COS 36-7 - Efficacy of fire in restoring Chinese privet invaded bottomlands

Tuesday, August 13, 2019: 3:40 PM
L006, Kentucky International Convention Center
James Stiles, James S. Cash and Christopher J. Anderson, School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL
Background/Question/Methods

Exotic invasive species are considered one of the primary threats to global biodiversity and Chinese privet (Ligustrum sinense) is one of the most pervasive exotic species in the southern United States. Current privet control methods use herbicides which have ecological and human health concerns. This project is investigating the utility of fire as an effective alternative. We are testing the hypothesis that prescribed fire can be used to restore bottomland forests along the Black Warrior River in Alabama. We are also evaluating the addition of torch treatments to help achieve control objectives in these forests that can be challenging to burn. To examine the efficacy of these approaches, study plots (20x20 m) occupied by Chinese privet were cut and allowed to re-sprout. Treatment plots received either prescribed fire only (n=3) or prescribed fire coupled with torch treatments (n=5). Control plots where privet was cut and not treated were also established (n=4). Pre- and post-treatment data were collected on percent cover of privet and other vegetation. Individual stems were marked and tracked to detect the rate of privet mortality. Additionally, we report the time and propane required to conduct torch treatments to help improve restoration planning and decisions applying these techniques.

Results/Conclusions

Preliminary data collected in 2018 indicate that both prescribed fire plus the addition of torch treatments reduced privet cover while increasing native grasses and forbs. To date, prescribed fire only plots had a 65.1±2.7% reduction in privet cover under breast height (1.4 m) and 57.6±30.5% reduction of privet over breast height. Torch treatment plots had a 76±10.2% reduction in privet cover under breast height and 89.4±8.3 % reduction in privet over breast height. Grass cover increased by 6.1 ±7.6% (fire only) and 39.6±30% (torch) while forbs increased 13±1.2% (fire only) and 27.7±21.9 % (torch) within the plots. None of the individually marked privet stumps were killed by a single prescribed fire. However, by the end of the 2018, 42% of privet that received torch treatments had died. On average it took 23.3 man/hours and 62.5kg of propane for each one hectare treatment. Initial results indicate adding torch treatments increases privet mortality rates, decreases the time needed to control privet, and may be a useful tool in the fight against this problematic invasive species.