Earth Partnership for Schools



Topography: Southern wet forests often grow along river margins and lake margins; on flood plain depressions; and in low areas subject to frequent flooding in late winter and spring.

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

Dominant Trees: Silver maple, black willow, cottonwood, river birch. American elm once was a dominant tree. Dutch elm disease significantly reduced its numbers. Different combinations of species are found in wet forests -- on pioneer sites with a recent soil disturbance, such as a sand bar or mud flat, black willow and cottonwood dominate. In wet soils along an upland edge, river birch and swamp white oak dominant. As the stands mature, silver maple and elm invade.

Common Trees: Green ash, swamp white oak.

Typical Shrubs: Shrubs play a minor role. Characteristic shrubs of the wet forest are eastern wahoo, buttonbush, and silky dogwood. Vines: poison ivy, woodbine, grape, moonseed, hog- peanut, wild yam, clematis, wild cucumber, carrionflower, and bittersweet.

Prevalent Groundlayer: Nettle, whitegrass, false nettle, wood sage, figwort. The composition of the groundlayer varies from site to site due to the fluctuating water supply. In some cases, the development of the groundlayer is delayed until mid-August. A few late summer bloomers include calico aster, spotted jewelweed, green-headed coneflower, and late goldenrod. Spring blooming perennials are at a distinct disadvantage due to seasonal flooding. From year to year the composition may change, depending on how different species respond to flooding.

Structure: Mature trees can reach very large sizes. Silver maple and cottonwood trees may measure a circumference of 17-20 feet. The canopy spread is proportionally large. A typical forest may have only about 85 trees per acre because of these large dominants. Many trees have multiple stems as a result of damage to trunks by ice and flood-carried debris. Low densities of seedlings and saplings are typical in a wet forest. Flooding conditions often yields poor seed germination. Distinct bands of vegetation of different types often develop. Willows are close to the river; silver maple is behind; and cottonwood stand in the background.

Soil: Sandy loams, silty clays, hard clays. Very poor to poor drainage.

Major Soil Series: Mostly undifferentiated colluvial soils.


Summary of Soil Analysis:



p H



3435 p.p.m.


82 p.p.m.


55 p.p.m.


14 p.p.m.

Stability: Subject to frequent flooding.
Typical Number of Species: Trees 21, Shrubs 26, Herbs 128, Total 175
Species Density: 29
Average Proportion 0.0% 19.2% 57.3% 20.3% 0.0% 0.0% 1.9% 0.5% 0.8%
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: Wood duck, red-shouldered hawk, vireos, northern oriole, wood thrush, scarlet tanager, and beaver.
Typical Examples: Wyalusing S.A., Tower Hill State Park, Merrick State Park, UW-Madison Arboretum.
Geographical Distribution: Along rivers, Minnesota to New York and New Jersey,

increasing in complexity rapidly toward the south in the Mississippi and Ohio valleys.