REDUCING SMOOTH SUMAC DOMINANCE IN NATIVE TALLGRASS PRAIRIE

Smooth sumac (Rhus glabra L.) is a resprouting shrub native to the tallgrass prairie region that increases in density without an active disturbance regime. Our objective was to use prescribed fire and herbicides to decrease smooth sumac density as a strategy to improve a degraded tallgrass prairie remnant. In two separate experiments repeated in space and time, we used prescribed fire in combination with herbicides at various rates and two application methods to develop an effective management scheme for reducing smooth sumac. We used a randomized complete block design with 13 herbicide treatments and a control with three replicates in burned and non-burned areas. Results were similar in both experiments in which herbicide treatment and burning were the significant main effects. All herbicide treatments reduced smooth sumac stem density compared to the control, but no distinct advantage was detected regarding specific herbicide, application rate, or whether the herbicide was applied as a broadcast spray or with a hand-held wick. We expected burning to make the plant more susceptible to herbicides, but burning increased stem density. In this tallgrass prairie remnant, we determined that herbicides were the most effective management tool in reducing smooth sumac stem density.