The last time I visited the old-growth stand of eastern hemlocks at Snyder-Middleswarth Natural Area, in central Pennsylvania’s Bald Eagle State Forest, the hemlocks were succumbing to a wooly adelgid infestation, and I figured they’d all be dead in a few years. That was early June 2007. My hiking buddy Lucy and I felt we should go back five years later and see what was taking the hemlocks’ place.
What we didn’t expect was that a few of the ancient hemlocks would appear untouched. Were these individuals blessed with some form of resistance to the invasive scale insects — or were they just lucky?
In general, though, 80-90 percent of the hemlocks were dead or almost dead, as expected. We were pleased to see their place was being taken more often than not by yellow birch, a long-lived tree already present on the site. Though the stand could no longer be characterized as old-growth, the forest as a whole retained many old-growth characteristics, especially (of course) large standing and fallen dead trees, but also deep moss and a diverse understorey.
The continued presence of a rare shrub called hobblebush testified to the relative absense of deer in the heart of the natural area — a very fortunate circumstance indeed. Further along, as the ravine grew less steep and more accessible to deer, we began to notice fewer shrubs and more red maple.
As in 2007, we were struck by the profusion of hemlock varnish shelf fungi and their attendant beetles, eating and mating with abandon. This time I also spotted a couple of the marvelously spiked horned fungus beasts, though I didn’t manage to get a good photo of them.
We were too late for most of the spring wildflowers, but the partridgeberry was just coming into bloom.
And whereas last time we found some weird fern galls, this time Lucy spotted some white galls on rhododendron leaves that were new to both of us.
“Swift Run” had struck us as a misnomer last time, but yesterday it was running very high, and was full of tannic foam as a result. I couldn’t resist eating a fingerful of foam, and was disappointed to find that it tasted of nothing but forest soil.
But mostly what caught our eye were the dead hemlocks.
As they shed their bark, they appear raw and red as fresh meat,
and up close one can see that numerous insects or insect larvae have been having a field day with them.
Death in a forest can be both fruitful and beautiful. We were relieved and impressed to see that the heart of this untouched preserve retained its garden-like qualities,
though the occasional lichen-draped branch fallen from a dead hemlock crown offered a sober reminder of how much biodiversity could be lost if the adelgid invasion does eventually result in 100% mortality of canopy-height hemlocks.
But the ravine still rings with winter wren and hermit thrush song, and given how rapidly the adelgid-created openings are filling in with yellow birch, it’s a safe bet that while the wildlife composition will change somewhat, Snyder-Middleswarth will remain a refuge for forest-interior species for decades if not centuries to come.