Loess Upland Prairie

Description

The reference plant community is categorized as a mesic tallgrass prairie and includes grasses, forbs, and varying components of shrubs. The reference community phase is dependent on a fire frequency of every one to six years. Shorter fire intervals maintain dominance by grasses, while less frequent intervals allow woody vegetation to increase their importance in the plant canopy. Grazing and drought disturbances have less impact in the reference phases, but do contribute to overall species composition, diversity, cover, and productivity.

Submodel

Description

Loess is the main contributing factor to the Midwest’s highly-productive agricultural soils, and as a result, much of the MLRA has been converted to cropland, including significant portions of this ecological site (USGS 1999). The continuous use of tillage, row-crop planting, and chemicals (i.e., herbicides, fertilizers, etc.) have effectively eliminated the reference community and many of its natural ecological functions in favor of crop production. Corn (Zea mays L.) and soybeans (Glycine max (L.) Merr.) are the dominant crops for the site. These areas are likely to remain in crop production for the foreseeable future.

Submodel

Description

The cool-season pasture state occurs when the reference state has been anthropogenically-altered for livestock production. Fire suppression, seeding of non-native cool-season grasses, removal of woody vegetation, periodic cultural treatments, and grazing by domesticated livestock transition and maintain this simplified grassland state (Rosburg 1994; USDA-NRCS 2003). Early settlers seeded such non-native cool-season species as smooth brome (Bromus inermis Leyss.) and Kentucky bluegrass in order to help extend the grazing season (Smith 1998). Over time, as lands were continually grazed by large herds of cattle, the non-native species were able to spread and expand across the prairie habitat, reducing the native species diversity.

Submodel

Description

Agricultural lands that have been abandoned and left fallow undergo ecological succession to the oldfield state. Two community phases define this state and are determined by time and human activities. Initially, the site is inhabited by ruderal, herbaceous annuals and perennials. As the land remains untouched from natural or anthropogenic disturbances, woody species begin to dominate eventually forming a near continuous canopy.

Submodel

Description

Prairie reconstructions have become an important tool for repairing natural ecological functioning and providing habitat protection for numerous grassland-dependent species. The historic plant community of the tallgrass prairie was extremely diverse and complex, and prairie replication is not considered to be possible once the native vegetation has been altered by post-European settlement land uses. Therefore ecological restoration should aim to aid the recovery of degraded, damaged, or destroyed ecosystems. A successful restoration will have the ability to structurally and functionally sustain itself, demonstrate resilience to the natural ranges of stress and disturbance, and create and maintain positive biotic and abiotic interactions (SER 2002). The reconstructed prairie state is the result of a long-term commitment involving a multi-step, adaptive management process. Diverse, species-rich seed mixes are important to utilize as they allow the site to undergo successional stages that exhibit changing composition and dominance over time (Smith et al. 2010). On-going management via prescribed fire and/or light grazing will help the site progress from an early successional community dominated by annuals and some weeds to a later seral stage composed of native perennial grasses, forbs, and shrubs. Establishing a prescribed fire regimen that mimics natural disturbance patterns can increase native species cover and diversity while reducing cover of non-native forbs and grasses. Light grazing alone can help promote species richness, while grazing accompanied with fire can control the encroachment of woody vegetation (Brudvig et al. 2007).

Submodel