Fire exclusion over the past century has substantially altered composition, structure, and fuel dynamics in upland oak-hickory (Quercus-Carya) forests in the Southeastern United States. Numerous restoration efforts have been made to re-establish historical disturbance regimes into these altered forests. However, our understanding of the implications of restorative disturbances on stand dynamics has primarily been limited to shifts in species composition and post-disturbance regeneration. Therefore, we examined annual radial growth responses of dominant upland oaks following a combination of prescribed fires (2004, 2006, 2008, 2010, 2012, and 2014) and thinning (starting in 2004) treatments (thin+burn) in stands which had previously been unburned since the early 1900s. Radial stem growth rates were quantified using tree cores from 22 post oak (Q. stellata) and southern red oak (Q. falcata) in a 2.5-acre thin+burn and control stand at the Strawberry Plains Audubon Center in northern Mississippi. Radial growth rates were not significantly greater following repeated thinning and prescribed burning than prior to treatment initiation for either post oak or southern red oak. For the first 6 years after the initial thin, the annual ring width for southern red oak was identical in the thin+burn (1.9 ± 0.1 mm year-1) and control (2.0 ± 0.2 mm year-1) stands. However, in 2010 radial growth for southern red oak in the thin+burn increased such that the annual ring width for 2010 was 22 percent greater in the thin+burn than in the control stands. In contrast to the positive growth response in southern red oak (2 percent), post oak demonstrated a significantly different (p = 0.014) negative response (-19 percent) in the relative percent change in total radial growth for the 11-year period post-treatment initiation when compared to the 11-year period prior to treatment initiation. Radial growth for both species was negatively impacted by a severe drought in 2007 with southern red oak exhibiting the greatest decrease in radial growth. Results from this study highlight the underlying role of climatic factors and species life history characteristics in evaluating radial growth patterns following forest disturbances.
Kidd, Kathryn R.; Varner, J. Morgan; and Brewer, J. Stephen, "Radial growth responses of upland oaks following recurrent restoration treatments in northern Mississippi" (2018). Faculty Publications. 508.