Change in Forest Tree Composition on the Lake Erie Islands due to the Invasion of the Emerald Ash Borer (Agrilus planipennis) and Invasive Plants

Emma Land^1,*, Lisa Kutschbach-Brohl², and Douglas D. Kane³

¹The Ohio State University F.T. Stone Laboratory Ohio Sea Grant School of Environment and Natural Resources, 878 Bayview Avenue, PO Box 119, Put-In-Bay, OH 43456. ²Lake Erie Islands Conservancy, PO Box 461, Put-in-Bay, OH 43456. ³Department of Biology and Environmental Science and National Center for Water Quality Research, Heidelberg University, Tiffin, OH 44883. *Corresponding author.

Northeastern Naturalist, Volume 30, Issue 4 (2023): 449–466

First published early online: 16 December 2023

Abstract
Since its initial invasion in 2002, Agrilus planipennis (Emerald Ash Borer [EAB ]) has devastated Fraxinus (ash) species in forest communities of the Midwestern United States. The forests of the Lake Erie Islands have a unique composition that is typically divided into 2 categories: upland forests, which have rockier soil and bedrock above lake level, and lowland forests, which have deeper soil and bedrock below lake level. We used plot-sampling methods in selected wooded preserves of both upland and lowland forests on South Bass and North Bass islands, OH. We compared our findings with data collected on those 2 islands as well as Middle Bass and Kelleys islands in previous studies from before infestation, during initial infestation in the 2000s, and approximately one decade later to monitor ash loss and to determine which species were regenerating in these new canopy gaps. We calculated importance values and subsequent Boerner values through determination of relative frequency, relative coverage, and relative density of individual tree species within study plots. Fraxinus pennsylvanica (Green Ash) was most negatively impacted by the EAB while Fraxinus quadrangulata (Blue Ash) was still important in upland forests due to regeneration seen in small saplings. Lonicera maackii (Amur Honeysuckle) began filling in canopy gaps in upland forests and lowland forests, while invasive species like Morus alba (White Mulberry), Rhamnus cathartica (Common Buckthorn), and Elaeagnus umbellata (Autumn Olive) filled in the canopy gaps of lowland woods. The decline in ash populations due to the EAB has allowed for further growth of numerous invasive plant species and transformed the composition of Lake Erie Island forests.

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