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One Gifford Pinchot Drive
Madison, WI 53726
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Research Natural Area

South Branch Beech Grove

[photo:] A large diameter beech tree (Fagus grandifolia) within the South Branch Beech Grove RNA (Photo: Chequamegon-Nicolet 2010)State: Wisconsin

County: Oconto

Forest: Nicolet

Ranger District: Lakewood-Laona

Established: 2015

Acres: 226

Description: The 226-acre (91 hectares) South Branch Beech Grove RNA features a mature upland forest of sugar maple (Acer saccharum) and American beech (Fagus grandifolia) bordering the edge of the National Forest. Pockets of large, mature beech (50 to 80 years old) are interspersed with areas in which pole-sized hardwoods predominate. The slow-growing, shade-tolerant beech reaches the northwestern edge of its range here. South Branch Beech Grove RNA is an excellent candidate to analyze old-growth northern mesic forest nested within a matrix of managed mature forest and second-growth forest. The RNA contains numerous rare and unique plant species and important habitat for the state-threatened red-shouldered hawk (Buteo lineatus).

Ecological Information

Physical and Climatic Conditions:

Nearest weather station, with distance and direction from RNA: Lakewood 3 NE (station no. 474523) about 18 mi (24 km) northeast of the RNA.

Annual precipitation (type, seasonal distribution): Annual precipitation averages 33 inches (84 cm), 64% of which falls between April and September. Average seasonal snowfall is 65 inches (164 cm).

Maximum and minimum temperatures: Daily summertime temperatures average 58° F; average daily maximum temperatures average 53° F. Average temperature in the winter is 25° F; average daily minimum temperatures average 30° F.

Elevation: Elevations range from 1,050 feet (320 m) to 1,100 feet (335 m) MSL.

Geology and Soils: Bedrock includes igneous, metamorphic, and volcanic rock that is greater than 100 feet from the land surface.  Geomorphologic processes include till deposition.

The majority of the soil falls into the Tilleda series. The Tilleda series consists of deep, well drained soils formed in loamy glacial till on ground moraines of late Wisconsinan age. These soils have moderate permeability. A smaller area of Padus soil is also present within the RNA. The Padus series consists of very deep well-drained soils, which are moderately deep to stratified sandy outwash. 

Aquatic Features: The RNA is located within the South Branch Oconto River watershed and will help protect the water quality within the area.

Ecological Classification & Inventory

Section: Northern Great Lakes Section (212T)

Subsection(s): Athelstane Sandy Outwash and Moraines (Tc)

Landtype: Mountain Moraines (Tc18)

Plant Communities:

Curtis Natural Communities

Kotar Habitat Types

Dominant Species

initial US National Vegetation Classification

Northern dry-mesic forest


red oak - red maple - sugar maple

Quercus rubra - Acer saccharum - Fagus grandifolia / Viburnum acerifolium Forest;   CEGL006173

Northern mesic forest


sugar maple - beech - red oak
sugar maple - basswood - beech

Acer saccharum - Fagus grandifolia - Betula spp. / Maianthemum canadense Forest;   CEGL005004

Complete Plant List

View or download (pdf)

Common Fauna: The RNA provides nesting and foraging habitat for the rare red-shouldered hawk (Buteo lineatus). Commonly hunted Wisconsin wildlife species occur within the RNA.

Common Shrub Species: The shrub layer is patchy and generally sparse where the canopy is closed and little light penetrates to the forest floor. Common species include maple-leaved viburnum (Viburnum acerifolium), beaked hazelnut (Corylus cornuta), American fly honeysuckle (Lonicera canadensis), and mountain maple (Acer spicatum).

Common Herbaceous Species: The ground layer is characterized by herbs such as Canada mayflower (Maianthemum canadense), bluebead lily (Clintonia borealis), wild sarsaparilla (Aralia nudicaulis), rosy twisted stalk (Streptopus lanceolatus), blue cohosh (Caulophyllum thalictroides), and hepaticas (Anemone acutiloba and A. americana).

Potential Research Topics: Topics for study include areas with beech, beech bark disease vulnerbility, rare plants, amphibians, bryophytes, and insects. 

Related Website:

Wisconsin State Natural Areas Program - South Branch Beach Grove Headwaters (No. 498)

Related Publications:

Brzeskiewicz, Marjory. 2015.  Establishment Record for South Branch Beech Grove Research Natural Area.  Chequamegon-Nicolet National Forest, Eagle River Ranger District, Forest County, Wisconsin.   36 pp.

Chadde, S. 1997.  Establishment Record for South Branch Grove Research Natural Area Nicolet National Forest.  On file in Park Falls Headquarters, WI.

Curtis, J. T. 1959.  Vegetation of Wisconsin.  University of Wisconsin Press, Madison WI.

DeJoode, Daniel Ray.  2003.  Effects of logging disturbance on understory plant communities in temperate forests.  A Ph. D. dissertation, University of Michigan - Ann Arbor.  Ecology and Evolutionary Biology.

Epstein, E. 1986.  Evaluation Report: South Branch Beech Grove Candidate RNA.

Janke, Steven. 1997.  South Branch Beech Grove Evaluation Report, August 1997. Unpublished report on file in Park Falls Chequamegon-Nicolet Office.

Kotar, J.; Kovach, J.; Burger, T.  2002.  A Guide to Forest Communities and Habitats of Northern Wisconsin (2nd edition).  Madison: University of Wisconsin, Department of Forest Ecology and Management.

NGDC. National Geographic Data Committee. 2012. National Vegetation Classification Standard (NVCS). Available online: Accessed 2012.

Last Modified: 02/23/2017