In the article linked below is a concise history, and some current news of human influences on our prairie and savanna ecosystems.
The Willamette Valley, SW Washington, Puget Sound outwash prairies, and southern B.C. are all connected (geologically and topographically). This pops out on a foggy day as seen from a weather satellite: note the light gray fogged-in valleys all the way from Oregon to Canada!
