Calcareous Rim Prairies

Description

This site is characterized as a wet prairie, which include a diversity of grasses, sedges, and forbs tolerant of poorly drained soils and calcareous conditions. Important species on this site include prairie cordgrass (Spartina pectinata Bosc ex Link), big bluestem (Andropogon gerardii Vitman) and Indiangrass (Sorghastrum nutans (L.) Nash). Sedges are an important component. Several species are possible including Bicknell’s sedge (Carex bicknellii Britton), woolly sedge (Carex pellita Muhl. ex Willd.), and Buxbaum’s sedge (Carex buxbaumii Whalen.). Tussock-forming species like Hayden’s sedge (Carex haydenii Dewey) and upright sedge (Carex stricta Lam.) are also common.

Orchids like the white lady’s slipper (Cypripedium candidum Muhl. ex Willd.) is an important species that can reflect the high calcium carbonate content. Common forbs include prairie blazing star (Liatris pycnostachya Michx.), compassplant (Silphium laciniatum L.), fourflower yellow loosestrife (Lysimachia quadriflora Sims), and swamp milkweed (Asclepias incarnata L.). Shrubs, such as willows (Salix L.) and dogwoods (Cornus L.), increase with the absence of frequent fire.

Today, high-quality, unplowed areas are extremely uncommon. Most remaining areas managed for tallgrass prairie were once tilled and utilized for agricultural production. It is therefore likely that hydrology has been altered and many of the historic native prairie species are extirpated even from these sites.

Resilience management

Prescribed fire and managed grazing are key resilience management practices. Prescribed fire is the controlled application of fire to modify vegetation structure and influence ecological processes. Prescribed grazing incorporates periods of grazing rest during the growing season which benefits tallgrass maintenance. Excessive grazing can quickly impact the vegetative composition and negatively impact soil stability.

Submodel

Description

Tillage is the primary mechanism affecting the transition to this state. In this state, dynamic soil properties such as bulk density, structure, organic carbon content, and saturated hydraulic conductivity are altered by agricultural practices. Hydrological modifications (tiling and ditching) are commonly installed to improve drainage, so natural hydrology is altered. Most areas in this state will remain in use for crop production in the foreseeable future – primarily in an intensive corn and soybean rotation.

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.

A small percentage of this ecological sites have been seeded back to grass. Some previously tilled areas have been converted to warm-season grasslands as part of the NRCS Conservation Reserve Program (CRP). Species seeded will depend upon the hydrology of the site and landowners objectives. 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 State 1.

Cool-season grasses are also feasible. The most common cool-season grasses are non-native species, such as 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 benefits and benefits for grassland birds.

Some tilled sites may revert to a woodland through abandonment; however, this is a small percentage of acres within MLRA 103 so is not currently given a community in this model.

Resilience management

Disturbance management and harvest management are resilience management practices. The maintenance of this state requires that the intensity, frequency, duration, and timing of agricultural practices (disturbances) be managed to control or modify vegetation structure.

Submodel

Description

In the absence of a natural fire regime or grassland management, this site will transition to a Wooded State. Unmanaged grazing, altered hydrology, and invasive species may impact the site. Community composition will vary depending on the type and severity of disturbances. Dominant tree species often include eastern cottonwood, black willow, green ash, and boxelder. Reed canarygrass, Kentucky bluegrass, and smooth brome are often present.

Few acres within MLRA 103 are in this State. Some remaining areas are conservation easements. Areas not in a conservation programs are likely to be jurisdictional wetlands, making it very unlikely they will be transitioned to the State 2 due to various wetland programs and laws, including the Swampbuster provision of the Food Security Act of 1985 (P.L. 99-198, as amended by P.L. 115-25) and the Minnesota Wetland Conservation Act (WCA) of 1991 (M.R. 8420.0100, as amended in 2009).
 

Submodel