Invasiveness Ranking System for Non-Native Plants of Alaska

4.3. Level of effort required.This question asks if the management of invasive populations requires no investment in human and financial resources (i.e.,populations are ephemeral), moderate, or a major, long-term investment of human and financial resources.A. Management is not required (e.g., species does not persist without repeated anthropogenic disturbance). 0B. Management is relatively easy and inexpensive; requires a minor investment in human and financial2resources.C. Management requires a major short-term investment of human and financial resources, or a moderate3long-term investment.D. Management requires a major, long-term investment of human and financial resources. 4U. UnknownShowing the possible range of responses and values of impacts. Justifications of questions are presented below each subsection in italics.Alaska Invasiveness Ranking System ResultsThe invasiveness ranks of 113 species are summarized in Appendix A and completed ranking forms are presentedin Appendix B. A total of 18 of these species are not recorded from Alaska and two of these (Centaurea solstitialisand Crupina vulgaris) were rejected from consideration in the climate screening phase. We did not rank all knownnaturalized non-native plants. We choose a selection based on those species that land managers were mostconcerned about. Some were perceived to be a threat, some were frequent occurrences and others were recentarrivals. It should be noted that the closely related Centaurea melitensis recently was observed as a seedling in anAnchorage greenhouse, and it reached sexual maturity after being repotted and placed outside (Nielsen pers.Figure 5. Frequency distribution of invasiveness ranks for 113 species ranked in the Alaskasystem.Histogram1512Frequency9630Mean = 58.83Std. Dev. = 15.687N = 11130405060708090Invasiveness16