Effects of Fire Regime on Hardwood Resprouting
By Kevin Robertson, PhD, Fire Ecology Scientist
Beginning in 2008, a generous donation from long-time Tall Timbers supporter, Gene Phipps, made it possible for the Fire Ecology Program to take on a new graduate student from Louisiana State University, providing her support for the first year of research at Tall Timbers. The student, Tracy Hmielowski, is studying one of the most important management goals of prescribed burning in southern pine forests, understory hardwood top-kill and control. Her work specifically focuses on determining the influence of time since last burn (1-4 years), season of burn (dormant versus early growing season), and ignition technique (head fire versus backing fire) on hardwood stem top-kill and re-sprouting vigor. She is testing her question by burning research plots on Tall Timbers under these different conditions and tracking resprout responses.
General observation and some past research predict that growing season burns cause hardwood resprouts to return less quickly and survive less often than dormant season burns, perhaps because plants have allocated much their resources above ground for growth when they are girdled at the base by fire. Tracy's research will look further into this idea by burning plants at different times of the year and then measuring their root growth, which indicates below-ground energy storage available for resprouting. To do this, she is applying fire and clipping treatments to potted water oaks, so that root biomass can be easily measured. Her research promises to provide insight into the mechanisms of hardwood resprouting response to different management approaches using fire.