Invasiveness Ranking System for Non-Native Plants of Alaska

Feasibility of ControlScoreSeed banks (0–3) 3The seeds of oxeye daisy may survive extended periods in the soil.Bossard et al. (2000) suggest that most oxeye daisy seeds remainviable for 20 years in the soil. Toole (1946) determine the viabilityof oxeye daisy seeds as 39 years. Chippindale and Milton (1934)found 8-, 22-, 24-, 50-, and 68-years old seeds in the soil beneathpastures.Vegetative regeneration (0–3) 2According to the PLANTS Database (USDA, NRCS 2002), oxeyedaisy has no resprout ability. However, Densmore et al. (2001)report that it sprouts from roots and stumps.Level of effort required (0–4) 3If infestations are small one or two chemical or mechanicaltreatments are required. Eradication of a large, well establishedpopulations can be difficult because of the abundant seedproduction and ability of rhizomes to resprout (Densmore et al.2001, Warner et al. 2003).Total for Feasibility of Control 8/10Total score for 4 sections 61/100§Linaria dalmatica L.Ranking SummaryEcoregion known or expected to occur inSouth CoastalInterior BorealArctic AlpineNoYesNoPotential Max. ScoreEcological Impact 40 16Biological Characteristics and Dispersal 25 14Amplitude and Distribution 25 19Feasibility of Control 10 9Relative Maximum 58Climatic ComparisonCollected inAlaska regions?CLIMEXsimilarity?South Coastal No NoInterior Boreal No YesArctic Alpine N0 NoLinaria dalmatica has not been documented in Alaska (Hultén1968, AKEPIC 2004, UAM 2004). It was recently found insoutheastern Yukon Territory, Canada (B. Bennett pers. com.)The native range of Linaria dalmatica extends from Croatia,Moldavia, and Romania, southward and eastward around theBlack Sea in the countries of Bulgaria, Albania, Greece, Crete,Turkey, Syria, Iran, and Iraq (Alex 1962). The CLIMEX matchingprogram shows that climatic similarity between Anchorage andareas where the species is documented is high. Anchorage hasa 56% and 52% overlap of climate similarity with Erzurum andSivas, Turkey, and 74% and 73% with Banff and Calgary, Alberta,Canada, respectively. The introduced range of the species alsoincludes Saskatoon and Regina, Saskatchewan (Vujnovic andWein 1977), which have a 65% and 63% climate match withFairbanks, respectively. Climatic similarity between Nomeand Juneau and areas where the species is documented is low.This suggests that establishment of Dalmatian toadflax may bepossible in the interior boreal ecogeographic region of Alaska.Ecological ImpactScoreImpact on Ecosystem Processes (0–10) 3Dalmatian toadflax stands may reduce soil moisture and nutrientavailability. Infestations of Dalmatian toadflax lead to thedominance by other invasive species in the community (Zouhar2003).common names: Dalmatian toadflaxImpact on Natural Community Structure (0–10) 5The plant is capable of forming dense colonies by creepingrhizomes (Carpenter and Murray 1998). On disturbed sites it canform a new vegetation layer.Impact on Natural Community Composition (0–10) 3Dense colonies of Dalmatian toadflax can push out native grassesand other perennials, thereby altering the species composition innative communities (Carpenter and Murray 1998).Impact on Higher Trophic Levels (0–10) 5Dalmatian toadflax is considered unpalatable for grazinganimals. Severe infestations likely reduces forage quality.Flowers are attractive to bumblebee and halictid bees and mayalter pollination ecology of sites where it occurs (Carpenter andMurray 1998). It hybridizes with other members of the genus(Vujnovic and Wein 1977).Total for Ecological Impact 16/40Biological Characteristics and Dispersal ScoreMode of Reproduction (0–3) 3Dalmatian toadflax reproduces by seed and by vegetative buds onthe roots. New infestations usually originate from seed. Robocker(1970) found that the plant produces from 140 to 250 seedsper capsule and one Dalmatian toadflax plant could potentiallyproduce 500,000 seeds. New plants can be produced whenvegetative buds sprout from lateral roots that are found in theupper 2-12 inches of soil (Alex 1962).Long-distance dispersal (0–3) 2Most of the seeds fall within short distances of the parent plant.When seeds fall onto crusted snow, they can be blown across thesurface (Zouhar 2003). Dalmatian toadflax may also be dispersedby cattle, deer, and other browsing animals (Robocker 1970,Vujnovic and Wein 1997).Spread by humans (0–3) 2Dalmatian toadflax was probably introduced to North America asan ornamental, and it is still used as a garden plant in many areas(Alex 1962, Vujnovic and Wein 1997).Allelopathic (0–2) 0No records were found concerning allelopathy.B-65