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

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.

Response of tallgrass prairie to fire frequency

This brief summarizes results from a study that was focused on eastern tallgrass prairie sites and examines how fire frequency influences the plant community. To investigate how fire frequency affects eastern tallgrass prairie, sites surveyed in 1976 were revisited in 2001 (25 years later). Sites ranged from those rarely (or never) burned to some which had been burned almost annually.

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:

Marlin L. Bowles and Michael D. Jones. 2013. Repeated burning of eastern tallgrass prairie increases richness and diversity, stabilizing successional vegetation. Ecological Applications 23:464-478.