Mysterious affliction killing beech trees

I recently received a rather disheartening note from John Pogacnik, biologist with Lake County Metroparks. The park district is in the extreme northeastern corner of the state and hard on the shores of Lake Erie. John, as many of you know, is an astute observer who spends much time afield.

In 2012 he began to notice some American beech, Fagus grandifolia, that were showing signs of ill health. Beech were already under assault in some regions by beech bark disease (BBD), which is a combination of introduced fungal and insect pests joining forces to attack and kill beech. BBD is widespread throughout northeastern North America, but doesn't seem to have (yet) caused widespread mortality in Ohio. Anyway, the new(?) issue detected by Pogacnik is not BBD.

A healthy American beech towers over the forest floor in Gross Woods State Nature Preserve, Shelby County. Beech can correctly be termed a keystone species. A great many other organisms are reliant on beech, and the trees fuel a forest ecosytem that is much richer than it would be without the trees. Beech typically occur in association with sugar maple, Acer saccharum, and beech-maple forests are a huge and vital part of the eastern deciduous forest ecosystem.

Mature trees typically form cavities that are used by Barred Owls, raccoons, flying squirrels and a number of other birds and mammals. The roots spawn the growth of one of our most specialized vascular plants, the beech-drops, Epifagus virginiana, which is parasitic on beech roots (without harming the tree). Beech also produce bounty crops of beech nuts some years, and this mast is an important food for numerous animals, including white-tailed deer, turkey, grouse, squirrels, wood ducks, chipmunks and many other creatures. Scores of moth - and some butterfly - caterpillars are also co-evolved with beech and depend on its foliage for food.

A forest deprived of its beech would be a far less diverse woodland.

John sent along some photos that show various stages of damage caused by the as-yet identified attacker. First signs of infestation involve dark striping on the green leaves as one looks into the backlit canopy. This can be seen well in the above photo.

The affected foliage then withers, dries, and yellows, as seen above and in the following two photos. Ultimately the diseased trees die, and John has already documented mortality and reports that many other beech appear on to be on their way out.