User:Minna8marie/Puget Sound Prairies

Puget Sound prairies (also called "South Sound prairies" and "Western Washington prairies") are rare ecosystems found west of the Cascade Mountain range, in Washington State. Similar ecosystems exist in British Columbia, and the Willamette Valley of Oregon State. Puget Sound prairies originally formed on glacial outwash soils following the last ice age. The prairies are characterized by soils that drain quickly (due to high glacial gravel content), and thus become very dry during months with low precipitation. Though native lands of the rest of Western Washington were forested, the prairie lands (due to soil conditions) supported grasses, non-woody drought-tolerant forbs and shrubs, and widely-spaced stands of trees (especially the Garry oak, Quercus garryana). For centuries, Native American communities who lived in the region set fires on these grasslands, which prevented the encroachment of evergreen trees onto prairie lands, and encouraged the growth of native prairie plants that were used for food and other uses.

Puget Sound prairies are Washington State's most endangered ecosystem. Fire suppression (and accompanying encroachment of forest species), human development, and introduction of non-native plant species has reduced the total area of this ecosystem type dramatically in the last century, and much of what remains is fragmented and degraded from its original conditions. A number of species are endemic to this ecosystem, and these species have become critically rare.