Invasiveness Ranking System for Non-Native Plants of Alaska

Germination requirements (0–3) 2Generally, Kentucky and rough bluegrass requires light and opensoil for germination and establishment (Butterfield et al. 1996,Sather 1996). However, some rough bluegrass cultivars do notrequire open surface and are recommended for overseeding inestablished lawns (Liskey 1999).Other invasive species in the genus (0–3) 3Poa annua L. and P. compressa L. (Hultén 1968, Royer andDickinson 1999, Whitson et al. 2000).Aquatic, wetland or riparian species (0–3) 1These grasses often invade wetland and riparian habitatsin addition to gardens, pastures, roadways, meadows, openwoodlands, and prairies (Rutledge and McLendon 1996). In itsnative range Kentucky and rough bluegrass inhabits swamps andmarshes, wet meadows, and streambanks (Gubanov et al. 2003,Tolmachev et al. 1995, Malyschev and Peschkova 1990).Total for Biological Characteristics and Dispersal 14/25Ecological Amplitude and Distribution ScoreHighly domesticated or a weed of agriculture (0–4) 4Kentucky bluegrass and spreading bluegrass were introducedas cultivars and have since undergone selective breeding. Over100 cultivars of Kentucky bluegrass have been developed. It iscommonly planted as a lawn and pastures grass (Butterfield et. al.1996, Wisconsin DNR 2003).Known level of impact in natural areas (0–6) 3Bluegrass has successfully invaded prairies and savannas inWisconsin and Nebraska (Weaver and Darland 1948, WisconsinDNR 2003). It is naturalized in dry to moist meadows in Oregonand Washington, and it is a major problem species in aspencommunities in central Colorado and South Dakota (Uchytil1993).Role of anthropogenic and natural disturbance in2establishment (0–5)Bluegrasses readily establish by seeds on disturbed sites.Kentucky bluegrass increases with grazing and burning (Sather1996, Weaver and Darland 1948).Current global distribution (0–5) 5These taxa are native to Europe. They have been introduced intoNorth and South America, New Zealand, and Australia (Gubanovet al. 2003, Hultén 1968).Extent of the species U.S. range and/or occurrence of5formal state or provincial listing (0–5)Kentucky, spreading, and rough bluegrasses are found naturalizedin nearly all American states and in Canada from Labrador to thewest coast. Poa pratensis is listed as an invasive weed in Nebraskaand Wisconsin. Poa trivialis is a restricted weed seed in NewJersey and Virginia (Invaders Database System 2003, USDA2002).Total for Ecological Amplitude and Distribution 19/25Feasibility of ControlScoreSeed banks (0–3) 3A maximum of 560 Poa pratensis seed/m2 in soil samples from aNetherlands pastures was reported. Seeds germinate within thefirst 4-years after burial (Sather 1996); however, other studiesindicate that the seed is no longer dormant 6 months after harvest(Butterfield et al. 1996). Chippindale and Milton (1934) stated intheir study that seeds of Poa trivialis may remain dormant in thesoil for 24, 40 and even 68 years.Vegetative regeneration (0–3) 1These grasses can resprout rapidly (Rutledge and McLendon1996).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 7/10Total score for 4 sections 52/100§B-99