Response of beetles (Coleoptera) at three heights to the experimental removal of an invasive shrub, Chinese privet (Ligustrum sinense), from floodplain forests

Chinese privet (Ligustrum sinense Lour.), an invasive shrub from Asia, is well established in the southeastern United States where it dominates many floodplain forests. We used flight intercept traps to sample beetles at three heights (0.5, 5 and 15 m) in similar to 2 ha plots in which L. sinense had (by chainsaws or mulching machine) or had not been removed from forests in northeastern Georgia. Removing L. sinense, particularly by machine, increased the richness and diversity of beetles and affected composition near the ground (0.5 m) but not in the forest canopy (15 m). There were no differences among treatments above the L. sinense canopy (5 m) aside from Xylosandrus crassiusculus, an exotic ambrosia beetle from Asia, dominating the beetle community at that height in control plots. Removing the L. sinense layer greatly increased beetle richness near the ground, resulting in vertical distribution patterns more similar to those observed in areas of forest devoid of L. sinense. We suspect that even organisms in the canopy will benefit from privet removal in the long term given that tree regeneration is nearly impossible in forests in which L. sinense has become well established.