Invasiveness Ranking System for Non-Native Plants of Alaska

Feasibility of ControlScoreSeed banks (0–3) 3The seeds of common groundsel can remain viable inundisturbed soils for more than 6 years (Roberts and Feast 1973).Vegetative regeneration (0–3) 0Common groundsel has no resprouting potential.Level of effort required (0–4) 2Common groundsel can be controlled by tillage in fall andearly spring. Mowing or grazing before seed set will prevent theinfestation from spreading. Herbicides are available for commongroundsel control (SAF 2000).Total for Feasibility of Control 5/10Total score for 4 sections 36/100§Silene noctiflora Lcommon names: night-flowering catchfly,S. latifolia ssp. alba L. white cockle,S. vulgaris (Moench) Garcke bladder campion,S. dioica (L.) Clairville red catchflyRanking SummaryEcoregion known or expected to occur inSouth CoastalInterior BorealArctic AlpineYesYesYesPotential Max. ScoreEcological Impact 40 13Biological Characteristics and Dispersal 25 9Amplitude and Distribution 25 13Feasibility of Control 10 7Relative Maximum 42Climatic ComparisonCollected inAlaska regions?CLIMEXsimilarity?South Coastal Yes –Interior Boreal Yes –Arctic Alpine No YesSilene noctiflora has been collected from Fairbanks, Anchorage,Healy, and the Kenai Peninsula (Hultén 1968, UAM 2004).Although this species is reported by Hultén (1968) from Nomeand Juneau, these specimens appear to be misidentified (McNeill1980). Silene vulgaris has been documented from the YukonTerritory in the vicinity of Dawson (Cody 1996, UAM 2004).Silene latifolia ssp. alba has been documented from Eklutna Valleyand the Matanuska and Susitna Valleys in Alaska (AKEPIC2004, UAM 2004). Silene dioica has been collected from Palmer(AKEPIC 2004). The CLIMEX matching program indicatesthe climatic similarity between Alaska and areas where Silenenoctiflora, S. latifolis ssp. alba, S. vulgaris, and S. dioica aredocumented as moderately high. The ranges for these speciesinclude Røros and Dombås, Norway (Lid and Lid 1994), whichhave a 76% and 63% climatic match with Nome; and from Bergen,Norway which has a 73% climatic match with Juneau. Silenelatifolia ssp. alba and S. dioica also have been documented fromarctic and subarctic Norway and Finland (Lid and Lid 1994,Thompson 1975). Thus establishment of these non-native Silenespecies in arctic alpine and south coastal ecogeographic regions islikely.Ecological ImpactScoreImpact on Ecosystem Processes (0–10) 3Silene species occupy disturbed ground and likely hindercolonization by native species. These weeds can decrease soilmoisture and nutrient availability (Royer and Dickinson 1999).B-118Impact on Natural Community Structure (0–10) 3These species have been observed in the existing layer ofvegetation in disturbed areas (I. Lapina pers. obs.). Red catchflyis capable of forming almost complete monocultures on bare soil(Matlack and Harper 1986).Impact on Natural Community Composition (0–10) 2These species compete for moisture, nutrients, and sunlight inpastures and crowd native plants (Royer and Dickinson 1999).Impact on Higher Trophic Levels (0–10) 5Grazing animals find Silene species unpalatable. These plants arealternate hosts for numerous viruses (Royer and Dickinson 1999).Hybrids of S. dioica and S. latifolia ssp. alba have been collectedin Canada (Douglas and MacKinnon 1998). The flowers of mostSilene species open in the evening and are moth-pollinated. Redcatchfly flowers open during the day and are typically pollinatedby bees or butterflies (McNeill 1978).Total for Ecological Impact 13/40Biological Characteristics and Dispersal ScoreMode of Reproduction (0–3) 3Silene species reproduce primarily by seed. Each plant of nightfloweringcatchfly is capable of producing up to 2,600 seeds.White cockle plants produce over 24,000 seeds (Royer andDickinson 1999) and red catchfly plants produced more than4,500 seeds in an experimental garden in Britain (Kay et al.1984). White campion and bladder campion are able to reproducevegetatively by root and stem fragments (Whitson et al. 2000).Long-distance dispersal (0–3) 0Most seeds fall from the parent plant to the ground (Guide toWeeds in British Columbia 2002).Spread by humans (0–3) 2The seeds are very similar to those of crop clovers and are difficultto separate. Consequently, seed impurities have been a majorsource of dispersal. Seeds also are capable of germination afterpassing through the digestive tract of domestic animals (McNeill1980, Royer and Dickinson 1999, Whitson et al. 2000).Allelopathic (0–2) 0There are no records of allelopathy.