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.

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.

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.

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.