Fire Lines Volume 15, Issue 8
RESEARCH BRIEF
Resprouting dynamics suggest different regeneration strategies for shortleaf pine and oak species following surface fires in Missouri Ozarks
Authors: Hope Fillingim, Benjamin O. Knapp, John M. Kabrick, Michael C. Stambaugh, Grant P. Elliott, Daniel C. Dey
This study by Fillingim et al. evaluated how surface fire influences the regeneration of shortleaf pine and co-occurring upland oaks in mixed pine-oak forests of the Missouri Ozarks. The authors had the opportunity to conduct their research on an operational restoration landscape with a long history of thinning and repeated prescribed burning, allowing them to sample pine and oak regeneration across a wide range of stem sizes under realistic management conditions. Prior to dormant-season burns in 2021, individual pines and oaks were paired by basal diameter within plots, then revisited after fire to determine survival mode (resisted top-kill, resprouted, or died). Fire intensity was indexed using temperature-sensitive paint tags, and post-fire resprouting performance (number of sprouts and sprout height) was measured after one growing season.
For both species groups, increasing stem size reduced the likelihood of top-kill, while greater fire intensity increased it. However, shortleaf pine reached resistance to top-kill at substantially smaller basal diameters than oaks: pine achieved ~50% resistance around 2.4 cm and ~90% resistance near 3.0 cm, whereas oaks required roughly 3.5 cm and 5.5 cm, respectively. Increasing fire intensity shifted these thresholds upward for both groups but amplified the advantage of pine, as oak size thresholds increased more with intensity. When top-killed, both species resprouted reliably, but their strategies differed. Shortleaf pine produced many more sprouts per individual, while oaks produced fewer sprouts but grew nearly twice as tall in the first post-fire growing season. Paired comparisons showed no stem size at which pine consistently outgrew oak following resprouting. Therefore, the competitive advantage for shortleaf pine occurred not through faster resprout growth, but through its ability to resist top-kill at smaller sizes, especially under moderate to higher fire intensity.
