Prairie Conservation Strategy - Habitats
he Prairie Conservation Strategy identifies areas in Benton County where habitat enhancement and reintroductions would provide the most benefit to at-risk and declining prairie species. Strategy habitats represent the needs of a diverse group of species that either use prairie habitat exclusively or during some part of their lifecycle.
These habitats were selected from the USFWS Recovery Plan for the Prairie Species of Western Oregon and Southwestern Washington and from the Oregon Conservation Strategy by the HCP Stakeholder Advisory Committee. Upland prairie/oak savanna, wet prairie, and oak woodlands have been reduced throughout the Willamette Valley due to conversion to agriculture and urban development.
Prairie habitat is especially imperiled in the Willamette Valley but Benton County still encompasses some of the highest quality remaining prairie and oak habitat remnants.
Upland prairies (also called grasslands) are characterized by perennial bunchgrasses and wildflowers. In the Willamette Valley, these prairies typically occur at fairly low elevations on the valley bottom on well drained soils and steep hillsides. This habitat can be seen at Beazell County Park in Kings Valley or Chip Ross Park and Fitton Green Natural Area in Corvallis.
Oak savannas are grasslands with scattered Oregon white oak trees. These open grown trees develop a full canopy structure and large limbs. Oaks are typically found on flat areas with good drainage or on rolling hills. Remnant oak trees can be seen throughout the Willamette Valley.
Wet prairies (also called wetland prairies) are a mosaic of ash swales, vernal pools, emergent marsh, and seasonally flooded grasslands that occur on poorly draining soils due to impervious layers under the soil or from frequent flooding. Wet prairies develop wetland soil characteristics that support facultative or obligate wetland plant species such as sedges and camas. Finley National Wildlife Refuge and Jackson-Frazier Wetland contain good examples of this habitat.
Oak woodlands have a higher density of oak than oak savanna but maintain a grassland/shrub understory due to filtered light. Acorn woodpeckers can be heard in these habitats at Finley National Wildlife Refuge.
The open structure of prairies, savanna, and oak woodlands persists when regular disturbance prevents the natural encroachment of competing tree and shrub species. Natural disturbances such as wildfire can maintain prairies but prescribed fire or mowing can have similar effects. If natural disturbance is suppressed and mowing or grazing maintenance is not practiced, these areas will become dominated by woody vegetation.