Whitman Mission National Historic Site - Environmental Factors

The Whitman Mission is located on the southern extreme of the Palouse Prairie Region in eastern Washington state. Originally, this prairie was dominated by perennial grasses, principally bluebunch wheatgrass which flourished over the plains. Intermixed with it were smaller patches of sandberg bluegrass and Idaho fescue. Large native herbivores were generally absent from the Palouse, and because of this, the grasses evolved with a low resistance to grazing. Subsequent grazing by domestic livestock and extensive cultivation for wheat are the main reasons why native perennial grasslands are now rare on the Palouse. The Cayuse Indians inhabited the area around Whitman Mission NHS prior to the 1850s. They practiced very little crop agriculture, depending instead on a partially nomadic existence which emphasized food gathering, horse raising, and salmon fisheries. Fire was used periodically by the Cayuse to burn particular areas to increase the production of wild forage and accessibility of plant foods, to facilitate hunting and travel by burning away underbrush, and to encircle game. The regularity with which the areas on, or near, the historic site were burned historically cannot be determined, but frequent cultural burning of any particular area was probably rare. It is probable that at the time the mission was established, a mixture of three plant communities occupied the site. At the time the mission was established in 1836, the Walla Walla River flowed through the site during times of high water. On the floodplains along the Walla Walla River and nearby Mill Creek, a narrow plant community consisting of dense tangled thickets of willows, cottonwoods, wild dogwoods, blackberries, elderberries, and other species common to riparian areas probably occurred. An association of perennial grasses, shrubs, and native forbs occupied the hillside area where soil depths and drainage were greater. Perennial grasses common to the Palouse dominated the rest of the Whitman Mission.