A Synthesis and Vulnerability Assessment of Terrestrial Invasive Species in the Aleutian and Bering Sea Islands
Major funding from the Aleutian and Bering Sea Island Land Conservation Cooperative
Assigning a numerical rank to an introduced species is an objective, quantifiable way to describe their relative impacts, and ranks are a valuable prioritization tool for land managers. We applied the Invasiveness Ranking System previously developed by the Alaska Natural Heritage Program to evaluate introduced species known to occur on Aleutian and Bering Sea Islands. This system uses sixteen criteria grouped into four categories to assess invasiveness: distribution, biological characteristics and dispersal ability, ecological impacts, and feasibility of control. Answers to individual questions are assigned a point value and the points are used to calculate subranks for each of the four sections. Each section is weighted to reflect its overall contribution to a species’ invasiveness. Distribution, biological, and ecological sections are each worth 30 points, and feasibility of control is worth 10. Where questions cannot be answered with available literature and expert review, weights are adjusted to compensate for unknowns.
The Alaska Natural Heritage Program conducted a review of published and grey literature, and solicited contributions from experts, to address criteria outlined in the Invasiveness Ranking System. Our review summarized 17 species historically or presently known to occur on Aleutian and Bering Sea Islands. Our findings can help land managers prioritize species and islands for management, to increase the efficacy of resources and control efforts. The species’ biological information provided can help inform control strategies, and the ecological impacts detailed herein can provide guidance for monitoring programs. This project can assist not only land managers, but also the general public, in better understanding the impacts of introduced species, so that proactive steps can be taken to manage and prevent future introductions.