Invasiveness Ranking System for Non-Native Plants of Alaska

Hieracium umbellatum L.Ranking SummaryEcoregion known or expected to occur inSouth CoastalInterior BorealArctic AlpineYesYesYesPotential Max. ScoreEcological Impact 30 13Biological Characteristics and Dispersal 20 16Amplitude and Distribution 25 9Feasibility of Control 7 4Relative Maximum 51Climatic ComparisonCollected inAlaska regions?CLIMEXsimilarity?South Coastal Yes –Interior Boreal Yes –Arctic Alpine Yes YesThis species has been collected near Coldfoot in the BrooksRange (edge of the arctic alpine ecogeographic region);Fairbanks, Anchorage, Tanana Lowlands, and Matanuska–Susitna Valley (interior boreal ecogeographic region); andWrangell Island and Petersburg (south coastal ecogeographicregion) (AKEPIC 2007, UAM 2004). Hieracium umbellatum hasbeen collected from the edge of the arctic alpine ecogeographicregion on the southern side of the Brooks Range (AKEPIC2007). This specific site is a more interior boreal plant communityand has relatively warm summers, but cold and long winters.Additionally, its range includes subarctic regions such asNorthwest Territory and Yukon Territory, Canada and Siberia,Russia (Douglas et al. 1998, USDA, ARS 2004), with a greaterthan 50% climatic similarity between known sites and Nome(CLIMEX 1999). This suggests that establishment in arctic andalpine regions of Alaska may be possible.Ecological ImpactScoreImpact on Ecosystem Processes (0–10) 5Narrowleaf hawkweed consumes soil moisture and nutrients. Itcan form relatively dense stands in only weakly disturbed sitesand is likely to delay establishment of native species (M. Carlsonpers. obs., I. Lapina pers. obs.).Impact on Natural Community Structure (0–10) 3It establishes in an existing herbaceous layer, changing the densityof the layer (I. Lapina pers. obs.).Impact on Natural Community Composition (0–10) 5Narrowleaf hawkweed has been observed in naturally disturbedareas following forest fires in interior Alaska (Villano 2007) aswell as partially disturbed roadsides areas in Alaska (I. Lapinapers. obs.). It likely reduces the diversity and density of nativespecies in these disturbed habitats.Impact on Higher Trophic Levels (0–10)UImpact on higher trophic levels is unknown.Total for Ecological Impact 13/30Biological Characteristics and Dispersal ScoreMode of Reproduction (0–3) 2Narrowleaf hawkweed spreads by both seed and rhizomes (Plantsfor a future 2002).Long-distance dispersal (0–3) 3Seeds have pappus and are likely wind dispersed (Douglas et al.1998).common names: narrowleaf hawkweedB-49Spread by humans (0–3) 3Narrowleaf hawkweed has been observed spreading alongtransportation corridors (I. Lapina pers. obs.). It has been used asan ornamental (Plants for a future 2002).Allelopathic (0–2)UUnknownCompetitive Ability (0–3) 3It has moderate competitive abilities with other non-nativespecies on disturbed sites (I. Lapina pers. obs.). The plant isadapted to all soil types (sandy, loamy, and clay). It can grow innutritionally poor soil and withstand semishade (Plants for afuture 2002).Thicket-forming/Smothering growth form (0–2) 1Narrowleaf hawkweed is capable of forming dense nearlymonocultural stands in disturbed sites in south-central Alaska.Plants can grow up to 4 feet tall and overshadow other herbaceousplants (I. Lapina pers. obs.).Germination requirements (0–3)UUnknownOther invasive species in the genus (0–3) 3Hieracium aurantiacum L., H. caespitosum Dumort, H. pilosellaL., and H. piloselloides Vill. (Royer and Dickinson 1999, USDA,NRCS 2006).Aquatic, wetland or riparian species (0–3) 1In Alaska narrowleaf hawkweed is generally observed indisturbed mesic areas. However, in its native range it grows alongstreambanks, moist meadows, grasslands, and forests (Douglasset al. 1998, Gubanov et al. 1995). It has been noted invading 40year old abandoned fields along the Stikine River (M. Shephardpers. com.).Total for Biological Characteristics and Dispersal 16/20Ecological Amplitude and Distribution ScoreHighly domesticated or a weed of agriculture (0–4) 2Narrowleaf hawkweed is known as an ornamental (Plants for afuture 2002).Known level of impact in natural areas (0–6) 0The impact of narrowleaf hawkweed in natural areas has not beendocumented.Role of anthropogenic and natural disturbance inestablishment (0–5)Narrowleaf hawkweed has been observed only in sites withdisturbed substrates (I. Lapina pers. obs., Villano 2007).Current global distribution (0–5) 5The native range of narrowleaf hawkweed includes Europe,temperate Asia, and North America. It is known from subarcticregions in Northwest Territory and Yukon Territory, Canadaand Siberia, Russia (Douglas et al. 1998, ITIS 2004, USDA, ARS2004).Extent of the species U.S. range and/or occurrence offormal state or provincial listing (0–5)Introduced populations in North America extend from Alaskasouth to Idaho and northwestern Oregon (Hitchcock &Cronquist 1990, Welsh 1974). However, it is considered native toUnited States as far south as Colorado and Nebraska (ITIS 2004,USDA, ARS 2004). This species is on threatened and endangeredplants list in New Hampshire (USDA 2002). It is not listed asnoxious in any American states or Canadian provinces (Rice2006).Total for Ecological Amplitude and Distribution 9/2502