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Stoddard Fire Plots
By Ron Masters, PhD
The Tall Timbers Research Station Fire Ecology Plots were established on the Beadel Parcel of the property in 1959. The objective was to study the effects of fire return intervals ranging from annual burning to 75 years. Eighty-four one-half acre square plots were placed by Herbert L. Stoddard, Sr. on a wide selection of habitat and soil types. Land used for these plots had been uniformly burned during the winter of 1959-1960, and subjected to frequent winter fire for many years prior to the beginning of the study. The plots were measured and described by Leon Neel and James Preston Greene (Tall Timbers Research Station 1962). Each plot corner was permanently marked with a concrete post, and each plot was identified by a coded numbering system on one of the corner post. Today in honor of Mr. Stoddard, they are referred to as the Stoddard Fire Plots.
In 1997 the decision was made to abandon longer winter fire interval plots (greater than a 3-year burn interval), all summer burned and most unburned plots. The data suggested that longer fire intervals (> 7 years) had little different influence on plant succession compared to unburned plots. Also, some thought that plot size was too small to gain broad inferences about forest succession or wildlife response, plus summer burns were not replicated, and plot size may have influenced fire behavior. At that time retained plots consisted of 3 replications of 1-, 2-, and 3-year winter burn intervals, a single replication of an unburned treatment, and a 75-year interval winter burned treatment, which has not been burned.
In 2002 a portion of NB66 was also set aside as an additional unburned replication. Therefore 3 units have now been retained as unburned “controls” in order to balance the experimental design. In 2006, three replications of the 4-year interval plots were reinstated to provide long-term comparison with other long-term data sets. Even though they had an increased fire frequency (2-year interval) for several years and some hardwood thinning, the vegetation still illustrates the cumulative 4-year interval effects.
Valuable inferences can be gained from these winter (late February-March) burn treatments because replicates were roughly blocked on topography and similarity of soils. Other studies have shown similar results with regard to post-fire succession and fire frequency. Findings from these plots will help to direct future research on larger scale plots.
Several studies continue on the Stoddard Fire Plots. One headed up by Drs. Glitzenstein and Streng is re-assessing herbaceous vegetation response to fire frequency. In another project Dr. Kevin Robertson and Angie Reid continue work with fuels ecology and fire behavior. They have also been involved with research on woody response to fire frequency Carbon respiration and storage is also being studied on these plots by the Fire Ecology Lab and various collaborators. Dr. Ron Masters has examined canopy cover dynamics over time and Dr. Claudia Listopad has assessed the use of LiDAR as a means to characterize fine scale forest structure on these plots. Soil nutrient status related to fire frequency is another ongoing study the Fire Ecology Lab is leading.
- Apparently, growing season burns (various months) did not control hardwood midstory development.
- 3-year winter fire interval is an ecological threshold. At 3-year and longer intervals woody vegetation asserts dominance over herbaceous vegetation.
- 3-year winter fire intervals slow but do not halt lower-midstory hardwood development. During some burn cycles, hardwood development may be suppressed and in other burn years hardwoods may gradually increase, depending possibly on soil and fuel moisture.
- Fuel structure and composition changes from herbaceous to litter-dominated fuels as hardwoods creep into the midstory—causing greater difficulty in generating adequate fire intensity to control hardwoods.
- Fire intervals longer than 3 years had lower percent survival of original overstory pine trees than frequently winter burned plots.
- 2-year winter fire intervals suppress woody vegetation; not eliminate it.
- 1-year winter fire intervals prevent pine seedling establishment and units are dominated by herbaceous understory.
- Species richness increases with shorter fire return intervals.
- Canopy development is halted by 1-year burns and increases over time with longer intervals.
- Annual winter burns suppress pine basal area growth.
- Annual winter fires have not significantly decreased survivorship of overstory pine.
- Annual winter burns favor cotton rat (Sigmodon hispidus) and disadvantage cotton mouse (Peromyscus gossypinus). The species of small mammal favored varied with frequency (see Masters 2007).
- Small mammal response appeared to be dependent on vegetation structure and composition.
- These findings corroborate other studies that were completed at larger scales.
- In initial sampling the 1-year interval fire plots had the lowest carbon and nitrogen, the 2-year plots had the highest, and the longer intervals had intermediate levels. In the 1-year fire interval, herb and woody vegetation is kept relatively sparse and at low annual productivity. During 2-year fire intervals, there is a great deal of growth in both herbaceous and woody vegetation, which is transferred to high root turnover rates and addition of organic matter to the soil. At longer intervals, woody plants dominate and begin to survive fires, thus carbon and other nutrients are reallocated from the soil to storage in woody plants above and below the ground, or leached because of loss of the herbaceous layer.
Anonymous. 1962. Tall Timbers Research Station Fire Ecology Plots. Tall Timbers Research Station Bulletin No. 2. 178 p.
Beckage, B.; Stout, I.J. 2000. Effects of repeated burning on species richness in a Florida pine savanna: A test of the intermediate disturbance hypothesis. Journal of Vegetation Science 11:113-122
Glitzenstein, J. S., Donna R. Streng, R.E. Masters, and W.J. Platt. 2008. Clarifying Long-Term Impacts of Fire Frequency and Fire Season in Southeastern Coastal Plain Pine Savannas. Eastern Grassland Symposium Proceedings, Columbia, SC. 6: 14-24.
Hermann, S.M. 1995. Stoddard Fire Plots: lessons for land management thirty-five years later. Pages 13–20 in L.A. Brennan, K. Gainey, T. Pruden (eds.). Proceedings of the Tall Timbers Game Bird Seminar, Tall Timbers Research Station, Tallahassee, FL. 91 p.
Listopad, C., J. Drake, R.E. Masters, J. Weishampel. 2011. Portable and Airborne Small Footprint LiDAR: Forest Canopy Structure Estimation of Fire Managed Plots. Remote Sensing 3: 1284-1307; doi:10.3390/rs3071284.
Masters, R. E. 2007. The importance of shortleaf pine for wildlife and diversity in mixed oak-pine forests and in pine-grassland woodlands. In: Kabrick, John M.; Dey, Daniel C.; Gwaze, David, eds. Shortleaf pine restoration and ecology in the Ozarks: proceedings of a symposium; 2006 November 7-9; Springfield, MO. Gen. Tech. Rep. NRS-P-15. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 35-46.
Masters, R. E., K. Hitch, W. J. Platt, and J. A. Cox. 2005. Fire – The missing ingredient for natural regeneration and management of southern pines. Proceedings of the Joint Conference, Society of American Foresters and Canadian Institute of Forestry, Edmonton, Alberta, Canada. October 2-6, 2004. CD-ROM unpaged.
Mehlman, D.W. 1992. Effects of fire on plant community composition of North Florida second growth pineland. Bulletin of the Torrey Botanical Club 119(4):376-383
Vogl, R.J. 1973. Fire in the Southeastern Grasslands. 12th Annual Tall Timbers Fire Ecology Conference Proceedings, Tall Timbers Research Station, Tallahassee, FL. 492 p.