The Offset Design Process
45
BBOP Pilot Project Case Study – Ambatovy Project
0
200
400
600
800
1000
1200
1400
1600
1800
0
5
20
40
75
90
Post-project mitigation level (%)
Habitat hectares loss
Table 8: Biodiversity loss calculations scenarios at impact site and effect of post-impact remediation
Habitat type – forest
Percentage of attributes
rehabilitated
Year
HABITAT HECTARES loss
0%
0 (without mitigation)
1,168
5%
0 – 7
1,110
20%
7 – 15
934
40%
15 – 30
701
75%
30 – 60
292
90%
60 – 120
117
For the forest habitat, the results show a significant difference for the varying levels of post-impact mitigation.
However, in order to obtain a more realistic assessment of the post-impact condition, the Project considered
the influence of forest rehabilitation on the habitat hectares loss numbers over time. Although the temporal
factor is not considered in the habitat hectares loss calculations, a basic simulation was designed that
integrated basic forest regeneration activities and specific ecosystem dynamics in the context of the Ambatovy
forests. There are four essential steps in forest regeneration:
1. Erosion control (involves engineering, addition of organic matter and water control).
2. Planting of heliophytes species (including native and potentially some non-natives).
3. Planting of native tolerant species to increase ground cover.
4. Assisted natural succession of native species.
The inclusion of post-impact rehabilitation based on these activities shows a distinct decrease in the habitat
hectares loss score over time, due to forest regrowth patterns and increases in the values of attributes
(Pearson correlation R2 = -0.98
p
< 0.001, n = 6; see Graph 1).
Graph 1: Post-impact mitigation influence on biodiversity loss for forest habitats at
IMPACT SITE
