Invasiveness Ranking System for Non-Native Plants of Alaska

Feasibility of ControlScoreSeed banks (0–3)UUnknownVegetative regeneration (0–3) 2Narrowleaf hawkweed can resprout from rhizomes (Plant for afuture 2002).Level of effort required (0–4) 2Control options have not been investigated. Populations in southcentralAlaska appear to be persisting and spreading withoutcontinual disturbance (I. Lapina pers. obs.).Total for Feasibility of Control 4/7Total score for 4 sections 44/82§Hordeum jubatum L.Ranking SummaryEcoregion known or expected to occur inSouth CoastalInterior BorealArctic AlpineYesYesYesPotential Max. ScoreEcological Impact 40 18Biological Characteristics and Dispersal 25 16Amplitude and Distribution 25 20Feasibility of Control 10 9Relative Maximum 63Climatic ComparisonCollected inAlaska regions?CLIMEXsimilarity?South Coastal Yes –Interior Boreal Yes –Arctic Alpine Yes –Special Note–nativity: Hordeum jubatum is native to westernNorth America and has become naturalized in eastern NorthAmerica, as well as Europe (Hitcock and Cronquest 1971, ITIS2002, USDA 2002). Judging from herbarium records (Universityof Alaska Museum 2004), it is most likely to have been present insmall populations in eastern interior Alaska prior to the 1900s.However, it has spread dramatically in the last half centuryassociated with accelerated human disturbances. Populationsin much of Alaska are generally associated with anthropogenicdisturbance and are most likely introduced or introgressedgenotypes as in Phalaris arundinacea in the Pacific Northwest(see Merigliano and Lesica 1998). Greater study, using molecularand morphological markers and paleoecological study isnecessary to tease apart the patterns of nativity of this species inAlaska.Hordeum jubatum has been collected in all ecogeographic regionsin Alaska (Hultén 1968, UAM 2004).Ecological ImpactScoreImpact on Ecosystem Processes (0–10) 3Foxtail barley accumulates high amounts of salt in its stems andleaves, reducing soil salinity (Badger and Ungar 1990, Keiffer andUngar 2002).Impact on Natural Community Structure (0–10) 3Foxtail barley has been observed creating a dense graminoid layeralong barren river bars and eroding slopes (J. Conn pers. obs.,I. Lapina pers. obs.).common names: foxtail barleyImpact on Natural Community Composition (0–10) 5Hordeum jubatum was often the dominant species in Ohiowhere soil salinity averaged about 0.6%. At moderate salinityconcentrations, it made up 90–100% of the vegetation cover(Badger and Ungar 1990). In Alaska it has been recorded forminglarge component of the herbaceous vegetation (J. Conn pers.obs.). These high densities are believed to reduce populations ofother grasses and forbs.Impact on Higher Trophic Levels (0–10) 7In early summer foxtail is palatable to browsing animals. Manywaterfowl species eat the seeds and leaves of foxtail barley. Inlate summer, the sharp pointed awns may cause damage to themouth, eyes, and skin of animals. This plant is host for numberof viruses (MAFRI 2004, Royer and Dickinson 1999, Tesky1992, Whitson et al. 2000, Woodcock 1925). Hordeum jubatumis interfertile with numerous species, forming hybrids (Hultén1968, Murry and Tai 1980, Welsh 1974).Total for Ecological Impact 18/40Biological Characteristics and Dispersal ScoreMode of Reproduction (0–3) 1This plant reproduces primarily by seed. Each plant is capable ofproducing more than 180 seeds (Royer and Dickinson 1999).Long-distance dispersal (0–3) 3The seeds are dispersed by wind or transported in the hair ofanimals (Royer and Dickinson 1999, Tesky 1992).Spread by humans (0–3) 3Foxtail barley has been grown as an ornamental (Tesky 1992).It also is a potential crop contaminant (USDA, ARS 2004). Thisgrass has increased in frequency as a response to human activitiesthat increase soil salinity (Badger and Ungar 1994).Allelopathic (0–2) 0No records are found concerning allelopathy.Competitive Ability (0–3) 1Foxtail barley is capable of dominating sites with high soilsalinity, but it is typically a poor competitor with other species atlow salinities (Badger and Ungar 1994).Thicket-forming/Smothering growth form (0–2) 0This plant can grow 1 to 2 feet tall (Whitson et al. 2000)Germination requirements (0–3) 2As a pioneer on disturbed sites, foxtail barley likely adaptedto germinate in open soils (Tesky 1992). However, it has beenobserved in wet meadows without obviously open soils in Alaska(M. Carlson pers. obs.)Other invasive species in the genus (0–3) 3Hordeum murinum L., H. pusillum Nutt., and H. vulgare areconsidered weeds in United States (USDA 2002, Whitson et al.2000).B-50