Invasiveness Ranking System for Non-Native Plants of Alaska

Elymus repens (L.) Gould.Ranking SummaryEcoregion known or expected to occur inSouth CoastalInterior BorealArctic AlpineYesYesYesPotential Max. ScoreEcological Impact 40 20Biological Characteristics and Dispersal 25 15Amplitude and Distribution 25 19Feasibility of Control 10 5Relative Maximum 59Climatic ComparisonCollected inAlaska regions?CLIMEXsimilarity?South Coastal Yes –Interior Boreal Yes –Arctic Alpine Yes –Elymus repens has been reported from all ecoregions of Alaska(Hultén 1968, Densmore et al. 2001, AKEPIC 2004).Ecological ImpactScoreImpact on Ecosystem Processes (0–10) 7Quackgrass consumes soil moisture and limiting nutrients(Batcher 2002). It may alter secondary succession following fires,where its cover can dramatically increase (Snyder 1992).Impact on Natural Community Structure (0–10) 5Quackgrass establishes in an existing layer, changes the densityof the layer, and often forms a new layer on disturbed substrates(Irina Lapina pers. obs.).Impact on Natural Community Composition (0–10) 5The species is able to exclude native vegetation, resulting in anoverall loss of biodiversity in other climates (Batcher 2002).This plant is not observed in undisturbed plant communities inAlaska and does not appear to pose an imminent threat to naturalcommunity composition (J. Conn and M. Shephard pers. com.,Densmore et al. 2000). Elymus repens is a cool-season grass thatcan photosynthesize and grow during early spring. It can suppressspecies that grow in warmer season (Batcher 2002).Impact on Higher Trophic Levels (0–10) 3Elymus repens provides cover for numerous small rodents, birds,and waterfowl in grassland systems. It is allelopathic (Batcher2002). This grass is highly palatable to grazing animals (USDA2002).Total for Ecological Impact 20/40Biological Characteristics and Dispersal ScoreMode of Reproduction (0–3) 2Quackgrass is an aggressive perennial reproducing by seed andspreading by a shallow mass of rhizomes. Each stem can produceup to 400 seeds, although 20–40 is more common.Long-distance dispersal (0–3) 2Seed dispersal mechanisms are unknown, although seeds remainviable after passing through the digestive systems of manydomestic animals (Batcher 2002).Spread by humans (0–3) 3Quackgrass is planted for livestock. It has been used to revegetatemine tailings (Snyder 1992) and is often a contaminant in hay andstraw (Royer and Dickinson 1999).common names: quackgrassAllelopathic (0–2) 2This grass is allelopathic. It produces ethylacetate, cyclichydroxamic acids, and several other phytotoxins from itsshoots and roots. These compounds can suppress the growth orreproductive vigor of competing plants (Batcher 2002).Competitive Ability (0–3) 2Quackgrass competes strongly with cultivated crops. Itsproduction of allelopathic toxins contributes to its high level ofcompetitiveness (Batcher 2002). Without soil disturbance, thisplant does not appear to compete strongly with native grasses andforbs in Alaska (J. Conn pers. com.).Thicket-forming/Smothering growth form (0–2) 1Elymus repens can form dense stands (Batcher 2002), but isgenerally not significantly taller than other grasses and forbs.Germination requirements (0–3) 0The species requires open soil and disturbance to germinate(Densmore et al. 2001). Seeds germinate either in the fall orspring. Alternating temperatures are required for germination(15–25 °C diurnal fluctuations) (Batcher 2002).Other invasive species in the genus (0–3) 3Elymus sibiricus L.Aquatic, wetland or riparian species (0–3) 0This grass can invade gardens, yards, crop fields, roadsides,ditches, and other disturbed, moist areas. It can also colonizemixed-grass prairies and open woodlands (Batcher 2002). It isoften a serious pest in alkaline wetlands in arid regions of Oregonand California (M.L. Carlson pers. obs.)Total for Biological Characteristics and Dispersal 15/25Ecological Amplitude and Distribution ScoreHighly domesticated or a weed of agriculture (0–4) 4It is a serious threat in crops and gardens (Batcher 2002,Densmore et al. 2001). Many palatable hybrid crosses ofquackgrass and other species have been developed and planted forlivestock (Snyder 1992).Known level of impact in natural areas (0–6) 2Elymus repens is invading the land between riparian and uplandhabitats in Selver Creek Preserve, Idaho (Batcher 2002). Thisgrass has invaded natural areas in Oregon and Ohio (Batcher2002). It invades Wisconsin oak–hickory forest openings (Snyder1992).Role of anthropogenic and natural disturbance inestablishment (0–5)This plant in not observed in undisturbed plant communities inAlaska (Densmore et al. 2001). Once established on disturbedsites it can easily colonize adjacent undisturbed areas (Batcher2002, Snyder 1992).Current global distribution (0–5) 5It is native to Eurasia (temperate Europe and Central Asia:Afghanistan, India, Pakistan). It is now found in South America(Argentina and Chile), North Africa, Australia, New Zealand,Indonesia, and occurs even in Greenland (Batcher 2002, Hultén1968).3B-35