Environmental Assessment
Volume B-4.1
Mine
Flora
Ambatovy Project
192
January 2006
Table 4.1-11 Impact Description Criteria for Exotic and Unwanted Plant Species
Direction
Magnitude
Geographic
Extent
Duration
Reversibility
Frequency
neutral:
no change
in exotic and
unwanted species
negative:
a change
in exotic and
unwanted species
negligible:
no
measurable effect on
exotic and unwanted
species
low:
low amounts of
exotic and unwanted
species
moderate:
moderate
amounts of exotic and
unwanted species
high:
high amounts of
exotic and unwanted
species
local:
effect
restricted to the
LSA
regional:
effect
extends beyond
the LSA
short term:
<3 years
medium
term:
3 to
30 years
long term:
>30 years
reversible or
irreversible
low:
occurs
once
medium:
occurs
intermittently
high:
occurs
continuously
4.1.7.3 Mitigation
The main areas of mitigation include:
•
Implementation of an invasive species control program.
•
Reclamation.
•
Environmental education.
4.1.7.4 Results
There is a high potential for the spread of weeds or unwanted species within the
mine site, reclamation areas and azonal conservation areas. Currently,
heliophytic (sun-adapted) vines exist within the mine site that may permanently
alter species succession by spreading into the adjacent azonal and zonal forests.
As vegetation is cleared during the construction phase, areas become susceptible
to invasion by unwanted species due to full sun conditions and the lack of
competitors. Vehicle traffic will increase sharply within the mine area as
construction begins and will continue at high levels during operations. Vehicles
provide a vector to transport weeds from areas on and off-site into new areas as
they are become cleared.
4.1.7.5 Impact Analysis
Residual Impacts to Exotic and Unwanted Species
Over the life of the mine, it is expected that exotics and unwanted plant species
will invade reclaimed areas and forest edges. The degree to which these species
