GROWTH-PATTERNS OF PERENNIAL GRASSES IN THE ANNUAL GRASSLAND TYPE OF SOUTHWEST OREGON

Southwest Oregon and northern California foothills are currently dominated by a variety of annual plant species. This study was designed to assess the potential of established perennial grasses to occupy two sites in the foothills ecosystem, Mediterranean/Maritime climatic regime, of southwest Oregon. Soils at Sites 1 and 2 are Darrow silty clay loam (fine, montmorillonitic, mesic Vertic Argixerolls) and Carney clay (fine, montmorillonitic, mesic Typic Chromoxerets), respectively, and annual precipitation at the sites averages 500 mm. Growth patterns of the perennial grasses were contrasted among each other and to the resident annual plants during fall, winter and spring growth periods. Of the perennial grasses, Idaho fescue (Festuca idahoensis Elmer), native to the area, and 'Beber' orchardgrass (Dactylis glomerata L.), introduced, most closely emulated the growth patterns of the resident annual grasses. These grasses initiated growth sooner, continued some growth through the winter and matured earlier than the other perennial grasses tested. Once established, Idaho fescue and Berber orchard-grass should be able to effectively compete with the resident annuals for resources and maintain their populations.