Merits of native and introduced Triticeae grasses on semiarid rangelands

Experiments were conducted on four semiarid range sites to compare stand es tablishment, productivity, and persistence of several introduced perennial Triticeae grasses with that of their native counterparts. On Intermountain sites with severe water limitations (< 300 mm), native grasses were more di fficult to establish, less productive, and less persistent than the introdu ced grasses. Stands of native grasses declined most rapidly under defoliati on. At locations where moisture conditions were more favorable, particularl y where more summer precipitation occurred, native Triticeae grasses establ ished and persisted relatively well compared with the introduced entries. A lthough difficult to establish, stands of the rhizomatous native, western w heatgrass [Pascopyrum smithii (Rydb.) A. Love] increased during the seasons after establishment. Choice of plant materials to be used in range seeding programs should be based on objective criteria. To do otherwise will perpe tuate degradation of soil resources, especially on sites that are dominated by weedy annual species such as cheatgrass (Bromus tectorum) and medusahea d rye (taeniatherum asperum). It is proposed that adapted introduced grasse s be equally considered along with native grasses as a component of seed mi xtures on environmentally harsh sites that have been burned, infested with competitive weedy species, or otherwise degraded.