scholarly journals Variables That Influence Changes in Fire Severity and Their Relationship with Changes Between Surface and Crown Fires in a Wind-Driven Wildfire

2013 ◽  
Vol 59 (2) ◽  
pp. 139-150 ◽  
Author(s):  
Albert Alvarez ◽  
Marc Gracia ◽  
Marc Castellnou ◽  
Javier Retana
Keyword(s):  
Fire Severity ◽  
Crown Fires ◽  
In Fire

Charcoal signatures defined by multivariate analysis of charcoal records from 10 lakes in northwest Wisconsin (USA)

2011 ◽  
Vol 75 (1) ◽  
pp. 125-137 ◽  
Author(s):  
Elizabeth A. Lynch ◽  
Sara C. Hotchkiss ◽  
Randy Calcote
Keyword(s):  
Late Holocene ◽  
Climate Changes ◽  
Regional Climate ◽  
Fire Regimes ◽  
Small Scale ◽  
Regional Patterns ◽  
Crown Fires ◽  
Sand Plain ◽  
In Fire ◽  
Standard Techniques

AbstractWe show how sedimentary charcoal records from multiple sites within a single landscape can be used to compare fire histories and reveal small scale patterns in fire regimes. Our objective is to develop strategies for classifying and comparing late-Holocene charcoal records in Midwestern oak- and pine-dominated sand plain ecosystems where fire regimes include a mix of surface and crown fires. Using standard techniques for the analysis of charcoal from lake sediments, we compiled 1000- to 4000-yr-long records of charcoal accumulation and charcoal peak frequencies from 10 small lakes across a sand plain in northwestern Wisconsin. We used cluster analysis to identify six types of charcoal signatures that differ in their charcoal influx rates, amount of grass charcoal, and frequency and magnitude of charcoal peaks. The charcoal records demonstrate that while fire histories vary among sites, there are regional patterns in the occurrence of charcoal signature types that are consistent with expected differences in fire regimes based on regional climate and vegetation reconstructions. The fire histories also show periods of regional change in charcoal signatures occurring during times of regional climate changes at ~700, 1000, and 3500 cal yr BP.

Heterogeneity in fire severity within early season and late season prescribed burns in a mixed-conifer forest

2006 ◽  
Vol 15 (1) ◽  
pp. 37 ◽  
Author(s):  
Eric E. Knapp ◽  
Jon E. Keeley
Keyword(s):  
Sierra Nevada ◽  
Prescribed Burning ◽  
Fire Severity ◽  
Basal Area ◽  
Conifer Forest ◽  
Fuel Loading ◽  
Early Season ◽  
Late Season ◽  
Fuel Loads ◽  
In Fire

Structural heterogeneity in forests of the Sierra Nevada was historically produced through variation in fire regimes and local environmental factors. The amount of heterogeneity that prescription burning can achieve might now be more limited owing to high fuel loads and increased fuel continuity. Topography, woody fuel loading, and vegetative composition were quantified in plots within replicated early and late season burn units. Two indices of fire severity were evaluated in the same plots after the burns. Scorch height ranged from 2.8 to 25.4 m in early season plots and 3.1 to 38.5 m in late season plots, whereas percentage of ground surface burned ranged from 24 to 96% in early season plots and from 47 to 100% in late season plots. Scorch height was greatest in areas with steeper slopes, higher basal area of live trees, high percentage of basal area composed of pine, and more small woody fuel. Percentage of area burned was greatest in areas with less bare ground and rock cover (more fuel continuity), steeper slopes, and units burned in the fall (lower fuel moisture). Thus topographic and biotic factors still contribute to the abundant heterogeneity in fire severity with prescribed burning, even under the current high fuel loading conditions. Burning areas with high fuel loads in early season when fuels are moister may lead to patterns of heterogeneity in fire effects that more closely approximate the expected patchiness of historical fires.

Mapping fire regime ecoregions in California

2020 ◽  
Vol 29 (7) ◽  
pp. 595 ◽  
Author(s):  
Alexandra D. Syphard ◽  
Jon E. Keeley
Keyword(s):  
Fire Regime ◽  
Fire Severity ◽  
Fire Regimes ◽  
Unsupervised Classification ◽  
Fire Frequency ◽  
The State ◽  
Reduction Strategies ◽  
Lower Variability ◽  
Fire Characteristics ◽  
In Fire

The fire regime is a central framing concept in wildfire science and ecology and describes how a range of wildfire characteristics vary geographically over time. Understanding and mapping fire regimes is important for guiding appropriate management and risk reduction strategies and for informing research on drivers of global change and altered fire patterns. Most efforts to spatially delineate fire regimes have been conducted by identifying natural groupings of fire parameters based on available historical fire data. This can result in classes with similar fire characteristics but wide differences in ecosystem types. We took a different approach and defined fire regime ecoregions for California to better align with ecosystem types, without using fire as part of the definition. We used an unsupervised classification algorithm to segregate the state into spatial clusters based on distinctive biophysical and anthropogenic attributes that drive fire regimes – and then used historical fire data to evaluate the ecoregions. The fire regime ecoregion map corresponded well with the major land cover types of the state and provided clear separation of historical patterns in fire frequency and size, with lower variability in fire severity. This methodology could be used for mapping fire regimes in other regions with limited historical fire data or forecasting future fire regimes based on expected changes in biophysical characteristics.

FIRE SEVERITY AND ECOSYTEM RESPONSES FOLLOWING CROWN FIRES IN CALIFORNIA SHRUBLANDS

2008 ◽  
Vol 18 (6) ◽  
pp. 1530-1546 ◽  
Author(s):  
Jon E. Keeley ◽  
Teresa Brennan ◽  
Anne H. Pfaff
Keyword(s):  
Fire Severity ◽  
Crown Fires

Refuges for birds in fire-prone landscapes: The influence of fire severity and fire history on the distribution of forest birds

2014 ◽  
Vol 318 ◽  
pp. 110-121 ◽  
Author(s):  
Natasha M. Robinson ◽  
Steven W.J. Leonard ◽  
Andrew F. Bennett ◽  
Michael F. Clarke
Keyword(s):  
Fire History ◽  
Fire Severity ◽  
Forest Birds ◽  
In Fire

scholarly journals Identifying Post-Fire Recovery Trajectories and Driving Factors Using Landsat Time Series in Fire-Prone Mediterranean Pine Forests

2020 ◽  
Vol 12 (9) ◽  
pp. 1499 ◽  
Author(s):  
Alba Viana-Soto ◽  
Inmaculada Aguado ◽  
Javier Salas ◽  
Mariano García
Keyword(s):  
Time Series ◽  
Fire Severity ◽  
Driving Factors ◽  
Pine Forests ◽  
Recovery Rates ◽  
Tasseled Cap ◽  
Successional Stages ◽  
Mediterranean Pine ◽  
Recovery Dynamics ◽  
In Fire

Wildfires constitute the most important natural disturbance of Mediterranean forests, driving vegetation dynamics. Although Mediterranean species have developed ecological post-fire recovery strategies, the impacts of climate change and changes in fire regimes may endanger their resilience capacity. This study aims at assessing post-fire recovery dynamics at different stages in two large fires that occurred in Mediterranean pine forests (Spain) using temporal segmentation of the Landsat time series (1994–2018). Landsat-based detection of Trends in Disturbance and Recovery (LandTrendr) was used to derive trajectory metrics from Tasseled Cap Wetness (TCW), sensitive to canopy moisture and structure, and Tasseled Cap Angle (TCA), related to vegetation cover gradients. Different groups of post-fire trajectories were identified through K-means clustering of the Recovery Ratios (RR) from fitted trajectories: continuous recovery, continuous recovery with slope changes, continuous recovery stabilized and non-continuous recovery. The influence of pre-fire conditions, fire severity, topographic variables and post-fire climate on recovery rates for each recovery category at successional stages was analyzed through Geographically Weighted Regression (GWR). The modeling results indicated that pine forest recovery rates were highly sensitive to post-fire climate in the mid and long-term and to fire severity in the short-term, but less influenced by topographic conditions (adjusted R-squared ranged from 0.58 to 0.88 and from 0.54 to 0.93 for TCA and TCW, respectively). Recovery estimation was assessed through orthophotos, showing a high accuracy (Dice Coefficient ranged from 0.81 to 0.97 and from 0.74 to 0.96 for TCA and TCW, respectively). This study provides new insights into the post-fire recovery dynamics at successional stages and driving factors. The proposed method could be an approach to model the recovery for the Mediterranean areas and help managers in determining which areas may not be able to recover naturally.

Predicting the ignition of crown fuels above a spreading surface fire. Part I: model idealization

2006 ◽  
Vol 15 (1) ◽  
pp. 47 ◽  
Author(s):  
Miguel G. Cruz ◽  
Bret W. Butler ◽  
Martin E. Alexander ◽  
Jason M. Forthofer ◽  
Ronald H. Wakimoto
Keyword(s):  
Particle Temperature ◽  
Fire Spread ◽  
Management Decision ◽  
Fuel Particle ◽  
Surface Fire ◽  
Heat Transfer Theory ◽  
Crown Fires ◽  
Fuel Particles ◽  
Fire Flame ◽  
In Fire

A model was developed to predict the ignition of forest crown fuels above a surface fire based on heat transfer theory. The crown fuel ignition model (hereafter referred to as CFIM) is based on first principles, integrating: (i) the characteristics of the energy source as defined by surface fire flame front properties; (ii) buoyant plume dynamics; (iii) heat sink as described by the crown fuel particle characteristics; and (iv) energy transfer (gain and losses) to the crown fuels. Fuel particle temperature increase is determined through an energy balance relating heat absorption to fuel particle temperature. The final model output is the temperature of the crown fuel particles, which upon reaching ignition temperature are assumed to ignite. CFIM predicts the ignition of crown fuels but does not determine the onset of crown fire spread per se. The coupling of the CFIM with models determining the rate of propagation of crown fires allows for the prediction of the potential for sustained crowning. CFIM has the potential to be implemented in fire management decision support systems.

Effect of fire severity on long-term occupancy of burned boreal conifer forests by saproxylic insects and wood-foraging birds

2010 ◽  
Vol 19 (4) ◽  
pp. 500 ◽  
Author(s):  
Antoine Nappi ◽  
Pierre Drapeau ◽  
Michel Saint-Germain ◽  
Virginie A. Angers
Keyword(s):  
Boreal Forests ◽  
Fire Severity ◽  
Fire Regimes ◽  
Conifer Forests ◽  
Saproxylic Insects ◽  
Dead Trees ◽  
Brown Creeper ◽  
Canadian Boreal Forest ◽  
In Fire

Fire severity can vary greatly within and among burns, even in the Canadian boreal forest where fire regimes consist mostly of stand-replacing fires. We investigated the effects of fire severity on the long-term occupancy of burns by (i) saproxylic insects and (ii) three wood-foraging birds. Based on observations made 6 to 11 years after fire in burned conifer forests that varied in fire severity in Quebec, Canada, our results indicate that low-severity portions of the burns likely provided snag conditions suitable for the long-term presence of deadwood-associated insects and birds. The black-backed woodpecker, a post-fire forest specialist, was still abundant 6 and 8 years after fire. This pattern was likely explained by the persistence of several saproxylic insect species that are associated with recently dead trees and by the positive effect of lower fire severity on the abundance of Arhopalus foveicollis, a cerambycid with a long life cycle in dead wood. The American three-toed woodpecker and the brown creeper, and their associated prey (Scolytinae beetles), were more abundant in burned stands of lower v. higher severity. We conclude that less severely burned snags and stands within high-severity burns may favour the long-term presence of trophic webs that involve saproxylic insects and wood-foraging birds in burned boreal forests.

scholarly journals Pyrodiversity promotes avian diversity over the decade following forest fire

2016 ◽  
Vol 283 (1840) ◽  
pp. 20161703 ◽  
Author(s):  
Morgan W. Tingley ◽  
Viviana Ruiz-Gutiérrez ◽  
Robert L. Wilkerson ◽  
Christine A. Howell ◽  
Rodney B. Siegel
Keyword(s):  
Fire Ecology ◽  
Fire Suppression ◽  
Spatial Scales ◽  
Fire Severity ◽  
Strong Support ◽  
Bird Diversity ◽  
Community Model ◽  
Avian Biodiversity ◽  
In Fire ◽  
Wildfire Regimes

An emerging hypothesis in fire ecology is that pyrodiversity increases species diversity. We test whether pyrodiversity—defined as the standard deviation of fire severity—increases avian biodiversity at two spatial scales, and whether and how this relationship may change in the decade following fire. We use a dynamic Bayesian community model applied to a multi-year dataset of bird surveys at 1106 points sampled across 97 fires in montane California. Our results provide strong support for a positive relationship between pyrodiversity and bird diversity. This relationship interacts with time since fire, with pyrodiversity having a greater effect on biodiversity at 10 years post-fire than at 1 year post-fire. Immediately after fires, patches of differing burn severities hold similar bird communities, but over the ensuing decade, bird assemblages within patches of contrasting severities differentiate. When evaluated at the scale of individual fires, fires with a greater heterogeneity of burn severities hold substantially more species. High spatial heterogeneity in severity, sometimes called ‘mixed-severity fire', is a natural part of wildfire regimes in western North America, but may be jeopardized by climate change and a legacy of fire suppression. Forest management that encourages mixed-severity fire may be critical for sustaining biodiversity across fire-prone landscapes.

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