Beech Bark Disease (BBD) is a disease complex in which scale insects and fungi components attack American beech (Fagus grandifolia Ehrh.), a major component of many Northern forests. BBD causes a decline and eventual mortality of dominant beech, and is known to persist in affected forests long past initial mortality events, often causing multiple waves of mortality. Forests affected by BBD may face changes in composition and successional trajectory. It has been suggested that the dynamics of BBD in the Northern Great Lakes Region are not analogous to dynamics in the Eastern Northern Hardwoods Forests. We investigated the relationship between suspected influences in the condition of beech-containing forests in two National Lakeshore Properties in Michigan. Ecological inventories were conducted in 2017 and 2018. The average scale coverage per stem and ratio of living American beech basal area was compared to determine if there were significant differences between two study properties. Beech trees above 12.5 cm in diameter at breast height had their condition and severity of scale infestation on each bole assessed. Stepwise linear regression was performed in R (3.5.1) to look for influential factors among a suite of biogeographic factors collected via field observation and publicly available GIS data.
Results/Conclusions
Preliminary results will be presented from three years of forest inventory following disease progression. The two study sites had no significant difference in the amount of scale infestation, but did have a difference in the ratio of American beech basal area which had died, indicating that the sites are in different phases of the disease (Advance Front and Killing Phase). Vigor of American beech was influenced by the amount of scale present, elevation, minimum and maximum mean annual temperature, soil type, total basal area, total beech basal area and the basal area of living beech surrounding points. Amount of scale present was correlated with vigor, minimum mean annual temperature, basal area of beech, and site. Much of the existing research in the factors influencing severity of BBD has occurred in Eastern forests of North America. Studies in newly affected ecoregions are necessary to understand the dynamics of BBD across a broader scale. An understanding of influential biogeographic factors on intensity of BBD can guide restoration efforts aimed at preserving American beech as a major component of forests in the Northern Great Lakes region.