Beech Bark Disease in Ontario: Implications to Forest Structure and Composition

Beech bark disease (Neonectria faginata) may cause major changes to forest structure and composition in southern Ontario. The purpose of this study was to determine the impact of beech bark disease on forest structure, and composition in the Lake Simcoe sub-watersheds. This study also aimed to determine the variables that determined the susceptibility of American beech (Fagus grandifola) stands to the disease. The sub-watersheds were sampled using the Vegetative Sampling Protocol (VSP). Differences in species compositions, forest structure, and other abiotic variables between plots with beech bark disease, and those without the disease were analyzed. The results show that beech bark disease changes the structure and composition of forests by eliminating most of the over-story beech from the stand. The loss of over-story beech may have benefited Sugar maple (Acer saccharum) ; and may benefit other mid-tolerant species, like Red oak (Quercus rubra), Bitternut hickory (Carya cordiformis), Choke cherry (Prunus virginiana), and Black cherry (Prunus serotine). Regression analysis showed the intensity of the beech bark disease in a stand was determined by the relative cover of beech in the sub-canopy. The results show a possible secondary outbreak of the disease in the region. This study provides management recommendations to manage against a secondary outbreak of the disease.