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