Impact of Armillaria root disease on succession in red pine plantations in southern Ontario

Armillaria root disease created openings in southern Ontario red pine plantations that are gradually succeeding to hardwood-dominated mixedwoods through natural regeneration. A study of 13 root disease centres found several tree and shrub species colonizing the openings. Black cherry was the most important hardwood and white pine the most important conifer colonizer. Mortality of black cherry and white pine regeneration was greater than for other species. Long-term survival of conifers in the centres is doubtful, and high mortality of black cherry is expected. Other hardwood species may fare better but with growth and yield losses due to Armillaria infection. Key words: Armillaria root disease, red pine plantations, succession, disturbance ecology, Armillaria ostoyae