Effects of prescribed burning regimes and habitat on seedling abundance at the Ozark National Scenic Riverways, Missouri

Background/Question/Methods

On the oak-hickory and pine woodlands and glades of the Missouri Ozarks, land managers, including the National Park Service, have been applying fire to restore ecosystems. In light of recent issues with decreased overstory species recruitment in the central hardwoods region, there is a question of whether or not prescribed fire is affecting seedling abundance, to what extent species are affected by fire, and if those effects differ by habitat. Data collected by fire effects scientists at the Ozark National Scenic Riverways, including the number and height of seedlings of several species across the Park, were examined to test the hypotheses that 1) the prescribed fire program is having a positive effect on the number of seedlings, given multiple fires over time, that 2) various tree species are responding in predictable ways to the burning, and that 3) fire affects seedlings in a habitat-specific manner. Variables used to examine these effects included the habitat type, burn status (data that reflects seedlings counts from the last burn relative to the current growing season, including pre-burn data), and the interaction of habitat type and burn status, with plot number being run as a random variable. Seedling abundance was the response variable.

Results/Conclusions

Initial results show that the burn status of each plot, the habitat type, and the interaction of burn status and habitat significantly affect the number of seedlings in each plot. Results indicate that response to prescribed fire varies by species. Comparing species such as Amelanchier arborea, Sideroxylon lanuginosum, and Carya texana demonstrates some variation in species responses. A. arborea seedlings showed a significant negative response to burn status, but not to habitat or the burn status/habitat interaction. S. lanuginosa seedlings showed no significant response to habitat type, burn status, or their interaction. C. texana seedlings showed significant responses to habitat type, burn status, and the interaction of the two; however, the relationship was positive immediately after burns, whereas subsequent burning reduced the number of C. texana seedlings. These findings indicate that the prescribed burning regime at the Ozark National Scenic Riverways, as well as habitat differences, influence seedling growth, supporting the first and third hypotheses, and that response is species specific, supporting the second. Overall, prescribed burning is promoting seedling abundance at the Park.