Fire models may underestimate fire behavior in tallgrass prairie - observations from southern Ontario

Understanding how fuels and fire behavior are linked is important for those using prescribed fire as a land management tool. The authors of this study sought to:

1) Compare rapid assessment tools for fuel loading,

2) measure fire behavior, and

3) compare observed fire behavior to model predictions (Canadian FBP, Behave, Australian grass)..

To better understand the relationship between fuels and fire behavior in southern Ontario’s tallgrass prairie fuel type, and compare observed fire behavior to model predictions the authors of this study collected detailed fuel and fire behavior measurements. Accurately measuring fire behavior is a challenge, and the intensive sampling for this study is an example of how to collect detailed quantitative fire behavior measurements.

When comparing the model predictions to observed rate of spread, models typically under predicted fire behavior. Even the custom Behave model, which had the highest correlation with observed values, was found to under predict fire spread. The authors found that the model with the most reasonable fit, when considering both correlation and prediction bias, was the Australian grassland fire spread model.

Understanding strength and weaknesses of model assumptions and predictions can help prescribed burn practitioners plan and achieve successful burns.

Management Implications

• A field guide developed from this research is available online: http://cfs.nrcan.gc.ca/publications?id=33093
• Default settings in commonly used fuel models may underestimate fuel loads and fire behavior in tallgrass prairie
• The Robel pole was found to be an accurate rapid assessment of fuel loads in tallgrass prairie sites

For further summary of  the study's results and implications for management, view or download a PDF version of the research brief: "Fire behavior observations from southern Ontario."

The original paper is:

Kidnie, Susan, and B. Mike Wotton. 2015. Characterisation of the fuel and fire environment in southern Ontario’s tallgrass prairie. International Journal of Wildland Fire 24: 1118-1128.

Herpetofauna distribution across habitat gradients

In the Upper Midwest, There is limited quantitative information as to how the herpetofauna community (i.e., reptiles and amphibians, hereafter herp community) varies along the grassland – savanna- forest gradient. This lack of baseline data makes it difficult to determine the impacts of management activities, including prescribed fire.

The authors of this study surveyed the herp community along a prairie to forest gradient. Sites were established in northwest Indiana in 1999. Drift fence arrays with funnel traps were set up at 25 sites. To determine how the herp community responded to fire and changes in vegetation structures site variables were measured at each array. Site variables included environmental variables (e.g., % cover bare ground, stem density, canopy cover) and fire history (e.g., time since last fire).

There were opposing effects of fire on the herp community, with some species having strongly positive responses and other species strongly negative. The authors suggest that this pattern is the result of frequent fire having a generally positive effect on herps by maintaining habitat being coupled with short term negative impacts of prescribed fire (e.g. decreased cover). Additionally, diversity in the habitat requirements of species, for example some reptiles seek out open areas while others avoid them, can lead to opposing trends in the data.

The complexities of these patterns demonstrate the value in assessing the herp community as a whole and over time. If research or monitoring efforts are focused on a single species or habitat type, the results may not represent the broader herp community or predict the response in neighboring habitat types.

Management Implications

• The habitat needs of reptiles and amphibians differ, leading to differences in the herp community across a grassland to forest habitat gradient
• Maintaining diverse habitats, with a range of fire histories, can support a wider range of habitat needs
• Herpetofauna communities are most diverse in savanna habitats

For further summary of  the study's results and implications for management, view or download a PDF version of the research brief: "Herpetofauna distribution across habitat gradients." 

The original paper is:

Grundel, Ralph, David A Beamer, Gary A. Glowacki, Krystalnn J. Frohnapple, Noel B. Pavlovic. 2015. Opposing responses to ecological gradients structure amphibian and reptile communities across a temperate grassland-savanna-forest landscape. Biodiversity Conservation 24:1089-1108.

Response of herpetofauna to patch burn grazing

There is little information as to how patch burn grazing impacts herpetofauna (reptiles and amphibians, hereafter herps). This study was conducted near Nevada, Missouri, to determine how herps responded to fire, cattle grazing, and patch burn grazing. The author hypothesized that fire and cattle grazing would have a negative impact on herps (e.g., reduced species richness, increased patch extinction, greater mortality).

Patches of burn only, graze only, patch burn grazing, and control were established on the landscape for this experiment. Herpetofauna surveys were conducted in 2011 and 2012, before and after patch burn grazing. Additionally, vegetation in two habitat types (aquatic and riparian) and water quality were measured.

The study found that patch burn grazing may increase reptile species richness as this management approach creates a variety of habitat patches across a site. There was no response in the amphibian community to treatments. This study evaluated short term effects of fire and grazing, and continued monitoring would be needed to detect if there were long term positive or negative impacts of patch burn grazing on the reptile and amphibian community.

Management Implications

• Patch burn grazing increased heterogeneity of landscape, and was associated with increased reptile diversity
• Burn only treatments did not influence water quality
• Cattle had a negative impact on water quality, which could lead to negative impacts on amphibian eggs
• Adult amphibians returned to the same streams to breed despite patch-burn grazing

For further summary of  the study's results and implications for management, view or download a PDF version of the research brief: "Response of herpetofauna to patch burn grazing"

The original paper is:

Larson, Danelle, M. 2014. Grassland fire and cattle grazing regulate reptile and amphibian assembly among patches. Environmental Management 54:1434-1444.

Expansion of woody species in tallgrass prairie

The authors of this study used a combination of long term demographic data and field measurements to investigate what traits allow native woody species to outcompete grasses, even when fire is used as a management tool.

The study was conducted at Konza Prairie Biological Station in the Flint Hills of Kansas.Twenty six years of data from permanent plotsestablished in 1983 were used to examine changes in woody species cover.

In general, the authors found evidence that a positive feedback loop contributed to the ability of Cornus drummondii to encroach tallgrass prairie. Once established, this shrub has a deep root system, spreads via clonal growth, and reduces fine fuels needed to carry fire. These clonal resprouts are more likely to survive fires, and thus able to expand across the landscape at a higher rate. 

Management implications

• Woody cover can increase in tallgrass prairie managed with relatively frequent fire
• Determining the mechanisms that enablewood species to expand is critical formanagement (e.g., species with clonal growth more likely to survive fire or mowing)

For further summary of the study's results and implications for management, view or download a PDF version of the research brief: "Expansion of woody species in tallgrass prairie."

Or read the open access article in the online journal Ecosphere:

Ratajczak, Zak, Jesse B. Nippert, Jeffery C. Hartman, and Troy W. Ocheltree. 2011. Positive feedbacks amplify rates of woody encroachment in mesic tallgrass prairie. Ecosphere 2(11):121.  http://dx.doi.org/10.1890/ES11-00212.1

Fifty years of prairie fire – a case study from Iowa

Small, isolated prairie remnants often show a decline in native species over time, and their sustainability is questioned. Given the rarity of tallgrass prairie in the upper Midwest, it is important to monitor changes over time to determine the long term impacts of land management.

This case study sought to document changes in the vegetation at Kalsow Prairie, one of the largest virgin prairies remaining in Iowa. Management at Kalsow, prior to 1950, was predominantly annual summer mowing, after 1950 management was gradually shifted to spring burning.

Implications for managers:

• Managing the same way over time (e.g., burning in the spring every 2 years) may not maximize biodiversity of the plant community due to the strong selection pressure.
• Larger isolated prairie sites may be less prone to establishment of non-native species when managed with fire
• Prescribed fire may stabilize prairie communities, and keep non-native species from establishing

For further summary of the study's results and implications for management, view or download a PDF version of the research brief: "Fifty years of prairie fire – a case study from Iowa."

The original paper is:

Reference:

Dornbush, Mathew E. 2004 Plant community changes following fifty-years of management at Kalsow Prairie Preserve, Iowa, U.S.A. American Midland Naturalist 151:241-250.

Differences between upland and lowland savannas may indicate need for different restoration strategies

The authors of this study wondered if upland savannas are a good reference surrogate for lowland savannas or if there are key differences in how these sites respond to restoration techniques.

Implications for managers:

• Using upland savanna restoration strategies in lowland savanna sites may lead to loss of unique lowland characteristics
• Multiple historical sources (e.g., maps, surveyor descriptions, tree density) provide a more comprehensive view of past conditions
• Evaluate historical data with future climate conditions in mind

For further summary of the study's results and implications for management, view or download a PDF version of the research brief:"Differences Between Upland and Lowland Savannas May Indicate Need For Different Restoration Strategies."

The original paper is:

Reference:

Dettman, Connie L., Catherine M. Mabry, and Lisa A Schulte. 2009. Restoration of Midwestern U.S. savannas: One size does not fit all. Restoration Ecology 17(6):772-783.

Influence of fire history on high quality oak savannas

Influence of fire history on high quality oak savannas 

Knowing how the history of an oak savanna influences the stand structure may help inform restoration plans in the future. This study examined how the structure of high quality oak savanna sites may have been influenced by a history of fire, grazing, and single tree selection harvesting.

Implications for managers:

• Including punctuated longer fire free intervals in management plans can allow for recruitment in frequently burned sites  
• Combining prescribed fire with other disturbances (grazing, single tree harvest) can be used as part of land management plans in oak savannas to achieve uneven age structure on restoration sites
• Restoration plans should incorporate strategies for removing woody and herbaceous invasive species prior to implementing fire free intervals that allow for oak regeneration

For a summary of the study's results and implications for management, you can download a PDF version of the research brief here.

The original paper is:

Cody D. Considine, John W. Groninger, Charles M. Ruffner, Matthew D. Therrell, Sara G. Baer. 2013. Fire history and stand structure of high quality Black Oak (Quercus velutina) sand stands. Natural Areas Journal 33:10-20.

Effects of prairie restoration on butterfly communities

Effects of prairie restoration on butterfly communities

This study looked at the butterfly communities found in restored prairie sites in the Loess Hills in Iowa. Restoration sites were managed with prescribed fire, grazing, and a combination of fire and grazing.

Implications for managers:

• There is not a single best managementpractice for butterfly communities
• Knowledge of species present on site – and potential positive and negative responses – can help restoration planning
• Using a variety of management practices may be best way to increase species richness and abundance

For a summary of the study's results and implications for management, you can download a PDF version of the research brief "Effects of prairie restoration on butterfly communities."

The original paper is:

Jennifer A. Vogel, Diane M. Debinski, Rolf R. Koford, and James R. Miller. 2007. Butterfly responses to prairie restoration through fire and grazing. Biological Conservation 140:78-90

Short term effects of returning prescribed fire to oak woodland

This study evaluated the effects of two prescribed fires conducted on a site being restored to a white oak dominated woodland. Stand structure, understory species composition, light levels, and soil nutrients were compared between burned and unburned units within the Kelly Hertel Woods section of the Marengo Ridge Conservation Area in northeast Illinois.

Implications for Managers:

• Low intensity prescribed fire alone will not favor oak regeneration in restoration sites.
• Higher intensity prescribed fire or mechanical removal may be necessary to remove non-oak species.
• Protecting oak seedlings and saplings from mammalian herbivory may be necessary to promote survival into larger size classes.

 For a summary of the study's results and implications for management, you can view or download a PDF version of "Short term effects of returning prescribed fire to oak woodland."

This research brief for research managers summarizes the following peer-reviewed publication:

Stan, Amanda B., Lesley S. Rigg, and Linda S. Jones. 2006. Dynamics of a managed oak woodland in Northeastern Illinois. Natural Areas Journal 26(2):187-197.

Do Open Grown Oaks Indicate Former Savanna?

One method for identifying former oak savannas is identifying open grown oaks. However, some of these large, open-grown trees have established post-settlement. Further complicating the ability to identify former oak savannas is the lack of historical records at some sites, making human impacts of logging, farming, grazing, and oteher disturbances unknown.

Authors of this study conducted in central Iowa hypothesized that tree recruitment would be related to site history, and that the open-grown oaks which would be seen as indicators of savanna habitat may have established post-settlement.

Of the results, the most notable may be that the open-grown oaks on this site were established post-settlement. The open-grown characteristics likely developed as the result of a savanna-like landscape being maintained through grazing and possibly periodic fire.

For a summary of the study's results and implications for management, you can view or download a PDF version of "Do Open Grown Oaks Indicate Former Savanna?"

This research brief for research managers summarizes the following peer-reviewed publication:

Karnitz, Holly, and Heidi Asbjornsen. 2006. Composition and age structure of a degraded tallgrass oak savanna in central Iowa. Natural Areas Journal 26:179-186.

Measuring prescribed fire temperatures

Prescribed fire is used in the Northern Great Plains region to enhance native vegetation and control invasive plants. Fire characteristics, including fire temperatures and duration of lethal heating, are dependent upon fuel loads, fuel moisture, and environmental conditions (e.g. ambient temperature). Measurement of fire characteristics is important because these characteristics are related to plant tissue damage and other measures of fire severity.

Maximum temperature and heating duration differed by year, site, and treatment in complex ways. These differences were mainly attributed to the effects that annual variation, site variation, and time since previous fire can have on fuel loading.

For a summary of the study's results and implications for management, you can view or download a PDF version of "Measuring prescribed fire temperatures in South Dakota."

This research brief for research managers summarizes the following peer-reviewed publication:

Michelle K. Ohrtman, Sharon A. Clay, and Alexander J. Smart. 2015. Surface temperatures and durations associated with spring prescribed fires in eastern South Dakota tallgrass prairies. The American Midland Naturalist 173(1):88-98.

Evaluating sixteen years of restoration in prairie

Long-term studies can track changes over time, and provide examples of expected community trajectory under similar restoration activities. In this study, authors focused on tallgrass prairie remnant at the University of Michigan Nichols Arboretum in Ann Arbor. 

After 16 years of research comparing prescribed fire treatments (annual fires and fires every three years), the authors did not observe changes in dominance or richness related to differences in fire frequency. 

For a summary of the study's results and implications for management, you can view or download a PDF version of "Evaluating sixteen years of restoration in prairie."

This research brief for research managers summarizes the following peer-reviewed publication:

Heslinga, Justin L., Robert E. Grese. 2010. Assessing plant community changes over sixteen years of restoration in a remnant Michigan tallgrass prairie. American Midland Naturalist 164:322-336.

MONITORING PHENOLOGY OF A THREATENED PLANT TO DETERMINE SEASONAL TIMING OF PRESCRIBED FIRE

At sites in Minnesota where the western prairie fringed orchid (WPFO) occurs managers face the challenge of timing burns to avoid damaging WPFO flowers while also controlling invasive smooth brome. This study used data collected by citizen scientists to track flowering of WPFO and development of smooth brome to determine the seasonal timing of prescribed fires.

Implications for managers:

• Data on timing of plant development can be used to plan management activities
• Fall prescribed fires may be effective at controlling smooth brome, and have less negative impact on western prairie fringe orchid
• Citizen scientists can collect meaningful data to inform management decisions

For a summary of the study's results and implications for management, you can view or download a PDF version of "Timing prescribed fire to meet multiple objectives - An exampe from Minnesota." 

This research brief for research managers summarizes the following peer-reviewed publication:

Lori A. Biederman, Judith Beckman, Jeanne Prekker, Derek Anderson, Nancy P. Sather, Rolf Dahle. 2014. Phenological monitoring aids habitat management of threatened plant. Natural Areas Journal 34:105-110.

Does long term use of prescribed fire influence soil properties?

Researchers at the Morton Arboretum in Illinois compared soil properties and vegetation between sites burned for over 20 years to sites that had been left unburned. In addition to finding positive effects of fire on the vegetation of burned sites, some soil nutrients were found at higher concentrations in sites with a history of prescribed fire management. 

Implications for management:

• The oak-dominated forests in this study managed with history of prescribed fire had greater nutrient levels compared to unburned sites
• Management of these sites with long term low-severity fires did not result in negative impacts on soil which have been observed following high severity fires (e.g., loss of soil C, decreased invertebrate diversity)
• The benefits of prescribed fire for productivity of oak woodlands may be the result of increased soil nutrients in addition to increased light availability

For a summary of the study's results and implications for management, you can view or download a PDF version of "Does long term use of prescribed fire influence soil properties?" 

This research brief for research managers summarizes the following peer-reviewed publication:

Scharenbroch, B.C., B. Nix, K.A. Jacobs, M.L. Bowles. 2012. Two decades of low-severity prescribed fire increases soil nutrient availability in a Midwestern, USA oak (Quercus) forest. Geoderma 80-91.

Can burning benefit insects in isolated prairies?

The lack of long term data looking at how invertebrates respond to prescribed fire led Ron Panzer to conduct a six year study spanning three states. Invertebrates were grouped by their dependence on remnant prairie sites and populations tracked through multiple burns to determine rates of recovery. 

Implications for Management:

• Annual fires may not allow a long enough recovery time for a minority subset of prairie insects
• Burning every 2-3 years may balance concerns over insect recovery with other conservation goals (e.g., plants, birds)
• Remnant dependent insects recover at the same rate as remnant independent insects

For a summary of the study's results and implications for management, you can view or download a PDF version of "Can burning benefit insects in isolated prairies?" 

This research brief for research managers summarizes the following peer-reviewed publication:

Ron Panzer. 2002. Compatibility of prescribed burning with the conservation of insects in small, isolated, prairie reserves. Conservation Biology 16:1296-1307.

Prairie Burn Management and Native Species Diversity

The varying effects of fire frequency on native prairies continues to be the subject of study and interest among restorationists and ecologists in the Upper Midwest. This study, in prairie remnants in the eastern tallgrass prairie region, took a close look at species composition changes over five decades.

Among several crucial findings, the authors cautioned against site monitoring protocols based on plant species diversity, which in this resurvey remained stable--despite the clear shift toward common species and away from conservative specialist species.

Management Implications

• Continue to burn remnants. A burn regime of 4-17 fires in 20 years had the greatest influence on keeping species composition similar to 1950.
• Put monitoring emphasis on rare species rather than species diversity, as diversity does not always indicate a decrease in rare species.
• Managers may not need to go to great effort to remove all woody species. The most stable prairies had less than 50% canopy cover.

For a summary of the study's results and implications for management, you can view or download a PDF version of "Prairie Burn Management and Native Species Diversity."

This research brief for research managers summarizes the following peer-reviewed publication:

Milbauer, M. L., and M. K. Leach. 2007. Influence of species pool, fire history, and woody canopy on plant species density and composition in tallgrass prairie. J. Torrey Bot. Soc. 134: 53–62. 2007.

Oak Barrens Management and Understory Plant Recovery

This study focuses on the continuing, long-term restoration work at a large site in central Wisconsin, dominated by oak and jack pine and where understory diversity tends to be low (Pennsylvania sedge  often the dominant species). The site is typical and representative of former oak and pine barrens habitats throughout the Upper Midwest that have converted to closed-canopy forests following European settlement. Common restoration treatments include reintroduction of fire as well as canopy thinning and removal.

For a summary of the study's results and implications for management, you can view or download a PDF version of "Oak Barrens Management and Understory Plant Recovery."

Management Implications

• Consider site history, the length of time since canopy closure, and the importance of the seed bank prior to treatment.
• Locate a high quality reference site nearby on which to base recovery efforts.
• Be prepared to develop a seed list and reseed if seed bank shows low diversity
• Remove timber first. The best recovery of barrens species occurred with the greatest reduction in canopy cover along with prescribed fire.
• More research is needed to fully understand the best approach.

The publication:

Jeffrey L. Ralston and James Cook. 2013. Impact of Prescribed Fire, Timber Removal, and the Seed Bank on Understory Plant Diversity and Canopy Cover in an Oak-Pine Barrens, Central Wisconsin, USA Ecological Restoration 31:395-411

How does patch burn grazing affect bird diversity in highly-fragmented landscapes?

The management treatments used in this study were motivated by research that has shown an increase in the population size and diversity of grassland bird species when a fire-grazing interaction is used in the western tallgrass prairie. The research team compared three management strategies and their effect on grassland bird species richness and density in fragmented landscapes.

For a summary of the study's results and implications for management, you can view or download a PDF version of "Using fire and grazing to promote bird diversity."

Management Implications 

• Patch-burn grazing may effectively create variable forage height and maturity that can benefit grassland bird species though stocking rates must be carefully determined to ensure sufficient residual biomass
• The necessary low stocking rate makes this approach more appropriate on public lands and private recreational lands where profit from livestock is not the main driver
• Grassland bird response to management of grassland structure may remain limited due to factors in the surrounding landscape

The original paper was published in the open access journal Ecosphere.

Finn C. Pillsbury, James R. Miller, Diane M. Debinski, and David M. Engle. 2011. Another tool in the toolbox? Using fire and grazing to promote bird diversity in highly fragmented landscapes. Ecosphere 2(3): article 28.

Oak Savanna Restoration: Which bird species increase with changes?

These two studies examined how bird communities respond to restoration of oak barrens and savannas. In both cases bird communities were not the focus of restoration efforts, but did respond to the altered vegetation.

For a summary of the study's results and implications for management, you can download a PDF version of the research brief: "Can oak savanna restorations for other species benefit bird communities?"

Management Implications

• Using prescribed fire to restore oak savannas and barrens also maintains habitat for birds, like the Red-headed Woodpecker, that are species of concern
• Management activities focused on Karner blue butterflies can also benefit avian species of concern
• Small restored patches can benefit bird communities, especially when located close to existing oak savanna and barren patches

This research brief for resource managers reviews the following peer-reviewed publications :

Jeffrey D. Brawn. 2006. Effects of restoring oak savannas on bird communities and populations. Conservation Biology 20:460-469. 

Eric M. Wood, Anna M. Pidgeon, Claudio Grattion, Timothy T. Wilder. 2011. Effects of oak barrens habitat management for Karner blue butterfly (Lycaeides samuelis) on the avian community. Biological Conservation 144:3117-3126. 

Is fire alone enough to restore oak savannas?

This study in central Wisconsin compared degraded oak savanna sites which were only burned to sites which were harvested and then burned. Based on the results, the authors discussed the pros and cons of both techniques as part of a restoration plan which we summarize here.

For a summary of the study's results and implications for management, you view or download a PDF version of the research brief here.
 

This research brief for resource managers reviews the following peer-reviewed publication:
 

Scott Nielsen, Chad Kirschbaum, and Alan Haney. 2003. Restoration of Midwest oak barrens: Structural manipulation or process-only? Conservation Ecology 7(2):10.