Invasiveness Ranking System for Non-Native Plants of Alaska

Long-distance dispersal (0–3) 3The seeds can be dispersed a long distance by wind and water. Thespines on the seeds of bitter dock facilitate distribution on animalfur and bird feathers (DiTomaso and Healy 2003, Cavers andHarper 1967). Fruits are very lightweight and winged. The outerpart of perianth may be enlarged into a tubercle which facilitateswater dispersal (DiTomaso and Healy 2003). Fruits of curlydock float for 1–6 months in fresh water and for 15 months in saltwater. Seeds of bitter dock remain floating in disturbed water for24 hours (Cavers and Harper 1967).Spread by humans (0–3) 3Curly dock is a common contaminant of commercial seeds(Dorph-Petersen 1925, Singh 2001). The seeds can also be easilydispersed by attaching to clothing and fur of domestic animals.Seeds can also pass thought the digestive system of cattle (Caversand Harper 1964).Allelopathic (0–2) 0Allelopathy has not been recorded for dock species.Competitive Ability (0–3) 1Seedlings of docks have low competitive ability and cannotestablish in vegetated areas. However, once established, thesespecies became difficult weeds (Cavers and Harper 1964). Theresults of greenhouse experiments showed that bitter dock wasmore competitive than Poa trivialis and Lolium perenne (Gibsonand Courtney 1977).Thicket-forming/Smothering growth form (0–2) 0Curly dock, bitter dock, and dooryard dock have not beenobserved forming dense thickets in Alaska (M.L. Carlson pers.obs., I. Lapina pers. obs.).Germination requirements (0–3) 0Dock species require open soil and removed vegetation forsuccessful germination and establishment (Cavers and Harper1964). Establishment from seeds was observed only in openhabitat, such as disturbed shingle beaches or on freshly cultivatedfield (Cavers and Harper 1964).Other invasive species in the genus (0–3) 3Rumex acetosella L. is invasive in Connecticut and Iowa (USDA,NRCS 2006).Aquatic, wetland or riparian species (0–3) 3Despite the fact that curly, bitter, and dooryard docks arecommon on disturbed ground, such as agricultural fields,roadsides, and waste grounds (DiTomaso and Healy 2003, Welsh1974), these species may also invade riparian areas, includingwet meadows, riverbanks, pond edges, and irrigation ditches(DiTomaso and Healy 2003, Royer and Dickinson 1999).Total for Biological Characteristics and Dispersal 16/25Ecological Amplitude and Distribution ScoreHighly domesticated or a weed of agriculture (0–4) 2Curly dock and bitter dock are serious agricultural weeds in manycountries (Cavers and Harper 1964, Royer and Dickinson 1999).However, this weed is not a big agricultural problem in Alaska (J.Conn pers. com.).Known level of impact in natural areas (0–6) 1Curly dock is recorded invading California wetlands and causinglow impact on plant communities and higher trophic levels (Cal-IPC 2003).Role of anthropogenic and natural disturbance in1establishment (0–5)Curly, bitter, and dooryard dock generally colonize disturbedground, however, it may occasionally establish in intact wetlandcommunities (Cavers and Harper 1964, DiTomaso and Healy2003). In Alaska these species are always associated with roadsidedisturbance (M.L. Carlson pers. obs.).Current global distribution (0–5) 5These species of docks are indigenous to Europe. They havebeen introduced into North and South Africa, North and SouthAmerica, Asia, Australia, and New Zealand. Curly dock and bitterdock are found in arctic habitats in Norway and northern Russia(Cavers and Harper 1964, Hultén 1968).Extent of the species U.S. range and/or occurrence offormal state or provincial listing (0–5)Curly and bitter docks are distributed throughout most of theUnited States. Dooryard dock can be found in the northeastUnited States and in Alaska (USDA, NRCS 2006). Rumex crispusis declared noxious in Indiana, Iowa, Michigan, and Minnesota(USDA, NRCS 2006). Rumex crispus is a federal noxious weed inCanada (Royer and Dickinson 1999).Total for Ecological Amplitude and Distribution 14/25Feasibility of ControlScoreSeed banks (0–3) 3Seeds of docks can remain viable in the soil for over 38 years(Toole 1946) and even over 80 years (Darlington and Steinbauer1961).Vegetative regeneration (0–3) 2Adventitious buds on the roots and underground stems producenew shoots after aboveground damage. New shoots can produceautumn flowers very quickly (Monaco and Cumbo 1972).Level of effort required (0–4) 3Hand-cutting plants below the ground or herbicide applicationcan control infestations of docks. Monitoring after treatment isrequired due to long-lived seed banks and the ability to regeneratefrom root fragments (Cavers and Harper 1964, DiTomaso andHealy 2003).Total for Feasibility of Control 8/10Total score for 4 sections 48/100§5B-112