Loamy Upland Savannas

Description

The Loamy Upland Savannas ecological site reference state is a mesic savanna that exhibits a diversity of native grasses and forbs along with a variety of shrubs and scattered oak and aspen. Plant community structure and composition within the Reference State are variable and dependent upon the impacts of drought, grazing, and fire events. Fire was historically present on this site but to a lesser degree than the prairie ecological sites of MRLA 103. This reduced occurrence of fire resulted in a grassland community that included woody shrubs and scattered trees. Fire frequency will control plant community structure and composition. Areas frequently burned are a shrubby prairie. Longer fire intervals result in more trees and a true savanna ecosystem. Areas protected from fire will eventually transition to a woodland.

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. Grazing management guidelines vary by site depending on specific site characteristics and management objectives.

Characteristic vegetation in the reference savanna state includes bur oak, aspen, American hazelnut, leadplant, and big bluestem. Other mesic prairie grasses species and native forbs will be present in a reference plant community. High-quality, untilled areas of the Loamy Upland Savannas ecological site are uncommon in MLRA 103 as most sites have been transitioned to agricultural production.

Submodel

Description

Soil tillage is the primary mechanism to transition a site to the Tillage State. In this state, dynamic soil properties such as bulk density, structure, organic carbon content, and saturated hydraulic conductivity are altered by agricultural practices. Certain 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.

Some areas in this ecological site are not appropriate for intensive crop production due to slope. Areas included in this ecological site have slopes between 0-40%. Where the gradient exceeds 20%, farm machinery is limited.

A few areas within this ecological site have been seeded back to grass. Under conservation programs such as the NRCS Conservation Reserve Program (CRP), previously tilled areas have been converted to warm-season grasslands. Native forbs are commonly included in seed mixes to benefit wildlife and pollinators. Although highly beneficial to wildlife, these sites generally lack the diversity of native plant species that occurs in the Reference State. Cool-season grasses are also feasible. Species selection will depend on the landowner’s objectives and site specifics. Although cool-season grasslands are not as species rich or biologically diverse as warm-season grasslands, they still offer various soil health benefits and some ecological benefits for grassland bird species.

Most tilled areas will remain in crop production in the foreseeable future.

Submodel

Description

This State is characterized by a disturbed and degraded woodland condition. Characteristics of this site include the dominance of trees (no longer a true savanna community), the presence of invasive plant species, and a reduction in the diversity of native understory.
Trees include bur oak and mixed hardwoods. Invasives, such as Kentucky bluegrass and common buckthorn, are often dominant the understory. As the tree and shrub density increases, the ground layer plant diversity decreases and transitions to more shade-tolerant species.

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