Category Archives: adelgid
Yesterday afternoon, I managed to get this one, blurry photo of a barred owl down in the hollow before it flew. It was first spotted by Steve this past Saturday, and has been seen a couple times since, always within a few hundred feet of the halfway point between the Juniata River and the end of the driveway at the houses. Perhaps not coincidentally, this is also where the lower hollow, with its steep stream banks and hemlocks, gives way to the more open and deciduous upper hollow.
Barred owls are uncommon visitors here on the mountain. The last one we know about appeared on the 2006 Christmas Bird Count, also down in the hollow, though a little higher above the road. This relative scarcity may be due to the fact that we have so few hemlocks. If so, we may see even fewer barred owls in the future: the hemlock woolly adelgid damage is now conspicuous on many of our trees.
It’s all up and down the hollow. We’ve probably had it for a couple of years, but were too much in denial about the possibility to look for it closely. It’s easy to overlook in the early stages of an infestation, as you can see.
What does this mean for Plummer’s Hollow? Among other things, that some of the last really nice areas, spared from the tender mercies of loggers back in the late 70s, 80s and early 90s (before we consolidated ownership) will lose one of their main “climax” species. The deep hollow will no longer be as dark a place. And meanwhile, up on the drier slopes of Laurel Ridge, the mountain laurel is dying from a mysterious blight…
UPDATE: Marcia wrote about her discovery here.
Marcia reports that she found the first sign of hemlock woolly adelgids in Plummer’s Hollow a couple days ago: remanants of the woolly masses on the undersides of a few twigs on a hemlock tree along the Ten Springs Extension Trail above the Big Pulloff — i.e., less than a half-mile from the bottom. This is what we’ve been dreading for some time now, as we’ve watched the adelgid wave move toward us from the southeast, where some of the best-known old-growth remnant stands, such as The Hemlocks Natural Area and Sweetroot Natural Area, have been destroyed. Adelgids have already established themselves north of us in the Rothrock State Forest, so we knew it was only a matter of time.
Though doubtless the northeast-facing slopes of Plummer’s Hollow were covered with old-growth hemlock two hundred years ago, now only a remnant population of second- or third-growth trees numbering in the low hundreds hangs on in the deepest parts of the hollow. This may be to our advantage, though, in slowing the advance of the adelgids — some reports indicate that hemlocks in rich, mixed conifer-deciduous forests hold out longer than those in pure stands. We are, of course, hoping against hope that a biological control will take hold. Insecticides aren’t effective against the adelgid, and in any case we wouldn’t allow their use even if they did work — overall biodiversity has to take precedence.
We’re in the middle of a cold snap right now, with nighttime temperatures hovering just above zero F, and needless to say we are cheering the cold on. We’d welcome temperatures ten or even twenty degrees colder than that, despite the inconveniences that might cause us. The loss of all mature hemlocks in Pennsylvania, while not catastrophic for the species as a whole, could have a devastating effect on forest ecostystems, especially cold-water fisheries.