Impacts of beech bark disease on stand composition and wildlife resources in Michigan

Beech bark disease was discovered in Michigan in 2000 and will likely kill at least 50% of mature American beech trees. Our study was designed to collect benchmark data that will allow us, in future studies, to determine how understory composition, wildlife resources, and stand productivity are affected by beech bark disease. We assessed the potential impact of beech bark disease in forest stands with varying beech densities (low, moderate, and high) and infestation of Cryptococcus fagisuga (absent, light, and heavy). Variables were measured in 62 stands throughout the Upper and Lower Peninsulas of Michigan in 2002 and 2003. Regenerating beech stem density did not differ among stands and no current evidence suggests dense beech thickets will regenerate in stands impacted by beech bark disease in Michigan. Beech snags were significantly more abundant in stands with heavy C. fagisuga infestation than in stands where C. fagisuga was absent or infestation was light, suggesting tree mortality from beech bark disease had occurred. Coarse woody debris volume and beech nut mass appeared to be highest in stands with heavy C. fagisuga infestation, although means were not statistically different. Long-term monitoring of these stands will be necessary to document the effects of beech bark disease as it progresses throughout Michigan.