Jozani biodiversity inventory report 2002 - Coastal Forests of Kenya ...

herb species. The rest of the habitats showed a relatively high diversity with the highest number
(16 species) recorded in the evergreen scrub forest, Gmelina plantation and the Syzigium–Elaeis
dominant ground water forest. The low diversity in the herb layer of Callophylum plantation and
similar habitats can be explained by lack of enough light at the floor of such vegetation resulting
in dominance of shade loving species such as Stenochlaena and Phymatodes as was observed in
most habitats with closed canopy. The Albizia dominated forest showed the highest number of
species in the shrub layer followed by the scrub forest whereas the lowest number was recorded
in the salt marsh swamp grassland and wooded grassland. The habitats with high number of
shrubs may indicate a high regeneration process of the forest. The evergreen forest had highest
diversity (24 species) of three species (Appendix III) and only tree species in the Casuarina
plantation. This may imply that Casuarina equisetifolia has a suppressing effect on other species
and is probably affecting the indigenous species.
4.1.3 Indicator species and tools to diagnose ecological condition
A forest is sound when it is able to sustain its structure in the face of regular and incidental
natural disturbance. The main criterion for forest integrity is the occurrence of all species of
organisms and age classes of all organisms in a particular proportion of social organization
(Herlocker, 1999). The loss of a particular species is a symptom of poor forest condition.
Fluctuating climatic conditions also affect the ecological condition and inflict vegetation changes.
Results from this study shows that some species have declined or disappeared through harvesting
such as Croton sylvaticus and Burttdavya nyasica. Decline in these species is of great concern for
conservation especially of timber trees.
Indigenous timber tree species of Milicia excelsa and others have been reported from Jozani
Forest, but the majority were not encountered during this study. Callophylum inophyllum was
introduced to replenish timber production.
The species inventory and population composition are not adequate to evaluate ecological
integrity (condition) for planning and management. It is laborious to make exhaustive inventory
of species diversity and their relative population composition in order to evaluate ecological
integrity for planning and management. For convenience, it is preferable to adopt new
approaches, which rapidly assess forest integrity without detailed inventories of all major groups
of forest species. However, this is a hypothesized approach to use rapid simple measurement of
the appropriate set of indicators resulting in standardized approach techniques (Koop et al.,
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