Yellow River Ice-Walled Lake Plain

Yellow River Ice-walled Lake Plain features a fairly large and relatively undisturbed ice-walled lake plain that is probably unmatched in species richness – for this landform – anywhere else in the Chequamegon-Nicolet National Forest. Ice-walled lake plains are common on the end moraine of the Chippewa Lobe, which marks the farthest advance of ice during the last part of the Wisconsin Glaciation. However, because of their comparatively flat surfaces and fertile boulder-free soils within an otherwise rugged end moraine, most ice-walled lake plains have long since been converted to agriculture while most similar sites within the Forest boundary have been highly used for timber production. This one supports a rich mesic hardwood forest that supports a species composition more typical of a southern mesic forest with sugar maple and basswood dominating the canopy. Associates include white ash, red oak, bitternut hickory, and butternut.

The understory is fairly open and the shrub layer is poorly developed. The ground flora includes an outstanding display of spring ephemeral wildflowers and is exceptionally rich with species including squirrel corn, toothwort, false rue-anemone, dog-tooth violet, Virginia water-leaf, sharp-lobed hepatica, bloodroot, rosy twisted stalk, Goldie's fern, and bulblet bladder fern. Numerous rare plants also occur here. Other high-ranking communities include a rich, mixed swamp hardwood forest that has developed on a perched wetland found on the somewhat poorly drained interior of the lake plain.

This swamp forest is drained by several well-developed erosion channels which are served at the original outlet when the surrounding glacial ice melted away. Linked to the site by a typical wet black ash swamp along a riparian drainage, is a representative stand of good quality hemlock-hardwood forest characteristic of the original forest which historically dominated extensive areas of the end moraine. The forest is composed of large hemlock, yellow birch, and sugar maple. Characteristic herbaceous species are Canada mayflower, yellow blue bead lily, mountain wood sorrel, three-leaved goldthread,

American starflower, partridgeberry, bunchberry, and numerous ferns. Super-canopy white pine is present. The ice-walled lake plain drains to both the north and south by rather striking dendritically-patterned erosion channels with steep sides and depths up to 25 feet below the surface of the plain. Many fern species thrive in the moist, shady microclimate of these ravines and hemlock is frequent on the steep slopes. Rare birds include the cerulean warbler (Dendroica cerulea) and black-throated blue warbler (D. caerulescens). Other resident birds include ovenbird, red-eyed vireo, wood thrush, least flycatcher, and scarlet tanager. Yellow River Ice-walled Lake Plain is owned by the US Forest Service and was designated a State Natural Area in 2007.