Retrospective evaluation of the onset period of the visual symptoms of dieback in five Appalachian sugar maple stand types

In the early 1980s, a sharp increase in dieback of sugar maple (Acer saccharum Marsh.) was reported across large areas of the north-eastern American continent. Despite numerous studies, there are conflicting interpretations as to the causes of dieback that can be linked to uncertainties as to when the occurrence of the visual symptoms appeared. Three different approaches were used to determine the onset period of the visual symptoms of dieback in Appalachian sugar maple stands: (1) dendrochronological analysis; (2) retrieval of information in official documents that reported dieback symptoms; and (3) development of a questionnaire sent to private forest land owners. Dieback severity was evaluated annually in 104 Appalachian sugar maple stands in southwestern Quebec. Results indicated that the pattern of dieback progression did not vary significantly among the five different types of sugar maple stand that were examined. The three investigative approaches led to the conclusion that the onset of the visual ...