Environmental Assessment
Volume B-4.1
Mine
Flora
Ambatovy Project
155
January 2006
Table 4.1-2 Total Tree Species Richness by Vegetation Type Within Forest Plots
and Subplots
Cumulative Number of
Tree Species by
Diameter Class
(a)
Vegetation Type
Survey
Area (ha)
≥
10 cm
5–9.9 cm
Total
Number of
Tree
Species
azonal thicket
1.16
104
61
165
azonal forest
3.93
252
46
298
azonal type transitional forest
1.12
131
83
214
transitional forest
2.92
267
152
419
zonal forest
1.57
255
114
369
marsh edge forest
0.12
37
nd
37
(a)
Number of species listed is cumulative. All species within the
≥
10 cm diameter class were counted
first, followed by all species in the 5 to 9.9 cm class, but not in the
≥
10 cm class.
nd = No data.
Previous estimates made in the late 1990s by Phelps Dodge, which included
herbaceous and other plant groups, indicated that as many as 105 families and
1,378 species occur in the mine LSA, which is more than 10 percent of the
12,000 total species estimated to be present in Madagascar, indicating the
diversity of the project area.
At a global scale, plant species richness for Madagascar is estimated at 12,000
species, 1,600 genera, and 180 families, which places the island among the most
biologically diverse regions in the world, along with portions of Brazil, Zaire,
Cameroon and Mexico (Guillaumet 1984; Mittermeier et al. 1997).
4.1.3.7 Sampling Adequacy
Forest Structure Data Set
Species-area curves based on trees ≥10 cm DBH were developed for the zonal
forest, transitional forest, azonal forest, azonal thicket, and all forest types
combined. None of the species area curves were found to flatten out completely
to an asymptotic level (i.e., at the peak of species richness), but some were
approaching that state. The number of new species predicted to be added with
each additional plot ranged between less than one and three species among
vegetation types.
The biological data set of tree species presented in this EA allowed for a
quantitative assessment of habitats within the mine LSA, and is, therefore,
considered adequate for EA purposes.
