No abstract

Pyrus calleryana (Callery pear) is an invasive plant that threatens ecosystems in the eastern United States. We investigated the efficacy of various control techniques on P. calleryana invasion in grasslands. Treatments were applied to (a) P. calleryana stems that had experienced mowing annually for several years and were sprouting (n = 100 stems; "trees-sprouting") and (b) stems that had established ca. 10 years earlier, had never been cut, and were single-stemmed trees (n = 40 stems; "trees-intact"). In both experiments, existing stems were cut and randomly assigned one of the following treatments: cut only (control), burning, freezing, or herbicide, and in the trees-sprouting experiment there was also a negative control of monitoring existing sprouts. All trees in which the cut stumps were treated with herbicide were effectively killed, whereas stems in all other treatments, in both experiments, generated a vigorous sprout response. In the trees-sprouting experiment, there was a strong overall effect of treatments (RMANOVA; p < 0.001) and prescribed fire created a statistically significant increase in sprout number in relationship to the negative control (post-hoc test; p = 0.036). In the trees-intact experiment, there was vigorous sprouting in response to all treatments other than herbicide. Stump freezing resulted in a delay in sprout response; however, all frozen stems eventually sprouted. The ability of this species to sprout vigorously, even after experiencing frequent and intense ecological disturbance, creates the potential for a fundamental alteration of old-field succession in habitats where this species is present.