Environmental Engineering Reference
In-Depth Information
Table 2.1
Information needed for risk assessment for invasive species (adapted
from Stohlgren and Schnase 2006), and selected examples.
Information needed
Description or examples
1. Information on
species traits
Propagule size, number, and mode of dispersal (e.g.
wind, water current, animal-assisted); growth rate, age
to reproduction, competitive capabilities, predation
prowess, etc.
A
nity to disturbed areas and per cent disturbed areas
in a county, available phosphorus in lakes and aquatic
plant productivity, agricultural (corn) fi elds and
non-indigenous bird abundance.
2. Matching species
traits to suitable habitats
3. Estimating exposure
h e number, distribution, and virility of propagules,
or the frequency and intensity of their arrival by
various pathways.
4. Surveys of current
distribution and
abundance
Current presence and abundance, and 'absence' in
areas; museum records; known barriers and
corridors to invasion, pathways of invasion.
5. Understanding of
data completeness
h e geographical extent of the data; sampling
intensity; temporal extent of surveys and monitoring;
data on associated species and habitats; key gaps in
information.
6. Estimates of the
'potential' distribution
and abundance
Usually modelled from point or polygon data from a
few known locations extrapolated to larger, un-surveyed
(or poorly surveyed) areas. h ese models should be
presented with a quantifi ed level of uncertainty.
7. Estimates of the
potential rate of spread
Rates of spread may not be simple dispersion models
given complex pathways by wind, birds, human trade
and transportation. Spread may be multi-directional,
with areas of contraction and extirpation.
8. Probable risks,
impacts, and costs
Economic costs (containment costs and opportunity
costs), environmental costs (competition with or
predation of native species, altered ecosystem services,
or disturbance regimes), and costs to human health.
9. Containment
potential, costs, and
opportunity costs
Some species are more easily contained than others.
Long-term restoration costs must be considered.
Actual costs include the 'costs of doing nothing' and
opportunity costs associated with selecting some
species for control while others continue invading
and spreading.
10. Legal mandates and
social considerations
Legal directives may restrict choices for invasive species
management. Likewise, social considerations aff ect
management decisions.
