Experimental Disturbance Plots at the Ross Natural History Reservation

Emporia State University

The structure of native, grassland ecosystems is maintained by biotic and abiotic disturbances.  Climate, fire, and grazing all interact to maintain expanses of herbaceous vegetation that are relatively free of trees and shrubs (Axlerod 1985, Botanical Review 51:163-201).  With the suppression of historic wildfires, the mesic tallgrass prairie of eastern Kansas develops into shrubland, savanna, and forest (Briggs et al. 2005, BioScience 55:243-254).   

Various options exist to emulate natural disturbances or otherwise control the encroachment of woody vegetation in remnant tallgrass prairie.  Here at Emporia State University, we are conducting an experiment to determine what best controls encroaching woody vegetation in tallgrass prairie.  The experiment is taking place at ESU’s 200-acre (81-ha) Ross Natural History Reservation (RHNR).  Experimental treatments include combinations of inter-annual fire frequency and seasonality, and mechanical disturbance by mowing.

Importantly, the experimental plots are also being used by students and faculty 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.

Seventy-two, 30-m x 30-m plots were established in 2007 by mowing fire-guard lanes to define experimental plot boundaries in the northeastern 40-acre (16-ha) portion of the RHNR(see photos below).  Nine experimental treatments were applied, replicated with 8 plots each, include the following:  2 burn seasons (spring or fall), 2 burn frequencies (every 1 or 3 years), mowing (initial summer cutting in 2009 + burn treatments, or un-mowed + burn treatments) and undisturbed control plots.  The treatments were applied in a stratified-random design according to pre-existing shrub cover.  Initial application of the disturbance treatments began in fall of 2008 with the fall-burned 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.

 

 

 

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).