TfflsLA 



Shingleton Bog, Michigan 



by Robert H.Mohlenbrock 



In Hiawatha National Forest, in Michi- 

 gan's Upper Peninsula, a five-square-mile 

 wetland is known locally as Shingleton 

 Bog. But because most of the area is not 

 very acidic, the term bog is inappropriate 

 under the definitions developed by Michi- 

 gan botanist Howard Crum {see "This 

 Land," March 1994). Since it contains 

 ample sphagnum, or peat moss, it is a 

 peatland. Its various open areas, which are 

 best termed "fens," are interspersed with 

 tree-studded patches known as white 

 cedar swamps and black spruce muskegs. 



Among its habitats, Shingleton Bog has 

 a "poor" fen and a "patterned" fen. To see 

 them, I followed Hiawatha National Forest 

 ecologist Jan Schultz, regional forest 

 botanist Lawrence Stritch, and research 

 natural area coordinator Lucy Tyrrell 

 through a rather impenetrable white cedar 

 swamp adjacent to Forest Highway 225 1 . 

 The white cedar swamp is a natural com- 

 munity that gradually arose following the 

 retreat of the great glaciers that covered 

 the region some 12,000 years ago. At that 

 time, heavy, waterlogged soil began to 



Jack W. Dykinga 



20 Natural History 4/94 



build over the limestone bedrock. Sphag- 

 num mosses eventually covered much of 

 the soil, and their decomposed remains 

 began to accumulate as peat. 



The considerable calcium in the under- 

 lying limestone kept the peatland from be- 

 coming acidic, so that the fen maintained 

 itself until white cedar seedlings began to 

 invade. As more and more trees became 

 established and grew to maturity, their 

 dense cover promoted the growth of 

 shade-tolerant plants. 



The white cedar swamp was difficult to 

 walk through because of the low-hanging 

 branches, which often reach the ground. In 

 addition, there were weak areas in the mat 

 of sphagnum beneath the trees where one 

 could easily step through and twist an 

 ankle. Filling the understory were shoul- 

 der-high clumps of royal fern and cinna- 

 mon fern. Here and there, occasional pink 

 lady's-slipper orchids and bluebead lihes 

 grew among thick patches of low-grow- 

 ing, evergreen club mosses. 



The ground sloped down imperceptibly 

 as we made our way through the cedar 

 swamp. Even though I could not detect the 

 difference, the plants responded to the 

 slight change in soil and moisture. Almost 

 abruptly, the crowded, large white cedars 

 gave way to open habitat containing few 

 woody plants, all of them dwarfed and 

 gnarled. Apart from cedars, there was an 

 occasional tamarack, a few red maples, 

 and a scattering of shrubs — red choke- 

 berry, mountain holly, and raisin tree. As 

 we proceeded, the ground became wetter, 

 and water rose above the toes of our boots 

 with every step. 



Crum describes this type of community 

 as a poor fen because of its greater degree 

 of acidity, not because it lacks a diversity 

 of plants. Dozens of low-growing wild- 



Tamaracks and cattails, left, grow in 

 Shingleton Bog's "poor" fen. 

 Right: Pink lady's-slipper orchid. 



John Gerlach; Dembinsky Photo Associates 



