Invasiveness Ranking System for Non-Native Plants of Alaska

Current global distribution (0–5) 5Bull thistle is native to Europe, from Britain and Iberia northwardto Scandinavia, eastward to Western Asia, and southward toNorthern Africa. It is found on every continent except Antarctica(Zouhar 2002).Extent of the species U.S. range and/or occurrence of5formal state or provincial listing (0–5)Bull thistle has been reported in all 50 states and most Canadianprovinces (Zouhar 2002). It is considered noxious in 10 statesand 2 Canadian provinces (Invaders Database System 2003).Total for Ecological Amplitude and Distribution 18/25Feasibility of ControlScoreSeed banks (0–3) 0Cirsium vulgare does not accumulate a persistent seed bank (DeJong and Klinkhamer 1988, Klinkhamer and De Jong 1988). Seeddry-stored, at room temperature, for more than 3 years did notgerminate (Klinkhamer and De Jong 1993).Vegetative regeneration (0–3) 0Bull thistle propagates only by seed (Bossard et al. 2000).Level of effort required (0–4) 3Bull thistle will not withstand cultivation. Mechanically cuttingthe thistles at the soil surface is an effective method of control. Aprogram that involves cutting should be maintained for at least4 years. Chemicals can be used to control bull thistle as well(Rutledge and McLendon 1996).Total for Feasibility of Control 3/10Total score for 4 sections 60/98§Convolvulus arvensis L.Ranking SummaryEcoregion known or expected to occur inSouth CoastalInterior BorealArctic AlpineYesYesYesPotential Max. ScoreEcological Impact 40 18Biological Characteristics and Dispersal 25 14Amplitude and Distribution 25 16Feasibility of Control 10 8Relative Maximum 56Climatic ComparisonCollected inAlaska regions?common names: field bindweed, morning gloryCLIMEXsimilarity?South Coastal Yes –Interior Boreal No YesArctic Alpine No YesConvolvulus arvensis has been reported from Haines andKetchikan (AKEPIC 2004). The CLIMEX matching programindicates that climatic similarity between Nome and areas wherethe species is documented is high. The native range of the speciesincludes Røros, Norway (Lid and Lid 1994) and Zlatoust andBogolovsk, Russia (Gubanov et al. 2004), which have 76%, 71%,and 67% climatic similarity with Nome, respectively. There isalso climatic similarity between Fairbanks and areas within thenative range of field bindweed. Chita, Irkutsk, and Kirensk, Russiahave 79%, 78%, and 77% climatic similarity with Fairbanks,respectively. We conclude Convovlulus arvensis could potentiallyestablish in the interior boreal and arctic alpine ecoregions ofAlaska.Ecological ImpactScoreImpact on Ecosystem Processes (0–10) 3Field bindweed tends to occupy bare ground under openconditions. It is unclear how long this species may persist innative plant communities, but it can affect successional processes(Rutledge and McLendon 1996). The extensive root system offield bindweed reduces the soil moisture and nutrients available toother plants (Zouhar 2004).Impact on Natural Community Structure (0–10) 5Field bindweed can twine and may climb over forbs and shrubs,or form dense tangled mats on the ground, but it does not create anew layer (Gubanov et al. 2004, Zouhar 2004).Impact on Natural Community Composition (0–10) 5Field bindweed reportedly reduces cover of native grasses andforbs thereby decreasing biodiversity (Lyons 1982).Impact on Higher Trophic Levels (0–10) 5This plant attracts various pollinators including bees, honeybees,bumblebees, butterflies, and moths (Zouhar 2004). Fieldbindweed may be mildly toxic to some grazing animals (Lyons1998, Todd et al. 1995) although livestock has been observedconsuming field bindweed (Gubanov et al. 2004). This plant hostsseveral viruses (Weaver and Riley 1982).Total for Ecological Impact 18/40Biological Characteristics and Dispersal ScoreMode of Reproduction (0–3) 2Field bindweed reproduces by seed and rhizome. The number ofseeds per plant varies between 12 and 500 (Royer and Dickinson1999, Weaver and Riley 1982).Long-distance dispersal (0–3) 2Seeds fall near the parent plant, but can be dispersed farther bywater or passage through animals or birds (Harmon and Keim1934, Proctor 1968, Weaver and Riley 1982, Zouhar 2004).Spread by humans (0–3) 3Seeds can be dispersed by vehicles and machinery, and incontaminated farm and garden seed, as well as root balls. Fieldbindweed is planted as an ornamental ground cover and inhanging baskets (Zouhar 2004).Allelopathic (0–2) 2Field bindweed is highly allelopathic to other species (Reyndersand Ducke 1979 cited in Weaver and Riley 1982).B-25