Earth Partnership for Schools


WOODLAND PLANT COMMUNITY - NORTHERN MESIC FOREST

Distribution: At the time of settlement, northern mesic forest community types formed the largest woodland in Wisconsin. In northern Wisconsin, this mixed hemlock-hardwood community encompassed 11,740,750 acres, or 33.55% total land surface of Wisconsin. In the southern region, a few relic stands may be found on steep, north-facing hills and cliffs in the Driftless area.

General: The species composition of the northern mesic forest changes from east to west due to the range limits of some of the dominant trees. Beech is restricted to the counties along Lake Michigan and Green Bay. Hemlock reaches its western limit in Sawyer and Bayfield counties, and yellow birch decreases in numbers as it nears the St. Croix river. A typical stand may include small numbers of white pine as the super canopy.

Physical Environment: Northern mesic woods grow best in deep, loamy soils but can be found wherever the topography is not extreme.

Topography: Northern mesic forests often grow on glacial moraines, moist but well-drained slopes, north and east slope aspects, cool moist valleys, ravines, hollows under cliffs, protected coves.

Microclimate: The sheltered environment provides protection from direct sun exposure and prevailing dry winds. Evaporation is low, and temperatures are stable.

Composition: Species listed below are most likely found in the community.

Dominant Trees: Sugar maple, hemlock, beech, yellow birch, and basswood.

Common Trees: Ironwood, red oak, red maple, white birch, white ash, and balsam fir. American elm was once common in the northern mesic forest. Today, Dutch elm disease significantly reduces its numbers of trees larger than saplings.

Typical Shrubs: Beaked hazelnut, leatherwood, and maple-leaved viburnum. Canada yew was once a characteristic shrub but is now rare, due to heavy browsing of deer.

Prevalent Groundlayer: Canada mayflower, Solomon's seal, twisted-stalk, wild sarsaparilla.

Structure: The deep shade cast by the canopy trees restricts understory trees and shrubs to openings in the canopy. In areas where the canopy is thick, the lower levels are open and park-like. In woodlands dominated with sugar maple, a luxuriant carpet of spring ephemerals, woodland wildflowers, and ferns blanket the forest floor. Ephemerals, such as spring beauty, toothwort, or Dutchman's breeches bloom, set seed, then disappear from sight before the canopy leaves are full-sized. Later in the spring, trillium, wood phlox, and bellwort bloom. In the summer, a rich blanket of ferns spreads over the forest floor. A single footstep may trample 15 to 20 plants. In some forests, large numbers of shade tolerant sugar maple seedlings and small trees comprise the forest floor. In other forests, hemlock or beech may produce numerous seedlings. These seedlings may survive in the understory for many years then grow rapidly when a gap in the canopy forms. Hemlock seedlings have been found that are 100 years old and only 2" in diameter.

Stability: This forest is considered a climax type in the region because dominant trees are long-lived, prolific, and reproduce under their own shade. In absence of fire or other disturbance, succession will not evolve to another forest type.

Soil: Silt loams, dark colored loams rich in humus. Well-drained to moist soils.

Major Soil Series: Kewaunee, Onaway, Kennan, Otterholt, and Spencer.

 

Summary of Soil Analysis:

W.R.C.

247%

p H

5.6

Ca

4215 p.p.m.

K

93 p.p.m.

P

? p.p.m.

NH4

? p.p.m.

Typical Number of Species: Trees 27, Shrubs 46, Herbs 181, Total 254
Species Density: 33
Guild SE ES LS SV WA WG DI MY EV
Average Proportion 3% 57% 13% 14% 0% 0% 0% 2% 11%
Guild Key: SE = Spring Ephemeral; ES = Early Summer; LS = Late Summer;
SV = Shrub/Vine; WA = Winter Annual; WG = Wintergreen; DI = Dimorphic; MY = Mycotrophic; EV = Evergreen
Wildlife: White-throated sparrow, northern junco, purple finch, American redstart, yellow-bellied sapsucker, cedar waxwing, crossbills, red squirrel, pine martin.
Typical Examples: Plum Lake S.A., Flambeau Forest S.A., Peninsula Park Beach S.A.
Geographical Distribution: From Wisconsin east through Michigan and S. Ontario to New York and Pennsylvania.