Invasiveness Ranking System for Non-Native Plants of Alaska

Ecological Amplitude and Distribution ScoreHighly domesticated or a weed of agriculture (0–4) 4Yellow sweetclover is an important forage, hay, and pasturespecies and has spread from cultivation Also it is widely used forstabilization of disturbed sites (Densmore et al. 2001, Sullivan1992, Whitson 2000). It has been recommended for grasslandrevegetation by a number of federal agencies (Lesica and DeLuca2000).Known level of impact in natural areas (0–6) 4Yellow sweetclover invades valleys and prairies in Illinois, Iowa,Minnesota, Missouri, North Dakota, and Wisconsin (Eckardt1987) as well as Douglas fir, lodgepole pine, and grasslands of theWest and Midwest (Sullivan 1992)Role of anthropogenic and natural disturbance in3establishment (0–5)Yellow sweetclover tends to be eliminated in shaded sites,although it will persist on sites with periodic disturbances(Sullivan 1992). Burning stimulates germination by scarifyingseeds and yellow sweetclover will colonize areas disturbed by fire(Wisconsin DNR 2003).Current global distribution (0–5) 3Yellow sweetclover is a native to the Mediterranean area throughCentral Europe to Tibet (Eckardt 1987). It was introduced intoNorth and South America (Hultén 1968).Extent of the species U.S. range and/or occurrence of5formal state or provincial listing (0–5)The species is found in all 50 states (Wisconsin DNR 2003). It isdeclared noxious in Quebec (Invaders Database System 2003).Total for Ecological Amplitude and Distribution 19/25Feasibility of ControlScoreSeed banks (0–3) 3Seeds can remain viable in the soil for 11–50 years (Cole 1991,Eckardt 1987, Rutledge and McLendon 1996).Vegetative regeneration (0–3) 1Plants usually do not resprout when the stems are cut close to theground (Cole 1991).Level of effort required (0–4) 4Yellow sweetclover can be managed using mechanical orburning methods. Due to the long viability of seeds, sites must bemanaged on continuous basis (Cole 1991, Wisconsin DNR 2003).Total for Feasibility of Control 8/10Total score for 4 sections 65/100§Mycelis muralis (L.) Dumort.Ranking SummaryEcoregion known or expected to occur inSouth CoastalInterior BorealArctic AlpineYesNoNoPotential Max. ScoreEcological Impact 40 7Biological Characteristics and Dispersal 23 11Amplitude and Distribution 25 8Feasibility of Control 10 4Relative Maximum 31Climatic ComparisonCollected inAlaska regions?CLIMEXsimilarity?South Coastal Yes –Interior Boreal No NoArctic Alpine No NoMycelis muralis has been reported from Ketchikan, Wrangell, andKuiu Island in south coastal Alaska (AKEPIC 2004). The species’range includes Røros and Dombås, Norway (Lid and Lid 1994),which has a 76% and 63% climatic match with Nome, and 55%and 52% climatic match with Fairbanks, respectively (CLIMEX1999). However, its northern limit in Europe approximatelyfollows the 19.4 °F mean January isotherm (Clabby andOsborne 1958). These conditions are not typical for arctic alpineand interior boreal ecogeographic regions. We suggests thatestablishment of Mycelis muralis in interior boreal and arcticalpine ecogeographic regions is unlikely.common names: wall lettuceEcological ImpactScoreImpact on Ecosystem Processes (0–10) 1Wall lettuce is an early successional species with minimal cover(Clabby and Osborne 1999), which is likely to have minimalimpacts on ecosystem processes.Impact on Natural Community Structure (0–10) 2Wall lettuce cover in vegetation is low, often less then 10%, butcan approach 40%. The numbers of plants ranged from 1 to 16 perm² in Irish woodland (Clabby and Osborn 1999).Impact on Natural Community Composition (0–10) 1There are no records concerning the alteration of communitycomposition.Impact on Higher Trophic Levels (0–10) 3A number of insects and parasites have been observed for walllettuce. Mycorrhizal relationships are known to occur on walllettuce. Latex production may act as an antiherbivory device(Clabby and Osborn 1999).Total for Ecological Impact 7/40Biological Characteristics and Dispersal ScoreMode of Reproduction (0–3) 3Wall lettuce reproduces exclusively by seed. A plant may produceup to 500 seeds in shaded sites and up to 11,500 seeds in moreopen sites (Clabby and Osborne 1999).Long-distance dispersal (0–3) 3Achenes possess pappus and may by dispersed by wind (Douglas1955).Spread by humans (0–3) 2Wall lettuce can be dispersed along the transportation corridors(M. Shephard pers. com.).B-83