High-severity Areas Research Articles

Efficacy of resource objective wildfires for restoration of ponderosa pine (Pinus ponderosa) forests in northern Arizona

Current conditions in dry forests of the western United State have given rise to policy mandates for accelerated ecological restoration on U.S. National Forest System and other public lands. In southwestern ponderosa pine (Pinus ponderosa Laws.) forests, mechanized tree thinning and prescribed fire are common restoration treatments but are not acceptable for all sites. Currently there is much interest in managing naturally ignited fires to accomplish restoration objectives but few studies have systematically examined the efficacy of such “resource objective” wildfires for restoring historical ranges of variability (HRV). In this study we used field plots to retrospectively sample 10 resource objective fires on two national forests in northern Arizona. We used four burn severity classes identified on Monitoring Trends in Burn Severity (MTBS) maps to stratify field sampling and compared post-fire means for 12 structure and hazardous fuels attributes to HRV and guidelines for ecosystem management. Results indicated significant differences among burn severity classes in tree density, basal area, coarse wood loads, canopy cover, and canopy fuel loads. Furthermore, areas classified as moderate (M) burn severity met HRV ranges for more attributes (67%) than did other areas in other severity classes. High (H) severity areas were within HRV for the fewest (17%) of the 12 attributes. Restoration ranges for large snag density, tree patch density and maximum patch size, and tree diameter distribution were not met within any burn severity class. Resource objective fire landscapes were comprised mainly (85%) of areas classified as unburned/low (U/L) and low (L) burn severity, whereas the M severity class made up just 12% of fire landscapes on average. Overall effectiveness of resource objective fires for meeting restoration objectives was 42%. Results suggested that effectiveness may be increased by managing for proportionally more moderate burn severity on these landscapes. For this, managers will be required to accept greater risk in terms of escaped fires and high-severity fire, which, in turn, will necessitate increasing public awareness of the potential benefits and limitations of managing wildfires for restoring ponderosa pine forest ecosystems.

Effects of wildland fire on the tropical alpine moorlands of Mount Kenya

Tropical alpine ecosystems serve vital roles in the areas of hydrology, biodiversity and carbon storage, due to their unique set of climatic and topographic conditions. These ecosystems are particularly vulnerable to climate change and anthropogenic influence as they exist in a fragile balance. Mount Kenya is an example of such a tropical alpine environment, and in 2012 a large fire burned through the upper southwestern slopes of the mountain. The fire burned at the transition zone between the moorland and the forest at an elevation of 3300–4000m, and covered almost 100km2. The impacts of this fire on soil properties are investigated three years after the fire. The severity from the time of the fire was determined using a satellite derived index known as dNBR (difference Normalized Burn Ratio). This was used to stratify the fire scar into 3 classes: low, moderate, and high severity areas. Soil samples were collected from the top 10cm layer (O-horizon) in each of these 3 severity classes and from unburnt areas outside the fire scar, and analyzed in the laboratory for physical and chemical properties. The results mostly showed no difference in soil properties between the three severity classes and unburnt areas. Only cation exchange capacity (CEC) and bulk density were found to be significantly different between the severity classes (p<0.001 and p=0.003 respectively), with high severity areas having lower bulk density and higher CEC as compared to unburnt areas. When other explanatory variables were taken into consideration, only CEC remained significantly different according to severity rating. CEC increased from 40.13cmolckg−1 outside the fire to 65.91cmolckg−1 in the high severity areas. The increase in CEC can be explained either by an increase in organic matter, as partially burnt material gradually incorporated into the soil, or by a change in the quality of the organic matter. Thus the impact of fire on soil properties in the tropical alpine moorland of Mount Kenya appears to be small, at least after 3years.

Behind-Pipe-Log-Evaluation Study: Deepwater Subsea Abandonments

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 174777, “Behind-Pipe-Log-Evaluation Study: Deepwater Subsea Abandonments in the Gulf of Mexico,” by Glenn Donovan, SPE, Peter Fadesere, SPE, George Ware, and Lou Daigle, SPE, Shell Offshore, and Suparman, SPE, Gary Frisch, SPE, Phil Fox, Mike Englar, Gordon Moake, SPE, and Weijun Guo, SPE, Halliburton, prepared for the 2015 SPE Annual Technical Conference and Exhibition, Houston, 28-30 September. The paper has not been peer reviewed. Techniques for well-abandonment log evaluations have been studied in the Gulf of Mexico since 2012. Legacy practices typically used acoustic methods consisting of cement-bond-log (CBL) and ultrasonic-scanner devices. The new methods described in this paper consist of adding nuclear sensors to supplement the acoustic measurements and introduce novel processing methods. The overall solutions package consists of behind-pipe- evaluation techniques (BPETs). When properly modeled and analyzed, these data have the potential to reduce the cost of removing casing strings significantly. Introduction Much of the nonproductive time associated with well abandonments is attributed to difficulty circulating the stagnant material left behind in the casing-to-casing annuli during well construction. Many improvements have been made in the design of these fluids; however, drilling muds using barite as the weighting agent still suffer phase degradation over time, leaving a column of material with a density that increases with depth, except when solids bridging occurs. In extreme cases, the precipitated barite adheres to the outside of the casing wall, impeding the removal of the severed casing section. When traditional sonic and ultrasonic logs are run over concentric casing strings, the results can be misleading. Sonic logs such as the CBL do not yield quantitative results in concentric strings of casing because of the inability to predict the influence of the outer casing on the log response. Misleading data and experiences in well abandonments have left the industry actively seeking alternatives to the conventional method of identifying the material in the annulus, to increase the efficacy of the abandonment process. Abandonment Log-Evaluation Methodologies Historically, it has been common practice to use ultrasonic imaging technologies in combination with traditional sonic-waveform data to characterize the annular space of wells that are candidates for casing-retrieval operations. However, this approach is inadequate for evaluating a phenomenon that is often observed in older wells that contain concentric casing strings that were not cemented to the top of the string. In those cases, the original drilling fluid between the casing strings experiences degradation. As the drilling fluid degrades, solids in the fluid begin to settle out and migrate toward the bottom of the well or toward areas of high deviation or dogleg severity. The settling of these solids is commonly referred to as barite sag, mud sag, or barite settling.

Soil heating during the complete combustion of mega-logs and broadcast burning in central Oregon USA pumice soils

The environmental effect of extreme soil heating, such as occurs with the complete combustion of large downed wood during wildfires, is a post-fire management concern to forest managers. To address this knowledge gap, we stacked logs to create ‘mega-log’ burning conditions and compared the temperature, duration and penetration of the soil heat pulse in nine high intensity burned (HB) plots paired with adjacent masticated and broadcast burned low intensity burned (LB) plots at different soil depths (0, 5, 10 and 30 cm) in a Pinus ponderosa stand with volcanic pumice soils. Maximum soil surface temperatures ranges were 424–1168°C with a mean and standard error of 759 ± 9°C in the HB treatment and 42–360°C (107 ± 43°C) in the LB treatment. In the HB treatment, temperatures causing fine root and soil organism mortality (&gt;60°C) penetrated the soil to at least 10 cm, but were not recorded at 30 cm. In the HB treatment, mean duration above 60°C at 0–10 cm persisted for 4–13 h (7.61 ± 1.02 h). Soils in the LB treatment experienced lethal temperatures at the surface for about an hour (1.19 ± 0.70 h) and at 5 cm were mostly well below lethal temperatures with the exception of one at 57°C and another at 100°C that remained above 60°C for 1.4 h. Large areas of high burn severity may affect long-term forest productivity. Our quantification of soil heating establishes conditions for ongoing studies investigating the effects of soil burn severity on tree seedling growth, soil fungi and nutrients.

Landscape Patterns of Burn Severity in the Soberanes Fire of 2016

The Soberanes Fire started on July 22, 2016 in Monterey County on the California Central Coast from an illegal campfire. This disastrous fire burned for 10 weeks at a record cost of more than $208 million for protection and control. A progressive analysis of the normalized burn ratio from the Landsat satellite showed that the final high burn severity (HBS) area for the Soberanes Fire comprised 22% of the total area burned, whereas final moderate burn severity (MBS) area comprised about 10% of the total area burned of approximately 53,470 ha (132,130 acres). The resulting landscape pattern of burn severity classes from the 2016 Soberanes Fire revealed that the majority of HBS area was located in the elevation zone between 500 and 1000 m, in the slope zone between 15% and 30%, or on south-facing aspects. The total edge length of HBS areas nearly doubled over the course of the event, indicating a gradually increasing landscape complexity pattern for this fire. The perimeter-to-area ratio for HBS patches decreased by just 3% over the course of the fire, while the HBS clumpiness metric remained nearly constant at a relatively high aggregation value. Weather conditions during the Soberanes Fires showed maximum daily temperatures exceeding 30°C on seven different days (including the date of ignition), which puts the HBS to total area burned of this 2016 event near the expected percentage for large wildfires on the California central coast since the 1980s.

Vegetation Regrowth Following Wildfires in the Santa Cruz Mountains of Northern California Monitored Using Landsat Satellite Image Analysis

The Santa Cruz Mountain range in northern California is a coastal landscape with a history of extensive forest logging and frequent large wildfires that have recently destroyed numerous residential structures at the wildland interface. Results from Landsat satellite image time-series analysis since 1984 of the study area within the Los Gatos Creek and Corralitos Creek watersheds showed that none of the severe drought periods since the 1980s have notably inhibited rapid tree and shrub regrowth rates on steep hill slopes burned recently by the 1985 Lexington Fire and the 2008 Summit Fire. In high burn severity areas of both fires, post-fire vegetation types showed a marked increase in shrub cover, mainly at the expense of evergreen tree cover. Most of these low (·ha-1 of standing woody biomass on the burned areas. This study is the first of its kind to utilize a full 30-year record of Landsat vegetation index data to monitor tree and shrub regrowth after stand-replacing wildfires in California.

Fire severity affects mixed broadleaf–conifer forest bird communities: Results for 9 years following fire

ABSTRACT Wildfire is an important disturbance regime that can structure wildlife communities and their habitats for many years. Using a before-after-control-impact framework, we evaluated the effect of the Quartz Fire on a mixed broadleaf–conifer forest and associated bird community in southwestern Oregon, USA, over 10 yr. To assess whether fire severity explained changes better than simply whether an area was burned, we used a tiered sampling approach by comparing unburned control points with either all burned points combined (burned) or those same points partitioned by severity level (low, moderate, high). As expected, overall tree cover decreased while cover of shrubs increased in response to greater fire severity. This pattern was most pronounced in high-severity areas, where tree cover declined by 40% and remained depressed, but shrub cover recovered from 10% the year following fire to 75% by year 6. Ordinations of bird species density showed turnover in community composition in all burned areas comb...

Erosion rate predictions from PESERA and RUSLE at a Mediterranean site before and after a wildfire: Comparison & implications

Mediterranean ecosystems are commonly vulnerable to wildfires. Accelerated erosion processes due to wildfires in those environments constitute a major restrictive factor in their sustainability. This study aims at evaluating the use of the Revised Universal Soil Loss Equation (RUSLE) and the Pan-European Soil Erosion Risk Assessment (PESERA) models in predicting the changes in spatial variability of soil erosion following a wildfire event. A site in Greece on which a wildfire occurred in the summer of 2007 is used as a case study. Soil erosion rates for the site before and after the fire outbreak were estimated by the two models. Inputs for both models included climatic, land-use, soil type, topography, Earth Observation (EO) as well as management and other ancillary data.Both models showed a substantial increase of soil erosion rates in the affected area as a result of the fire, particularly towards the steeper slopes and on areas of high burning severity. Yet, there were noticeable differences in the predictions between the 2 models in terms of absolute estimates of soil erosion rates before and after the fire event. Mean pre-fire erosion rates from RUSLE were ~2.5 times higher than those from PESERA. RUSLE predicted considerably higher mean erosion in comparison to PESERA for the post-fire conditions, yet of much less spatial variability. Average post-fire soil loss value, compared to pre-fire, was about nine and six times greater when using the RUSLE and the PESERA model respectively. RUSLE predictions were most sensitive to topographic and rainfall erosivity factors. PESERA showed high sensitivity to the vegetation coverage as well as to the soil characteristics inserted as crusting and erodibility variables.To our knowledge, this is the first study performing an intercomparison of soil erosion rate predictions between these two models, particularly so in the context of the influence of wildfire events. This study provides a key contribution towards our ability to better understand the effect of fire on soil erosion in the Mediterranean and elsewhere, as well as the ability of those widely used models as efficient tools to be used for this purpose. The latter is of key significance and practical value for research and policy decision making purposes alike, where information on spatiotemporal estimates of soil erosion rates may be required.

Ten years of forest cover change in the Sierra Nevada detected using Landsat satellite image analysis

The Sierra Nevada of California is a region where large wildfires have been suppressed for over a century. A detailed geographic record of recent vegetation regrowth and disturbance patterns in forests of the Sierra Nevada remains a gap that can be filled with remote-sensing data. Landsat Thematic Mapper imagery was analysed to detect 10 years of recent changes (between 2000 and 2009) in forest vegetation cover for areas burned by wildfires between years of 1995 and 1999 in the region. Results confirmed the prevalence of regrowing forest vegetation during the period 2000 and 2009 over 17% of the combined burned areas. Classification of these regrowing forest vegetation areas by the Landsat normalized burn ratio (NBR) showed that there was a marked increase in average disturbance index (ΔDI) values in the transitions from low to moderate to high burn severity classes. Within the five combined wildfire perimeters, 45% of the high burn severity area delineated by the RdNBR analysis was covered by regrowing forest detected between 2000 and 2009. In contrast, a notable fraction (12%) of the entire 5 km (unburned) buffer area outside the 1995–1999 fires perimeters showed decline in forest cover, and not nearly as many regrowing forest areas, covering only 3% of all the 1995–1999 buffer areas combined. Based on comparison of these results to ground-based survey data and high-resolution aerial images, the Landsat difference index (ΔDI) methodology can fulfil much of the need for consistent, low-cost monitoring of changes due to climate and biological factors in western forest regrowth following stand-replacing disturbances.

Climate, fire size, and biophysical setting control fire severity and spatial pattern in the northern Cascade Range, USA.

Warmer and drier climate over the past few decades has brought larger fire sizes and increased annual area burned in forested ecosystems of western North America, and continued increases in annual area burned are expected due to climate change. As warming continues, fires may also increase in severity and produce larger contiguous patches of severely burned areas. We used remotely sensed burn-severity data from 125 fires in the northern Cascade Range of Washington, USA, to explore relationships between fire size, severity, and the spatial pattern of severity. We examined relationships between climate and the annual area burned and the size of wildfires over a 25-year period. We tested the hypothesis that increased fire size is commensurate with increased burn severity and increased spatial aggregation of severely burned areas. We also asked how local ecological controls might modulate these relationships by comparing results over the whole study area (the northern Cascade Range) to those from four ecological subsections within it. We found significant positive relationships between climate and fire size, and between fire size and the proportion of high severity and spatial-pattern metrics that quantify the spatial aggregation of high-severity areas within fires, but the strength and significance of these relationships varied among the four subsections. In areas with more contiguous subalpine forests and less complex topography, the proportion and spatial aggregation of severely burned areas were more strongly correlated with fire size. If fire sizes increase in a warming climate, changes in the extent, severity, and spatial pattern of fire regimes are likely to be more pronounced in higher-severity fire regimes with less complex topography and more continuous fuels.

Strategies for preventing invasive plant outbreaks after prescribed fire in ponderosa pine forest

Land managers use prescribed fire to return a vital process to fire-adapted ecosystems, restore forest structure from a state altered by long-term fire suppression, and reduce wildfire intensity. However, fire often produces favorable conditions for invasive plant species, particularly if it is intense enough to reveal bare mineral soil and open previously closed canopies. Understanding the environmental or fire characteristics that explain post-fire invasive plant abundance would aid managers in efficiently finding and quickly responding to fire-caused infestations. To that end, we used an information-theoretic model-selection approach to assess the relative importance of abiotic environmental characteristics (topoedaphic position, distance from roads), pre-and post-fire biotic environmental characteristics (forest structure, understory vegetation, fuel load), and prescribed fire severity (measured in four different ways) in explaining invasive plant cover in ponderosa pine forest in South Dakota’s Black Hills. Environmental characteristics (distance from roads and post-fire forest structure) alone provided the most explanation of variation (26%) in post-fire cover of Verbascum thapsus (common mullein), but a combination of surface fire severity and environmental characteristics (pre-fire forest structure and distance from roads) explained 36–39% of the variation in post-fire cover of Cirsium arvense (Canada thistle) and all invasives together. For four species and all invasives together, their pre-fire cover explained more variation (26–82%) in post-fire cover than environmental and fire characteristics did, suggesting one strategy for reducing post-fire invasive outbreaks may be to find and control invasives before the fire. Finding them may be difficult, however, since pre-fire environmental characteristics explained only 20% of variation in pre-fire total invasive cover, and less for individual species. Thus, moderating fire intensity or targeting areas of high severity for post-fire invasive control may be the most efficient means for reducing the chances of post-fire invasive plant outbreaks when conducting prescribed fires in this region.

Pre-wildfire management treatments interact with fire severity to have lasting effects on post-wildfire vegetation response

Land managers are routinely applying fuel reduction treatments to mitigate the risk of severe, stand-replacing fire in ponderosa pine communities of the southwestern US. When these treatments are burned by wildfire they generally reduce fire severity, but less is known about how they influence post-wildfire vegetation recovery, as compared to pre-fire untreated areas. We re-measured existing plots on the 2002 Rodeo–Chediski Fire 8years after the wildfire to track plant community and exotic species response, as well as patterns of pine regeneration. We compared areas that experienced high- and low-severity burning, and also examined how pre-fire treatment (cutting in an uneven-aged harvesting system with prescribed fire) modified vegetation response. We detected persistent differences between low- and high-severity areas for nearly all variables measured. In high-severity areas overall understory plant cover was 40.6%, nearly three times that observed in low-severity areas; shrub cover was 18.4%, four and a half times greater than that observed in low-severity areas. We also detected significantly higher exotic forb cover in high-severity areas, although overall exotic response was generally quite low (<2%). Although this represents a slight decrease in exotic cover since the initial 2004/2005 measurements, the frequency of several exotic species did increase through time (particularly Tragopogon dubius and Verbascum thapsus). Pre-fire treatment resulted in significantly higher pine regeneration frequency in treated versus untreated areas. Within low severity areas, mean pine regeneration frequency was 0.17 in pre-fire untreated areas versus 0.06 in areas that were not treated before the fire. Within high severity burned areas, mean pine regeneration frequency was 0.67 in pre-fire treated areas, but was only 0.19 in pre-fire untreated areas. This treatment effect in high-severity areas may be linked to reduction in the overall patch size of high burn severity in pre-fire treated areas, which resulted in a more heterogeneous mixture of low and moderate severity burning in the neighborhood. This pattern decreased distance to seed source, which likely facilitated the more frequent pine regeneration observed. In addition to the well-documented benefits of fuel reduction treatments in reducing subsequent fire severity, these data suggest that even where treated areas do burn severely the size of severely burned patches is limited in extent, which is likely to have important ramifications for future reforestation and retention of foundation species.

Modelling the Impacts of Wildfire on Ash Thickness in a Short‐Term Period

AbstractAsh can provide valuable soil protection. However, ash is also very mobile, and soil protection patterns can be quickly changed, favouring the protection of some areas and exposing others with implications for soil erosion. In this research, the effects of a high severity wildfire on ash thickness were studied, 1 and 15 days after the fire. For this evaluation, several interpolation methods were tested to identify the best spatial predictor of ash distribution. The results showed that 1 day after the fire, ash was thinner in high severity areas. Fifteen days after the fire, ash thickness decreased, and the spatial pattern changed. This implies that evaluation of fire severity based on ash thickness must take a place immediately after the fire because it is affected by (re)distribution. There was an increase in the spatial autocorrelation, and ash distribution corresponded to a specific spatial pattern, because of wind (re)distribution. One day after the fire, the most accurate predictor was Inverse to a Weight 3 (IDW3) that detected easily the small‐scale variability of ash thickness, and after 15 days, ordinary kriging identified a specific pattern of ash distribution. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Trends in Wildfire Severity: 1984 to 2010 in the Sierra Nevada, Modoc Plateau, and Southern Cascades, California, USA

AbstractData from recent assessments indicate that the annual area of wildfires burning at high severity (where most trees are killed) has increased since 1984 across much of the southwestern United States. Increasing areas of high-severity fire can occur when greater area is burned at constant proportion of high-severity fire, or when the proportion of high-severity fire within fire perimeters increases, or some combination of both. For the Sierra Nevada Forest Plan Amendment (SNFPA) area, which includes forestlands in eastern California and western Nevada, Miller et al. (2009a) concluded that the proportion of area burning at high severity in mixed-conifer forests had risen over the 1984 to 2004 period. However, no statistical assessment was made of the temporal trend in high-severity fire area because the analyzed dataset was incomplete in the early years of the study period. In this update, we use satellite-derived estimates of fire severity from the three most widely distributed SNFPA forest types to examine the trend in percent high severity and high-severity fire area for all wildfires ≥80 ha that occurred during the 1984 to 2010 period. Time-series regression modeling indicates that the percentage of total high severity per year for a combination of yellow pine (ponderosa pine [Pinus ponderosa Lawson &amp; C. Lawson] or Jeffrey pine [P. jeffreyi Balf.]) and mixed-conifer forests increased significantly over the 27-year period. The annual area of high-severity fire also increased significantly in yellow pine-mixed-conifer forests. The percentage of high severity in fires ≥400 ha burning in yellow pine-mixed-conifer forests was significantly higher than in fires ≥400 ha. Additionally, the number of fires ≥400 ha significantly increased over the 1950 to 2010 period. There were no significant trends in red fir (Abies magnifica A. Murray bis) forests. These results confirm and expand our earlier published results for a shorter 21-year period.

Modeling Relationships among 217 Fires Using Remote Sensing of Burn Severity in Southern Pine Forests

Pine flatwoods forests in the southeastern US have experienced severe wildfires over the past few decades, often attributed to fuel load build-up. These forest communities are fire dependent and require regular burning for ecosystem maintenance and health. Although prescribed fire has been used to reduce wildfire risk and maintain ecosystem integrity, managers are still working to reintroduce fire to long unburned areas. Common perception holds that reintroduction of fire in long unburned forests will produce severe fire effects, resulting in a reluctance to prescribe fire without first using expensive mechanical fuels reduction techniques. To inform prioritization and timing of future fire use, we apply remote sensing analysis to examine the set of conditions most likely to result in high burn severity effects, in relation to vegetation, years since the previous fire, and historical fire frequency. We analyze Landsat imagery-based differenced Normalized Burn Ratios (dNBR) to model the relationships between previous and future burn severity to better predict areas of potential high severity. Our results show that remote sensing techniques are useful for modeling the relationship between elevated risk of high burn severity and the amount of time between fires, the type of fire (wildfire or prescribed burn), and the historical frequency of fires in pine flatwoods forests.

Detecting post-fire burn severity and vegetation recovery using multitemporal remote sensing spectral indices and field-collected composite burn index data in a ponderosa pine forest

It is challenging to detect burn severity and vegetation recovery because of the relatively long time period required to capture the ecosystem characteristics. Multitemporal remote sensing data can provide multitemporal observations before, during and after a wildfire, and can improve the change detection accuracy. The goal of this study is to examine the correlations between multitemporal spectral indices and field-observed burn severity, and to provide a practical method to estimate burn severity and vegetation recovery. The study site is the Jasper Fire area in the Black Hills National Forest, South Dakota, that burned during August and September 2000. Six multitemporal Landsat images acquired from 2000 (pre-fire), 2001 (post-fire), 2002, 2003, 2005 and 2007 were used to assess burn severity. The normalized difference vegetation index (NDVI), enhanced vegetation index (EVI), normalized burn ratio (NBR), integrated forest index (IFI) and the differences of these indices between the pre-fire and post-fire years were computed and analysed with 66 field-based composite burn index (CBI) plots collected in 2002. Results showed that differences of NDVI and differences of EVI between the pre-fire year and the first two years post-fire were highly correlated with the CBI scores. The correlations were low beyond the second year post-fire. Differences of NBR had good correlation with CBI scores in all study years. Differences of IFI had low correlation with CBI in the first year post-fire and had good correlation in later years. A CBI map of the burnt area was produced using regression tree models and the multitemporal images. The dynamics of four spectral indices from 2000 to 2007 indicated that both NBR and IFI are valuable for monitoring long-term vegetation recovery. The high burn severity areas had a much slower recovery than the moderate and low burn areas.

Spatial and temporal controls on post-fire hydrologic recovery in Southern California watersheds

The current study investigates the spatial and temporal dynamics of post-fire vegetation and the subsequent influence on seasonal and annual hydrologic responses in chaparral-dominated watersheds. Post-fire climatology, burn severity, slope aspect, and vegetation behavior are evaluated for two basins burned during the 2003 Old Fire in the San Bernardino Mountains in Southern California. Climate and discharge data are used to evaluate seasonal and annual variability of post-fire hydrologic fluxes. Data obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) are used to estimate Enhanced Vegetation Index (EVI) and differenced Normalized Burn Ratio (dNBR). A Savitzky–Golay filtering technique and an integrated EVI annual fraction are utilized to assess vegetation recovery under a range of potential controls. Vegetation recovery is highly variable in both watersheds and is related to slope aspect (solar and water availability), initial biomass levels, and burn severity. South and west facing slopes show higher pre-fire EVI (biomass) and significant loss of vegetation cover after fire. Vegetation in both watersheds responds to an extreme wet season during the second post-fire year, however recovery rates are not sustained. North and east aspects show the quickest biomass gain relative to pre-fire conditions by the end of the study period (WY 2010), while the west and south slopes show lower biomass recovery. High burn severity areas show the slowest recovery across all slope aspects, with these regions just approaching 90% of pre-fire biomass by the end of the seven-year post-fire period. The variable rate of vegetation recovery across the watersheds results in significant changes in annual and seasonal discharge throughout the post-fire period. Runoff ratios remain elevated in both systems and there is increased dry season flow for much of the study period, indicating that plant water consumption and flowpaths are not back to pre-fire behavior by the end of WY 2010.

Fire and vegetation type effects on soil hydrophobicity and infiltration in the sagebrush-steppe: II. Hyperspectral analysis

Hyperspectral remote sensing methods were developed to identify and differentiate post-fire characteristics in burned sagebrush-steppe. This shrub-steppe environment is typical of the Intermountain West, where wildfire intervals are frequent. After a 78,000ha wildfire in 2005 in southern Idaho, soil water repellency and fire severity were evaluated with field and airborne spectroscopy measurements. A hyperspectral analysis correctly identified bare ground, low and high fire severity grass areas and low fire severity shrub areas, with accuracies between 74 and 92%. The differentiation of moderate and high fire severity areas was ambiguous, resulting in accuracies between 39 and 54%. The hyperspectral analysis of soil water repellency resulted in a representative map of its distribution with an accuracy of 65%. The analysis techniques conducted in this project signify spectroscopy to be beneficial for differentiating soil characteristics and fire severity classes in burned shrub-steppe areas, where the mostly bare, spectrally homogenous soils exhibit subtle but significant changes in reflectance. The spatial representation of post-fire soil and vegetation conditions may provide a better understanding of post-fire vegetation and surficial processes (water and wind erosion) in shrub-steppe.

Postfire seedling recruitment at the southern limit of lichen woodland

Although fire is the primary mechanism driving regeneration in open black spruce ( Picea mariana (Mill.) BSP) lichen woodland, there are limited data concerning the sources of seedling mortality across the range of burn severity. We monitored planted seedlings in areas of high and low burn severity in Terra Nova National Park (Newfoundland, Canada) to determine sources and patterns of mortality of black spruce seedlings among burn treatments following a recent burn (2002). The importance of herbivory by small mammals as a source of seedling mortality was evaluated using small cages that excluded voles and non-native snowshoe hare. Overall seedling mortality was high (79%) in all areas; mortality was similar in areas of low (73%) and high (76%) burn severity, and highest in edge areas adjacent to closed-canopy forest (90%). Drought, rather than herbivory, was the most common cause of mortality during the first two seasons following germination. Seedling mortality at the southern edge of the lichen woodland was comparable to that found in other studies, but sources differed, emphasizing the spatially variable nature of mortality. Based on the level of seedling recruitment, our results suggest lichen woodland will return at this site.

Changes in Forest Structure After a Large, Mixed-Severity Wildfire in Ponderosa Pine Forests of the Black Hills, South Dakota, USA

Abstract We evaluated changes in forest structure related to fire severity after a wildfire in ponderosa pine forests of the Black Hills, South Dakota, where 25% burned at low, 48% at moderate, and 27% at high severity. We compared tree mortality, fine (FWD) and coarse woody debris (CWD) and tree regeneration in areas burned under different severity. With low severity, mortality was limited to small trees (&amp;lt;15 cm dbh) with no reduction in basal area (BA) compared with unburned areas. FWD and CWD were 60% less than the unburned forest. With moderate severity, 100% mortality of small trees and significant large tree mortality resulted in an 50% reduction in BA and an open stand structure dominated by a few large trees. After 5 years, FWD and CWD recovered to unburned levels. With high severity, a lack of seed source makes regeneration unlikely. After 5 years, FWD equaled levels in unburned stands and CWD loads exceeded the unburned forest by 74%. The future landscape will be a mosaic of patches with forest structures determined by developmental trajectories set in motion by different fire severities. There will be patches of fully stocked, single canopy forest, multistory forest, and persistent grass- and shrub-dominated communities. High fuel loads in moderate and high severity areas remain a concern for management as does the lack of regeneration in high severity areas.