Of Wisconsin's 2.1 million acres that were native prairie when Europeans arrived 150 years ago, less than 10,000 acres (<0.5% of the original acreage) of varying quality native prairie remains today. The mid-continental grassland biome has been greatly reduced and degraded throughout its range, generally from farming and grazing and conversion to woody vegetation with the cessation of fires, but also from urban and suburban development. Tallgrass prairies and related oak savannas are now the most diminished and threatened plant communities in the Midwest and among the most altered in the world. As a result, an estimated 15-20% of the state's original grassland flora is now considered rare. Grassland mammals and birds have fared somewhat better, using surrogate grasslands such as hayfields and pastures for their survival needs. However, with conversion from pastures and hayfields to more row crop agriculture, some grassland birds and mammals have also been dramatically impacted over the last 30 years. For example, grassland birds as a group are the fastest declining bird group in the state.
Surrogate grasslands now represent the vast majority of grassland habitat in the state and are similar in structure to the former prairies that occurred in Wisconsin. Surrogate grasslands include agricultural habitats such as hayfields, small grains (oats, wheat, and barley), row crops (corn, soybeans, and potatoes), fallow fields, old fields, pastures, and set-aside fields (e.g., CRP) planted to non-native cool-season grasses (such as smooth brome (Bromus inermis), Timothy (Phleum pratense), redtop (Agrostis gigantea), orchard-grass (Dactylis glomerata), bluegrass (Poa pratensis and P. compressa), and quack-grass (Elymus repens)) or native warm-season grasses (such as big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium), Indian grass (Sorghastrum nutans), switch grass (Panicum virgatum), and side-oats grama (Bouteloua curtipendula)). Examples of other surrogate prairie grasslands include young conifer plantations, orchards, parks, golf courses, airports, roadsides, cut-over or burned-over forests, and mossed bogs (bogs from which Sphagnum moss has been removed for commercial purposes). Surrogate grasslands also include other idle grasslands, such as those on public or private lands managed for wildlife. Usually, idle grasslands are composed of non-native grasses and forbs, but they also can be plantings of one or several native prairie species, but typically fall far short of the rich species diversity of the original prairie.
Surrogate grasslands occur in every ecological landscape in Wisconsin; however, the highest concentrations of surrogate grasslands are in the Western Prairie, Western Coulee and Ridges, Southwest Savanna, Central Sand Plains, Northwest Sands, and Southeast Glacial Plains Ecological Landscapes. It is estimated that roughly 3 million acres of agricultural land currently provide surrogate grassland habitat.
