Dormant season grazing may decrease wildfire probability by increasing fuel moisture and reducing fuel amount and continuity

2015 ◽  
Vol 24 (6) ◽  
pp. 849 ◽  
Author(s):  
Kirk W. Davies ◽  
Chad S. Boyd ◽  
Jon D. Bates ◽  
April Hulet
Keyword(s):  
Fire Suppression ◽  
Cumulative Effect ◽  
Basal Area ◽  
Fuel Moisture ◽  
Herbaceous Perennials ◽  
Wildfire Suppression ◽  
Winter Grazing ◽  
Dormant Season ◽  
Exotic Annual Grass ◽  
Fuel Characteristics

Mega-fires and unprecedented expenditures on fire suppression over the past decade have resulted in a renewed focus on presuppression management. Dormant season grazing may be a treatment to reduce fuels in rangeland, but its effects have not been evaluated. In the present study, we evaluated the effect of dormant season grazing (winter grazing in this ecosystem) by cattle on fuel characteristics in sagebrush (Artemisia L.) communities at five sites in south-eastern Oregon. Winter grazing reduced herbaceous fuel cover, continuity, height and biomass without increasing exotic annual grass biomass or reducing bunchgrass basal area or production. Fuel moisture in winter-grazed areas was high enough that burning was unlikely until late August; in contrast, fuels in ungrazed areas were dry enough to burn in late June. Fuel biomass on perennial bunchgrasses was decreased by 60% with winter grazing, which may reduce the potential for fire-induced mortality. The cumulative effect of winter grazing from altering multiple fuel characteristics may reduce the likelihood of fire and the potential severity in sagebrush communities with an understorey dominated by herbaceous perennials. Dormant season grazing has the potential to reduce wildfire suppression expenditures in many rangelands where herbaceous fuels are an issue; however, increasing woody vegetation and extreme fire weather may limit its influence.

Exotic annual grass invasion alters fuel amounts, continuity and moisture content

2013 ◽  
Vol 22 (3) ◽  
pp. 353 ◽  
Author(s):  
Kirk W. Davies ◽  
Aleta M. Nafus
Keyword(s):  
Moisture Content ◽  
Plant Communities ◽  
Large Scale ◽  
Cumulative Effect ◽  
Fuel Moisture ◽  
Annual Grass ◽  
Fire Cycle ◽  
Exotic Annual Grass ◽  
Fuel Characteristics ◽  
Fuel Moisture Content

Many exotic annual grasses are believed to increase wildfire frequency to the detriment of native vegetation by increasing fine fuels and thus, creating a grass-fire cycle. However, information on differences in fuel characteristics between invaded and non-invaded plant communities is lacking, or is based mainly on speculation and anecdotal evidence. We compared fuel biomass, cover, continuity and moisture content in plant communities invaded and not invaded by cheatgrass (Bromus tectorum L.), an exotic annual grass, in 2010 and 2011 in south-eastern Oregon, USA. Annual grass-invaded communities had higher fine fuel amounts, greater fuel continuity, smaller fuel gaps and lower fuel moisture content than did non-invaded plant communities. These conditions would increase the probability that ignition sources would contact combustible fuels and that fires would propagate. Fuel characteristics in the annual grass-invaded communities in our study may also support faster spreading fires. Fuel moisture content was low enough to burn readily more than a month earlier in annual grass-invaded communities than in non-invaded communities, thereby expanding the wildfire season. The cumulative effect of these differences in fuel characteristics between exotic annual grass-invaded and non-invaded plant communities is an increased potential for frequent, large-scale, fast-spreading wildfires. We suggest that research is needed to develop methods to mediate and reverse these changes in fuel characteristics associated with B. tectorum invasion.

Concurrent and antecedent soil moisture relate positively or negatively to probability of large wildfires depending on season

2016 ◽  
Vol 25 (6) ◽  
pp. 657 ◽  
Author(s):  
Erik S. Krueger ◽  
Tyson E. Ochsner ◽  
J. D. Carlson ◽  
David M. Engle ◽  
Dirac Twidwell ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Growing Season ◽  
Fuel Moisture ◽  
Fuel Production ◽  
Antecedent Soil Moisture ◽  
Plant Water Stress ◽  
Wildfire Occurrence ◽  
Water Capacity ◽  
Available Water Capacity ◽  
Dormant Season

Measured soil moisture data may improve wildfire probability assessments because soil moisture is physically linked to fuel production and live fuel moisture, yet models characterising soil moisture–wildfire relationships have not been developed. We therefore described the relationships between measured soil moisture (concurrent and antecedent), as fraction of available water capacity (FAW), and large (≥405 ha) wildfire occurrence during the growing (May–October) and dormant (November–April) seasons from 2000 to 2012 in Oklahoma, USA. Wildfires were predominantly grass and brush fires but occurred across multiple fuel types including forests. Below-average FAW coincided with high wildfire occurrence each season. Wildfire probability during the growing season was 0.18 when concurrent FAW was 0.5 (a threshold for plant water stress) but was 0.60 when concurrent FAW was 0.2 (extreme drought). Dormant season wildfire probability was influenced not only by concurrent but also by antecedent FAW. Dormant season wildfire probability was 0.29 and 0.09 when FAW during the previous growing season was 0.9 (near ideal for plant growth) and 0.2, respectively. Therefore, although a wet growing season coincided with reduced wildfire probability that season, it also coincided with increased wildfire probability the following dormant season, suggesting that the mechanisms by which soil moisture influences wildfire probability are seasonally dependent.

The economic benefit of localised, short-term, wildfire-potential information

2015 ◽  
Vol 24 (7) ◽  
pp. 974 ◽  
Author(s):  
Laine Christman ◽  
Kimberly Rollins
Keyword(s):  
Fire Suppression ◽  
Economic Value ◽  
Information Service ◽  
Risk Scenarios ◽  
The Us ◽  
Wildfire Suppression ◽  
Information Products ◽  
The Difference ◽  
Wildland Management ◽  
Us West

Wildfire-potential information products are designed to support decisions for prefire staging of movable wildfire suppression resources across geographic locations. We quantify the economic value of these information products by defining their value as the difference between two cases of expected fire-suppression expenditures: one in which daily information about spatial variation in wildfire-potential is used to move fire suppression resources throughout the season, and the other case in which daily information is not used and fire-suppression resources are staged in their home locations all season. We demonstrate the method by constructing a hypothetical wildland management unit calibrated to represent a region typical in the US West. The method uses estimated suppression costs and probabilities of significant fire, as provided by an information service, to estimate expected suppression costs. We analyse differences in expected suppression costs for a range of risk scenarios. Economic savings occur for the majority of risk scenarios. This approach can be used to evaluate investments in wildfire-potential information services, and for assessing the value of investing in new resources.

Sharing contracted resources for fire suppression: engine dispatch in the Northwestern United States

2017 ◽  
Vol 26 (2) ◽  
pp. 113 ◽  
Author(s):  
Katie M. Lyon ◽  
Heidi R. Huber-Stearns ◽  
Cassandra Moseley ◽  
Christopher Bone ◽  
Nathan A. Mosurinjohn
Keyword(s):  
Fire Suppression ◽  
Geographic Area ◽  
Wildfire Suppression ◽  
The Usa ◽  
Fire Planning ◽  
System Data ◽  
The Right ◽  
Northwest Region ◽  
Insight Into ◽  
National Resource

As demand for wildfire response resources grows across the globe, a central challenge is developing new and flexible systems and capacity to ensure that resources needed for fire response arrive when and where they are needed. Private contractors have become increasingly important in providing equipment and services to support agency wildfire suppression needs in the USA. Understanding the capacity of contracted resources for federal agency fire suppression needs is critical for preseason fire planning and response. Using National Resource Ordering and Status System data, we examined Northwest region engine dispatches from 2008 to 2015. The number of times and days engines were out on assignments increased over the study period, and dispatch centres routinely shared engines within and outside their geographic area. However, in 2015, not all of the available engines were recorded as utilised at peak demand during one of the largest fire seasons in the Northwest. This study provides insight into the ways in which fire managers share important resources such as engines and the information they have available to make decisions during an incident, and raises questions about what the right amount of capacity is to be able to respond in extreme fire years.

Fall and spring grazing influence fire ignitability and initial spread in shrub steppe communities

2017 ◽  
Vol 26 (6) ◽  
pp. 485 ◽  
Author(s):  
Kirk W. Davies ◽  
Amanda Gearhart ◽  
Chad S. Boyd ◽  
Jon D. Bates
Keyword(s):  
Grazing Management ◽  
Management Tool ◽  
Fuel Moisture ◽  
Fire Propagation ◽  
Shrub Steppe ◽  
The World ◽  
Steppe Communities ◽  
Fuel Characteristics ◽  
Wildfire Season ◽  
Fire Ignition

The interaction between grazing and fire influences ecosystems around the world. However, little is known about the influence of grazing on fire, in particular ignition and initial spread and how it varies by grazing management differences. We investigated effects of fall (autumn) grazing, spring grazing and not grazing on fuel characteristics, fire ignition and initial spread during the wildfire season (July and August) at five shrub steppe sites in Oregon, USA. Both grazing treatments decreased fine fuel biomass, cover and height, and increased fuel moisture, and thereby decreased ignition and initial spread compared with the ungrazed treatment. However, effects differed between fall and spring grazing. The probability of initial spread was 6-fold greater in the fall-grazed compared with the spring-grazed treatment in August. This suggests that spring grazing may have a greater effect on fires than fall grazing, likely because fall grazing does not influence the current year’s plant growth. Results of this study also highlight that the grazing–fire interaction will vary by grazing management. Grazing either the fall or spring before the wildfire season reduces the probability of fire propagation and, thus, grazing is a potential fuel management tool.

Changes in white pine blister rust infection and mortality in limber pine over time

2013 ◽  
Vol 43 (10) ◽  
pp. 919-928 ◽  
Author(s):  
Cyndi M. Smith ◽  
David W. Langor ◽  
Colin Myrholm ◽  
Jim Weber ◽  
Cameron Gillies ◽  
...  
Keyword(s):  
Mountain Pine Beetle ◽  
Fire Suppression ◽  
Basal Area ◽  
White Pine Blister Rust ◽  
White Pine ◽  
Pinus Flexilis ◽  
Limber Pine ◽  
Blister Rust ◽  
Dead Trees ◽  
Pine Beetle

Limber pine (Pinus flexilis E. James) is under threat from white pine blister rust (WPBR), mountain pine beetle, drought, and fire suppression across its range in western North America. In 2003–2004, we established 85 plots to assess the mortality and incidence of WPBR on limber pine, and remeasured them in 2009. Infection was evident in 74% of the plots in 2003–2004 and 88% of the plots in 2009. The proportion of dead trees increased from 32% in 2003–2004 to 35% in 2009. The percentage of live trees infected increased from 33% in 2003–2004 to 43% in 2009. Mean live limber pine basal area in 2009 ranged from 0.03 to 77.8 m2/ha per plot. Twenty (24%) of the plots had no seedlings in the first measurement, but only 15% in the second measurement. Seedling infection was low (8% in 2003–2004 and 4% in 2009). In 12 plots that were measured three times, mortality increased from 30% of all trees in 1996 to 50% in 2003, then decreased to 46% in 2009. Infection decreased from 73% of live trees in 1996 to 46% in 2003, then increased to 66% in 2009. High mortality and infection levels suggest that the long-term persistence of many limber pine populations in the southern part of the study area are in jeopardy, and continued monitoring is needed to assist with management decisions.

scholarly journals Silviculture can facilitate repeat prescribed burn programs with long-term strategies

2022 ◽  
pp. 104-111
Author(s):  
Robert A. York ◽  
Jacob Levine ◽  
Daniel Foster ◽  
Scott Stephens ◽  
Brandon Collins
Keyword(s):  
Fuel Consumption ◽  
Prescribed Fire ◽  
Fire Suppression ◽  
Relative Proportion ◽  
Canopy Cover ◽  
Basal Area ◽  
Fuel Load ◽  
Prescribed Burn ◽  
Wildfire Hazard ◽  
Initial Entry

A significant expansion of prescribed fire activity will be necessary to mitigate growing wildfire hazard in California forests. Forest managers can facilitate this expansion by promoting forest structures that allow for more effective implementation of prescribed fire, for both initial-entry and repeat burns. We analyzed changes in surface fuel during a series of three burns in replicated mixed-conifer stands following a period of over 100 years of fire suppression and exclusion. Total fuel load, proportion of pine present, canopy cover and basal area of live trees were relevant forest-structure components that influenced plot-scale fuel consumption. The study highlighted the importance of pre-fire fuel load and the relative proportion of pine in the overstory, which both led to greater amounts of fuel consumption. The initial-entry burn dramatically reduced all fuel categories (fine fuel, coarse wood and duff). Following each burn, fuel recovered until the next burn reduced loads enough to maintain low fuel levels. We apply the results to provide an example of how to determine the timing of prescribed fires.

Fire weather thresholds and burnt area in Portugal

2021 ◽  
Author(s):  
Tomás Calheiros ◽  
Akli Benali ◽  
João Neves Silva ◽  
Mário Pereira ◽  
João Pedro Nunes
Keyword(s):  
Land Use ◽  
Cluster Analysis ◽  
Fire Suppression ◽  
Cumulative Effect ◽  
Weather Conditions ◽  
Weather Data ◽  
Fire Weather ◽  
Burnt Area ◽  
Fire Weather Index ◽  
Large Fires

<p>Fire strongly depends on the weather, especially in Mediterranean climate regions with rainy winters but dry and hot summers, as in Portugal. Fire weather indices are commonly used to assess the current and/or cumulative effect of weather conditions on fuel moisture and fire behaviour. The Daily Severity Rating (DSR) is a numeric rating of the difficulty of controlling fires, based on the Canadian Fire Weather Index (FWI), developed to accurately assess the expected efforts required for fire suppression. Recently, the 90th percentile of DSR (90pDSR) was identified as a good indicator of extreme fire weather and well related to the burnt area in some regions of the Iberian Peninsula. The purposes of this work were: 1) to verify if this threshold is adequate for all continental Portugal; 2) to identify and characterize local variations of this threshold, at a higher spatial resolution; and, 3) to analyse other variables that can explain this spatial heterogeneity.</p><p>We used fire data from the Portuguese Institute for the Conservation of Nature and Forests and weather data from ERA5, for the 2001 – 2019 study period. We also used the Land Use and Occupation Charter for 2018 (COS2018), provided by the Directorate-General for Territory, to assess land use and cover in Portugal. The meteorological variables to compute the DSR are air temperature, relative humidity, wind speed and daily accumulated precipitation, at 12 UTC. DSR percentiles (DSRp) were computed for summer period (between 15<sup>th</sup> May and 31<sup>st</sup> October) and combined with large (>100 ha) burnt areas (BA), with the purpose to identify which DSRp value is responsible of a large amount of BA (80 or 90%). Cluster analysis was performed using the relation between DSRp and BA, in each municipality of Continental Portugal.</p><p>Results reveal that the 90pDSR is an adequate threshold for the entire territory. However, at the municipalities’ level, some important differences appear between DSRp thresholds that explain 90 and 80% of the total BA. Cluster analysis shows that these differences justified the existence of several statistically significant clusters. Generally, municipalities where large fires take place in high or very high DSRp are located in north and central coastal areas, Serra da Estrela, Serra de Montejunto and Algarve. In contrast, clusters where large fires where registered with low DSRp appear in northern and central hinterland. COS2018 data was assessed to analyse if and how the vegetation cover type influences the clusters’ distribution and affects the relationship between DSRp and total BA. Preliminary results expose a possible vegetation influence, especially between forests and shrublands.</p>

Dormant-Season Moderate Grazing Prefire Maintains Diversity and Reduces Exotic Annual Grass Response Postfire in Imperiled Artemisia Steppe

2021 ◽  
Vol 79 ◽  
pp. 91-99
Author(s):  
Kirk W. Davies ◽  
Jon D. Bates ◽  
Chad S. Boyd ◽  
Rory O'Connor ◽  
Stella Copeland
Keyword(s):  
Annual Grass ◽  
Dormant Season ◽  
Exotic Annual Grass

scholarly journals Effects of wildfire suppression chemicals on people and the environment

2013 ◽  
Vol 2 (2) ◽  
pp. 129-137
Keyword(s):  
Aquatic Ecosystems ◽  
Fire Suppression ◽  
Fire Retardant ◽  
Terrestrial Ecosystems ◽  
Fish Kill ◽  
Smoke Emission ◽  
Broad Array ◽  
Wildfire Suppression ◽  
A Site ◽  
Potential Human Health

Fire agencies worldwide apply millions of gallons of fire suppression chemicals on a broad array of ecosystems. These chemicals are considered to have minimal effects on the health of people who might be exposed to them. Only incidents of skin and eye irritation have been reported as a result of prolonged fire retardant and firefighting foam contact. Fire suppression chemicals have minor toxicological or ecological effects and, as a result, do not generally harm terrestrial ecosystems. Major impacts, suppression chemicals have on the environment, may be through the adverse effects on water quality, and subsequently to aquatic ecosystems. Retardants may encourage eutrophication and, in some cases, contribute to fish kill when applied on watersheds, or if accidentally applied directly to water bodies. Foams are generally more toxic than retardants to aquatic biota, but they are applied in much smaller quantities. Application of retardants increases the total amount of smoke and airborne particulate produced, but air quality implications are minimal since additional smoke emission by the retardant is insignificant compared to the major output by the wildfire. Recommendations are offered for mitigation of potential human health and environmental impacts from the use of fire suppression chemicals, nevertheless, risks must be assessed on a site-by-site basis.

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