Biology Reference
In-Depth Information
An initial step in any early detection program involves compiling existing infor-
mation on species and site characteristics to develop an efficient monitoring
approach. This information is used to prioritize among species and sites that are
most important to monitor, and develop predictive models to optimize monitoring
efforts by narrowing their spatial and temporal scope. In this chapter, we discuss
the issues associated with compiling and using information to develop and improve
the efficiency of early detection monitoring plans. This chapter does not address
monitoring tools (e.g., remote sensing) or specific monitoring methodologies (e.g.,
plot-based sampling), but rather describes a framework for narrowing the search
area within which those other tools and methodologies can be applied. The frame-
work we present is structured around three types of monitoring plans that succes-
sively reduce the size of the area within which early detection monitoring is
conducted: the (1) generalized, (2) prioritized, and (3) optimized monitoring plans
(Fig. 2.1) .
2.2
Evaluating Available Data
The information collection stage is perhaps more important than any other step in
developing monitoring programs, because all future actions are based on analyses
stemming from the information collected. Consequently, we feel it is important not
to just supply a “cookbook” of what information to collect and what to do with it,
but also to emphasize the importance on thinking about what types of information
are most useful for different phases of the invasion process, including colonization,
population establishment, and subsequent spread (Groves 1986; Cousins and
Mortimer 1995; Rejmanek 2000; Richardson et al. 2000).
Before any information is compiled, the resources available for conducting an
early detection program should be realistically evaluated. Time spent compiling
vast amounts of information to develop an early detection plan is wasted if there is
little hope of supporting the efforts needed to synthesize the information into an
implementation plan or to implement the plan itself. Time and money are obvious
limitations, but so too are institutional support and the personal commitment of
staff. Turn-over rates of personnel can also be a hindrance, since extensive training
is often required to develop effective early detection teams (M. Brooks pers. obs.).
Spatial and temporal scales are also very important to consider prior to com-
piling data. As mentioned above, early detection programs can be developed for
areas as small as local projects to as large as continents. Clearly, the amounts and
types of information needed vary among these spatial scales. For example, as
geographic scale increases, so too do landscape variability, land-use variability,
the range of potential sources of nonnative propagules, and many other factors
influencing plant invasions, which should be considered when developing early
detection programs.
In most cases there is information available on the site characteristics within a
management unit. This includes vegetation maps and assessments that can be used
