Invasiveness Ranking System for Non-Native Plants of Alaska

Vicia villosa RothRanking SummaryEcoregion known or expected to occur inSouth CoastalInterior BorealArctic AlpineYesYesNoPotential Max. ScoreEcological Impact 40 22Biological Characteristics and Dispersal 22 11Amplitude and Distribution 19 12Feasibility of Control 10 3Relative Maximum 53Climatic ComparisonCollected inAlaska regions?common names: winter vetch, hairy vetchCLIMEXsimilarity?South Coastal No YesInterior Boreal Yes –Arctic Alpine No NoVicia villosa is reported from interior boreal ecogeographic regionof Alaska (Hultén 1968). The climatic similarity between Nomeand areas where the species is documented is relatively low(CLIMEX 1999). This species withstands winter temperaturesto -30 °F (some cultivars to 7 °F), and requires 100 frost-freedays (USDA 2002). Winter temperature in Nome can reach-54 °F (WRCC 2001) and the number of frost-free days is at thephysiological limit of Vicia villosa. It is unlikely to establish inthe arctic alpine ecogeographic region of Alaska. Vicia villosa hasbeen reported from Bergen, Norway (Lid and Lid 1994), whichhas 76% climatic similarity with Juneau. Thus establishment insouth coastal ecogeographic region of Alaska is possible.Ecological ImpactScoreImpact on Ecosystem Processes (0–10) 7Hairy vetch alters edaphic conditions due to fixation ofatmospheric nitrogen (USDA 2002). It can significantly reduceavailable soil water (Nielson and Vigil 2005).Impact on Natural Community Structure (0–10) 7Hairy vetch often overgrows herbaceous vegetation and forms adense herbaceous layer (Whitson et al. 2000).Impact on Natural Community Composition (0–10) 3Hairy vetch overtops herbaceous and low-woody species and cancause reductions in the number of individual native species in thecommunity (M. Shephard pers. obs.).Impact on Higher Trophic Levels (0–10) 5Hairy vetch is reported to be both slightly toxic and highlypalatable to grazing animals (USDA 2002). The foliage of hairyvetch is eaten by deer (Graham 1941). Vicia species host severalinsect pests and disease organisms. The flowers are visited bynative bees and may alter pollination ecology of the surroundingarea (Aarssen et al. 1986).Total for Ecological Impact 22/40Biological Characteristics and Dispersal ScoreMode of Reproduction (0–3) 1Winter vetch reproduces by seed only (Aarssen et al. 1986). Thisplant produces moderate amounts of seed (USDA 2002).Long-distance dispersal (0–3) 0The seeds are large and are not easily dispersed (M. Shephardpers. obs.).Spread by humans (0–3) 2Hairy vetch is a forage plant that sometimes escapes cultivation(Welsh 1974). It is a crop seed contaminant (USDA, ARS 2004).Allelopathic (0–2) 0None (USDA 2002).Competitive Ability (0–3) 3Winter vetch has the ability to fix nitrogen (USDA 2002) andit competes for resources with other species. Winter vetch isa very hardy species. It demonstrates high frost, drought, andflood tolerance (Brandsæter et al. 2002, Walsh and Skujins 1981,Hoveland and Donnelly 1966).Thicket-forming/Smothering growth form (0–2) 2Winter vetch has a climbing growth habit with stems up to 6 feetlong (Hultén 1968).Germination requirements (0–3)UUnknownOther invasive species in the genus (0–3) 3Vicia cracca L., V. sativa ssp. nigra (L.) Ehrh, V. benghalensisL., V. disperma DC., V. hirsuta (L.) S.F. Gray, V. lathyroides L.,V. pannonica Crantz, and V. tetrasperma (L.) Schreber (Hultén1968, USDA 2002, Whitson et al. 2000).Aquatic, wetland or riparian species (0–3) 0Winter vetch has escaped cultivation and is common alongroadsides and disturbed areas (Whitson et al. 2000).Total for Biological Characteristics and Dispersal 11/22Ecological Amplitude and Distribution ScoreHighly domesticated or a weed of agriculture (0–4) 4Winter vetch has been used as a both a forage and rotation crop(Welsh 1974, Whitson et al. 2000).Known level of impact in natural areas (0–6)Unknown.Role of anthropogenic and natural disturbance inestablishment (0–5)Winter vetch establishes in areas with anthropogenic soildisturbance (Pojar and MacKinnon 1994, Whitson et al. 2000).Current global distribution (0–5) 3Native range of winter vetch includes northern Africa, temperateAsia, and Europe (USDA, ARS 2004).Extent of the species U.S. range and/or occurrence offormal state or provincial listing (0–5)Winter vetch occurs in nearly all American states (USDA 2002).It is not considered noxious in North America (Invaders DatabaseSystem 2003).Total for Ecological Amplitude and Distribution 12/19Feasibility of ControlScoreSeed banks (0–3) 0The seeds of winter vetch can remain viable for less than 2 years(McKee and Musil 1984).Vegetative regeneration (0–3) 1Some of the winter vetch cultivars have good regrowth ability(Brandsæter et al. 2002).Level of effort required (0–4) 2Control of winter vetch can be achieved relatively easily bymechanical methods or herbicides applications (Aarssen et al.1986).Total for Feasibility of Control 3/10Total score for 4 sections 48/91§U05B-140