Environmental Assessment
Volume B-4.4
Mine
Natural Habitats and Biodiversity
Ambatovy Project
293
January 2006
Table 4.4-6 Change (%) in Landscape Metrics for Full Development of the Mine
Relative to Baseline Conditions for Natural Habitats and Land Use
Areas in the Local Study Area
Landscape Metric
Azonal
Habitat
Transitional
Forest
Zonal
Forest
Ephemeral
Pools
Marsh Edge
Forest
Marsh Other
(a)
total area
-71.4
-23.1
-3.1
-87.2
0.0
0.0
27.2
mean area of patch
-96.7
-86.6
-34.0
-56.3
0.0
0.0
35.1
number of patches
767
475
47.2
-73.3
0.0
0.0
-6.4
mean distance to nearest
neighbour (MDNN)
-80.6
-70.3
-13.5
17.0
0.0
0.0
-1.7
coefficient of variation in
distance to nearest
neighbour (CVDNN)
-23.8
-14.1
-1.9
-10.5
0.0
0.0
-3.2
total edge
-20.0
-15.7
2.6
-83.3
0.0
0.0
13.3
Note: Values calculated as (application case – baseline) / baseline.
(a)
Includes mine infrastructure, pasture, rice paddies, eucalyptus woodlots, slash and burn areas, and villages.
Application of the project infrastructure also resulted in fragmenting the existing
habitats within the LSA. Average size of azonal patches decreased by 97%
(from 460 to 15 ha) with a correspondent increase in the number of patches
(from 3 to 26). Similarly, mean patch size of transitional habitat decreased 87%
(from 372 to 50 ha) and the number of patches increased from four to 23 due to
project development (Table 4.4-6). In contrast, the 56% decrease in average
patch size (from 0.2 to 0.07 ha) of ephemeral pools was associated with a 73%
decrease (from 30 to 8) in the number of pools, which was coupled with the small
area of individual patches. Six of these remaining pools are located in the
proposed Ambatovy and Analamay conservation areas.
Smaller patches can result in negative effects similar to those linked to habitat
loss. At some point the area of patches may be too small to support a viable local
population, or the distance between local populations too great for effective
emigration which reduces re-colonization success and metapopulation
persistence (Hanski 1996; Pulliam 1996; Turner 1996; Fahrig 2003).
Changes in population and community interactions (e.g., competition, mutualism,
commensalism, parasitism and predation) may result in a loss of plant and animal
species. Conversely, the loss of species can negatively alter or impair ecosystem
function, stability and resilience (Lawton 1994). For example, studies near
Manaus in Amazonian Brazil have demonstrated that small fragments contain
fewer species of termites, beetles, frogs, understorey birds, small mammals, and
primates than larger or more continuous forest patches (see Turner 1996). Other
studies have shown that there was a recognizable difference in the composition
and species richness of a beetle community in a 100 ha patch relative to
continuous forest (Laurance and Bierregaard 1996). Some amphibian species of
