Swamps
Black ash swamp habitat: A number of black ash swamps occur along the shores of Gogebic Lake, being apparently partially flooded during periods of heavy rains and during stages of high water. In a swamp of this type near the north end of Gogebic Lake on the west side, black ash (Fraxinus nigra) is the dominant tree, the trunks reaching diameters up to 2 feet. Elms (Ulmus americana) sometimes reaching a trunk diameter of 3 feet are common, and yellow birches and hard maples are common also. Black maples are rare, and lindens are few. The trees are high and the forest crown nearly closed. Underbrush is common in the more open places, this being mostly mountain maple (Acer spicatum) with a few young firs, young arbor-vitae, and Virginia creepers (Parthenocissus quinquefolia). There are numerous ferns, and herbs are abundant. Under the more closed parts of the forest canopy the ground is mostly bare, underbrush and herbs being scanty. Smaller black ash swamps occur in the Cisco Lake Region, and in the vicinity of Little Girl's Point a number of small black ashes were noted in a swamp of mixed arbor-vitae and black spruce.
Arbor-vitae swamp habitat: In the Cisco Lake Region arbor-vitae (Thuja occidentalis) occurs commonly near the edges of the lakes and in the wet depressions in the forest. Near Gogebic Lake also the arbor-vitae grows commonly near the shores of the lake and in wet places in the woods, especially at the edges of swamps. But the trees in both these areas, so far as seen, were small, and the arbor-vitae did not form a dominant species, but occurred in a small percentage mixed with the other types of forest. However, in part of the region near Gogebic Lake extensive arbor-vitae swamps are reported to occur. In the vicinity of Little Girl's Point arbor-vitae swamps are common, occupying the wet lower northern slopes of the high ridge.
In a swamp of this type three miles southeast of the point arbor-vitae is the dominant tree, reaching trunk diameters of two feet and more. Under the dense shade of the high forest crown there are many young trees of the same species, and the forest has evidently reached a temporary climax. Of other trees, a few small yellow birch, a few young firs and hemlocks, and one fallen white spruce (Picea canadensis) were noted. The ground is very wet and there are numerous tiny streams, which frequently disappear under the ground. Fallen trees and decaying logs on the ground make a thick tangle, very difficult to penetrate. The underbrush is scanty; mountain maple is rather common, and there are a few young black ashes. Much moss grows on the ground and on the decaying logs.
In a depression two miles south of Little Girl's Point is a mixed growth of arbor-vitae, black spruce, with a few black ashes. The trees are mostly small, none of them exceeding about eight inches in trunk diameter. In August the ground was very wet, there being standing water in some places, and the ground was heavily covered with sphagnum. This situation may be considered transitional between the black spruce bog and the arbor-vitae swamp. No traps for mammals were set in this situation.
Bogs
Leather leaf bog habitat: In the northwestern corner of Fish-hawk Lake and at several places along the channel connecting Lindsley and Cisco lakes a heavy growth of leather leaf (Chamaedaphne calyculata) adjoins and overhangs the water, a considerable portion of the growth actually floating on the water. With the leather leaf is associated much sweet gale (Myrica gale) and alders, and these plants form almost the entire mat in some of the wetter areas. At other places sphagnum becomes abundant and the conditions approach those of a sphagnum bog. Other plants commonly found in the leather leaf bog in the Cisco Lake Region are the Labrador tea (Ledum groenlandicum), swamp laurel (Kalmia potifolia), wild rosemary (Andromeda glaucophylla), small cranberry (Oxycoccus oxycoccus), pitcher-plant (Sarracenia purpurea), and small trees of black spruce and tamarack. In a typical leather leaf bog on the Ontonagon River near the outlet from Thousand Island Lake a large beaver house is located.
Sphagnum bog habitat: In a restricted sense the name is here applied to the part of a bog which is free from trees. It differs from the leather leaf bog in having a greater amount of sphagnum, for while the leather leaf bog when first developed over the water has little or no sphagnum, the sphagnum bog, as here considered, is almost entirely covered by sphagnum. The shrubs found in the two situations are apparently identical, except that the leather leaf is less abundant. A small bog of this type borders the edge of Mud Lake in the Cisco Lake Region, and small parts of many bogs are free from trees. So far as was determined, the mammal fauna is the same as that for the black spruce—tamarack bog, from which the only difference is the absence of trees.
Black Spruce—Tamarack Bog habitat: The dominant bog tree in this region is the black spruce (Picea mariana), which is usually small and stunted. With the black spruces are a lesser number of small tamaracks (Larix larcina), which in places may be dominant. The ground is heavily covered with sphagnum, which is normally soaked with water. Shrubs are abundant, though usually not forming a closed mat. Of the shrubs the leather leaf is the most abundant, though Kalmia, Andromeda, Ledum, and blueberries are common. A few young white pines and red maples were noted. Sedges occur frequently, and the pitcher plant is very characteristic.