Effect of deer and Amur honeysuckle (Lonicera maackii) understory removal method on restoration of understory plants

Invasive honeysuckle (Lonicera maackii) is frequently removed from natural areas due to its negative impacts, yet deer may thwart restoration efforts. We investigated the success of native understory plants after removal of honeysuckle using two removal methods in the presence and absence of deer.  The first removal method (cut/paint) consisted of cutting the stems followed by application of the herbicide garlon. The second removal method (basal application) consisted of applying the garlon to the base of the intact stem, leaving the dead stems in place. Light level in the cut/paint treatment was significantly higher than in the basal application treatment which was significantly higher than in the uncut treatment. In 2005, we transplanted seedlings of Impatiens capensis. Condition and height of Impatiens were higher in the cut/paint treatment compared to the basal application treatment. Impatiens plants were taller in the absence of deer. In 2006, we counted Impatiens seedlings, presumably a result of transplant seeds. The number of Impatiens seedlings was significantly higher in the cut/paint treatment. There was a trend towards greater seedling number in the deer-absent treatment. Spring and fall naturally-recruiting native species richness was significantly higher in the cut/paint and basal application treatments than the uncut treatment. Spring species richness was also significantly affected by the interaction of removal method and fencing. When fenced, there were more species and number of individuals in cut/paint treatments than in basal application treatments. When unfenced, both the cut/paint and basal application treatments had similar species richness, indicating a protective effect of the standing stems against deer damage. In both the spring and fall, there were significantly more individuals of the invasive species Alliaria petiola in the cut/paint treatment than in the uncut treatment.  Our results indicate differences between removal methods in successful understory restoration in the presence and absence of deer.