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Ecological Status of Introduced Brome Grasses (Bromus Spp.) in Desert Vegetation of Southern Nevada

Beatley, Janice C.
Ecology 1966 v.47 no.4 pp. 548-554
Artemisia, Bromus rubens, Coleoptera, annuals, grasses, indigenous species, introduced species, shrubs, vegetation, Nevada
Of the plant species introduced on the Nevada Test site, Nye County, Nevada, Bromus rubens and B. tectorum are well established in the present vegetation mosaic. B. rubens is frequently the dominant winter species in Colegyne (blackbrush) communities at 4,000—5,000 ft. Relative density (or absence) of populations is a site characteristic, as indicated by quantitative data from 18 study sites in Yucca Flat in the Years 1963—65. Like the native species, it occurs in higher densities on disturbed sites of areas where it is already established in the undisturbed vegetation. Its success is in part due to a growth regime and environmental requirements unlike those of the native winter annuals, and perhaps to higher percentage survival to maturity as in the 1963—64 season. It is not aggressive in the region today. B. tectorum is confined to disturbed sites at the higher elevations (5,000—7,500 ft) where vegetation is Artemisi (sagebrush) or Armenisia—Pinyon—Juniper. It is numerically and really increasing with an increase in disturbed sites at these elevations. Fire is promoted by both species, but the contribution of B. rubens is much greater, either directly or indirectly, because it is identified with Coleoptera vegetation, the shrub type in the region most susceptible to fire.