Grandma Lake Wetlands Research Natural Area

Grandma Lake Wetlands RNA. Photo by Lucy Tyrrell, USDA Forest Service.

Eagle River - Florence
The RNA is notable for a pristine, undeveloped bog lake and a surrounding open mat composed primarily of sphagnum moss, sedges, rushes and low ericaceous shrubs that support a flora that is both diverse and unusual. The balance of the wetland within the RNA boundary is a conifer swamp, composed primarily of tamarack (Larix laricina) and black spruce (Picea mariana). There are 5 species of uncommon plants, including a large population of a rush (Juncus stygius), which was previously unknown in Wisconsin, common arrow grass (Triglochin maritimum), dragon’s mouth orchid (Arethusa bulbosa), and two sedges (Carex livida and C. tenuiflora).

Ecological Information

Physical and Climatic Conditions

Nearest weather station, with distance and direction from RNA:
Nicolet College Weather Station, south of Rhinelander, Wisconsin, is located approximately 41 miles (66 km) southwest of the RNA.
Annual precipitation (type, seasonal distribution) :
The mean annual precipitation is 30.6 inches (78 cm). Average annual snowfall is 56 inches (142 cm).
Maximum and minimum temperatures:
The mean high temperature occurs in July at 68 ºF and the mean low temperature in January at 0 ºF.
The elevation of Grandma Lake is 1520 feet (463 m).
Geology and Soils:
Two soils dominate the uplands, Padus and Stambaugh, which are both deep and moderately drained. 20 acres of wetland are open bog. Precambrian metamorphic rock underlie this area. The bedrock surface is irregular and slopes east and southeast approximately 7-10 feet per mile. Topography is hummocky due to the collapse of sediment deposited on stagnant ice.
Aquatic Features:
Grandma Lake, a shallow, soft, seepage lake, covers 44.4 acres (18 ha) and has a maximum depth of 9 feet (3 m).

Ecological Classification & Inventory

Southern Superior Uplands (212J)
Brule and Paint Rivers , Drumlinized Ground Moraine (212Jl)
Plant Communities:

SAF Cover Types (list acres):

Kuchler Types (list acres):

5 Balsam fir (16) 85 Conifer Bog (140)
13 Black spruce-tamarack (140) 97 Northern Hardwoods (174)
16 Aspen (60)  
25 Sugar maple-beech-yellow birch (98)  

Complete Plant List

Common Shrub Species:
Heath family (Ericaceae), bog clubmoss (Lycopodium inundatum), leatherleaf (Chamaedaphne calyculata), Labrador tea (Ledum groenlandicum), swamp laurel (Kalmia polifolia), bog-rosemary (Andromeda glaucophylla), cotton grass (Eriophorum sp.), speckled alder (Alnus rugosa), cranberry (Vaccinimum macrocarpon), bulrush (Scirpus hudsonianus), sedge (Carex oligosperma).
Common Herbaceous Species:
Dragons mouth orchid (Arethusa bulbosa), pitcher plant (Sarracenia purpurea), sundews (Drosera intermedia and D. rotundifolia), naked bladderwort (Utricularia cornuta), white water lily (Nymphaea tuberosa), water-shield (Brasenia schreberi), pipewort (Eriocaulon aquaticum).
Common Mammal Species:
Snowshoe rabbit (Lepus americanus), mink (Mustela vison), muskrat (Ondatra zibethicus), beaver (Castor candensis), black bear (Ursus americanus), white-tailed deer (Odocoileus virginianus).
Common Bird Species:
Black tern (Chlidonias nigra), common loon (Gavia immer), American bittern (Botaurus lentiginosus), Lincoln's sparrow (Melospiza lincolnii), white-throated sparrow (Zonotrichia albicollis), Nashville Warbler (Vermivora rufacapilla), yellow-rumped warbler (Dendroica coronata), common yellowthroat (Geothlypis trichas), mallard (Anas platyrhynchos), black duck (Anas rubripes), cedar waxwing (Bombycilla cedorum), semi-palmated plover (Charadrius hiaticula semipalmatus).

Related link: Wisconsin State Natural Areas Program Grandma Lake Wetlands

Related Reports and Publications

Fouse, Fred. 1991. Establishment Record for Grandma Lake Wetlands Research Natural Area within the Nicolet National Forest, Florence County, Wisconsin. 111 pp.

Howe, R.W. 1996. Birds of the Nicolet National Forest. Report submitted to the U.S. Forest Service, Rhinelander, WI.

Last Modified: August 20, 2021