Experimental Seasonal Burn Plots

at the Ross Natural History Reservation

William E. Jensen, Brenda A. Koerner, David A. McKenzie, and Darren Rebar

Department of Biological Sciences, Emporia State University

 

Background:

The structure of grassland ecosystems is maintained by biotic and abiotic disturbances.  Climate, fire, and herbivory all interact to maintain expanses of herbaceous vegetation that are relatively free of trees and shrubs (Axlerod 1985).  In the absence of historic wildfires, the mesic tallgrass prairie of eastern Kansas develops into shrubland, savanna, and forest (Briggs et al. 2005).  Much is known about the effects of inter-annual frequency of spring-applied fires on tallgrass prairie communities and ecosystem level function (Briggs et al. 2005).  Unfortunately, concurrent spring burns in the Flint Hills landscape of eastern Kansas and Oklahoma have had negative effects on air quality (Liu 2014), prompting recommendations for land managers to diversify burning schedules (Kansas Department of Health and Environment 2018).  However, less is known about how fire affects tallgrass prairie communities and ecosystems when applied during other seasons (Towne and Kemp 2008).  Nonetheless, there is evidence that fire applied during the growing season can be as effective as spring fires in restricting encroachment by woody plants (Adams et al. 1982, Weir et al. 2018).  The objective of our study is to provide an experimental landscape for students and faculty to investigate biotic responses to seasonally-variable prescribed fire in tallgrass prairie.

 

Methods:

            The experiment is taking place at Emporia State University’s Ross Natural History Reservation (RNHR), where woody encroachment into tallgrass prairie has progressed despite periodic disturbance by fire (Harrell et al. 2007).  The project site is located in the northeastern 16 ha (40 acre) portion of the RNHR (grids A43, and A44, Spencer 1980) (Fig. 1).

Ross_seasonal plots and inset_2

Fig. 1.  Location of the Seasonal Burn Plots (red outlines) at the Ross Natural History Reservation (yellow border, inset).  Plot labels indicate season of burn, schedule for burning in odd- (“O”) or even- (“E”) numbered calendar years, and replicate numbers 1-3 per odd- or even-year burns.

            Eighteen plots (≤0.36 ha, Fig. 1) are being burned biennially in either summer (15 August to 15 September, during growing season and availability of volunteers), fall (15 October to 15 November, roughly the start of dormant season), and spring (15 March to 15 April, approximate start of growing season) (n = 6 per each of 3 treatments).  Only three plots are burned per treatment, per year, alternating between odd and even years.  This design allows burned and unburned plots per seasonal treatment available for research each year, improves independence of adjacent plots, and makes burning more logistically feasible.

            Treatments per plot (Fig. 1) were assigned to plots as follows:  the southwestern corner plot was randomly selected for the spring-burn treatment.  All other plots were systematically arranged for maximum interspersion in a checkerboard pattern to minimize common plot boundaries between similar treatments.  Initiation of the assignment of treatments to subsequent plots began with the plot immediately north of the southwestern corner plot, and the plot was randomly selected to receive a summer-burn treatment to set the pattern of interspersion.  Odd- vs. even-year alternation was selected randomly beginning with the southwestern-most plots per treatment and adjusted to maximize interspersion to prevent common boundaries between similar treatments per year (e.g., preventing two summer-odd-years sharing plot boundary, or even corners).  Fire guards mowed between plots are ≥3 m wide.  The current vegetation cover of the research area ranges from almost entirely non-woody plant species, typical of eastern Kansas tallgrass prairie, to almost entirely woody species typical of a prairie in rapid transition to shrubland and forest.

            Natural Areas equipment used to conduct the burning and mowing operations includes: drip torches, tampers, tractor and “Gator” UTV with water tanks, etc.

            The project will continue indefinitely as long as sufficient interest in using the project site persists.

 

Purpose of study:

            The framework of prescribed fire treatments establishes a long-term experiment to support ecological research at both the undergraduate and graduate levels at Emporia State University.  This project serves to support research and other field exercises for courses such as Field Ecology (EB 481), Projects in Ecology and Biodiversity (EB 409), Plant Ecology (BO 459/759), and Soil Science (GB/ES 539).  The opportunities for undergraduate and graduate-level research will likely result in oral or poster presentations at professional scientific meetings and peer-reviewed publications. 

 

Literature Cited:

Adams, D. E., R. C. Anderson, and S L. Collins.  1982.  Differential response of woody and herbaceous species to summer and winter burning in an Oklahoma grassland.  Southwestern Naturalist 27:55-61.

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

Briggs, J. M., A. K. Knapp, J. M. 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

Harrell, K., J. S. Aber, and R. O. Sleezer.  2007.  Ross Natural History Reservation: Six decades of changing land cover and management documented by aerial photography.  Emporia State Research Studies 43:53-63.

Kansas Flint Hills Smoke Management.  2015.  Available at: http://www.ksfire.org (Accessed 22 August 2018).

Liu, Z., 2014. Air quality concerns of prescribed range burning in Kansas. Kansas Agricultural Experiment Station and Cooperative Extension Service MF3121. Kansas State University, Manhattan, KS, USA (4 pp.).

Spencer, D.  1980.  Ross Natural History Reservation:  the first twenty years, 1959 to 1979.  Emporia State University, Emporia, KS, USA (64 pp.).

Towne, E. G. and K. E. Kemp.  2008.  Long-Term response patterns of tallgrass prairie to frequent summer burning.  Rangeland Ecology & Management 61:509-520.

Weir, J. R., D. Elmore, R. F. Lamb, D. M. Engle, B. W. Allred, T. G. Bidwell, S. G. Fuhlendorf.  2018.  Burning in the growing season.  Oklahoma Cooperative Extension Service, Technical Bulletin E-1025, Oklahoma State University, OK, USA (12 pp.).  Available at: http://www.ksfire.org (Accessed 22 August 2018).