Common (Translated Scientific) Name: Smooth Brome - Knapweed species - Pepperweed species Western North American Ruderal Grassland & Shrubland Macrogroup

Colloquial Name: Western North American Ruderal Grassland & Shrubland

Hierarchy Level:  Macrogroup

Type Concept: This ruderal macrogroup occurs in temperate areas throughout the western North America and is composed of disturbed upland grasslands, meadows and shrublands dominated by non-native and generalist native species. It is abundant in waste areas and disturbed land in temperate areas throughout the western U.S. and southwestern Canada, including coastal areas, often as abandoned pastures, roadside margins or other weedy places. Sites are not mowed or otherwise maintained. Generally, these are areas that have been extremely disturbed by heavy equipment, such as old plowed fields, townsites, abandoned millsites, or livestock holding areas and other "waste" places that are now covered in invasive shrub or herbaceous species not native to western North America. Vegetation of the macrogroup can be a monoculture of a single non-native species, or a mix of several non-native forbs and graminoids, often associated with generalist native species. Graminoids include Agrostis gigantea, Agrostis stolonifera, Bromus inermis, Dactylis glomerata, Elymus repens, and Poa pratensis (which may have been purposefully seeded for forage or to prevent soil erosion). Numerous other non-native herbaceous species may be present to dominant, including Agrostis capillaris, Anthoxanthum odoratum, Bromus hordeaceus, and Holcus lanatus. Native grasses and forbs may be present with low cover, or sometime abundant if they are generalists or ruderal species. Invasive non-native shrublands are less common, but some may be dominated by Alhagi maurorum, Cytisus striatus, Cytisus scoparius, or Rubus armeniacus.

Diagnostic Characteristics: This widespread upland shrubland and grassland macrogroup is dominated by invasive, non-native shrubs, grasses or forbs, often with generalist or "weedy" native species. Widespread dominant and diagnostic herbaceous species include naturalized forage species such as Agrostis gigantea, Agrostis stolonifera, Anthoxanthum odoratum, Bromus inermis, Cynosurus echinatus, Dactylis glomerata, Holcus lanatus, Phalaris aquatica, Phleum pratense, Poa pratensis, and numerous other non-native herbaceous species such as Acroptilon repens, Cardaria draba, Carduus nutans, Centaurea spp., Cirsium arvense, Lepidium latifolium, Linum bienne, and Linaria spp. There are relatively few non-native temperate upland shrublands, but Alhagi maurorum, Cytisus scoparius, Genista spp., and Cytisus striatus (or Cytisus scoparius) can form shrublands best in less xeric regions.

Rationale for Nominal Species or Physiognomic Features: No Data Available

Classification Comments: This macrogroup may be difficult to distinguish from native grasslands where native species are present. The test is that the non-native species, especially invasive species, far outweigh native species in abundance, such that a well-trained observer cannot tell what the native counterpart may have been or to do so is only speculation. This macrogroup can also include vegetation dominated by native ruderal species when caused by anthropomorphic disturbance such as old fields.

Restoration stands of planted or seeded native grasses such as Festuca idahoensis ssp. roemeri, Festuca rubra, or Leymus mollis are considered ruderal due to the fact that the planted species are the only native species present. If long-term restoration efforts succeed in re-establishing composition typical of native plant associations, then stands could be reclassified into that type.

Currently, this macrogroup is defined as occurring in the Rockies and westward, and thus is excluded from the Great Plains, where ~Great Plains Ruderal Grassland & Shrubland Macrogroup (M498)$$ replaces it. But association ranges may need to be adjusted to reflect this pattern.

Similar NVC Types: No Data Available

note: No Data Available