Biology Reference
In-Depth Information
After invading species have established localized populations, eradication becomes
a priority (Rejmanek and Pitcairn 2002). If eradication is not feasible then control of
populations (i.e., reducing abundance and/or dispersal pathways and vectors) within
the boundaries of local infestations may be an alternative. However, it is important to
recognize that even if eradication or control is successful, species could be reintro-
duced into an area. Clearly, high priority species in this stage would be those that tend
to fit the definition of a “transformer species,” which cause significant changes in
community and ecosystem characteristics (Richardson et al. 2000) and have ecologi-
cal and life-history characteristics associated with rapid spread potential. Therefore,
the primary focus of prioritization at the establishment phase includes: (1) actual and
potential impacts, (2) distribution and abundance, (3) life-history characteristics,|
(4) biogeographic range, and (5) management feasibility (Table 2.1).
Species in the more advanced invasion stages of spread and equilibrium are
widely distributed and are often relatively abundant. Eradication is unlikely
(Rejmanek and Pitcairn 2002), so containment of existing populations or prevent-
ing them from becoming established in high priority sites (see next section) are
Table 2.1
Information needed to develop prioritized lists of species in different phases of the
invasion process
A. Colonization phase
1) Invasiveness potential
Tendency to be invasive elsewhere
2) Biogeographic range
Natural (“native”) range
Nonnative (“invasive”) range
3) Land cover types where invasive
4) Potential Impacts
B. Establishment phase
1) Actual and potential impacts
Ecosystems
Structure
Species composition
2) Distribution and abundance
Distribution in target sites
Distribution in adjacent sites
Abundance in adjacent sites
3) Life history characteristics
Dispersal
Reproduction
4) Biogeographic range
Regional range
5) Management feasibility
Availability of control methods
C. Spread and equilibrium phases
1) Management feasibility Availability of control methods
Size of infestation
Accessibility to infestations
2) Distribution and abundance Trend in target sites
Distribution in target sites
Abundance in target sites
3) Life history characteristics Dispersal
4) Actual impacts Ecosystems
Structure
Species composition
The categories within each phase are ranked in general order of importance
