Clayey Wet Savannas

Description

The Clayey Wet Savannas ecological site reference state exhibits a diversity of wet-tolerant native grasses and forbs along with scattered hardwood species. Plant community structure and composition within the reference state are variable and dependent upon the impacts of drought, grazing, fire events, and human disturbance. Fire was historically present on these savanna sites but to a lesser degree than the prairie ecological sites. This reduced occurrence of fire resulted in a plant community that included more woody vegetation and scattered trees. A secondary trigger for maintenance or conversion of this ecological site is grazing. Intensive grazing can reduce the extent of highly palatable species thereby allowing the growth of less desirable plants to increase.

Characteristic vegetation includes big bluestem, prairie cordgrass, woolly sedge, and native forbs. Aspen and other hardwoods are present. High-quality, untilled areas of the Clayey Wet Savannas ecological site are uncommon in MLRA 103 as most sites have been transitioned to agricultural production.

Dominant plant species

1. quaking aspen (Populus tremuloides), tree

2. big bluestem (Andropogon gerardii), grass

3. prairie cordgrass (Spartina pectinata), grass

4. woolly sedge (Carex pellita), grass

Submodel

Description

Soil tillage is the primary mechanism to transition a site to the Tillage State. Tillage alters dynamic soil properties such as bulk density, structure, organic carbon content, and saturated hydraulic conductivity. Certain conservation practices can mitigate the impacts of traditional agricultural practices on soil health. Conservation tillage minimizes soil disturbance and can improve soil structure and overall soil health. Corn or soybean plantings and a cover crop rotation can build soil structure, improve infiltration rates, reduce runoff and erosion, and protect water quality. Drainage modifications such as ditching and tiling are often present.

A few areas within this ecological site have been seeded to grass. Under NRCS conservation programs, some previously tilled areas have been converted to warm-season grasses. Native forbs are commonly included in seed mixes to benefit wildlife and pollinators. Cool-season grasses are also feasible. Species selection will depend on the landowner’s objectives and site specifics. Common species include reed canarygrass and Kentucky bluegrass. Although cool-season grasslands are not as species rich or biologically diverse as warm-season grasslands, they still offer soil health and wildlife benefits.

Most areas in this state will remain in use for crop production in the foreseeable future – primarily in an intensive corn and soybean rotation.

Dominant plant species

1. corn (Zea mays), grass

2. soybean (Glycine max), grass

Submodel

Description

This State is characterized by a disturbed and degraded woodland. Characteristics include an increase in shrubs and hardwood trees (no longer a true savanna community), the presence of invasive plant species, and a reduction in the diversity of native understory species. Hardwood trees have increased and invasives, such as Kentucky bluegrass and common buckthorn, may dominant the understory. As the tree and shrub density increases, the ground layer plant diversity decreases and transitions to more shade-tolerant species.

Dominant plant species

1. quaking aspen (Populus tremuloides), tree

2. Kentucky bluegrass (Poa pratensis), grass

3. common buckthorn (Rhamnus cathartica), grass

Submodel