Secondary succession, which follows forest harvesting, begins with the growth of herbs, shrubs, and trees and eventually leads to a mature forest. However, young, commercially important trees are often suppressed by undesirable plants, and the prolific growth of clonal shrubs and trees poses a particularly difficult obstacle for conifer regeneration. Many undesirable plants regenerate quickly via clonal expansion by rhizomatous growth, stem base sprouting, root flickering, and layering of branches. Often, these undesirable plants must be controlled to ensure conifer survival and growth in young plantations.
The efficiency of vegetation control methods can be enhanced by adjusting the conifer release treatments to the regeneration phase of the competing species when they are most vulnerable. This requires autecological knowledge of the competing plants, because the potential for rapid vegetative growth often depends on microclimatic conditions and a plant's ability to develop sprouts from dormant or adventitious buds. Numerous authors have emphasized the need for a better understanding of the autecology of noncrop species for effective control of competing vegetation and an enhancement of silvicultural success (Bell 1991, Wagner and Zasada 1991, Wagner 1993).