COMPILING, SYNTHESIZING AND ANALYZING EXISTING BOREAL FOREST FIRE HISTORY DATA IN ALASKA

Wildland fires play a critical role in maintaining the ecological integrity of boreal forests in Alaska. Identifying and maintaining natural fire regimes is an important component of fire management. There are numerous research projects that directly or indirectly address historical fire regimes in the Alaskan boreal forest, but many are unpublished, have many unprocessed dendrochronological (tree age and fire scar) samples, or their data were used for other purposes. Furthermore, no assessment of these data exists to understand how fire has historically affected the boreal forest ecosystems of Alaska. The goal of this project was to compile and synthesize existing Alaska boreal-forest fire-history literature and datasets (http://frames.nbii.gov/alaska/borealfirehistory). We include a literature review and synthesis of publications related to fire regimes in boreal forests in Alaska (the pending general technical report “Fire Regimes of the Alaskan Boreal Forest”), and incorporate the reference information into the Alaska Fire Effects Reference Database (http://frames.nbii.gov/alaska; funded by JFSP as part of project 05-4-2-03: Expanding FIREHouse to Alaska). Fourteen published and unpublished fire-history or stand-age datasets were compiled and processed into the Alaska Fire History Database (http://frames.nbii.gov/documents/alaska/fire_history/ak_fire_history_db.zip), and data summarized by plot are available through a dynamic map interface (within the Alaska Fire and Fuels Research Map; http://afsmaps.blm.gov/imf/imf.jsp?site=firehouse). Data compiled in the Alaska Fire History Database have also been submitted to the International Multiproxy Paleofire Database (IMPD). Finally, some of the project funds were used to clean up and improve data within the Alaska Large Fire Database, a database started in the early 1990s that includes reported fire locations since 1939 and fire perimeters since 1942 (http://afsmaps.blm.gov/imf/imf.jsp?site=firehistory)

The Fire and Tree Mortality Database, for Empirical Modeling of Individual Tree Mortality After Fire

Wildland fires have a multitude of ecological effects in forests, woodlands, and savannas across the globe. A major focus of past research has been on tree mortality from fire, as trees provide a vast range of biological services. We assembled a database of individual-tree records from prescribed fires and wildfires in the United States. The Fire and Tree Mortality (FTM) database includes records from 164,293 individual trees with records of fire injury (crown scorch, bole char, etc.), tree diameter, and either mortality or top-kill up to ten years post-fire. Data span 142 species and 62 genera, from 409 fires occurring from 1981-2016. Additional variables such as insect attack are included when available. The FTM database can be used to evaluate individual fire-caused mortality models for pre-fire planning and post-fire decision support, to develop improved models, and to explore general patterns of individual fire-induced tree death. The database can also be used to identify knowledge gaps that could be addressed in future research

Using hyperspectral imagery to estimate forest floor consumption from wildfire in boreal forests of Alaska, USA

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 end members 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 (R2¼0.5 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

DOES SEASON OF BURNING AFFECT FUEL DYNAMICS IN SOUTHEASTERN FORESTS?

Land managers in the southeastern United States (U.S.) have actively used prescribed fire, primarily in the winter or dormant season, as a tool to control the growth of understory vegetation since the middle of the last century. There is evidence, however, that burning during the growing season may have different, and in some cases more desirable effects on ecosystem processes, vegetation structure, vegetation composition and, by virtue of these factors, understory fuels and potential fire behavior. We conducted an experiment to document and test for potential differences in the rate of fuel re-growth and accumulation following prescribed fires during the dormant and growing seasons. In other words, as a fuel management treatment, do growing season prescribed fires have a different lifecycle than dormant season prescribed fires? We tested the hypotheses that fuels re-grow and accumulate more slowly following growing season fires, and that growing season fires change the structure and composition of the understory fuelbed to a larger degree when compared to dormant season fires. Our study measured fuel amount and composition annually following dormant and growing season prescribed fires for approximately two years in longleaf pine (Pinus palustris) flatwoods ecosystems in western (Eglin Air Force Base) and north-central (Apalachicola National Forest and St. Marks National Wildlife Refuge) Florida. We attempted to confirm anecdotal observations that fuel reduction that results from growing season burns lasts longer and also that the structure and composition of the post-fire fuelbed differs between growing season and dormant season fires. Confirmation of these observations could allow fire managers to adjust the intervals between fuel-reduction burns for the landscapes they manage, enabling treatment of more area for the same amount of effort and expense. As well, results from this study could suggest which treatments are most effective for restoring the structure and composition of understory fuels in flatwoods communities that have experienced a departure from desirable, historical conditions. Prescribed fires at our managed, mesic longleaf pine flatwoods sites maintained reduced shrub and herbaceous fuel loading, coverage and height at least two years post-fire. Our experiment showed very little difference in post-fire fuel dyanamics related to season of burn, although the temperature of the fire did appear to affect shrub regrowth, with hotter fires producing a larger and longer-lasting reduction in shrub loading and coverage. We observed differences in post-fire fuel dynamics between the western and north-central Florida study regions and suspect those differences are related to regional variations in species composition

Evaluation of the CONSUME and FOFEM fuel consumption models in pine and mixed hardwood forests of the eastern United States

Reliable predictions of fuel consumption are critical in the eastern United States (US), where prescribed burning is frequently applied to forests and air quality is of increasing concern. CONSUME and the First Order Fire Effects Model (FOFEM), predictive models developed to estimate fuel consumption and emissions from wildland fires, have not been systematically evaluated for application in the eastern US using the same validation data set. In this study, we compiled a fuel consumption data set from 54 operational prescribed fires (43 pine and 11 mixed hardwood sites) to assess each model’s uncertainties and application limits. Regions of indifference between measured and predicted values by fuel category and forest type represent the potential error that modelers could incur in estimating fuel consumption by category. Overall, FOFEM predictions have narrower regions of indifference than CONSUME and suggest better correspondence between measured and predicted consumption. However, both models offer relia..., Des prédictions fiables de consommation des combustibles sont essentielles dans l’est des États-Unis (É.-U.) où le brûlage dirigé est souvent utilisé en forêt et où la qualité de l’air est une préoccupation croissante. Les modèles de prédiction CONSUME et FOFEM ont été conçus pour estimer la consommation des combustibles et les émissions associées aux feux de forêt, mais ils n’ont pas été systématiquement évalués pour être appliqués dans l’est des É.-U. en utilisant le même ensemble de données de validation. Dans cette étude, nous avons compilé un ensemble de données de consommation de combustibles à partir de 54 brûlages dirigés opérationnels (43 pinèdes et 11 stations de forêt feuillue mélangée) pour estimer l’incertitude associée à chaque modèle et leurs limites d’application. Les zones d’indifférence entre les valeurs mesurées et prédites par catégorie de combustibles et par type forestier représentent l’erreur potentielle que les modèles pourraient engendrer en estimant la consommation de combustible..