Habitat             Calamus Swamp: a Glacial Relict by Jim McCormac A basic ecological tenet has it that disturbance changes and often revitalizes habitats - indeed, given great enough impacts, entirely new communities can be formed. Well, very few forces of disturbance ever changed the face of Ohio like the last glacial advance some 12,000 years ago. This glacier is known as the Wisconsinan ice sheet, and it scrubbed roughly 2/3rd of Ohio flat. Rolling over all but the hill country of southeastern Ohio, giant waves of ice weighing many millions of tons rearranged the topography like a herd of colossal D-9 Cat bulldozers run rampant. As the climate gradually warmed and the massive cloak of ice retreated northward, it left in its wake a new terrain. Stream courses flowed where none had existed prior; gravelly moraines, eskers, and kames now provided the elevational relief; and - perhaps most interesting to present day naturalists - glacial lakes were created. These glacial lakes - or kettle holes, as they are sometimes called - dotted the landscape, primarily in west central, northeast, and northwest Ohio. They were formed when massive blocks of ice were calved from the face of the thawing glacier, and fell to the soft, wet earth, creating depressions of varying sizes and shapes. As the blocks melted, lakes of cool, clear water remained. Of course, plants abhor a vacuum, and the process of ecological succession quickly began. Over time, many of these lakes developed the characteristics of peat bogs, such as Triangle Lake Bog State Nature Preserve in Portage County. Plant associations in this type of glacial lake are based on a substrate of Sphagnum mosses, and were colonized by species often associated with bogs, such as Leatherleaf, Chamaedaphne calyculata , and Tamarack, Larix laricina. Glacial lakes in the central Ohio region tended to evolve towards more of a mixed emergent marsh plant community, quite different from the more acidic sphagnum bogs. Unfortunately, most of Ohio's kettle holes - no matter what form they took - have disappeared from the landscape. The vast majority has succumbed not to development, drainage, farming, or other modern day activities of man, but to the relentless process of ecological succession. Given enough time, these once open water bodies are slowly filled in with dead plant material, and eventually disappear altogether. Today, many of Ohio's natural lakes are carpeted with swamp forests, and are virtually undetectable from ground level. However, with a bird's-eye view from high above, the former kettles can still be seen. For instance, an airplane flight over parts of Williams County in extreme northwest Ohio when the leaves have fallen reveals a landscape liberally pockmarked with the circular outlines of glacial lakes, now grown over and obscured by a mantle of trees. In central Ohio today - as defined by Franklin County and its adjoining counties - glacial lakes are an extremely rare commodity. In fact, only one naturally vegetated and undisturbed kettle is known to survive in this region - Calamus Swamp. Located in Pickaway County about 1.5 miles west of the City of Circleville, Calamus Swamp has long been known to people interested in natural history. In the 1930s, a student at The Ohio State University produced a Master's Thesis describing the natural features of Pickaway County, and noted similarities in vegetation between Calamus Swamp and the nearby Stage's Pond State Nature Preserve. Unfortunately, the aquatic vegetation in Stage's Pond has been almost completely eliminated, having fallen victim to excessive sedimentation and fertilizer runoff from surrounding lands. Consequently, Calamus Swamp serves as a time capsule offering evidence of the plant associations that used to occur in central Ohio glacial lakes. Today, a visit to Calamus reveals a beautiful and lushly vegetated 19-acre kettle hole, characterized by several distinct plant communities that support a number of unusual plants and animals. The deepest areas are normally covered with several feet of water, and support deepwater plants such as Coontail, Ceratophyllum demersum and Spatterdock, Nuphar advena . Of botanical significance in this habitat are two species of carnivorous plants, Humped Bladderwort, Utricularia gibba , and Common Bladderwort, U. vulgaris. These free-floating aquatics have finely dissected underwater leaves that possess tiny bladders, which have a hair-trigger trap door that allows them to snap open and ingest tiny animals passing by. They are most spectacular in the summer months, when their tiny yellow violet-like flowers poke above the water's surface, so thickly in places that they resemble a fine golden mist. In other areas, dense thickets of Swamp Loosestrife, Decodon verticillatus, send out pendulous shoots of magenta flowers. The shoreline is ringed with a jungle of Buttonbush, Cephalanthus occidentalis - a wetland shrub that has ball-like white flower clusters that resemble Christmas tree ornaments. Other places have thick stands of Bur-reed, Sparganium eurycarpum and River Bulrush, Scirpus fluviatilis , interspersed with brilliant purple Blue Flag, Iris virginicus. The wetland periphery is forested with swamp woodland, typified by Green Ash, Fraxinus pennsylvanicus , American Elm, Ulmus americanus , and Silver Maple, Acer saccharinum , among others. An interesting mystery is how this wetland came to be known as "Calamus Swamp". Clearly the name comes from the plant called Sweet Flag, Acorus calamus. However, this is no documented record of Sweet Flag here, nor is the habitat appropriate. Nevertheless, the site has carried this moniker for as long as anyone can remember - decades at least. A likely explanation might be a case of mistaken identity with Bur-reeds, which are common. Vegetatively, the leaves of Bur-reed and Sweet Flag are quite similar, and an early investigator probably made the misidentification that led to the name of this site. In any event, this name has stuck, and virtually all who are familiar with the wetland know it by this name. Along with diverse plant associations come diverse assemblages of animals, and Calamus Swamp is no exception. Tiger Salamanders - a spectacular mole salamander measuring up to 8 inches in adult form - are found here, as are at least 5 species of frogs. Many birds have been recorded, including the gorgeous Prothonotary Warbler, a multitude of waterfowl, Least Bittern, Common Moorhen, and many others. Dr. David Stansbery of The Ohio State University has studied Calamus Swamp since 1957, and he has recorded an incredible array of the smaller forms of animal life, including oddities like the Ohio Fairy Shrimp. It is indeed fortunate that this remarkable wetland survives in a pristine condition, particularly in light of the fact that most of our glacial lakes have been degraded by man's activities. The primary reason is due to the exemplary conservation ethic of the landowner, Mrs. Ada Burke. Ada and her family have owned Calamus Swamp and much of the surrounding land for over 100 years, and have always recognized the swamp as an unusual treasure worthy of protection. Because of their conscientious stewardship, the plants and animals of Calamus Swamp survive to this day. To insure that Calamus Swamp is protected for future generations to enjoy, Mrs. Burke donated Calamus Swamp and critical buffer areas to Columbus Audubon. Page updated 06/10/03 © Columbus Audubon 2003