Invasiveness Ranking System for Non-Native Plants of Alaska

Phalaris arundinacea L.Ranking SummaryEcoregion known or expected to occur inSouth CoastalInterior BorealArctic AlpineYesYesYesPotential Max. ScoreEcological Impact 40 33Biological Characteristics and Dispersal 25 20Amplitude and Distribution 25 24Feasibility of Control 10 6Relative Maximum 83Climatic ComparisonCollected inAlaska regions?CLIMEXsimilarity?South Coastal Yes –Interior Boreal Yes –Arctic Alpine Yes –Special Note–nativity: Some populations of Phalaris arundinaceaL. are possibly native in Alaska. Four sites that may harbor nativeforms are from hot springs of interior Alaska (Big Windy, Kanuti,Kilo, and Manley Hot Springs; “N?” in figure). Active miningoccurred in these areas in the early 20th century and seeds mayhave been brought in with livestock. If these populations arenative they represent important and likely unique components tothe biodiversity and biogeographic history of Alaska and Beringia.Phalaris arundinacea in these remote locations should not beremoved. However, monitoring may be critical as introgressionwith other cultivated and weedy forms can result in substantialincreases in invasiveness (Merigliano and Lesica 1998).Populations south of the Alaska Range are generally associatedwith anthropogenic disturbance and are most likely introducedor introgressed genotypes as in the Pacific Northwest (seeMerigliano and Lesica 1998). These introduced populations posea serious threat to communities and ecosystem function.Phalaris arundinacea has been documented in the south coastal[Skagway, Craig, and Petersburg (Hultén 1968) and Juneau,Seward, Sitka, and Ketchikan (UAM 2004)], interior boreal[Fairbanks, Anchorage, and Talkeetna (Hultén 1968) and Circle,Tanana, Big Windy, Kilo, Manley, and Kanuti (UAM 2004)], andarctic alpine [Bettles (UAM 2004)] ecoregions in Alaska.Ecological ImpactScoreImpact on Ecosystem Processes (0–10) 9Reed canarygrass promotes silt deposition and causes seriousconstrictions of waterways and irrigation canals. Additionally,it may alter soil hydrology (Lyons 1998) and increase watertemperatures (Lantz. 2000).Impact on Natural Community Structure (0–10) 7Reed canarygrass can form dense, persistent, monospecific stands(Lyons 1998), eliminating low herbaceous layers and inhibitingwoody seedling growth (M.L. Carlson pers. obs.).Impact on Natural Community Composition (0–10) 9The stands of Phalaris arundinacea exclude and displace nativeplants and animals (Hutchison 1992, Lyons 1998, WSDE 2003).It apparently inhibits the growth of other species for 3–5 months,eventually eliminating these species (Rutledge and McLendon1996). Canarygrass has invaded the emergent vascular plantcommunities in Iowa. Eleven species disappeared on these sites(Apfelbaum and Sams 1987).common names: reed canarygrassImpact on Higher Trophic Levels (0–10) 8Waterfowl, upland game birds, riparian mammals, and fish alluse reed canarygrass for cover and food (Snyder 1992). Lyons(1998) suggested that reed canarygrass grows too densely toprovide adequate cover for small mammals and waterfowl. It canalso overgrow irrigation ditches and small natural watercourses,impacting aquatic species. Reed canarygrass contributes toincreased water temperatures and decreased habitat values forsalmon and other wildlife. Dense stands can form a physicalbarrier to migrating salmon (Lantz 2000, Whatcom Weeds 2003).Total for Ecological Impact 33/40Biological Characteristics and Dispersal ScoreMode of Reproduction (0–3) 2Reproduction is from seed and vegetatively by stout creepingrhizomes (Lyons 1998, Rutledge and McLendon 1996).Long-distance dispersal (0–3) 2The seeds have no adaptations for long-distance dispersal. Bothrhizome fragments and seeds may wash downstream alongstreams and rivers (Rutledge and McLendon 1996).Spread by humans (0–3) 3Reed canarygrass has been planted widely for forage and forerosion control (Lyons 1998, WSDE 2003). It also is a seedcontaminant (USDA, ARS).Allelopathic (0–2) 0Reed canarygrass is not known to be allelopathic.Competitive Ability (0–3) 3Reed canarygrass is highly competitive with other species (Lyons1998, Rutledge and McLendon 1996). Phalaris arundinacea istolerant of freezing temperatures and begins to grow very early inthe spring.Thicket-forming/Smothering growth form (0–2) 2Reed canarygrass forms dense and impenetrable mats ofvegetation (Lyons 1998). It can reach 3–6 feet in height (Welsh1974).Germination requirements (0–3) 2The seeds of reed canarygrass germinate immediately afterripening, there are no known dormancy requirement (Apfelbaumand Sams 1987).Other invasive species in the genus (0–3) 3Phalaris aqatica L., P. brachystacys Link, P. canariensis L.,P. caroliana Walter, P. minor Retz., and P. paradoxa L.Aquatic, wetland or riparian species (0–3) 3Reed canarygrass occurs in marshes, fens, wet meadows andprairies, flood plains, old fields, roadsides, and ditches (Hutchison1992, Lyons 1998, Rutledge and McLendon 1996).Total for Biological Characteristics and Dispersal 20/25Ecological Amplitude and Distribution ScoreHighly domesticated or a weed of agriculture (0–4) 4Reed canarygrass has a long agronomic history. It was cultivatedfor forage as early as 1830s. There are 11 reed canarygrasscultivars used as forage, ornamental, and for erosion control(Hutchison 1992, Lyons 1998, Merigliano and Lesica 1998).Known level of impact in natural areas (0–6) 6Reed canarygrass may threaten populations of many speciesin wetlands in Ohio, Oregon, and Montana (Lyons 1998). Itthreatens upland oak savannas in south-central Wisconsin(Snyder 1992). Canarygrass has invaded the emergent vascularplant communities in Iowa. Eleven species disappeared on thesesites (Apfelbaum and Sams 1987).B-91