Environmental Engineering Reference
In-Depth Information
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Time
Fig. 5.1
Five phases of invasion: 1. Pre-introduction; 2. Introduction; 3.
Naturalization; 4. Expansion; 5. Saturation (Cousens and Mortimer 1995;
Groves 1999, 2006; Colautti and MacIsaac 2004).
inter-specifi c competition, predation, parasitism, and the availability of pollinators
and dispersal vectors. Abiotic factors may be climatic or edaphic, or topographic
barriers to dispersal. Containment can be defi ned as a management strategy that
seeks to impose additional anthropogenic limits to the distribution of an invasive
species so that the realized range is kept to a fraction of the potential range (Kriticos
et al
.
2006). 'Partial containment', refers to a strategy that involves attempting to
slow the rate of spread of an invasive species (Cacho 2004).
I have described containment in terms of restrictions to an invasive species'
distribution. A containment strategy can be applied at any management scale, for
example, from a whole country down to the level of a single paddock. Whatever
the scale, a containment strategy focuses on restricting the species range. Generally,
containment strategies applied at the fi nest scales are more likely to be applicable
to sessile organisms such as plants. In practice, the spatial distribution of eff ort—a
key aspect of any strategic approach to the management of an invasive species—
may be similar, regardless of whether the objective is containment or control.
Control is defi ned here as management that attempts to reduce the impact of
an invasive species without necessarily restricting its range. Under a control strat-
egy, an invasive species' realized range may approximate its potential range but the
goal is to reduce its abundance, and so the impact, to levels below those it would
otherwise attain.
an end-point
Containment and control strategies, including biological control (see Chapter 6),
seldom have an end-point and require activity indefi nitely. Containment is a valid
