Cedar Swamp

General Description

Cedar swamps may also be considered lowland coniferous forest. In this case, they are listed under wetlands because cedar swamps are highlighted as such in the Leelanau Habitats Map.

Cedar swamps often occupy large areas of low, swampy plains in Leelanau County. Less extensive Cedar swamps often occur along stream corridors, and where springs and seeps discharge from hillsides. The presence of the Cedar swamp indicates wet conditions and relatively nutrient-rich soils.

Northern white cedar gives this community its characteristic appearance. Many cedar stands form nearly impenetrable thickets, where twisting, tilting cedar trees reach upward toward the sunlight. Because groundwater is only a few inches to several feet below the surface, cedar trees are shallow rooted, with the roots of several trees often intertwined. Frequently a thick carpet of mosses is held above the swamp water by the network of roots.

Common associates of white cedar include black spruce and the fragrant smelling balsam fir. In wetter areas, tamarack is often found. Drier areas may have large white pines and hemlocks towering above the cedar forest. Several deciduous trees are commonly found in cedar swamps including yellow birch, red maple, white birch, and green ash.

Dense cedar forests let very little light through to the forest floor, severely limiting the growth of understory plants. Some plants which can survive these conditions include the early coralroot orchid (Corallorhiza trifida), small rattlesnake plantain, nude mitrewort (Mitella nuda), kidneyleaf violet (Viola renifolia), and partridgeberry. Where no sunlight filters through, the ground is nearly barren.

Where sufficient sunlight penetrates the canopy, an appreciable increase in forest floor vegetation occurs. Open wet spots often contain sizable populations of marsh marigold (Caltha palustris) or fringed loosestrife (Steironema ciliatum). Sometime associates include labrador tea (Ledum groendlandicum), bog buckbean (Menyantes trifoliata), bog buckthorn, Canada blueberry and swamp thistle. One of the most beautiful of orchids, the showy ladies slipper, occurs primarily in cedar swamps that are open enough to allow considerable sunlight through to the forest floor.

Shady low spots in cedar forests contain enchanters nightshade (Circaea alpina), green gentian (Halenia deflexa), bog shinleaf (Pyrola asarifolia), grass of Parnassus (Parnassus glauca), and water horsetail (Equisetum fluviatile).

Sphagnum moss is nearly as dominant on the forest floor as cedar is in the canopy of the forest. Sphagnum soaks up 25 times its own weight in water, and the lush carpet of sphagnum provides a fertile seed bed above the water for understory plants and tree seedlings.

The cool shady environment makes the cedar swamp a favorable area for ferns, and many species thrive here. Royal fern (Osmunda regalis), cinnamon fern (Osmunda cinnamomea), bulblet bladder fern (Cystopteris bulbifera), and sensitive fern are common. Rattlesnake fern and several wood ferns (Dryopteris species) are less common.

Maintaining the Habitat

Cedar swamps are a relatively stable forest type in Leelanau County, well adapted to local conditions. Left alone, cedar forests tend to maintain their species composition over long periods of time. Several tree species often associated with cedar swamps are likely to die out with time because their seedlings are intolerant of shade. These include tamarack aspens, and birches. Large disruptions such as extensive windthrow or logging are necessary to keep these species present.

White cedar has become a valuable timber for construction of log homes, decking, and any outdoor use because of resistance to decay. Selective logging for cedar is not advised, however, because cedar will not regenerate well due largely to predation of deer on young cedar seedlings.

Value to Wildlife

Cedar is a preferred winter food for white-tailed deer. Deer pass much of the late winter in cedar swamp yarding areas, with available white cedar browse an important determinant for survival in harsh winters.

While providing shelter and food for deer, cedar swamps also harbor a wide variety of other game and non-game species. Snowshoe hares, red squirrels, and porcupines are often found in cedar swamps. Larger swamps in Leelanau County support populations of bobcat and possibly black bears.

Hydrologic Function

Cedar swamps flanking riparian areas act a giant sponge, soaking up flood waters, and preventing the inundation of adjoining property. Additionally, the trees take up a huge amount of water through root systems. This water is transpired through leaves and needles. When extensive swamps are cut, collapsing roots systems and lack of uptake for transpiration actually make the ground surface wetter. Many of these cut areas are very soggy and virtually impassable on foot.

Forested swamps help to maintain the quality of surface waters by intercepting sediments and nutrient runoff from surrounding upland sites. Additionally, uptake of nutrients from groundwater, which typically flows under riparian swamps, reduces the levels of algae-causing nutrients in area lakes and streams.