Invasiveness Ranking System for Non-Native Plants of Alaska

Poa compressa L.Ranking SummaryEcoregion known or expected to occur inSouth CoastalInterior BorealArctic AlpineYesYesYesPotential Max. ScoreEcological Impact 40 6Biological Characteristics and Dispersal 25 10Amplitude and Distribution 25 17Feasibility of Control 7 5Relative Maximum 39Climatic ComparisonCollected inAlaska regions?CLIMEXsimilarity?South Coastal Yes –Interior Boreal Yes –Arctic Alpine Yes –Poa compressa is documented in all ecogeorgaphic regions inAlaska (Hultén 1968, UAM 2004, AKEPIC 2005).Ecological ImpactScoreImpact on Ecosystem Processes (0–10) 1Canada bluegrass is generally restricted to non-nativecommunities and likely has little impact on native plantcommunities and ecological processes (I. Lapina pers. obs.,Rutledge and McLendon 1996).Impact on Natural Community Structure (0–10) 1Canada bluegrass occurs in sparse stands and likely does not alterthe density of the layer (I. Lapina pers. obs., Sather 1996).Impact on Natural Community Composition (0–10) 1In Alaska, Canada bluegrass is restricted to non-nativecommunities and it does not seem to be changing speciescomposition (I. Lapina pers. obs.).Impact on Higher Trophic Levels (0–10) 3Canada bluegrass is grazed by livestock and wildlife species(Gubanov et al. 2003, Dore and McNeill 1980). Canada bluegrasshybridizes with Kentucky bluegrass (Dale et al. 1975).Total for Ecological Impact 6/40Biological Characteristics and Dispersal ScoreMode of Reproduction (0–3) 2Canada bluegrass reproduces by both seeds and rhizomes(Rutledge and McLendon 1973). In Alaska, it does not seem to bereproducing aggressively.Long-distance dispersal (0–3) 2Cattle and deer seem to carry the seeds widely (Dore and McNeill1980). However, the grass does not have any specific adaptationsfor long-distance dispersal.Spread by humans (0–3) 3Canada bluegrass is used as a pasture grass and for erosion control(Rutledge and McLendon 1996, Hitchock and Cronquist 1973).It is also a common seed contaminant (USDA, ARS 2005).Allelopathic (0–2) 0This species is not listed as allelophathic (USDA 2002).Competitive Ability (0–3) 0Canada bluegrass appears to be a poor competitor with otherexotic plants (Turkington 1994). In experiments by Turkington(1994) Canada bluegrass was the poorest invader and it was lessresistant to invasion by other species. Invasive potential andresistance to invasion by other species decreases with the age ofthe Canada bluegrass stand. Canada bluegrass is also less adaptedto grazing pressures (Sather 1996, Turkington 1994).common names: Canada bluegrassThicket-forming/Smothering growth form (0–2) 0Canada bluegrass does not form dense stands, and it does notpossess climbing or smothering growth habit (Welsh 1974,Hultén 1968).Germination requirements (0–3) 0Canada bluegrass geminates better on bare soil (Turkington1994). It does not appear capable of germinating in areas whereplants are already established.Other invasive species in the genus (0–3) 3Poa annua L., P. pratensis L., and P. trivialis L. (USDA 2002,Whitson et al. 2000, Royer and Dickinson 1999, Hultén 1968).Aquatic, wetland or riparian species (0–3) 0Canada bluegrass is a weed of waste places, roadsides, and yards(Gubanov et al. 2003, Hultén 1968).Total for Biological Characteristics and Dispersal 10/25Ecological Amplitude and Distribution ScoreHighly domesticated or a weed of agriculture (0–4) 4Canada bluegrass is used as a pasture grass and for erosion control(Rutledge and McLendon 1996, Hitchock and Cronquist 1973).However, it is not used as widely as Kentucky bluegrass (USDA2002).Known level of impact in natural areas (0–6) 3Canada bluegrass is known to cause little impact on native plantcommunities and successional processes in Rocky MountainNational Park, Colorado (Rutledge and McLendon 1996).Role of anthropogenic and natural disturbance inestablishment (0–5)Canada bluegrass is much more capable of colonizing bare ground(Turkington 1994).Current global distribution (0–5) 5Canada bluegrass is native to Europe, Western Asia, andNorthern Africa (USDA, ARS 2005). It is introduced to Northand South America, New Zealand, and Eastern Asia (Gubanov etal. 2003, Hultén 1968).Extent of the species U.S. range and/or occurrence offormal state or provincial listing (0–5)Canada bluegrass is found in nearly all American states andCanadian provinces. This species is listed as an invasive weed inConnecticut (USDA 2002).Total for Ecological Amplitude and Distribution 17/25Feasibility of ControlScoreSeed banks (0–3)UUnknownVegetative regeneration (0–3) 2Burning or grazing may result in increased resprouting (Rutledgeand McLendon 1996).Level of effort required (0–4) 3Chemical methods and burning might be useful. Practices thatwill damage bluegrass may often harm the native species more(Butterfield et al. 1996, Sather 1996).Total for Feasibility of Control 5/7Total score for 4 sections 38/97§05B-97