Plant species composition and restoration potential through soil seed bank in Zaraninge and Mbwebwe coastal forests, Bagamoyo District, Tanzania
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Date
2009
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Publisher
Sokoine University of Agriculture
Abstract
The aim of the study was to assess plant species composition and its relation with
soil seed bank as a basis for forest restoration through natural regeneration in
Zaraninge and Mbwebwe coastal forests, Bagamoyo District Tanzania. Eighteen
sample plots of size 0.07 ha were established systematically along transect in each of
the two forests. Soil samples were collected within each plot at 0-10cm, 10-20cm and
20-30cm depths. The analysis was based on Importance Value Index computed from
the average of relative basal area, density and frequency. Soil samples were analyzed
for seed density of different plant species at the different depths. 62 and 50 plant
species were identified in Zaraninge and Mbwebwe forests respectively. Out of 62
vascular plants identified in Zaraninge three species were rare plants, 35 common
species and seven endemic to coastal forests. Mbwebwe forest had three rare plants,
26 common species and five endemic to coastal forests. The Shannon-Winner and
Simpson Diversity Indices were 2.843, 0.093 and 2.5, 0.12 for Zaraninge and
Mbwebwe forests respectively showing that the forests have high species diversity.
The seed bank density for vascular plants was 2,782seeds m-2 and l,170seeds
and for rare plants was 103 and 68seeds m-2 for Zaraninge and Mbwebwe forests
respectively. 71 seedlings emerged from all samples of the two forests, most of them
being herbs and grasses. One rare plant species germinated from both forests.
Majority (55%) of the seedlings emerged from 0-10cm soil layer. Based on the
number of germinated seeds there was no close relationship between species
composition of standing vegetation and composition of the seed bank. It is concluded
that forest restoration through soil seed bank may greatly depend on seed bank at the
m-2
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surface soil horizons. The study suggests longer germination trial in order to capture
full soil seed bank potentials.
Description
Dissertation
Keywords
Plant species, Soil seed, Coastal forests, Species composition