Biology Reference
In-Depth Information
expert opinion, or both (Randall et al. 2001; Hiebert and Stubbendieck 1993; Timmins
and Owens 2001). Attributes are then scored on an ordinal scale.
2.4.2.2 Prioritization for Early-Detection of Nonnative Plants
Prioritization for early-detection monitoring has not resulted in the wide range of
approaches that have been developed for the task of prioritizing for control efforts.
However, the basic premise of both is the same, and there is no compelling reason
that systems developed to inform control efforts could not be used (with minor
modifications) to help inform early-detection monitoring efforts. They both rely on
information related to threat potential, spread potential, range of potential geo-
graphic/ecological sites, and feasibility of control. The one primary difference is
that species that have low feasibility of control should raise their priority level in
terms of early-detection monitoring, but may lower its priority level in terms of
control. Basically, species that are more difficult to control should have higher pri-
ority in situations where early-detection monitoring is used to identify new popula-
tions and keep them from establishing. In contrast, among species already
established within a region, those that are more difficult to control may be priori-
tized lower for control efforts than those which are easier to control.
2.4.3 Information Needed for Prioritization
Relatively few life history characteristics have been found to be consistently good
predictors of invasiveness (Kolar and Lodge 2001). Therefore, rather than spending
inordinate amounts of time trying to collect as much information as possible on a
very large number of species and site attributes (the “shotgun” approach), a more
logical and focused approach will produce better (and more timely) results. When
prioritizing species, careful attention needs to be given to what phase of the inva-
sion process the rankings are meant to address. Management objectives will differ
among the phases as will the relative importance of species attributes.
2.4.3.1 Information for Prioritizing Species
The management objective for species in the colonization phase of invasion is to
prevent their introduction and establishment. Developing a list of species with the
greatest potential for being introduced into the area of interest is a critical step in any
effort to prevent such introductions. In most cases, this phase will be the most diffi-
cult to develop a prioritized list for because the pool of potential species will likely
be quite large. Once a list of candidate species is developed, useful information for
prioritizing includes: (1) invasiveness potential, (2) biogeographic range, (3) land
cover types where typically invasive, and (4) potential impacts (Table 2.1).
