Restoration of oak-hickory dominated forests on the Cumberland Plateau through prescribed burns and mechanical thinning

The University of the South, Department of Forestry and Geology

Lily Castle Tidwell and Katie A. Kull

Figure 1: Map of Studied Areas on Domain

Figure 2: Compartment 46 in 2010 and 2015

Figure 3: Compartment 20 in 2011 and 2015

Figure 4: Compartment 8 in 2013 and 2015

Introduction•Decline of oak-hickory forests throughout eastern United States: mature oaks and hickories remain in canopy, but regeneration is insufficient•Non-native pines, red maple, and other undesirable species overtake young oaks and hickories (Iverson et al 2007)•Non-native Eastern white and loblolly pines replacing native shortleaf pine•Fire suppression and planting of Eastern white pine since 1930s contributing to oak-hickory decline (Iverson et al 2007)•Mechanical thinning and regular mid- to high-intensity growing season fires result in suppression of undesirable species and improvement of oak-hickory regeneration, growth, and stem form (Iverson et al 2007, Blankenship and Arthur 2005, Brose and Lear 1998)•Study Objectives: 1) regenerate oak and shortleaf pine, 2) open the canopy to create understory diversity, 3) examine the effects of fire and thinning, 4) remove planted pine and unwanted regeneration, and 5) help students gain management and fire experience

MethodsSite Descriptions•Located in Sewanee, Franklin County, Tennessee•Soils: sandy loam, sandstone parent material, 1.8-3.4’ deep •Average temp 55ºF, annual precipitation 55-60” •Compartment 46: Eastern white pine and loblolly pine planted in 1960s, thinned in 2010, burned in 2013 and 2015 •Compartment 20: thinned in 2011, burned in 2013 and 2015 •Compartment 8: debris from F1 tornado in 2010, salvage logged in 2011, pines harvested in 2013, burned in 2014Data Collection•One-twentieth acre circular plots •All trees within plot of breast height or greater measured for diameter at breast height, species recorded•Brown transects used to measure fuel loads

Comp 46 ’10 to ‘15

Comp 20 ’11 to ‘15

Comp 8 ’13 to ‘15

Basal Area (m²/ha) -60% -49% -23%Oak Basal Area (m²/ha) -46% -73% -20%Pine Basal Area (m²/ha) -99.9% -21% -14%Trees per Hectare >4cm DBH -83% -72% --

Trees per Hectare -40% -65% --Oaks per Hectare -58% -54% --Pines per Hectare -85% -25% --Fuels (tons/acre) +23% +27% --

Table 1: Changes in Stand Composition

Results Compartment 46: One thinning, three burns•60% reduction in total basal area (m²/ha)•46% reduction in oak BA•99.9% reduction in pine BACompartment 20: One thinning, one burn•49% reduction in total BA•73% reduction in oak BA•21% reduction in pine BACompartment 8: 3 harvests/thinnings, one burn•23% reduction in total BA, pine & oak reduced about equally•Twice as much pine BA as oak BA•50% higher fuel load than other compartments

Discussion•Compartment 46: most fire, best results for oak regeneration•Compartment 20: moderate thinning and burning, mediocre results for oak regeneration•Compartment 8: extensive thinning, uniquely high fuel load during fire, poor results for oak regeneration •Spectrum of thinning with more fire correlates with spectrum of more successful oak regeneration

Conclusion•Our data are consistent with trends observed in other studies of oak-hickory forests (Iverson et al 2007, Blankenship and Arthur 2005, Brose and Lear 1998)•Oak-hickory forests on the Cumberland Plateau seem to respond to thinning and fire in typical ways•Continued and expanded study of differentiated thinning and fire disturbance regimes will lead to a more thorough understanding of oak-hickory and shortleaf pine restoration on the Cumberland Plateau

Works Cited•Blankenship, B.A.; Arthur, Mary A. 2006. Stand structure over 9 years in burned and fire-excluded oak stands on the Cumberland Plateau, Kentucky. Forest Ecology and Management 225(1-3):134-145.•Brose, Patrick H.; Van Lear, David H. 1998. Responses of hardwood advance regeneration to seasonal prescribed fires in oak-dominated shelterwood stands. Canadian Journal of Forest Research. 28: 331-339.•Iverson, L. R., T. F. Hutchinson, A. M. Prasad, and M. P. Peters. 2008. Thinning, fire, and oak regeneration across a heterogeneous landscape in the eastern US: 7-year results. Forest Ecology and Management, v. 255, no. 7, p. 3035-3050. 10.1016/j.foreco.2007.09.088.

8 20 46Oak regeneration success

Successful fires

Figure 5: Fires and oak regeneration