Environmental Assessment
Volume C-4.4
Slurry Pipeline
Natural Habitats and Biodiversity
Ambatovy Project
153
January 2006
Direct impacts from the pipeline on habitat and biodiversity indicators were
assessed through changes in the area and composition of habitats on the
landscape. Changes in habitat area and composition were determined by
applying the slurry pipeline footprint to the landscape (application case) within
the LSA. The footprint included a 25 m buffer on each side of the pipeline to
produce an average 50 m wide impact zone.
The potential impact of the project on biodiversity indicators was estimated by
calculating the relative difference between application case and baseline habitat
areas using the following equation:
(application case value – baseline value) / baseline value
The resulting value was then multiplied by 100 to give the percent change in
habitat area associated with the project relative to baseline conditions, and to
provide both direction and magnitude of the impact. Changes in habitat area
were then used with assessment criteria (see below) to predict impacts from the
project on biodiversity potential among habitats and within the LSA. A
qualitative assessment of fragmentation effects on biodiversity potential is also
provided. Impacts to habitats associated with human land use activities
(negligible biodiversity potential) were not assessed here (see Volume C,
Section 5.3 [Land Use]).
Impacts were assessed for the period of construction through operation, and the
closure phase. It is assumed that maximum impacts will occur during the period
of construction through operation, particularly during construction when the
direct loss and alteration of habitats will be greatest. The intent of further
decision-making is to further mitigate impacts to natural habitats and biodiversity
as much as possible, and fine-tuning of the pipeline route will be conducted in
collaboration with engineering and environmental inputs. Thus, the assessment
provided here is conservative (i.e., impacts are likely overestimated).
Assessment Criteria
Residual impacts were determined based on a classification system that
incorporates direction, magnitude, geographic extent, duration, reversibility and
frequency of the impact as described in Volume A (Section 7.4). Definitions of
the residual effect classification terms that are specific to habitats and
biodiversity are provided in Table 4.4-5. An explanation for the classification of
magnitude is provided in Volume B (Section 4.4.4.2). Determination of the
overall environmental consequence uses magnitude, geographic extent and
duration, and is described in Volume A (Section 7).
