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Plant diversity in a Central African rain forest: Implications for biodiversity conservation in Cameroon
Table 3.5 Summary of the number of species of the various growth forms recorded in 136 vegetative
subplots of 5 m x 5 m each covering 0.34 ha.
Forest types
Floristic composition
50
Coastal
Forest
Swamps
Forest rich in
Caesalpinioideae
Forest rich in
Calpocalyx and
Sacoglottis
Mixed evergreen Submontane
and semi-deciduous
forest
forest
Trees
27 6 35 38
37 26
Shrubs/small trees 87 14 148 102 134 74
Herbs 88 14 142 98 105 77
Lianas 30 3 36 33 32 11
Total No of species 232 37 368 271 308 188
Total No of families 67 27 76 63 68 47
Table 3.6 Pearson correlation coefficients between the Shannon diversity (H’) of the various growth
forms recorded for all vascular plants with DBH ≥ 1 cm in 145 plots of 0.1 ha each.
Life forms Large trees Shrubs/small
trees
Herbs Lianas
Large trees 1
Shrubs/small trees 0.47** 1
Herbs 0.46** 0.29** 1
Lianas 0.003 0.20* 0.19* 1
Pearson correlation is significant for * P < 0.05 and ** P < 0.01
the number of herbaceous species (Table 3.5), moving from 25 species (in 145 plots
of 0.1 ha each) to 257 species (in 136 subplots of 25 m² each covering 0.34
ha).Trees and shrubs were the most diverse growth forms followed by lianas and
herbaceous species respectively (Table 3.4). The Shannon diversity (H’) of trees
varied from 3.96 (swamps) to 4.67 (submontane forest), for shrubs from 3.32
(coastal forests) to 4.66 (submontane forest) and for herbaceous species from 0.53
(coastal forests) to 1.03 (forest rich in Calpocalyx and Sacoglottis).
There was a significant positive correlation between the number of large and
medium sized tree species and that of shrubs/small trees (F1, 143 = 112.033, R² =
0.439, P < 0.001) and woody climbers (F1, 143 = 26. 986, R² = 0.159, P < 0.001).
There was also a significant positive correlation between the diversity of large and
medium sized trees and that of the shrubs/small trees and woody climbers (Figures
3.3 & 3.4). The correlations between the diversity/species richness of large and
medium sized trees and that of the herbaceous species were not significant (F1, 143 =
0.001, R² = 0.00002, P = 0.975 for Shannon diversity and F1, 143 = 0.0387, R² =
0.0003, P = 0.844 for species richness). The Shannon diversity (H’) was
significantly different among the various growth forms (F3, 34.6 = 151.290, P < 0.001)
when correcting for differences in vegetation types (GLM: F10, 30 = 2.727, P < 0.01
for vegetation type included as a random factor). A Tukey multiple comparison test
showed that all growth forms were significantly different from each other (P < 0.05)
with trees having the highest mean value (H’ = 3.37) and the lowest (H’ = 0.24) for
the herbaceous species.