Invasiveness Ranking System for Non-Native Plants of Alaska

Potentilla recta L.Ranking SummaryEcoregion known or expected to occur inSouth CoastalYesInterior BorealYes*Arctic AlpineNo* Southern portion of interior boreal region (see climate comparison below).Potential Max. ScoreEcological Impact 40 20Biological Characteristics and Dispersal 25 13Amplitude and Distribution 25 17Feasibility of Control 10 7Relative Maximum 57Climatic ComparisonCollected inAlaska regions?CLIMEXsimilarity?South Coastal No YesInterior Boreal No NoArctic Alpine No NoPotentilla recta has not been collected in Alaska (Hultén 1968,Welsh 1974, AKEPIC 2004, UAM 2004). The climatic similaritybetween Fairbanks and Nome and areas where the species isdocumented is low (CLIMEX 1999, Gubanov et al. 2003, Lid andLid 1994). Thus establishment in interior boreal and arctic alpineecogeographic regions is unlikely. However, sulphur cinquefoilis known to invade grasslands in Montana (Rice 1991) where theclimatic similarity between Anchorage (southern interior borealecoregion) and Harve and Kalispell, Montana is 66% and 64%respectively. Climatic similarity between Juneau and areas wherethe species is documented is high. The native range of Potentillarecta includes Bergen, Norway, which has 73% of climaticsimilarity with Juneau. Thus establishment in the south coastaland the southern part of interior boreal ecogeographic region maybe possible.Ecological ImpactScoreImpact on Ecosystem Processes (0–10) 3Natural successional processes may become altered in plantcommunities thoroughly infested by sulphur cinquefoil (Endressand Parks 2004, Powell 1996). As a pioneer species, it likely bindsdisturbed soil and prevents erosion (Werner and Soule 1976).Impact on Natural Community Structure (0–10) 3Sulphur cinquefoil is capable of changing the density of thevegetative layer.Impact on Natural Community Composition (0–10) 7Severe infestations of sulphur cinquefoil often decrease the nativeplant diversity and may compromise the reproductive success andabundance of the co-occurring native cinquefoils (Endress andParks 2004). Sulphur cinquefoil typically produces more flowersthan native Potentilla species; therefore, may attract more insectpollinators, causing reduced reproductive success of co-occurringnative cinquefoils (Endress and Parks 2004).Impact on Higher Trophic Levels (0–10) 7Although elk and deer have been observed browsing on sulphurcinquefoil, high tannin levels make this plant unpalatable to mostwildlife (Endress and Parks 2004, Kadrmas and Johnsoon 2004,Werner and Soule 1976). A great number of phytophagous andpollinating insect species are associated with sulphur cinquefoil(Batra 1979, Powell 1996). Potentilla species do not readilyhybridize (Acharya Goswami and Matfield 1975).Total for Ecological Impact 20/40common names: sulphur cinquefoilBiological Characteristics and Dispersal ScoreMode of Reproduction (0–3) 3Sulphur cinquefoil reproduces exclusively by seed. A single plantcan produce approximately 1,650 seeds. At a population densityof 2.7 plants per m² about 4,400 seeds per m² may be producedeach year. (Endress and Parks 2004, Werner and Soule 2004).Long-distance dispersal (0–3) 2Most seeds fall passively to the ground; however, longer distanceseed dispersal can occur by attachment to, and consumption ormovement by birds, small mammals, and grazing animals. Seedscan also be dispersed longer distances by wind or in melting snowand surface flows (Endress and Parks 2004, Powell 1996, Wernerand Soule 2004).Spread by humans (0–3) 3Seeds can be dispersed by attachment to clothes, boots, vehicles,and earth-moving equipment (Endress and Parks 2004), or insoil, hay and bedding for animals, and as plants collected for floralarrangement (Powell 1996).Allelopathic (0–2) 0The species is not known to be allelopathic (Powell 1996, Wernerand Soule 1976).Competitive Ability (0–3) 3Sulphur cinquefoil is very competitive. It can displace nativespecies in grasslands and forest habitats (Endress and Parks2004) and has been shown to outcompete and displace invasivespecies such as yellow starthistle (Centaurea solstitialis L.),spotted knapweed (Centaurea biebersteinii DC), and leafy spurge(Euphorbia esula L.) on several sites in Montana, Nevada, Oregon,and British Columbia. Sulphur cinquefoil is not known to persistunder a 100% canopy cover of other vegetation (Kadrmas andJohnson 2004, Powell 1996, Zouhar 2003).Thicket-forming/Smothering growth form (0–2) 0Sulphur cinquefoil does not form dense thickets and does nothave a climbing growth habit (Pojar 1999, Whitson et al. 2000).Germination requirements (0–3) 2Sulphur cinquefoil germinates and establishes better inabandoned agricultural fields and other disturbed areas (Endressand Parks 2004, Kadrmas and Johnson 2004). Seedling mortalitywas high in sites with established vegetation in Montanagrasslands (Peter 2002 cited in Zouhar 2003).Other invasive species in the genus (0–3) 0There are a number of introduced Potentilla species in NorthAmerica, but none are listed as weeds (USDA 2002).Aquatic, wetland or riparian species (0–3) 0Sulphur cinquefoil is found in disturbed open ground, wasteplaces, roadsides, pastures, and overgrazed grasslands (Endressand Parks 2004, Pojar 1999, Powell 1996) but it may also colonizeundisturbed forest, shrub, and grassland communities (Endressand Parks 2004, Whitson et al. 2000). Soil moisture conditionswhere it grows range from dry to moist.Total for Biological Characteristics and Dispersal 13/25Ecological Amplitude and Distribution ScoreHighly domesticated or a weed of agriculture (0–4) 2Sulphur cinquefoil often impacts cultivated strawberry fields butis not a serious agricultural weed (Werner and Soule 1976, WS-NWCB 2005).B-105