Grasslands of the United States

Grasslands of the United States
Name	Grasslands of the United States
Biome	Temperate grassland, prairie, prairie pothole, steppe
Countries	United States
Climate	Continental, semiarid, humid continental
Dominant plants	Native grasses, forbs
Dominant animals	Bison, pronghorn, prairie dog

Grasslands of the United States Grasslands of the United States encompass extensive temperate prairies, mixed-grass steppe, tallgrass prairie, and shortgrass prairie across the central and western United States. These regions include historically contiguous ecosystems that intersect with major features such as the Mississippi River, Rocky Mountains, Great Plains, Great Basin, and Gulf Coast marsh margins, and have influenced figures and institutions from Lewis and Clark expeditions to programs by the United States Department of Agriculture and the National Park Service.

Overview and Definitions

The term encompasses diverse ecoregions recognized by agencies like the Environmental Protection Agency (United States), the United States Geological Survey, and the National Oceanic and Atmospheric Administration as distinct from forests, deserts, and wetlands. Definitions used by the U.S. Fish and Wildlife Service, the Nature Conservancy, and academic centers at Harvard University, University of California, Berkeley, and Kansas State University emphasize native grass assemblages dominated by species such as Big bluestem, Little bluestem, Switchgrass, and Buffalo grass. Policy frameworks from the Farm Service Agency and legislation like the Soil Conservation Act and programs by the Natural Resources Conservation Service inform land classification and management.

Major Grassland Regions

Major regions include the Tallgrass Prairie of the Midwestern United States stretching into Iowa, Illinois, and Missouri; the Mixed-grass prairie across Nebraska, Kansas, and South Dakota; the Shortgrass prairie of Colorado and Wyoming; the Central Mixed-Grass Plains and the Western Great Plains adjacent to the Rocky Mountains and Black Hills. Additional grassland systems include the Pampas-like steppe influences in the Great Basin and rangelands near Santa Fe, Albuquerque, and Phoenix that interface with the Chihuahuan Desert. Protected landscapes include Tallgrass Prairie National Preserve, Badlands National Park, The Nature Conservancy preserves, and sites managed by the Bureau of Land Management and the National Wildlife Refuge System such as Prairie Pothole Region refuges.

Ecology and Biodiversity

Grassland communities host keystone species including the American bison, Pronghorn, Black-footed ferret, Greater prairie-chicken, and American burying beetle. Plant assemblages feature Andropogon gerardii, Sorghastrum nutans, Panicum virgatum, and a diversity of forbs that support pollinators like the Monarch butterfly and birds such as the Sandhill crane and Eastern meadowlark. Soil scientists at Iowa State University, ecologists at Smithsonian Institution and botanists at the Missouri Botanical Garden document rich soil carbon pools, microbial communities studied by researchers at University of Illinois Urbana-Champaign and Oregon State University, and hydrological functions linked to the Mississippi River Basin and Ogallala Aquifer. Fungal partners, mycorrhizal networks investigated by teams at Cornell University and Michigan State University, underpin nutrient cycling that sustains grassland productivity.

Historical Land Use and Human Impact

Indigenous nations including the Lakota, Cheyenne, Comanche, Apache, Pawnee, and Osage shaped grassland fire regimes, bison migrations, and plant distributions prior to contact and treaties such as the Treaty of Fort Laramie (1851). Euro-American expansion during the Lewis and Clark Expedition era, the Homestead Act of 1862, the rise of railroads like the Union Pacific Railroad, and agricultural intensification by settlers transformed contiguous prairie into cropland for corn and soybean production centered in counties across Iowa, Illinois, and Nebraska. The Dust Bowl of the 1930s prompted responses from agencies including the Civilian Conservation Corps, the Soil Conservation Service (now NRCS), and legislation such as the Taylor Grazing Act. Cattle ranching practices linked to brands and ranches across Texas and Montana altered fire regimes and grazing patterns.

Conservation and Management

Conservation efforts involve the Nature Conservancy, National Audubon Society, Sierra Club, Pheasants Forever, and federal initiatives like the Conservation Reserve Program administered by the Farm Service Agency, and landscape-scale projects by the Northern Great Plains Council. Restoration science at institutions such as Kansas University, University of Nebraska–Lincoln, and Oklahoma State University guides prairie reconstruction, prescribed burning protocols developed with the U.S. Fish and Wildlife Service, and grazing management informed by research from the Rocky Mountain Research Station. Collaborative conservation engages state agencies like the Kansas Department of Wildlife and Parks, tribal governments including the Oglala Sioux Tribe, and international programs such as the North American Wetlands Conservation Act where prairie pothole protection is relevant.

Threats and Climate Change Impacts

Contemporary threats include conversion to intensive agriculture driven by commodity markets tied to exchanges such as the Chicago Board of Trade, fragmentation from energy infrastructure including Keystone XL proposals and wind energy developments sited in counties across Texas and the Great Plains, invasive species like Centaurea stoebe (spotted knapweed), alterations due to altered fire suppression policies, and groundwater depletion in the Ogallala Aquifer. Climate change models from the Intergovernmental Panel on Climate Change, regional assessments by the National Climate Assessment, and studies at Princeton University and Stanford University project shifts in precipitation patterns, increased drought frequency affecting American bison forage, and northward biome shifts impacting species recorded by the Audubon Society and researchers at the University of Montana. Adaptive management strategies promoted by the U.S. Forest Service and NGOs emphasize resilience through connectivity conservation, assisted migration, and diversified land tenure approaches.

Category:Biomes of the United States