Invalid Unit Specified
M493 Bromus inermis - Centaurea spp. - Lepidium spp. Western North American Ruderal Grassland & Shrubland Macrogroup

The U.S. National
Vegetation Classification
Type Concept Sentence: This upland macrogroup contains ruderal grasslands, meadows and shrublands found on human-disturbed sites, and dominated by non-native and generalist native species that occur in temperate areas throughout the western U.S. (Rockies westward) and southwestern Canada.
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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: This macrogroup may be dominated by many temperate non-native species such as Agrostis gigantea, Agrostis stolonifera, Bromus inermis, Dactylis glomerata, 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, and Linaria spp. There are relatively few non-native temperate upland shrublands, but Alhagi maurorum and Cytisus striatus (or Cytisus scoparius) are common. Bromus inermis, Centaurea spp., and Lepidium spp. are widespread cool semi-desert western species that were chosen to represent this macrogroup.
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:
M046 Californian Ruderal Grassland, Meadow & Scrub, note: is similar and characteristic differences need to be determined between Mediterranean and Temperate non-native grasslands & shrublands.
M301 Western North American Ruderal Marsh, Wet Meadow & Shrubland, note: may overlap in transition zones where upland species intermix with wetter forbs and graminoids.
M498 Great Plains Ruderal Grassland & Shrubland, note: may overlap where vegetation shares wide-ranging non-native species.
M499 Western North American Cool Semi-Desert Ruderal Scrub & Grassland, note:
M511 North Pacific Coastal Ruderal Grassland & Shrubland, note:
M512 North American Warm Desert Ruderal Scrub & Grassland, note: "is similar but typically has more heat-tolerant or cold-sensitive species, such as Bromus rubens or Eragrostis lehmanniana, dominating the vegetation."
Physiognomy and Structure: This macrogroup includes ruderal vegetation with an open to dense shrub canopy and/or an herbaceous layer dominated by annual or perennial grasses or forbs.
Floristics: Vegetation of the macrogroup can be a monoculture of a single non-native species, or a mix of several non-native forbs and graminoids. Native grasses and forbs may be present with low cover, or sometime abundant if native species is acting as a ruderal species. Graminoids include Aira caryophyllea, Aira praecox, Anthoxanthum odoratum, Agrostis gigantea, Agrostis stolonifera, Bromus inermis, Bromus diandrus ssp. rigidus (= Bromus rigidus), Bromus sterilis, Cynosurus echinatus, Dactylis glomerata, Elymus repens, Holcus lanatus, Schedonorus arundinaceus (= Schedonorus phoenix), Phalaris aquatica, Phleum pratense, Poa pratensis, Thinopyrum intermedium, and many other species which may been purposefully seeded to prevent soil erosion or for livestock forage, but have naturalized. Highly invasive and wind- and animal-distributed non-native species include Acroptilon repens, Agrostis capillaris, Aira caryophyllea, Aira praecox, Anthoxanthum odoratum, Cardaria draba, Carduus nutans, Centaurea spp., Cirsium arvense, Cirsium vulgare, Descurainia sophia, Halogeton glomeratus, Holcus lanatus, Hypericum perforatum, Lepidium latifolium, Linaria spp., Schedonorus arundinaceus, Sisymbrium altissimum, Trifolium pratense, and Verbascum thapsus. Numerous other non-native herbaceous species may be present to dominant. Native forbs and ferns that can be increasers with disturbance may be present to abundant and include Cerastium arvense, Galium aparine, Heracleum maximum, Marah oreganus, and Pteridium aquilinum. Invasive non-native shrublands are less common, but some may be dominated by Alhagi maurorum, Cytisus scoparius, Cytisus striatus, or Rubus armeniacus. This macrogroup may grade into wetter areas and may have transition zones where mesic forbs intermix with wetter forbs and graminoids found in ~Western North American Ruderal Marsh, Wet Meadow & Shrubland Macrogroup (M301)$$.
Dynamics: Vegetation included in this macrogroup is often the result of disturbance.
Environmental Description: This ruderal macrogroup is abundant in waste areas and disturbed land in temperate areas throughout the western U.S. and Canada, including coastal areas, often as abandoned pastures, roadside margins or other weedy places. Sites are not mowed or otherwise maintained. Most stands occur below approximately 1500 m (5000 feet) in elevation. Generally, these are areas that have been heavily disturbed by clearing, livestock, and heavy equipment, such as old plowed fields, townsites, abandoned millsites, livestock holding areas such as around stock tanks, old corrals or rabbit warrens and other "waste" places that are now covered in invasive shrub or herbaceous species not native to western North America. Substrates, aspects and landforms are variable, but do not include coastal sand dunes.
Geographic Range: This ruderal grassland and shrubland macrogroup occurs in disturbed areas throughout temperate western North America (Rockies and westward in the U.S. and Canada).
Nations: CA, US
States/Provinces: BC, CA, CO, MT, NE, NV, OR, UT, WA, WY
US Forest Service Ecoregions (2007)
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Plot Analysis Summary:
Confidence Level: Moderate
Confidence Level Comments:
Grank: GNA
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Synonomy: > Agrostis (gigantea, stolonifera) - Festuca arundinacea (Bent grass - tall fescue meadows) Semi-natural Stands (Sawyer et al. 2009) [45.106.00]
> Centaurea (solstitialis, melitensis) (Yellow star-thistle fields) Semi-natural Stands (Sawyer et al. 2009) [42.042.00]
> Centaurea (virgata) (Knapweed and purple-flowered star-thistle fields) Provisional Semi-natural Stands (Sawyer et al. 2009) [42.043.00]
> Holcus lanatus - Anthoxanthum odoratum (Common velvet grass - sweet vernal grass meadows) Semi-natural Stands (Sawyer et al. 2009) [42.050.00]
> Lolium perenne (Perennial rye grass fields) Semi-natural Stands (Sawyer et al. 2009) [41.321.00]
> Poa pratensis (Kentucky blue grass turf) Semi-natural Stands (Sawyer et al. 2009) [42.060.00]
Concept Author(s): K.A. Schulz, in Faber-Langendoen et al. (2014)
Author of Description: K.A. Schulz
Acknowledgements:
Version Date: 15Oct2014
References:
  • Esser, L. L. 1993b. Phleum pratense. In: Fire Effects Information System [Online]. USDA Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). [http://www.fs.fed.us/database/feis/] (accessed 16 December 2013).
  • Faber-Langendoen, D., J. Drake, S. Gawler, M. Hall, C. Josse, G. Kittel, S. Menard, C. Nordman, M. Pyne, M. Reid, L. Sneddon, K. Schulz, J. Teague, M. Russo, K. Snow, and P. Comer, editors. 2010-2019a. Divisions, Macrogroups and Groups for the Revised U.S. National Vegetation Classification. NatureServe, Arlington, VA. plus appendices. [in preparation]
  • Howard, J. L. 1996b. Bromus inermis. In: Fire Effects Information System [Online]. USDA Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). [http://www.fs.fed.us/database/feis/] (accessed 16 December 2013).
  • Sawyer, J. O., T. Keeler-Wolf, and J. Evens. 2009. A manual of California vegetation. Second edition. California Native Plant Society, Sacramento CA. 1300 pp.
  • Uchytil, R. J. 1993. Poa pratensis. In: Fire Effects Information System [Online]. ]. USDA Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). [http://www.fs.fed.us/database/feis/] (accessed 16 December 2013).