Experimental Disturbance Plots at the Ross Natural History Reservation

Emporia State University

The structure of grassland ecosystems is maintained by biotic and abiotic disturbances.  Climate, fire, and herbivory all interact to maintain expanses of herbaceous vegetation relatively free of woody plant growth intolerant to such disturbances (Axlerod 1985).  In the absence of wild fires that historically occurred in the Great Plains, the open tallgrass prairie of eastern Kansas develops into shrubland, savanna, and forest (Briggs et al. 2005). 

Various options exist to replicate natural disturbances or otherwise control the encroachment of woody vegetation in tallgrass prairie.  Here at ESU, we are attempting an experiment to determine what best controls invasive woody vegetation (“invasive” does not mean “exotic” as the encroaching woody plants are, for the most part, native species).  The experiment is taking place at ESU’s Ross Natural History Reservation, where woody encroachment into tallgrass prairie communities has progressed despite periodic (triennial) disturbance by fire.  Experimental treatments include combinations of different inter-annual fire frequencies (annual or triennial) and seasonality (fall or spring burns), mechanical disturbance (initial mowing), and an undisturbed control treatment.

In addition to providing an experimental design for investigating the efficacy of woody vegetation control, the experimental plots can be used by students at ESU and abroad for various investigations of biotic responses to disturbance in tallgrass prairie.  Please contact Bill Jensen for more information on the accessibility of these plots for your research.

The Experimental Disturbance Plots came into being in July 2007 with the creation of 72, 30x30-m plots (see photos below).  Initial application of the disturbance treatments began in fall of 2008 with the fall-burn plots.  The first spring-burn treatments were applied in April 2009.  

 

Location of experimental disturbance plots at the Ross Natural History Reservation.

Location of experimental plots within ESU's 200-acre (81 ha) Ross Natural History Reservation.

 

Experimental plot codes.

Plot treatment codes (by character order):

1-3. CON_ = untreated control.  Otherwise…

1. U = un-mowed, M = mowed

2. F = fall burn, S = spring burn

3. Burned annually (1) or every 3 years (3)

4. Treatment replicate ID (A through H)

 

Ross Experimental Disturbance Plots as seen from low altitude aerial photograph (kite platform). Photo by ESU's Dr. James Aber.

Ross Experimental Disturbance Plots as seen from low altitude aerial photograph (kite platform,

view from northwest).  Photo by ESU's Dr. James Aber.

 

Shrub-encroached tallgrass prairie at ESU's Ross Reservation

Shrub-encroached tallgrass prairie at ESU's Ross Reservation.

 

Fire-guard boundary of each experimental plot.

Fire-guard boundary of each experimental plot.

 

Quadrat sampling of shrub stem densities.

Quadrat sampling of shrub stem densities.

 

Student research on the Experimental Disturbance Plots.

Biology student research on the Experimental Disturbance Plots

(photo by ESU's Dr. Brenda Koerner).

 

Students assisting with burning plots in fall, 2008.

ESU students help with applying the first burns of the Experimental Disturbance Plots

in Fall, 2008 (photo by ESU's Dr. Brenda Koerner).

 

Illustration of fall-burned, spring burned, and control (un-burned) plots.

Illustration of vegetative regrowth on fall-burned plots (at right), freshly-burned

spring-burned plots (background), and unburned control plots (fore- and background).

Literature Cited

Axelrod, D. I.  1985.  Rise of the grassland biome, central North America.  The Botanical Review 51:163-201.

Briggs, J. M., A. K. Knapp, J. K. Blair, J. L. Heisler, G. A. Hoch, M. S. Lett, and J. K. McCarron.  2005.  An ecosystem in transition: causes and     

     consequences of the conversion of mesic grassland to shrubland.  BioScience 55:243-254.