Saturday, June 16, 2012

Cranberry Island, a "floating" bog

A while back, I was asked to create a field trip, which would then be raffled off with the proceeds supporting Operation Feed. Stephen, who works in another agency of my department, placed the winning bid, and he and seven of his friends joined me yesterday to visit a truly unique site.

We met at the docks at Buckeye Lake State Park, and boarded this vessel. The Queen of the Lake II is owned by the Greater Buckeye Lake Historical Society. Their director, J-me Braig, very graciously arranged to deliver us to our destination, which requires the use of a boat. Several excellent GBLHS volunteers accompanied our expedition, and they were a wealth of information about Buckeye Lake, and the special place that was our targeted destination.

Here it is - the place that requires water travel across one of central Ohio's inland seas to visit. Cranberry Island State Nature Preserve, which lies just off the north shore of Buckeye Lake, in Licking County. Cranberry Island is often referred to as a "floating island", although it isn't free-floating. Back in the 1820's, canal systems were hailed as the future of transportation systems, and construction of the Ohio & Erie Canal was in full swing.

A low but vast valley occupied the region between Columbus and Zanesville, just south of Heath. Canal engineers thought that by damming and flooding "The Great Swamp", they'd create an ideal canal feeder lake, and thus blocked and diverted flow from the South Fork Licking River and inundated the "swampy" valley, which in reality was anything but a swamp.

By today's standards, the inundation of this low valley would be considered an environmental tragedy by most, as there were hundreds if not a thousand+ acres of open sphagnum bog blanketing the area. Such a boreal habitat would have been commonplace in Ohio for several thousand years after the departure of the Wisconsinan glacier, our last ice sheet, but by the 1800's boggy environs had become quite rare.

The well-used and weatherbeaten planking that traverses Cranberry Island. If you were in a hurry, it wouldn't take long to stroll the boardwalk - the island is only 11 acres or so in size, and the pathway covers but part of that. But most visitors aren't in a hurry, and there are a lot of interesting things to see. Cranberry Island is a living museum, offering a glimpse into Ohio's glacial past. Most such habitats have long since passed into woodland, the victims of natural vegetative succession. One must venture much further north, into northern Michigan, before similar boggy habitats become commonplace.

See Cranberry Island while you can. It's rapidly shrinking, due to multiple factors. When the island first arose when the lake was created in 1830, the youngest and most buoyant part of the bog slowly rose with the lake waters. Cranberry Island was born, and it was thought to have been as large as 65 acres when first spawned. The island is attached to the core of peat below the lake, the waters of which are only 5 or 6 feet deep. A hole drilled down through the island revealed the peat depth to be about 37 feet.

This island is indeed unique, as it's thought to be the only acidic sphagnum bog surrounded by a lake. The usual state of affairs is that bogs form around the margins of glacial lakes, and then slowly take over the lake and fill it in with vegetation. Here, the opposite is true. A chemical clash between alkaline lake waters and the acidic bog substrate means that Cranberry Island is slowly "melting"; being dissolved by the lake. As alkalinity increases along the shoreline, trees gain a foothold and grow. When trees get large enough, they tend to topple and take big chunks of the bog with them. Some experts think that the island may only last for a few more decades.

Much of the original bog flora remains, and flourishes. Mid-June is a good time to visit, as two species of showy orchids are in bloom. This is rose pogonia, Pogonia ophioglossoides, which is a threatened species in Ohio. It was beginning to fade a bit, losing some of its pinkish luster. The small-leaved stems all around the orchid is large cranberry, Vaccinium macrocarpon, the island's namesake. This is the cranberry of commercial cultivation, and it is the dominant plant of Cranberry Island's meadows.

This is grass-pink orchid, Calopogon tuberosus, which was just coming into peak bloom. I wrote about the bizarre and deceptive pollination strategy of this plant IN THIS POST.

The pitcher-plants, Sarracenia purpurea, are always crowd-pleasers. Although pitchers certainly occur in sphagnum bogs, the species apparently was not present on Cranberry Island. Legend has it that a woman brought a few plants out some time around 1900, and planted them. The pitcher-plants flourished and there are now scores of them. I've written about the interesting habits of this carnivorous plant HERE.

This is Cranberry Island's other carnivorous plant, the round-leaved sundew, Drosera rotundifolia. Its tiny leaves are covered with hairs that glisten with dewlike drops. This liquid looks mighty scrumptious to small insects, which fly in to investigate. Big mistake. Once a bug lands on a sundew leaf, it is snared by the dewdrops, which have the consistency of Elmer's Glue. The plant then slowly enfolds its leaf around the victim, and drains it of valuable nitrogen and proteins.

The Greater Buckeye Lake Historical Society recently took over management of Cranberry Island, and they are doing a fabulous job of handling the stewardship of this state treasure. I'd highly recommend setting up a tour through GBLHS and making a visit to the island. Access is by permit only, and besides, you need a boat to get there, so GBLHS is your gateway to the wonders of the world's only "floating" bog island.

The Society also has a fabulous museum located at 4729 Walnut Road right in the heart of the community of Buckeye Lake and only minutes from the boat ramp from which Cranberry Island tours depart. Stop in and visit when you're out at the lake.

Today was the annual Cranberry Island Open House, and the hard-working staff of the Greater Buckeye Lake Historical Society probably shuttled several hundred bog enthusiasts out to Cranberry Island. Or, if they weren't bog enthusiasts before their trip, they probably were by its conclusion. I hope this big day went well, and thanks again to the Society for taking such excellent care of Cranberry Island!

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1 comment:

Brent C. Kryda said...

Thanks very much for posting this, especially considering what a limited lease on life the island has left.