Shenandoah Sinkholes!

Last summer, I visited the Shenandoah Valley sinkholes, one of the stranger ecosystems present in Virginia. The rocks here started the weirdness- calcerous limestone overlayed by acidic sedimentary substrate result in solution holes with acid-loving flora, often more typical of the Atlantic Coastal Plain, around the edges. Typically sinkholes/solution holes are neutral to basic in pH thanks to their limestone bedrock. The acidic substrate above, however, makes for completely different flora in this small region. Each sinkhole contains a different mix of flora, too, varying in species composition wildly.

tiny sinkhole
Smallest sinkhole I found- this one had very little flora

I arrived at the site after dark, having found no satisfactory campsites. As a result, I camped in the parking lot. This may not be strictly legal, but I was unable to find regulations suggesting I couldn’t practice dispersed camping in this section of a national forest and I figured camping in the parking lot was safer for the more sensitive flora. It began to rain gently as I finished setting my tent, and I noticed a brilliant orange critter crossing the road- a Red-spotted Newt!

Red Spotted Newt/Cricket
Red-spotted Newt (Notophthalmus viridescens) with a cricket companion

Intrigued by the fact that newts were out and about, I ventured down the road, and was rewarded with approximately 20 or so more newts out and about. One longer-tailed individual proved to be a new species for me in Virginia, the Long-tailed Salamander, much more familiar to me from southern Illinois herping. The Shenandoah Valley is on the eastern edge of this species’ range and I’d rarely seen these out and about even back in southern Illinois.

Long-tailed Salamander on road
Long-tailed Salamander (Eurycea longicauda)

A few more salamanders further, I found a White-spotted Slimy Salamander, a member of the complex of identical-looking Slimy Salamanders found across Eastern North America. Slimy Salamanders are better thought of as sticky salamanders. When handled, as a defensive mechanism they produce a glue-like substance from glands in their skin. I’ve had an easier time getting superglue off my hands. As handling salamanders is generally bad for their health as well, I recommend letting slimy salamanders be.

White-spotted Slimy on road
White-spotted Slimy Salamander (Plethodon cylindraceus)

A slender shape on the road suprised me- an Eastern Worm Snake! A secretive burrower, worm snakes are most often found by flipping over rocks, logs, or trash. I’ve had particularly good luck with this species under old carpeting. These adorable little derpy snakes have never bit me- their teeth likely couldn’t break skin if they tried. I let it go to the side of the road, post photos, and retired to bed satisfied.

Wormsnake in Hand (east)
Eastern Worm Snake (Carpophis vermis)

In the morning, I wandered over to the first of several sinkholes- one dammed in years past by humans. This one had a more constant water level and thus developed permanent aquatic vegetation. Unaltered sinkholes vary wildly in water levels, another factor in the strange vegetation of this region.

dammed sinkhole
Dammed Sinkhole

The dammed sinkhole did have a few weird plants despite its alterations, the most interesting of which is carnivorous. Utricularia radiata is known only from the Atlantic Coastal Plain in Virginia, and then from these sinkhole ponds. It’s a bizarre outlying population, and sets the stage for many of the other plants found here. This bladderwort, like others of its genus, uses specialized vacuum traps to gather zooplankton from the water, kill them, and use the nitrogen in their bodies for further growth.

Utricularia radiata
Utricularia radiata

Unlike many of the more common bladderworts, this species has inflated bases, allowing it to float on the surface of the water. Others are semi-terrestrial, rooting into permanently wet soil, or simply live in water without inflated bases.

Utricularia radiata out of water
Close up of Utricularia radiata

My next plant discovery was almost equally bizarre, if far more common in Virginia. Pinesap is a plant with no chorophyll, and thus no means of making its own food as in more typical plants. Instead, Pinesaps connect to an underground superhighway of nutrients- the mycorrhizal network.

Pinesap (Monotropa hypopitys)

Throughout the soil, fungi and plant roots intermingle and fuse together, exchanging nutrients each organism requires to survive. Pinesap and other myco-heterotrophic species tap into this network and steal nutrients without providing any contribution in return. Pinesap populations indicate a healthy mycorrhizal network that can tolerate such thievery, and thus such parasites are a sign of high-quality habitat.

Allegheny Chinkquapin
Allegheny Chinkapin (Castanea pumila)

One of the nearby trees likely unwittingly providing to the Pinesaps is Allegheny Chinkquapin, seen in fruit. Closely related to the nearly-extinct American Chestnut, Chinquapins also suffer from the devastating chestnut blight fungus, just to a lesser extent. Thankfully this species survives in decent numbers, producing large quantities of nuts.

I continued down the path past the Chinquapins, and eventually found a paired set of sinkholes with a narrow isthmus between them. Golden daisies bloomed from midwater- my goal for the day!

Helenium montanum
Twin Sinkhole with Helenium virginicum

Virginia Sneezeweed, Helenium virginicum, is a Federally Threatened plant species found only around seasonally inundated sinkholes in Virginia and Missouri, at sites where acidic soils are underlain by limestone bedrock. Virginia Sneezeweed seeds can only germinate above water, so the water’s rising and falling in accordance with rainfall and groundwater movements causes populations to fluctuate. Few other plants can survive the dramatic inundations of this habitat.

Helenium montanum close
Virginia Sneezeweed (Helenium virginicum)

One of the few other plants found here is exclusive to this habitat in Virginia- Common Pipewort (Eriocaulon aquaticum), a species more typical of southern Canadian wetlands that randomly occurs in these strange sinkhole habitats due to the layers of peat that have accumulated at the edges. There’s only five sites in Virginia where this plant remains, four sinkhole ponds and one Coastal Plains pond on the Delmarva coast. Common Pipewort earns its name in the Northeast, where it occurs around natural wetlands near the Atlantic Coast and in peaty wetlands further inland around the Great Lakes.

Eriocaulon aquaticum
Common Pipewort (Eriocaulon aquaticum)

Suprisingly neither Virginia Sneezeweed nor Common Pipewort are the rarest plant at this site in terms of global population or number of Virginia populations. That honor goes to a plant I’d initially written off as an aster, Boltonia montana. Present only in a handful of sinkhole ponds in Augusta county, Virginia, and limesink ponds in north-central New Jersey, the recently-described Boltonia montana blooms around the edges of these ponds as they dry down each fall.

Boltonia montana
Mountain Doll’s Daisy (Boltonia montana)

The federal government does not list Boltonia montana owing to a lack of noted declines in its eleven individual populations, but given its limited range and habitat, I consider it to be the rarest of the strange flowers of the Shenandoah Valley Sinkhole Ponds. For comparison, federally-threatened Helenium virginicum has about 80 known populations, 50 or so in Missouri and 30 or so in Virginia. I’m glad to have seen it, and I hope that the government analysis is correct and that Boltonia montana will maintain itself. At any rate, the Shenandoah Valley sinkholse are one of the most unique botanical communities I’ve had the pleasure of visiting, though I visited an almost equally-bizarre community a few hours later…

To be continued

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