The Offset Design Process
36
BBOP Pilot Project Case Study – Ambatovy Project
7.3.5.1 The habitat hectares approach
This section:
Introduces the ‘
HABITAT HECTARES
’ approach;
Describes how the ‘benchmark’ was defined for forest habitats; and
Explains how the Project’s residual impacts on biodiversity have been calculated using the benchmark.
The habitat hectares approach
Biodiversity loss was calculated using the habitat hectares approach, summarised as:
1. Completion of the Key Biodiversity Component Matrix (KBCM), which corresponds to conducting a
biodiversity assessment of species, habitats and ecosystems components and determining intrinsic
(significance and irreplaceability) and use (socioeconomic and cultural) values;
2. Completion of a table to review the application of the
MITIGATION HIERARCHY
to the key biodiversity
components;
3. Selecting attributes for the key biodiversity components using available or complementary data and
assigning ‘weights’ to each. For example:
Forest structural attributes can be selected and compared (weighed) against each other, e.g. tree
species richness is considered to be the most important attribute at Ambatovy and therefore has a
higher
WEIGHTING
than attributes related to forest physical structure.
Taxa attributes such as quantitative fauna data (e.g. density) from priority species can also be
integrated and therefore allow key fauna data into the weighing of attributes; this reflects more
accurately the importance of species biodiversity in the habitat hectares scores.
4. Defining and selecting a
BENCHMARK
for selected habitats;
5. Calculating biodiversity loss at the
IMPACT SITES
by comparison to the benchmark, for each habitat
CONDITION
classes in light of impact levels;
6. Completion of a table to record and compare whether
POTENTIAL OFFSET SITES
could deliver conservation
gains for key biodiversity components; and
7. Calculating the habitat hectares gained at the offset site.
Using the previously cited information, habitat hectare scores were determined for all habitats (e.g., forests,
streams and ephemeral ponds). Calculation of the forest habitat hectare loss at Ambatovy requires the
following condition information:
Habitat types, namely azonal, transitional and zonal forests and respective surface areas (see Figure 4
showing the mine area habitat map);
Habitat condition class and respective surface areas (see Figure 4), namely:
– Quasi pristine primary forest (see definition in benchmark section hereafter,
Forest habitats
, 3rd and 4th
bullets);
– Disturbed / degraded primary forest; and
– Heavily fragmented and degraded primary forest.
Impact types, namely high (cleared footprint) and medium (environmental buffer) and respective surface
areas (see Figure 5).
