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Average PI
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Biodiversity hotspots and conservation priorities in Central African rain forests
y = -0.4979x + 120.19
F1,10 = 111.71, R 2 = 0.918, P < 0.0001
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Average GHI
Figure 5.4 Correlation between the average GHI scores and the average PI scores for the
various vegetation types.
Geostatistical results
The analysis of the spatial structure of the dataset did not show any preferential spatial
trend. Therefore, an omni-directional analysis of the semivariance (best described by a
spherical model) was applied. Figure 5.6 shows the semivariogram and its
characteristics. The GHI variable showed a strong spatial dependence within a range
of 10500 m. The nugget (645) was low compared to the total variance or sill (3700).
This suggests that more than 82% (100*(Sill-Nugget)/Sill) of the semivariance of GHI
could be modelled by the variogram over a range of 10 km. The output map of the
ordinary kriging (Figure 5.7) was reclassified into five GHI classes, partitioning the
conservation value of the Campo-Ma’an forest. This partition showed that 1% of the
area was characterised by a very high conservation value, 45% by a high conservation
value, 30% by an average conservation value, 15 % by a low conservation value and
9% by a very low conservation value. A considerable portion of the National Park and
the forests around Massif des Mamelles and Mont d’Eléphant was characterised by a
high conservation value, with highest values found in Dipikar Island, Massif des
Mamelles, Mont d’Elephant and in the submontane forest on hilltops. The forests in
the Ma’an area, around Campo and agro-industrial plantations, near villages and along
the roads had a low conservation value. Similar patterns were observed for the
distribution of strict and narrow endemic species (Figure 5.1).
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