Mgambo Forest Reserve: A biodiversity survey. - Eastern Arc ...

Mgambo Forest Reserve
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6.0 CONCLUSIONS
Authors: Bracebridge, C.E. and Oliver, S.A. pp. 73-74
This report presents the data collected during the baseline biodiversity survey of Mgambo Forest
Reserve. The report presents preliminary checklists of flora and fauna groups and categorises the
ecological type and endemic status of species. These two factors provide an indication of three
aspects of biodiversity and conservation:
1. the relationship between forest dependency and endemism;
2. the extent to which non-forest species are established in the reserve; and
3. the relationship between disturbance and areas of biological value.
Mgambo Forest Reserve was gazetted in July 1998. The gazetted reserve covers an area of
1,346ha, with an altitudinal range of 320m - 820m. The forest reserve has altered significantly in
recent years as a consequence of intensive overgrazing and fire damage. It is presently made up of
a mixture of riverine forest, lowland forest, scrub forest, Miombo woodland and open woodland,
all subject to a variety of different levels of disturbance.
6.1 Disturbance
Fire was the most significant threat to both flora and fauna in Mgambo FR, and was recorded in
just over two thirds of all vegetation plots sampled. There were no vegetation plots surveyed with
canopy heights greater than 20m. Open grass/bushland and woodland habitats were dominant in
burnt areas, increasing the susceptibility of the reserve to future fire disturbance.
One of the causes of deliberate fire was to provide fresh grazing for livestock, and, indeed,
another major disturbance category for Mgambo was grazing. This was also predominantly found
on the eastern side of the reserve. Other forms of disturbance, such as pole and timber extraction,
trapping, cultivation and pitsawing, were relatively low in Mgambo FR.
6.2 Species Richness
Mgambo FR was found to contain a minimum of 101 species of plant, 34 mammal, 10 bat, 52
bird, 25 reptile, 14 amphibian and 138 butterfly species (figures for molluscs and millipedes have
yet to be determined). The number of faunal species found in Mgambo FR was fewer than the
number found within nearby forest reserves, (refer to Frontier Tanzania, 2002c and 2002d, and
Frontier Tanzania, 1999). Relative to the other thirteen forest reserves surveyed by Frontier-
Tanzania Mgambo FR had a below average species richness for plants, and a below average
species richness of mammals, an average species richness for reptiles and amphibians and a high
species richness for butterflies. Species richness was likely to be associated with forest reserve
size and the degree of patchiness and/or isolation of forested areas. Mgambo FR is relavtively
small in size with patchy distribution of forest habitats that are isolated as a consequence of
grazing and fire disturbance.
6.3 Flora
Only one tree species recorded in the vegetation plots was endemic to the Usambara Mountains.
Twelve species were found to have ranges restricted to the Eastern Arc and/or East African
lowland forests. Five species were dependent on primary forest and 62 were forest dwelling.
Twenty-seven non-forest tree and shrub species were established within the reserve boundaries.
East Usambara Conservation Area Management Programme Technical Paper 59