conducting research on active wildland fires.

The objective of this paper is to present recommendations for fuels treatments in ponderosa pine forests in the Southwest, Colorado Front Range, and Black Hills of South Dakota. We have synthesized existing knowledge from the peer-reviewed literature and administrative studies and acquired local knowledge through a series of discussions with fuels treatment practitioners. We describe specific treatments, the circumstances under which they can be applied, and treatment effects. We provide recommendations related to where, how, and how often fuels treatments may be prescribed to achieve desired outcomes. Desired outcomes address social, political, economic, and ecological factors.

Wildfire is a major forest disturbance in interior Alaska that can both directly and indirectly alter ecological processes. We used a combination of pre- and post-fire forest floor depths and post-fire ground cover assessments measured in the field, and high-resolution airborne hyperspectral imagery, to map forest floor conditions after the 2004 Taylor Complex in Alaska’s boreal forest. We applied a linear spectral unmixing model with five endmembers representing green moss, non-photosynthetic moss, charred moss, ash and soil to reflectance data to produce fractional cover maps. Our study sites spanned low to moderately high burn severity, and both black and white spruce forest types; high cover of green or non-photosynthetic moss in the remotely sensed imagery indicated low consumption, whereas high cover of charred moss, ash or soil indicated higher consumption. Strong relationships (R2 = 0.5 to 0.6) between green moss estimated from the imagery and both post-fire depth and percentage consumption suggest that potential burn severity may be predicted by a map of green (live) moss. Given that the depth of the post-fire forest floor is ecologically significant, the method of mapping the condition of the organic forest floor with hyperspectral imagery presented here may be a useful tool to assess the effect of future fires in the boreal region.

Appropriate use of satellite data in predicting >1year post-fire effects requires remote measurement of surface properties that can be mechanistically related to ground measures of post-fire condition. The present study of burned ponderosa pine (Pinus ponderosa) forests in the Black Hills of South Dakota evaluates whether immediate fractional cover estimates of char, green vegetation and brown (non-photosynthetic) vegetation within a pixel are improved predictors of 1-year post-fire field measures, when compared with single-date and differenced Normalized Burn Ratio (NBR and dNBR) indices. The modeled estimate of immediate char fraction either equaled or outperformed all other immediate metrics in predicting 1-year post-fire effects. Brown cover fraction was a poor predictor of all effects (r2 < 0.30), and each remote measure produced only poor predictions of crown scorch (r2 < 0.20). Application of dNBR (1 year post) provided a considerable increase in regression performance for predicting tree survival. Immediate post-fire NBR or dNBR produced only marginal differences in predictions of all the 1-year post-fire effects, perhaps limiting the need for prefire imagery. Although further research is clearly warranted to evaluate fire effects data available 2–20 years after fire, char and green vegetation fractions may be viable alternatives to dNBR and similar indices to predict longer-term post-fire ecological effects.

We examined the influence of topography and stand structure on fire effects within the perimeter of the ~34 000 ha Jasper fire of 2000 in ponderosa pine (Pinus ponderosa Laws.) forests of the South Dakota Black Hills, USA. We used a remotely sensed and field-verified map of post-fire burn severity (accuracy 69%, kappa statistic 0.54), the Digital Elevation Model, and vegetation databases maintained by the Black Hills National Forest to empirically test relationships at 500 randomly located points in each of three severity classes. Burn severity was defined as the relative degree of post-fire change based on fire effects on soil, forest floor, and vegetation. This fire burned rapidly, yet created a patchy mosaic of effects (25, 48, and 27% low, moderate, and high severity). Stands burned by low and moderate severity fire had fewer trees (stand density index 13 cm diameter at breast height ha–1) and were found on less steep sites (slope < 18%). Denser stands (stand density index >470) with larger trees (average stand diameter >24 cm) or many small trees were more likely to burn with high severity effects. Our results suggest that managers should consider topography and stand structure together when making strategic decisions about which stands to thin or otherwise manage to reduce the severity with which forests will burn in wildfires.