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.

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.

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.

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.