|WHAT IS THE PALOUSE PRAIRIE?
In simple terms, the Palouse Prairie is a region that historically had short, cool season bunchgrasses with a high diversity of forbs or wildflowers and shrubs. The word “Pelus” has both Palus Indian and French origins with a “sea of grass” or “grassland plains” meaning. To define the size of the region is difficult. As Daubenmire, a renowned Palouse Prairie botanist, states “In my opinion, an attempt to formulate a definition of “Palouse” that is meaningful to science is futile” (Caldwell 1961).
The Palouse and its prairies have different meanings for different people. To some “the Palouse” is a small cultural region identified by the rolling dune-like fertile agricultural land with two major land-grant universities, University of Idaho and Washington State University, eight miles apart. For others, it is a large bioregion defined by the historic plant community, soils and land formations that encompass thousands of acres of grassland in the Inland Northwest. Others have applied the term “Palouse Prairie” to areas as far as the Bitterroot Mountains of Montana and the Jordan Valley of Utah.
For our purposes, the Palouse Prairie occurs within the Blue Mountains of Oregon, the Rocky Mountains of Northern Idaho and the channeled scablands in the Columbia Basin of Washington. This area is characterized by its rolling hills that look like lush green dunes, and its rich deep soil. The native short-grass grassland that typifies the Palouse extends roughly from the Rathdrum Prairie around Post Falls, Idaho to the Camas Prairie near Grangeville, Idaho (Lichthardt and Moseley 1997).
Figure 1. Map has been modified with red circle to show broader area considered by some to be within the Palouse bioregion and/or contain similar plant communities.
Vegetation and Climate
Historically, the Palouse prairie was dominated by cool-season perennial bunchgrasses like bluebunch wheatgrass (Pseudoroegneria spicata) and Idaho fescue (Festuca idahoensis). The Palouse prairie has cool wet winters and hot dry summers. Cool-season plants actively grow in the cooler months and are dormant once it is hot and dry.
Bunchgrasses grow in tufts and leave interspaces on the landscape which the wildflowers move into. Bunchgrass grasslands have a greater variety and amount of wildflowers than the tallgrass prairies of the Midwest. Tall grass prairies are dominated by rhizomatous grass species that form a dense mat, leaving little room for wildflowers.
Now the majority of the Palouse prairie is farmland and towns. It is estimated that less than 1% of the native Palouse vegetation remains making the Palouse prairie one of the most endangered ecosystems.
The success of agriculture, and wheat in particular, in this area is logical since wheat itself is a domesticated cool-season short-grass (Manning 1995). However, keep your eyes open when driving along our highways or biking on railroad beds. There is evidence of the Palouse prairie diverse vegetation along our roads, railroad tracks, corners of fields and lots, in pastures, along streams, open areas of pine forests and steep or rocky hills.
Biological Soil Crusts
The interspaces in between the bunchgrasses also allow for the formation of biological soil crusts. They are important components of many arid ecosystems.
These crusts serve a variety of functions including protection from soil erosion, trapping dust and nutrients which can increase the fertility of the soil, and providing safe sites for seeds to germinate. Biological soil crusts are made up of lichens, mosses, bacteria, fungus, etc. (Bowker et al. 2004). For centuries wildlife have walked on the crusts, but it is usually when the grass and wildflowers are lush in the late winter and spring and the crust is soft and resilient. Disturbance of the biological soil crusts occurs easily during the dry months when the crust forms a dry protective covering for the soil, sealing nutrients and keeping out weeds. They are sensitive to trampling and slow to recover (up to 100 years) so please let this serve as a reminder of the importance of staying on trails during all seasons.
The Palouse hills were formed in the ice ages when silt was blown in from the glacial outwash plains to the west and south (biology.usgs.gov/luhna). The Palouse prairie soils are predominantly described as silt loam and can be 10-80 feet deep. Silt loam soils often have good water holding capacity and plant available nutrients. Silt soils can be highly erodable however and plowed land is especially susceptible to wind and water erosion. Some farmers in the Palouse now utilize no-till and other methods to help reduce erosion.
Before the 1870’s the Palouse was used by Native Americans as hunting grounds, grazing for their horses (after domesticated horses were introduced in the 1700’s), and for gathering edible plants like camas (Cammasia quamash) (Kaiser 1961). The Palouse River drainage was occupied primarily by the Palouse people and the Nez Perce spent time in the southern portion of the Palouse. The northern regions were inhabited by the Couer d’ Alene’s and Spokane’s and the Cayuse’s were in the southwestern regions. There was much overlap between the groups as the cyclic pattern of hunting and gathering began at the lower elevations and gradually moved into the higher elevations with the availability of plant and animal resources. European Americans began to settle the Palouse in the 1860’s and by 1900 most of the original prairie had been plowed.
Bowker, M. A., J. Belnap, R. Rosentreter, and B. Graham. 2004. Wildfire-resistant biological soil crusts and fire-induced loss of soil stability in Palouse prairies, USA. Applied Soil Ecology 26:41-52.
Caldwell, H.H. 1961. The Palouse in Diverse Disciplines. Northwest Science 35: 115-121
Kaiser, V. G. 1961. Historical land use and erosion in the Palouse-A reappraisal. Northwest Science 35:139-153.
Lichthardt, J., and R. K. Moseley. 1997. Status and Conservation of the Palouse Grassland in Idaho. 14420-5-0395, Conservation Data Center, Idaho Department of Fish and Game, U.S. Fish and Wildlife Service.
Manning, R. 1995. Grassland: The History, Biology, Politics, and Promise of the American Prairie. Penguin Books, New York.
Prairie– a native grassland
Savanna- the transition from the forest to prairie; when 10-25% of the prairie is shaded by trees, it can be called a savanna
Shortgrass- where native grasses are ankle to waist high
Cool Season Grassland- when active growth and bloom time occurs between winter and mid-summer
Forbs- wildflowers, non-woody plants
Bunchgrass- grows in tufts; bunches leaves interspaces for wildflowers and biological soil crusts to move in; unlike rhizomatous grasses which form a dense mat
The care of the Earth is our most ancient and most worthy, and after all our most pleasing responsibility. To cherish what remains of it and to foster its renewal is our only hope. -Wendell Berry
1461 Thorn Creek Road, Genesee, Idaho 83832