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

VEGETATION CATEGORIES AND
MAIN EDAPHIC FEATURES
2. Albizia dominated forest, greater
part covered by coral rock (Legume
dominated forest of Burgess and
Clarke 2000)
3. Evergreen mixed dry forest or
Mixed evergreen scrub forest of
Burgess and Clarke, 2000 (Plates
23, 24).
4. Dry bushland and thicket (Gillmann
1949, White, 1983)(Plates 4, 5).
SPECIFICATIONS AND DEFINITIONS
Closed canopy formation dominated by Albizia adhianthifolia with
trees 30 - 35m high. Intermediate species include Blighia unijugata,and
Senna species. The Caesalpinioideae dominated dry forest suggests
relicts of the former Pan-african lowland forest shown to be stable with
healthy understorey regeneration (Burgess and Clarke, 2000). Mallotus
opposifolia is the most dominant middle canopy tree with density of
about 47.5 stems.ha -1 . The habitat is the most vulnerable to fires,
farming, hunting and grazing. The surface is moist, but leaf litter is
thin. There are indications of former plot farms within the forest
marked by ruins of long walls made of coral rocks. These were meant
to prevent vermin (wild pigs) from entering the farms. It is considered a
separate vegetation unit because the stands completely exclude other
canopy dominant species in the next category. Many members of
Caesalpinioideae produce seeds of short viability which do not tolerate
dessication and are not dispersed by wind or birds (Burgess and Clarke,
2000). Clearance of such a forest affects regeneration potential.
Relatively moist surface (surface limestone developed on coral rock),
represented by a mixed dominance of a few species which include
Diospyros consolatae (most dominant), Terminalia boivinii, Rapanea
melanophloeus, Olea woodiana, Apodytes dimidiata, Mystroxylon
aethiopicum, Maytenus mossambicensis, Ozoroa obovata and
Sideroxylon inerme. In shallow valley bottoms Ficus sur is common.
Canopy height is 10-25m with few emergent trees. The structure is
intermediate between the bushland and thicket category (below) with
trees below 10m tall and forest canopy over 25m. White (1983)
recognizes that scrub forest occurs as a narrow band separating
Zanzibar-Inhambane forest from the Somali-Masai regional centre of
endemism. Lianas are scarce or rare.
This category is transitional to scrub forest and represents a dwarf
bushland with clustered bushes on more xeric coral rock basement. The
dominant species are the same as above, but the structure is different. It
is dominated by shrubs with emergent trees to 10m. Thickets are well
developed in shallow valley depressions with a thin layer of litter.
Afzelia quanzensis occurs in this type of thickets. There are some
indications of previous farming, thus representing secondary
vegetation. Common emergent trees include Maytenus mossambicensis,
Mystroxylon aethiopicum, Apodytes dimidiata, and Diospyros
consolatae. All of these species occur in the previous category except
that the trees are of smaller sizes (