Invasiveness Ranking System for Non-Native Plants of Alaska

2.3. Potential to be spread by human activities (both directly and indirectly – possible mechanisms include: commercialsales, use as forage/revegetation, horticulture, spread along highways, transport on boats, contamination, etc.).Most non-natives rely on humans for transport and those that are regularly transported have a higher probability of escapingcultivation (Mack 2000, Kolar and Lodge 2001, Rejmanek 2001, Mack and Erneberg 2002).A. Does not occur. 0B. Low (human dispersal is infrequent or inefficient). 1C. Moderate (human dispersal occurs). 2D. High (there are numerous opportunities for dispersal to new areas). 3U. Unknown2.4. AllelopathicAllelopathic weeds often have a competitive advantage and are more likely to cause longer term ecosystem and communityalterations (see Pheloung et al. 1996).A. No 0B. Yes 2U. Unknown2.5. Competitive abilityThe presence of these traits obviously improves the probability of establishment (see Pheloung et al. 1996).A. Poor competitor for limiting factors. 0B. Moderately competitive for limiting factors. 1C. Highly competitive for limiting factors and/or nitrogen fixing ability. 3U. Unknown2.6. Forms dense thickets, climbing or smothering growth habit, or otherwise taller than the surrounding vegetation.The ability to form thickets or is taller than the surrounding vegetation is a trait shown to predict invasiveness elsewhere (Rejmanekand Richardson 1996, Goodwin, et al. 1999).A. No 0B. Forms dense thickets. 1C. Has climbing or smothering growth habit, or otherwise taller than the surrounding vegetation. 2U. Unknown2.7. Germination requirements.Species that are able to germinate in the absence of natural or anthropogenic have a greater risk of establishing in intactcommunities.A. Requires open soil and disturbance to germinate. 0B. Can germinate in vegetated areas but in a narrow range or in special conditions. 2C. Can germinate in existing vegetation in a wide range of conditions. 3U. Unknown2.8. Other species in the genus invasive in Alaska or elsewhere.Invasiveness is often associated with particular genera (e.g., Centauria and Bromus) and can be informative for a species in anotherregion (Darwin 1859, Rejmanek 1999).A. No 0B. Yes 3U. Unknown13