Mima Mounds: A Special Prairie

Mima Mounds: A Special Prairie. . , , What Makes a Prairie , Grasslands thrive where dry soil and frequent drought or fires limit or exclude trees and shrubs. The soils and climate in each of North America’s grasslands support a unique mix of native grasses, flowers, and other plants. , , What Does the Word “Prairie” Mean? , Prairie is the word used to describe level or gently rolling grasslands in North America. The name probably comes from early French explorers, prairie means meadow in French. , , Puget Sound Prairies Are Unique , The west side of the Cascade Mountains is known for forests, rivers, lakes and saltwater bays. Prairies and oak woodlands are found in areas of dry soil. They are threatened by invasive species and development. Grassland plans and oak trees provide food for insects, birds and animals that can’t live in other habitats. They are important to Washington’s biodiversity, its “web of life.” , , Puget Sound Prairies: A Gift from the Ice Age , Following the retreat of glacial ice, torrents of meltwater left deep deposits of gravelly, well drained soil. The climate slowly warmed and at first supported forests. About 10,000 years ago a warm period began, and prairie plants took hold on the dry soils of Mima Mounds and other nearby prairies. For the past 4,000 years a wetter, cooler climate has prevailed, and the prairies were maintained by Native American burning practices. , , Where Are Prairies Found? , Prairies once covered about 180,000 acres in western Washington. High quality native prairies cover only about three percent of this area today. Red areas on the map show glacial outwash soils. These areas were once covered with prairie vegetation. Only the areas shown in yellow remain as prairies.