Geology Reference
In-Depth Information
2.
Southen Malawi Group. This Group is
clearly a disincive derivaive from the
East Coast Escarpment Group,
91 %
of its
species occurring there.
3.
South of the Zambezi Group. This is
another disincive derivaive rom the East
Coast Escarpment Group,
78%
of its
species occurring there.
cal posiions, they have probably been less
important as sources from which colonising spe-
cies have spread. It could be argued that one
reason for the high species richness in the
Alberine Rift forests is that they have 'received'
colonising species from boh the East Coast
Escarpment and Cameroun, in addiion to their
being an important centre of evoluion. Also, both
the southen Malawi and South of the Zambezi
Group are derived to a considerable extent from
the East Coast Escarpment Group. The Cenral
East Africa Group is clearly derived from both the
Alberine Rift and East Coast Escarpment
Groups (see above).
The other Groups are all more disinct,
alhough a comparison of Tables
10.2
and 10.3
shows that all but two of the Cameroun Group's
non-endemic species occur in the Alberine Rift
Group. In terms of the disinciveness of the spe-
cies composiion of individual orests, seven
Montane Forest Groups c.an be recognised.
However, in terms ofbiogeographic origins, there
are only four significant Groups: Cameroun,
Ethiopia, Alberine Rift and the East Coast
Escarpment.
Consevation
It is important that adequate conservaion
measures be taken in each of the Montane Forest
Groups in order to ensure the preservaion of the
maimum possible biological diversity. At present,
forest conservation is reasonably effecive for the
South of the Zambezi Group, but elsewhere, the
situaion is ar from saisfactory (see Mackinnon
&
MacKinnon,
1986).
Several of the Central East
African orests are included in Naional Parks,
though, from a species conservaion point ofview,
these forests are not the highest prioriies.
However, the Intenaional Union for the Con-
servaion of Nature (IUCN) is now making prog-
ress in orest conservaion in the Usambara
Mountains, and other consevaion projects are
being carried out in the Uzungwa Mountains,
Mount Rwenzori, the Impenerable Forest and
the Virunga Volcanoes. Much more work is
needed on the montane forests of easten Zare,
most notably the Itombwe Mountains. In Ethiopia
the government has made impressive progress in
its efforts to conserve forest on the Bale Moun-
tains, and in Cameroun the Intenaional Council
for Bird Preservaion (ICBP) is involved in con-
servaion work, especially on Mount Oku. Two
areas where more effective conservaion is very
urgently needed are the mountains of southen
Malawi, where the area of forest remaining is iny,
and the Escarpment of Angola. More details on
the prioriies for forest bird conservaion in Africa
are given by Collar
&
Stuart
(1985, 1988).
Rfuia
The results of this analysis concur with those of
Hamilton
(1976)
and Diamond
&
Hamilton
(1980).
Three major cenres of endemism for
montane orest birds, these corresponding to he
Cameroun, Alberine Rift and East Coast Escarp-
ment Montane Forest Groups, can be idenified.
Hamilton
(1976)
points out that these cenres of
endemism are situated very close to similar con-
cenraions of lowland forest birds, and suggests
that they represent refugia where forest survived
during the driest periods of the Pleistocene.
Smaller reugia may have eisted in areas where
other endemics occur, notably Ethiopia and the
Angolan Escapment.
Table
10.2
emphasises the paricularly high
number of species and endemics around the
Alberine Rift, and this area may be the main
cenre of evoluion of the African montane orest
avifauna. Many of the more widespread montane
species, occurring in Cameroun and also in East
Africa, could well have originated from the
Alberine Rift area. The Cameroun and East
Coast Escarpment forests have also been import-
ant sites or the evoluion of montane species.
However, because of their less cenral geographi-
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